A Corvair Engine for the Bearhawk LSA
Source: 2024 Q1 Beartracks, David Swartzendruber
I am building a Bearhawk LSA and one of the engine options for the LSA is a Corvair auto engine conversion. This is what I have chosen for my LSA and I completed my engine build at the end of 2023 during a 3-day supervised build in William Wynne’s shop in Florida. Bob Barrows and William Wynne worked together to design a motor mount for the Corvair engine in the Bearhawk LSA and this mount is available from William. But I’ll back up and start at the beginning of my story.
Like many of you, I decided I wanted to build an airplane many years ago, about 33 years ago for me. However, along the way I lost that dream when it didn’t seem like time or money would allow that to happen. About five years ago, that dream was rekindled when I picked up an unfinished non-Bearhawk project for a very affordable price that was designed to use a VW engine conversion. As I thought about what to do for an engine, I came across the Corvair and William Wynne’s website, Flycorvair.net, and began to consider using a Corvair engine in that project. Through the information on Flycorvair.net, I also discovered the Bearhawk LSA was a good candidate for the Corvair engine and I became less enthusiastic about the project I had acquired. I eventually decided to order a Bearhawk LSA kit and sell the other project.
Having already started down the path of building a Corvair flight engine, I thought I would go ahead and complete that while I waited for my LSA kit to arrive. The first step is to get a conversion manual from William Wynne. This manual includes information about which core engines can be used to build a flight engine. I picked up a 1965 Corvair parts car for $250 and the engine from that car became my core. Corvair flight engines always start with a 1964-1969 engine because engines earlier than that had a smaller stroke, lower displacement and lower strength crank and rods. My core engine was locked up, but I was still able to disassemble it and discovered that the piston rings on one piston had rusted to the cylinder wall. To my surprise, I found that my 1965 engine had a crankshaft and rods from a 1963 or earlier engine. This ended up not making any difference because I decided to go all out and build the bored and stroked version that bumps the displacement up from 164ci to 200ci, also referred to as the 3.3L. The 3.3L engine requires a new billet crank, billet rods, forged pistons and special cylinders so my old crank and rods weren’t needed anyway.
I shipped my engine case and heads off to Sport Performance Aviation (SPA) in Florida for machine work on the case and heads and complete rebuild of the heads. Larger holes are bored into the case to accommodate larger cylinders and some clearance machining is done inside to allow the rods on the stroked crank to clear the case. SPA developed the 3.3L stroker parts, so I bought the new crank, rods, pistons, rings and cylinders from SPA. In addition, SPA has developed a 5th bearing system for the front of the crankshaft to react the propellor loads not normal to an automotive application. All the other standard conversion parts from William Wynne are also used in the 3.3L stroker, so I ordered those from William, including:
-Prop hub, safety shaft and hybrid mounting studs
-Ring gear, starter and aluminum top cover
-Billet aluminum oil pan with oil pickup tube and screen
-Oil filter housing, oil cooler adapter and AERO-Classics oil cooler
-Rebuilt oil case with high volume oil pump
-Rebuilt distributor with Willam’s dual ignition conversion
-Reground camshaft developed by Crane cams for William Wynne
-Alternator mounting bracket
-Modified valve covers to add oil fill tube and vent ports
-Billet aluminum pushrod tubes
-Rotec throttle body injector
-Stainless steel intake and exhaust manifolds
-Engine mount for Bearhawk LSA
-Fiberglass nose bowl
-Engine baffles are coming later but are also offered by William
Once I had all the parts, I began to assemble the engine. The case came back from SPA already closed with the crankshaft, camshaft and 5th bearing installed. This would normally be done at home on the lower displacement engines, but on the stroker motor SPA wants to make sure everything goes together with adequate clearance and rotates freely. I installed the hybrid studs, safety shaft, prop hub and ring gear on the front of the crankshaft and then added the oil case to the rear of the engine.
At this point, I masked things off and painted the engine case and rear oil case. I also cleaned up the new cylinders and painted them. More assembly would have followed from here, but I had decided to take advantage of the supervised engine build opportunity that William Wynne offers. I traveled to Florida with my partially assembled engine and all the other parts and over the course of three days, completed the engine build and test ran it on Williams test stand with a club prop. I liked the idea of spending 3 dedicated days and completing the engine and I also valued the opportunity to run the engine on the test stand and learn from William while I was there.
The amount of calendar time that passed during this whole process was greater than I originally thought it would be so I already had my LSA kit for 11 months by the time my engine ran. Of course this meant that when I returned home from Florida, I couldn’t resist installing the engine on the front of the airplane even though there is still a lot of other work to do on the fuselage. I got ahead of myself and installed the nose bowl to the prop flange, but now I need to go back and install the boot cowl before I can complete the cowling. The typical engine cowling used with the Corvair engine is very similar to the standard Bearhawk cowling. William Wynne sells a fiberglass nose bowl sized for the Corvair engine and then a sheet metal cowling is fabricated to go between the nose bowl and firewall with doors that open for easy pre-flight inspection.
Besides providing parts for converting Corvair engines, William Wynne provides education about the engine. Not just how to build the engine, but also how to own, operate and maintain the engine. I referred to a conversion manual that William sells, but there is also a Maintenance, Operations and Procedures manual that helps you through the flight test period and developing a POH for your aircraft. The support that William provides and the Corvair community that exists are a big part of why I decided to use a Corvair flight engine. I think there are some similarities between the Corvair community and the Bearhawk community in that I believe both draw more of the old school type homebuilders than you find in some of the other homebuilder circles.
For those of you who are interested in more details about the Corvair flight engine in general, I’ve listed some information below that largely comes from William Wynne’s website, Flycorvair.net.
More about the Corvair:
The Corvair is a General Motors designed engine, manufactured by Chevrolet. 1.8 million engines were built in the Tonawanda, NY engine plant between 1960 and 1969. The Corvair has been flying on experimental aircraft since 1960, and William Wynne has been working with them as flight engines since 1989.
Configuration: The engine is a horizontally opposed, air-cooled, six cylinder configuration. William only promotes its use as a simple, direct drive power plant. The engine configuration is very similar to Lycomings and Continentals.
Displacement: The engine is effective without a gearbox or belt drive because it has a comparatively large displacement. William supports versions that are 2700, 2850, 3000 and 3300cc. The smallest of these is twice as big as a Rotax 912. The 2850cc is very popular because it sits in a sweet spot for performance and value.
Power: The power ratings for these four displacements of Corvair flight engines are 100hp, 112hp, 116hp and 125+hp at 3000 rpm.
Weight: The 2700cc engine weighs 225 lbs ready to run.
This is effectively the same as a Continental O-200. It’s installed weight is 35 lbs more than a 912 Rotax, 25 lbs more than a Jabiru 3300 and 40 lbs lighter than a Lycoming O-235. 2850cc and larger Corvairs are slightly lighter than 225 lbs because the cylinders weigh about 5
lbs less. 3300cc Corvairs also use a billet crank which saves another 4 lbs. Aluminum pushrod tubes can be used on any of the engines to save another 1 lb.
Reliability: From the factory, the Corvair made up to 180 hp in the car and turned more than 5500 rpm. The flight engine is reliable and long-lasting because it is only operating at 55% to 70% of these levels. Conversion engines that run at the car’s red line rpm historically have short lives and cooling issues.
Cooling: The Corvair has a factory cylinder head temp limit of 575F. This is the highest limit on any mass-produced air-cooled engine ever built. The engine is also the first mass-produced turbocharged car. GM engineered the engine to have excellent heat tolerance and heat dissipation. In aircraft the engine typically runs at 325 to 350 CHT.
Parts availability: Every wearing part in the engine has continuously been in production for 5 decades. A high end Corvair conversion only has an original pair of cases, and oil housing and cylinder head castings. All other parts in the engine, including the crankshaft, are brand new. Many of the parts in the engine, like the lifters and valve train, are common to Chevy V-8s. There is no part availability issue.
Ignition: The fleet of flying Corvairs is about 500 aircraft. More than 90% of them have a dual ignition system built by William Wynne. His system uses two mostly redundant systems, one points based, the other a digital electronic system. The design has two of every part potentially subject to failure, but it utilizes one plug per cylinder. Six cylinder engines can fly on one cold cylinder, most four cylinder engines cannot. Plug fouling is unknown in Corvairs because the ignition system is 40,000 volts and uses a plug gap twice as wide as a magneto system.
Fuel: The Corvair can use either 100LL or automotive fuel. It is not bothered by ethanol in the fuel. When Corvairs were designed, car gas was a lot like 100LL; for the last 35 years every mile driven by Corvair cars was done on unleaded car gas. Many engines like 912s and modern car engines do not have exhaust valves that can withstand the corrosive nature of 100LL. William uses stainless and Inconel valves in Corvair flight engines.
Maintenance: The Corvair is low maintenance. The heads never need re-torquing. The valves have hydraulic lifters and never need to be reset or adjusted. William dislikes the term “maintenance free” because it implies a “no user serviceable parts inside” disposable appliance mentality. The Corvair is a solid, robust machine which holds its adjustments, but his program is aimed at teaching builders to be self-reliant owners.
My donor car:
Engine removed from car
Engine after disassembly
Bottom end as it returned from SPA
Bottom end after adding rear oil case, masking and painting
Masking removed and harmonic balancer added to rear of engine
Prop hub and ring gear added to the front of engine
New cylinders painted
Now at William Wynne’s shop in FL. Rods, pistons and cylinders installed.
Showing off my Bearhawk gear
Engine is repositioned to install the head from the top and then rotated to install the second head from the top as well.
Second head now installed and engine moved to the vertical stand
Valvetrain now installed
Ready to install oil pickup screen and oil pan
Oil pan now installed
Engine has moved to the test stand. Top cover, starter and oil filter housing now installed. Drip trays mounted on heads to catch oil during pre-oiling process performed with drill motor spinning the oil pump.
Pre-oil is complete, valve covers installed, and cooling shroud added in preparation for test run.
And it runs!
Back in Kansas, engine is waiting to be mounted on my LSA.
Engine mounted with William Wynne’s engine mount. The Corvair uses a bed mount.
20A alternator now installed.
Nose bowl installed. This nose bowl is designed to use the 13″ spinner from Van’s Aircraft.
Bearhawk Patrol Glider Tug “Lucy” Update
Source: 2021 Q3 Beartracks, Alan Aurthur
Link to previous articles:
Australian Bearhawk Patrol Glider Tug Called “Lucy”
Australian Bearhawk Patrol Glider Tug Called “Lucy”
Thirty-four months have gone by, and Lucy has completed just over 200 hours and 150 glider tows.
Climbing to 22000 feet, the real limiting factor is the pilot. Not only do you need a good supply of oxygen, the -38C outside air temperature means you need a good heater or very warm clothing. The other limiting factor is at 22000 ft the elevator control had reached full aft; this could be improved by some ballast in the baggage compartment or a passenger.
A few cross-country flights experimenting with prop pitch and cruising RPM revealed a few limitations with the Mazda engine. Firstly, that the mixture cannot be leaned or the EGTs rises rapidly up to over 1000C if you don’t watch it.
The fuel consumption has settled at between 11.8 and 13.2 gallons per hour and with the right pitch setting around 100kts cruise speed with around 50% throttle. The positive is that although it can burn expensive aviation gasoline it is much happier with 98 octane Mogas.
Very steep climbs are possible coupled with high climb rates and very high fuel flows. The downside is that with fuel levels below about 7.9 gallons per side the forward fuel outlet will unport and the injection pumps will suck air followed by a rapid increase in the EGTs and then rough running. The problem is not easily overcome. The header tank with the submerged pumps has about five minutes of fuel so with low fuel levels steep climb outs need to be limited to less than that. However, five minutes on full power equals a more than 5000ft climb.
Where the turbo charged Mazda engine really shines is in glider towing to more than the normal 2000 ft above ground level. Climbs with a glider on tow average 600 ft/min at sea level, this obviously reduces with altitude however at 10000 ft this is still around 350 ft/min. The average climb rate to 10000 ft was 440 ft/min.
The next step will be to see how high we can tow to; the guess is that around 15000 ft will be the practical limit. 15000 ft on a still winter’s day should produce a glider flight time of over two hours.
The real success is the Bearhawk Patrol airframe, we have had absolutely no problems and no failures in any of the kit components, our only problems have been with our custom engine installation and with a bit of luck it has now settled down. Time will tell.
Bearhawk Patrol Glider Tug Called “Lucy” Follow Up, Altitude Record
Source: 2020 Q3 Beartracks, Alan Arthur, Doug Harrington and Avon Furphy
Eighteen months have gone by down in Australia and Lucy has completed almost 100 hours and 85 glider tows.
Initially the Mazda 13B rotary engine was naturally aspirated and although the performance with around 180 – 200 HP was more than satisfactory for normal flying the performance towing a 600kg (1322 pounds) glider on a 40 degree Celsius day was not spectacular.
Early on we had a problem when the engine started to consume excessive amounts of oil, there were no leaks and the exhaust was not wet and oily, what was happening was that the engine runs so hot that the oil leaking into the combustion chamber was being burnt as additional fuel. At the same time the air fuel ratio indicator was showing an erratic mixture that could not be corrected by adjustments to the fuel map. Hindsight is a wonderful thing and now we know what causes erratic mixtures.
The engine had to be removed and the rotor oil seals replaced, on a Mazda rotary that means a complete strip down. The opportunity was taken while the engine was out to fit a standard Mazda turbo charger. That sounds simple but was anything but. The engine bay configuration and the engine mount necessitated a quite radical custom installation.
Starting with the fabrication of an exhaust manifold that placed the turbo charger behind the engine in a spot that was previously occupied by dual batteries and a few other accessories.
The batteries had to be moved to the rear fuselage to compensate for the anticipated additional weight forward of the C of G.
The exhaust system and mufflers had to be completely reworked.
The turbocharger needed to be restricted to a boost pressure of no more than 6 psi, the standard turbo engine had low compression rotors; ours had high compression rotors and the advice was that this combination of high compression rotors and high boost pressure would cause seal and pinging problems. The waste gate controller was modified so that it was producing a maximum of 5.6 psi.
The next area for rework was the intake manifold and throttle body. Space was a limiting factor, so the standard manifold was cut and welded to keep the intake system as low as possible and oriented in the easiest direction for the plumbing connections.
Space constraints dictated that an intercooler could not be fitted and was probably not necessary with the low boost pressure.
First engine runs proved to be very positive, boost pressure was spot on and manifold pressure was up to 42” at static rpm. Fuel flows had gone up considerably from around 35 liters per hour to 50 l/hr (9.2 gph to 13 gph).
One of our original problems before the turbo was having to run the ground adjustable prop in the full fine position to achieve acceptable RPM in climb. After the turbocharger was fitted, we had to increase the pitch to limit the RPM.
Glider towing times before the turbocharger were in the order to 9 minutes to 2000ft chock to chock towing a 600kg glider; after the turbo the times are in the order of 6 minutes. Lucy’s tow times now closely match the times that are produced by a Piper Pawnee. Our estimate is that Lucy is producing around 240HP
Thirty hours have been completed with the turbo with no problems of any kind. One of the most common problems with auto engines in aircraft is cooling and particularly during taxi and ground operations; our dual radiators and double sized oil cooler have proved to be up to the additional heat produced by the turbo.
Where to next? With the turbo charger the obvious question is how high will it go? When the ideal day came round, a clear blue sky and almost zero wind at any altitude it was time to borrow an oxygen system from the gliding club and see how high Lucy could climb.
A couple of practice climbs to 12500 ft and 15000 ft on previous days sorted out the radiator expansion tank problems and then a full throttle climb to 22000ft answered that question. Lucy’s operation ceiling is around 22000ft where the climb rate fell to around 100 ft/min. The Mazda rotary engine performed faultlessly and even picked up RPM as she climbed, no doubt due to reduced prop drag at higher altitudes. The real limiting factor is the pilot, not only do you need a good supply of oxygen the -38C outside air temperature means you need a good heater or very warm clothing.
What next, more glider towing and cross-country flights experimenting with prop pitch and cruising RPM with an aim to reach an economical cruise consumption.
Australian Bearhawk Patrol Glider Tug Called “Lucy”
Source: 2019 Q3 Beartracks, Alan Arthur
The gliding fraternity have been talking about auto engine powered tugs for decades and despite the efforts of many they haven’t become a reality (yet), recent changes to Civil Aviation Safety Authority (CASA) regulations have made it a far more practical proposition.
A casual conversation around the bar lead to a syndicate being formed to look at a private venture to install a Mazda 13B Rotary engine in a PA 25–150 (small Pawnee). The syndicate members Alan Arthur, Doug Harrington and Avon Furphy conducted an extensive search for a suitable aircraft and finally dismissed the idea as too expensive, too much work, too many ADs and too many owners that had an inflated idea of the true value of their aircraft.
The idea changed to building a kit aircraft similar to a Piper Super Cub, also with a Mazda Rotary engine. The Bob Barrows designed Bearhawk Patrol was selected and after some consideration an order was placed for a Bearhawk Patrol quick build kit with Bearhawk Aircraft in Austin Texas. The kit was ordered in July 2016 and after a couple of months sorting out options arrived in Perth Western Australia on 29 December 2016.
A couple of days later after it had cleared quarantine/customs, a trailer ride to Narrogin saw it installed in the new hangar at the Narrogin Gliding Club for the build. The kit consisted of a steel tube frame and other welded steel tubes and fittings and lots of raw material. The instruction manual was quite basic but I purchased CDs of the build details compiled by other builders and the kit manufacturer provided hundreds of photographs of other builders projects. The basic airframe went together quite quickly and by the end of January 2017 we had the first visit from the SAAA TC Geoff Danes and the AP for the project Bill Keehner.
Avon already had a Mazda 13B engine sitting in his shed waiting for a racing car project so he donated it to the project, it hadn’t run for many years so was shipped to Rotormotion in Perth for a complete overhaul and conversion for aircraft use. Rotormotion’s brief included a target HP between 210-240 Hp.
The auto engine installation consumed enormous amounts of time as our glider towing goal meant that we could not have any problems with engine cooling at relatively low airspeeds and high power settings. Consequently we selected a twin radiator system and a double sized oil cooler. Experience during the test flying program indicates that we may have got it right.
Avon’s Mazda rotary engine was a fuel injected and electronic ignition version from a Mazda RX7. All of the Mazda fuel injection and ignition system was discarded and instead twin aftermarket EMS Stinger systems were installed driving the standard injectors and twin spark plugs. Also discarded was the heavy exhaust manifold and all the environmental systems. After initial engine runs the custom exhaust was modified to include two straight through mufflers and ceramic coatings on the engine pipes.
PSRU selection proved to be a bit of a problem, all of the toothed belt systems seem to have disappeared, the only system we could find with good reports was a geared system from Autoflite in NZ. This PSRU is available in two or three gear versions and we chose the three geared one to keep the direction of rotation the same as Lycomings. It also moved the engine thrust line up closer to the original design position. After selecting the PSRU then we were able to order a prop to match. We ordered an IVOPROP Corp Magnum three bladed ground adjustable prop of 76” diameter.
The fuel system needed to be modified to incorporate dual high-pressure injection pumps. Initially I was going to build a header tank with dual submerged pumps but in the end found exactly the setup I had planned in an auto supply catalogue at a much cheaper price. The system is now gravity feed to the header tank and high pressure to the injectors, return fuel comes back to the header tank.
The aircraft relies on electrical power for engine operation so it was quite critical that everything was duplicated; not only is everything from dual batteries to the ignition boxes selectable but we have incorporated a panic switch that can change all selections to the opposite selection with the flick of one switch. At higher altitudes you can do some fault diagnosis but when towing a glider at 100 ft you don’t have time to play around with systems.
The airframe is part covered with aluminium alloy and part with fabric; we chose to use the Oratex prepainted fabric. The Oratex fabric is quite easy to use and being prepainted has no hazardous solvents to use, the glue is a water based hot melt glue. The fabric is about 80% the weight of other fabric systems which resulted in the aircraft center of gravity being well forward requiring lead ballast in the tail. If I was to build another Bearhawk I would plan to fit the dual batteries in the rear fuselage and not on the firewall.
Instrumentation did not need to be very complex and other than the engine monitor all are round steam gauges. For the engine management system we used the MGL Extreme EMS display which has the advantage of being in the main programmable. After 19 months, 4450 hours and a lot of engine runs and taxi tests the big day arrived. Word had spread and instead of having a quiet first flight there were dozens of spectators on Saturday 15 September 2018.
The SAAA team arrived early for the final inspection, Geoff Danes and Bill Keehner did their inspections and Bill issued the Phase 1 C of A. The aircraft flies really well; it took to the air as if it was made to fly.
Alan also says: Dennis and Donna suggested that I also send you some photographs of my fool proof control lock (you can’t leave it in and go flying).
4-Place Engine Selection Tips
Purchase your engine as late as you can. The longer you store the engine, the more susceptible it is to corrosion, damage, or obsolescence. You’ll need to have an engine to build the cowling, but if you are lucky enough to have access to a core, it will do just as well as an airworthy engine. There are some benefits to deciding on an engine plan early, such as being prepared for purchase if a good deal comes along, and planning the supporting systems accordingly.
Bob Barrows designed the Bearhawk around a 4-cylinder angle valve Lycoming O-360 that produced around 170 horsepower. His second prototype used the parallel valve Lycoming O-540 producing around 235 horsepower, in part just to see how it would do. The airplane is a great performer with the smaller engine. With the larger engine, it has been described as “barbaric.” There is a natural tendency to think that bigger is better when it comes to engines, but this is not always the case with airplanes. Don’t let your ego make the decision. Bigger engines are heavier, and often require additional system requirements that further compound the weight gain. Read more about this topic in the Bingelis books. Bob prefers to see the engine weight kept under 400 pounds. Continental 0-470/520 engines weigh a little more than that, so he has adjusted the design of the motor mounts for those engines.
To oversimplify, here are some rules of thumb: if you live in a place like the western United States where you’ll frequently be climbing to density altitudes above 10,000 feet, or if you’ll be regularly flying at weights above 2200 pounds, lean towards the larger engines. If you’ll not be regularly needing these kinds of performance demands, you can save around $10,000 in initial cost and 100 pounds of empty weight by using a smaller engine. Ongoing cost savings will include reduced fuel burn during takeoff and climb and reduced maintenance needs of the 4 vs 6 cylinders. Both configurations will burn essentially the same fuel in cruise at the same airspeed, but if you cruise both at a high power setting, the bigger engine will deliver around 15-20 extra knots for 3-5 more gallons per hour. Back at 65% power, the average fuel burn of a 540 is approximately 12.5 gph, versus 9 gph for the 0-360.
Drag increases noticeably with speeds above around 115 knots, and the resulting miles per gallon will reflect this.
Regardless of your choice, be prepared for a dizzying number of variants, some of which may seem like a bargain. They may indeed be a bargain, or they may be something totally unusable that will be expensive to reconfigure. The safest bet is to stay near the center of the envelope, so to speak. Here are some tips to help you narrow down the choices.
Consider what you’ll need for accessories, since this may narrow down the engine choice. Although not a requirement, a constant speed propeller is highly recommended, and will make it possible to better utilize both ends of the airplane’s speed envelope. If you plan to run a constant speed prop from the beginning, or if you think you might like to ever install one, consider this in your engine shopping, to ensure that you have the appropriate provisions for a prop governor and a hollow crank.
Many builders consider mounting an alternator on the vacuum pump drive pad. These alternators are available in a range of sizes and can serve as a backup to a front-mounted belt-driven alternator, or as the only alternator. Your choice here will determine whether you’ll need to have a vacuum pad and drive.
Most carbureted Bearhawks use gravity fuel systems. As designed, the system delivers adequate flow for engines in the recommended range, and will not require an engine-driven fuel pump. Builders choosing fuel injection will require an engine-driven fuel pump and the associated provisions in the accessory case, and likely other components aft of the firewall.
As far as ignition is concerned, there seems to be a consensus to avoid the varieties with a single magneto drive. Beyond that, builders have used traditional mags as well as the experimental electric options with good results.
Choosing a 4-Cylinder Lycoming
First, limit your search to those with Type I Dynafocal mounts, since these are the only ones that will fit the engine mounts provided by Bearhawk Aircraft. Bearhawk Aircraft does not support conical mount engines.
Some builders shop in the 0-320, 150/160 hp size, but those builders must pay particular attention to keeping the airplane light. Kept reasonably light, the overall performance will be better than a C-172 by a measurable amount.
The 180 hp 0-360 engine is probably the best choice for 90% of BH builders. It is available new from Lycoming (with special OEM pricing for kit builders), in various experimental engine kits from other suppliers, and is ubiquitous in its use in many applications. Some of the alternatives include Superior and Continental (which has recently bought ECI/Titan).
With 170-200 HP, the takeoff and climb performance will be on par with a Cessna 182, although cruise will be lower, around 110-115 knots. The wide deck and narrow deck options are both acceptable, but look to the angle-valve variants rather than the parallel valve. These engines would have been fuel injected in their original configuration, but with guidance from Bob many Bearhawks have flown with these cylinders and a carburetor. When Bob builds an engine like this for the 4-place Bearhawk, he uses a rear-intake sump and makes a special 90-degree adapter to move the carburetor aft. This puts the carburetor in about the same place as it would be for a 540, and makes the exterior intake much more streamlined. This is possible because the 4-cylinder engines leave cavernous space between the engine and the firewall, since the prop mounts at the same station regardless of the engine. Within the 360 variants, the final horsepower will be determined by the compression ratio. This will also determine the minimum fuel grade. A ratio in the 7:1 neighborhood will deliver around 170 hp with the ability to run 87 octane fuel, assuming you can find it without ethanol. Ratios near 8.5:1 will deliver around 180-190 hp with the ability to run ethanol-free 93 octane fuel. Higher ratios will require 100LL, but will deliver closer to 200 hp.
Adding fuel injection makes it an IO-360. This adds weight and complexity, and will provide a slight power increase.
There are a few 4-cylinder variants that increase displacement and horsepower. One is the IO-390, which produces in the neighborhood of 210 hp for a cost premium of $15,000-$20,000 over the angle-valve O-360. This variant has flown successfully in multiple Bearhawks. Another is the Titan IOX-409, which is rated for an astounding 230 hp, but at an equally astounding price. They also offer the 370 and 375 “Stroker” engines, which have parallel valve cylinders making 185 – 190 HP with a carb and 195-200 HP with fuel injection. With any engine choice, but especially with the less common choices, it may be beneficial to talk with a Bearhawk builder who has successfully implemented the design, which will help identify any required deviations from the basic configuration.
Choosing a Six-Cylinder Lycoming
The 0-540 series of engines are heavier, but provide an increase in overall performance that is hard to believe. However, nothing is free, as the useful load will go down at least 100 pounds. Experience shows that it may go down as much as 200 pounds if the larger engine inspires the builder to also install auxiliary fuel tanks (30 pounds), fuel pumps, etc. Choose a parallel-valve 0-540, not an angle-valve. The angle-valve engines weigh over 80 pounds more than the others. Whether it is a wide deck or narrow deck engine makes no difference. You’ll find variants producing 235 hp, 250, hp, 260 hp. 235 hp engines (“B” series) are lower compression engines capable of burning automotive fuel. They are cheaper and easier to acquire, and performance is still unbelievably good.
Hartzell constant speed props can only be used on O-540 A4XX, 0-540-B4XX, -J3XX engines. All other series of 540s, which are usually early engines, must be modified with heavier crank shaft counterweights or use a McCauley prop.
All 540 Lycomings can be easily modified with the heavier counter weights. They can be installed without disassembling the engine, by removing cylinder No. 6. The parts and instructions are available from: Johnston Aircraft Svc, Inc, P.O. Box 1457 Tulare Municipal Airport, Tulare CA 93274, 559-686-2161, www.johnstonaircraft.com.
There are two types of mount ears on 0-540s. The Type I has 1 3/8” holes the Type II has 2” holes. These determine which motor mount you’ll need from Bearhawk Aircraft, and which motor mount rubbers to buy. The mount lugs bolt to the engine case, so they are interchangeable, but expensive.
Continental 360/470
The six-cylinder Continental 0-470 engines represent good buys on the used market and are smooth running, well known engines. They are usually heavier than 0-540 Lycoming, and use McCauley props. The output will vary from 215-285 hp, depending on the output. The IO-470 is 260 hp, but there’s the probability of firewall interference with the longer fuel handling unit at the rear so it’s not recommended. The basic cowling design was for the Lycomings, so modifications will be required. These engines use an entirely different mounting strategy, and variants other than the O-470 will likely require custom mount fabrication. We say that the O-520, being heavier than the O-470, which is heavier than the O-540, is not a viable engine for the Bearhawk.
Automotive Engines
Bearhawk Aircraft does not provide any support services for automotive conversion, so you’ll be designing your own motor mount, cowling, etc. You are building your own airplane, and it is your experiment. It is your own choice to make, but consider the following. The automotive engines can seem seductive. What’s not to love about an initial price that is 1/10th that of a Lycoming? Traditional airplane engines were designed many decades ago, so surely there is the technology for making better engines now? Sometimes a builder starts down this path and feels like he has stumbled upon a secret alternative that nobody else knows about.
The big issue with auto engines is that we must not just consider the engine, but rather the overall task of powering the airplane. We often hear in hangar discussions that airplane engines are really simple. In some ways, they certainly are- but in many ways, they are not. Every aspect of their configuration has been carefully considered and engineered over decades of use. Design choices are not arbitrary- they are almost all based on making the most reliable overall powerplant possible, applying lessons learned from failures large and small. The same applies to engines designed for cars, perhaps even to a greater degree. The folks at Subaru have painstakingly engineered every detail of their engine, how it relates to every other aspect of the car, and how it is used in that application. But how does that application relate to the airplane environment? Airplane engines are designed to run near their maximum RPM for hours at a time. Car engines are designed to operate at maximum RPM for only a short time. When it comes to cooling, the airplane engines applicable to the 4-place Bearhawk are air-cooled. Most car engines are liquid-cooled, and are going to require a radiator. Where is that going to go? The airplane engines are direct-drive, turning the prop at the same RPM as the crank. Will the auto engine be able to deliver the performance you’d want in that configuration, or must it be geared down? How is fuel to be metered, and ignition to be delivered? How robust are those systems, and what is their failure mode? Do those devices give warning of failure before they completely quit? What kind of propeller choices are going to be available for the car engine? How hard is it going to be to service the airplane custom components when you are away from home and have a problem? What about insuring the plane when it is time to fly? What about resale value?
All of these questions get to the broader goal of providing a total powerplant solution. Mounting, cooling, fuel metering, intake, ignition, exhaust, and power transmission may sound like just a few little things to sort out, but experience shows that these are actually really big things to sort out. An auto conversion adds at least a year to the construction time, apples to apples. The majority of Bearhawk builders who have stuck it out and flown with auto engines have later switched to traditional airplane engines after their plane was flying. There are one or two notable exceptions, and for anyone still considering an auto engine, we strongly encourage you to get in touch with one of them.
Propeller Considerations
Most people use a constant speed propeller on the airplane, though it is not a necessity. A fixed pitch prop will save around thirty-five pounds and many thousands of dollars.
The downside to using a fixed pitch prop is that, of necessity, it will be a compromise in most parts of the flight regime. Because the Bearhawk has such a wide speed envelope, regardless of how you have a fixed pitch prop pitched, it will be slightly wrong at least part of the time. For example, one Bearhawk with a fixed pitch prop had a great takeoff roll and climb, but required a nearly immediate throttle reduction at level-off to prevent exceeding maximum RPM limits. With a constant speed prop, the throttle can wide open, or anywhere else, delivering much faster cruise speeds when desired. Special pricing is available on most props for kit builders when the props are purchased through Bearhawk Aircraft.
2000 Beartracks Mailbag: Q&A with Bob
Bob, Enclosed is a check for Bear-Tracks for another year. I do have a few questions:
1 – What is a good method to use to transfer the airfoil shape to the wood to be used for the form block for the wing ribs?
2 – What is the recommended radius for the wing rib form blocks? I believe that 1/8″ would be about right for both .025 and .032.
3 – Do you have an e-mail address and if so do you answer e-mail correspondence?
I have a piece of 1″ thick hard maple for the form block. I just need to transfer the airfoil shape to the wood and cut it out. I am ready to start with the ribs. Is Proto II in the air? I bet the performance is really great – Thanks for your time.
Paul Foster – #289 – Monte Vista, CO
Paul, Thanks for your questions and newsletter renewal. As for your questions
1) The best method to use is to glue drawing #7 to your form block with contact cement or Plyobond.
2) a 1/16″ radius will work best for both thicknesses of the aluminum.
3) I do not have an e-mail account. Proto II is flying great -look for a flying report in this issue of Bear-Tracks. -Bob
This letter was pulled from the Bearhawk E-group. For more information on the Bearhawk E-group see page 7.
Well, after several days of non-stop building, 023 is on the main gear. I stumbled across a new Scott 3200 tailwheel in some stuff my Dad purchased from someone’s attic. He got a bunch of stuff (including a 65 hp engine, prop, landing gear, etc) for less than the price of a new Scott! What a deal.
Anyway, related to tail leaf springs, after much discussion and some consulting with Bob, I have decided on purchasing a PA25 tail spring from Univair (part number PA25TWS1) for approximately $90. 1 decided on the PA25 because Bob recommended two leafs all the way to the tail wheel bolt. Taper rod was attractive but with the Scott tailwheel, side loads should not be a big problem – it will go to full swivel if a major side load occurs.
My plan on putting a Continental 0470 on my Bearhawk has been changed. Finding an engine mount damaged or not – is not easy. Any found, even damaged, seem to run between $500 & $700. The Lycoming 0540 seems easier to make an engine mount following Bob’s newsletter. Also, Bingelis only talks about Lycomings!
Compressing the landing gear shock strut took some thought. I used a bar clamp – very long – and it worked fine. Later Bob told me he used his drill press with the table moved off center – I wish I thought of that! Oh well, some days I make things harder than necessary.
Piper TriPacer Seats also took some work to find. I ended up paying $60 each – frames in very good condition and but they need covering. Seemed like allot but finding seats was not as easy as hoped. Salvage dealers did not have any. My source has a couple more sets if anyone is interested.
Well, that’s my story for now. If anyone is near Cincinnati (actually Florence, KY) or Elkton, Ky, let me know. I build my parts in Florence and assemble in Elkton. It would be great to have some other builders close to discuss building, etc.
Bill Johnson – #023 – Florence, KY
Hi Bob, So glad to hear that you are ready (perhaps already have) to fly #2. Our second wing is going together quickly. Should have both sides, including control surfaces before the end of the year. Looking forward to starting on the fuselage.
The photo is my left wing with control surfaces installed. I am starting to look for a wind damaged Maule or C180/182 to scavenge for the engine and other needed parts. Still having a ball with the whole project.
Pat Fagan – #232 – Pearblossom, CA
Also from the Internet -I have most of the systems hooked up or at least roughed in. All the flight controls are working. I am finishing up the fuel system now. #75 is being powered by a (1996) Ford Taurus 3.0 24 valve engine that I modified with a polybelt GT. The engine has run with no propeller but hasn’t been run to RPM or load yet. Items needing to be finished are the fuel system, engine control linkages, a few things left on the cowl, and trimming everything. I am installing a removable interior for complete inspections in the future. I know that a lot of little details need to be worked out yet.
I am in the process of moving again. This time I am going to build a house and hanger at an air park. I hope to continue working on the Bear hawk through out the house project and get it in the air by at least late summer. How is everyone else doing on progress?
I will be happy to answer any questions the group has and give my opinion of what I may have done different. I will say as far as the plans I have followed them to the line and had very good results, The project gets more interesting when you start to improvise beyond the main part of the plane, i.e. engine controls and all the other goodies. Enough for now. Happy building.
Tom Yeoman – #075 – Apache Junction, AZ
Hi, Bob,
Things are moving along, not on schedule, but forward.
I was saddened to hear of Ray Thurston’s passing – It was like hearing about a family member.
The enclosed picture shows the flanging tool I used for the rib “holes” – it was made from a standard flycutter and worked great! The wood handle was used to exert pressure on the bearing. Steel washers were glued to the form bloc to serve as bearings for the center pin. This might be helpful to other builders so I am passing it along. All the Best,
Walt Draxler – #082 – Arlington Heights, IL
Bob, I hope this letter finds you and Mike in good health and fun flying in your Bearhawks. Enclosed is a check for my newsletter renewal – I have been so busy that I forgot to send it in. I’ve finally got a good start on my Bearhawk. I have all my small steel parts cut out. I am just finishing all my ribs and I am about to start on the wing spars. My goal is to have the wings done by the beginning of winter. I am enclosing some long overdue pictures of my project. I will be looking forward to seeing you and Mike at EAA again this year. If you need a place to stay for a couple of nights you can stay at my place. I am about 40 miles from Oshkosh. Maybe that is too far, let me know. I sure would like to hear your comments about my project. I can take criticism. I hope to have the wings framed up by then. I have a question about the fuel tanks. I noticed in one of the newsletters that you weld and rivet them. Is the riveting necessary? Can I just weld them? Is the riveting for added strength or just to hold them together for welding?
Ray Gabriel – # 334 – Greenleaf, WI
Ray, thanks for the nice letter and your newsletter renewal. Your parts look very good in the photos that you sent. Mike and I might be able to stay over at your place for one night while at Oshkosh, check with us at Oshkosh. It would be interesting to look over your project. The rivets in the fuel tanks are only to hold the sheets in place for welding. ~ Bob.
Ray Gabriel using a Liebert Hole Cutting Machine. Ray reports that a user can cut all the holes in all the ribs in about 3 hours with this machine. Also pictured are all the 4130 steel and a few of the aluminum parts ready for bending and drilling.
Bob, I have been meaning to write for sometime to thank you for the information in your newsletter. I have been working on my seating arrangement. The front seats incorporate a “captain’s table” arrangement for the mounting. Adjustments are made by pulling a side lever to the right and sliding the seats back and forth. The back of the front seats fold forward to allow entry to the rear passenger area. The back of the rear seat is adjustable. I used 3/4″ x .035 square tubing for the windows and door frames. I know that it costs a little more but it sure is easy to work with. I’ve got to relocate the rear window frame 2″ higher.
The engine is a Lycoming 0-540 of 235 HP. It will be pulling a fixed pitch McCauley 8452 Prop. I hope to have it up and running by October 2000.
George Anderson – #153 – Daphne, AL
Hello Bob, Just got the Jan 2000 Bear-Tracks. I am always looking forward to receiving the next issue. Sorry that we didn’t make it to the fly-in in Oct. We were planning on coming down to the fly-in and visit relatives but I came down with the flu – so maybe next time.
Thanks for the information in the newsletter – It must be nice to have two Bearhawks!
Thank you for coming to our cook-out last summer and I hope you can make it to our next one sometime in June this year. Since the cook-out there have been 4 of my neighbors talking about building Bearhawks. My daughter and son-in-law are planning on building one as soon as they finish their Cessna 140. We might have to change the name of the airport from Hale’s Landing to Bearhawk Landing!
I have been busy working on the 1959 Cessna 172 that I am restoring – it’s almost done. The Koala 202 is almost ready to cover and I have most of the 4130 steel hardware for my Bearhawk wings made. I have too many projects and not enough time or money to finish them all.
Do you have plans for any future modifications for the Bearhawk? If so what? How about plans in the newsletter for seat frames and tracks. I have found that the Tri-Pacer seats are hard to find.
Dan Riffee – #267 – Hale’s Landing, WV
Dan, Sorry to hear that you were sick and couldn’t make it to the fly-in. Like you say maybe next year. Mike and I really enjoyed our trip to Hale’s Landing last year and are looking forward to it again this year. When you firm up a date – let us know.
Currently I have no more modifications to the Bearhawk design planned. Your idea for seat drawings is a good one and I will work on that for a future newsletter. -Bob
Bob, Enclosed is a check for the 2000 newsletter, also I have a few questions:
1) The part of the nose ribs that form the leading edge, have you noticed on the prototype or do you forsee a problem with fretting because the metal is not secured together at the leading edge tip?
2) On the plans it calls out a 1.25″ flange on the main spar and a 1″ on the rear. The newsletter has instructions for laying out spar blanks : Width = web finished height PLUS 2 x flange width PLUS 1/16″. This will give a larger flange than calls out in the plans, the same also with the 9/16″ and 1/2″ marker for the rib flanges. I wonder if it makes a difference or would I have clearance problems later?
3) Are the spar webs square on both ends or do the root ends have the shape of the wing attach fittings to fill the gap between the fittings?
I have started slowly on the wings, having trouble getting consistently sized ribs but getting there, I have all my tools and shop set up so far and having a lot of fun.
Mark Skiba – #349 – Camarillo, CA
Mark, Looks like you are really getting into the drawings and giving them a good going over. As for your questions: 1) Fretting has not shown to be a problem on the prototype and I don’t see any indication that it would start. 2) Slightly larger or smaller flanges will not cause a problem. 3) The spar blanks have the shape of the wing attach fittings.
Your ribs should be consistent within about 1/32″, let me know if you are still having trouble with the ribs. Maybe I can give you some more pointers for rib construction. ~ Bob
Mike and I received notice that Ray Thurston’s #005 BEARHAWK project has been purchased from his estate by John H. Dugdale. Ray had completed a tremendous amount of work on his BEARHAWK and it would have been a shame to see it go to waste.
Hi Bob,
I’m making good progress on the BEARHAWK. I’m on the wheels and rudder hook up to the pedals (I had to move the rudder pedals back from the firewall for brake cylinder clearance). I have a 0-470 and Prop and a good lead for the mount.
The seats are installed and I’m rigging up the rest of the tail. I have included a few photos of me forming the T25 ribs 1/8″ bend with a steel mandrel on the anvil.
Do you have a date for the fall BEARHAWK Cookout?
Will Graft – #365 – Wadsworth, OH
Wil, good to hear from you. I mention the distance used on my rudder pedal setback on page 5 of this issue. As for the cook out – we are still working out the best date as October has suddenly become very busy. We will have a firm date by Sept 1. ~Bob
The following post is from the BEARHAWK e-group.
Today I had to go see the IA who helped my brother restore his Citabria and I mentioned the e-mail list discussion of reverse engineering a set of EDO floats. The one hassle which he could see, would be forming the “hoop” stiffeners which give the rounded top of the floats their shape. He showed me an old partially torn up EDO and it looked like they were formed in a brake and then formed into their rounded shape, similar to how the fuel bay wing skin stiffeners are made for the BEARHAWK wings, only with a LOT more curve. So it would be a lot of trial and error compensating for springback, and it would have to be redone for each size hoop due to the taper of the floats. Not an insurmountable challenge, but probably easier to copy a float with flat top and sides.
He did mention that in the EDO line the model 2425 is not rounded like the others, and might make a good candidate for duplication. If the model number is also the displacement, that might be a bit on the small side, but may be close enough if you don’t increase the gross weight above what is specified for the landplane version.
Other than the hoops the rest of the float looked pretty straightforward and ought to be easy to copy if you could get the right extrusions. The one thing I noticed was LOTS and LOTS of closely spaced rivets. I think I would prefer to build my floats in fiberglass if a set of suitable plans become available. Matter of fact, my friend the IA asked “why don’t you just design your own?”
Del Rawlings – #316 – Cordova, AK
#232 is really coming along well now. I bent the top frame as you suggested and was pleased to find everything lined up! I almost have the entire frame tacked together.
I was wondering, do you call for any special bolts, like close tolerance or high strength in the wing struts or landing gear?
I am planning on an 0-540 for a powerplant, will any 0-540 core serve for setting up my motor mount or do I need the actual engine?
Pat Fagan – #232 – Pearblossom, CA
Pat, good to hear that the process worked, as for the special bolts question, the answer is no. The airplane was designed to use standard AN hardware. The actual engine would be best – short of that, make sure that the engine that you use is set up the same as your core and that it has the same mounting bosses that match your motor mount ~ Bob
Another note from the e-Group:
Has anyone perfected the “Barrows Method” of flanging the @#$% lightening holes?
Mike’s book as well as “BearTracks” makes this look real simple.
“Barrows” Method:
1. Wax it up.
2. Using the flange tool, lift the hole 30 degrees by smoothly going around it about 2-3 times.
3. Flip the rib over and push it down with the back of your flanging tool to lock in the 30 degrees and tame any bends.
4. Sit back, admire your work, and realize that you’re God’s Gift to the Bearhawk community and builders world over.
“Romanko” method:
1. Wax it up. (Even I couldn’t screw up this step)
2. Fail at smoothly taking the flanging tool around the @#$% hole. Instead, use the flanging tool like a soda pop opener and go around the @#$% hole lifting it up in increments equal to the width of the flanging tool.
3. Admire all waves you just put in the @#$% hole.
4. Wax it again, and go around the @#$% hole with the flanging tool, realizing the waves will never come out.
5. Flip the rib over and push the waves with the back of the flanging tool until you realize you really are having a hard time judging 30 degrees with your eye at 0400 in the morning. Induce more waves.
6. Sit back in amazement as you realize what was once a straight rib has turned into an oil can. Go outside. Look up. If you see stars, leave for the airport and get in some quick flying before work.
I know that some of you have built elaborate dies for forming your holes, but I really hate the thought of spending time doing that. Frankly, I’d prefer to keep everything “Barrows Simple”. I keep looking at Bob Barrows as my example. If he built THREE sets of wings using this method, it’s good enough for me. I think it’s just an issue of practice, but I really thought I’d have it down by now. Until I do, I will continue to refer to them as the @#$% lightening holes.
Bob Romanko – #399-Charlottesville, VA
Bob, Bob and I have agreed to conduct a personal workshop with you to perfect the “Barrows Method” of rib flanging. I got it on my first try. ~Mike
I found some rod ends at Sun & Fun for $12.00 each. Talked to the surplus dealer (Russell). He has about 1000 more of these jewels. The part number on the rod end is RE4H6-2 made by Fafnir (look at the Spruce catalog and you will see these are the right ones). If you would like to purchase, fax an order to Russell AT2 Surplus (847-432-6847). He said it takes time for him to fill orders so be patient.
Bill Johnson – #023 – Florence. KY
Bill, you look good sitting in that fuselage. I was able to confirm the rod end information with Russell – Order what you need builders! ~Mike
Bob, I’m enclosing some photos of my Bearhawk. I have completed the fuselage, both wings, wing-tips, fuel tanks (installed), nose bowl, and the seats. All cables are hooked up and operational.
I constructed the seats myself with 4130 tubing and
zig-zag springs for the seat bottoms and backs. They are fully adjustable front and back with a hinged back for access to the rear seat compartment.
I’m getting ready to mount my engine on the Bearhawk.
It is a Continental 0-470. I hope to have my Bearhawk in the air by next fall – God willing.
Things seem to be going very well building from your plans. I cut my first tube three years ago.
Sorry I missed seeing you and the prototype in May when I was on the east coast. Maybe it will work out better on my next visit. God Speed,
Boyd Newgen – 264 – Ontario, OR
Boyd, What a great letter to receive the day I return from Oshkosh! Thanks for all the great photos and keep them coming. I am glad to hear that you are making such good progress, ~Mike
Hi Bob & Mike, I have had the Bearhawk plans 5 years and I am only now just starting. I have done a Kitfox and a Thorp T-18 (which took People’s Choice at Oshkosh) in the early 80’s. I want my Bearhawk to do the same.
You mentioned that you stayed at Blackhawk Field in WI during your trip to Alaska. I hangared there for two years prior to coming to Oregon.
I am a steadfast promoter of the Bearhawk. Why someone didn’t think of it the 30 years proceeding Bob remains one of life’s mysteries!
Don Schindler – 068 – Springfield, OR
Dear Bob, Please send me a copy of the Utility Door Plans ($25 M.O. enclosed).
I have been studying the plans at great length, trying to create and assemble the aircraft in my mind. In this way I feel I will have an understanding of the aircraft as a complete idea and not just some parts to make and slap together. This activity alone has been a source of great entertainment for me.
I expect to be full bore into parts construction by the end of December.
I have a couple of questions for you concerning the plans – At the root end of the spars you show the .032 web is to be continued all the way under the spar end plates and the spar end inside plates. Also you show the web flange ending at the top and bottom of the spar slightly short of the corner angle of the end plates. this creates and inside right angle cut at the top and the bottom of the web material at the end of the flanges. Is this inside right angle cut a possible source of future web cracking from stress? Should I radius it or continue it as a gentle curve up to the flange?
Do the line diagrams of the fuselage tubing depict the inside, centerline, or outside of the tubes?
And finally are there any unusual cluster arrangements in the fuselage tubing joints?
Bion T. Rodgers – 436 – Mount Royal, NJ
Bion, You should have your utility door drawings by now – let me know what you think. As for your questions: You make a good point about the spar flange. There should be no sharp inside corners on ANY aircraft metal part. Use a 1/8″ radius or larger. The fuselage line drawings depict the CENTERLINE of each tube. And there are no unusual cluster joints used in the Bearhawk frame as designed. ~ Bob
Dear Bob, I was pleased to have made your acquaintance on the telephone the other day. As indicated I have purchased Ray Thurston’s Bearhawk project but have not yet collected it from Blenheim. I will collect it soon, in the meantime Mrs. Thurston has sent me the plans and I am studying these.
Ray has done a lot of work on his project and it is a tragedy that he was not able to complete it. I hope to be able to pick up where he left off and continue the quality of workmanship. I am not a trained engineer, but enjoy a challenge and have always had a “hands on” practical tendency to make and fix things – boats, engines, travelling irrigators amongst others.
We live on a small block (14 acres) about 14 miles from Christchurch. While we are within the Christchurch International Airport Control Zone, there is a possibility we could fly off the block (it is 515 meters long (that’s 1690 feet to you and me)). The big thing will be to not annoy the neighbors as the area is in the process of being divided into smaller and smaller blocks with people moving here from the city.
So far as the Bearhawk is concerned, I have not decided what engine to use yet. Personally I am not keen on air cooled engines, but there is considerably less work and less uncertainty involved in sticking with the Lycoming. I am also not keen on reduction drives as many of these seem to have some problems. I quite like the idea of an inverted, direct drive, alloy V8, such as Steve Whitman used in his Tailwind. No doubt this would take some development too. A Rover 3500cc can be stoked and resleaved to give over 5000cc and this would give enough HP, but this too would take some development.
I would appreciate if you could provide me with a bit more specific performance data re: the Bearhawk than is contained on the websites. If this has been published in the newsletters do not bother to repeat it (I am awaiting receipt of the back issues from Mrs. Thurston). I am interested in the specific performance of the prototypes – e.g. estimated HP of the engines and the cruise speed at 2400 RPM for each, climb rate, fuel burn at cruse. Do your take off and landing figures represent literally lifting off the ground or are they the traditional 50 foot obstacle clearance? Also can you supply some data on the Bearhawk’s ability to handle cross winds. I look forward to meeting you someday in the U.S. or in New Zealand
John Dugdale – 005 – Canterbury, NEW ZEALAND
John, Thank you for the introduction and I hope that you find the Bearhawk to be to your satisfaction once you begin construction. I considered Ray to be a very good friend even though he was on the other side of the planet and I am pleased to learn that all his hard work will not go to waste. I think that you will find the answers to most of your questions in the back issues of the newsletters. My performance figures represent actually lifting off the ground. I personally think that the Bearhawk handles crosswinds quite well. The nearest production airplanes that would be close in crosswind competence would be the Husky, Super Cub or Citabria. ~Bob
1996 Beartracks Mailbag
Source: 1996 Beartracks
Bob – Thanks for the good talk we had yesterday – that was what was needed to push me over the edge. After nagging my wife for about six months, it wasn’t difficult to convince her that I needed to purchase the plans for the Beerhawk. Please find my check enclosed.
I’ve been on the Cozy e-mail list for several months and have really enjoyed it The list is a bunch of guys with e-mail access that share information with each other. I’m going to miss it I think the Internet is a great vehicle for the exchange of problems and solutions, as well as a source of encouragement for weary builders.
A similar e-mail list for the Bearhawk would be invaluable. I know that you are not set up to give such a service, and I’m not asking you to make an investment in that area. However, I manage a system on the Internet, and I have enough bandwidth to handle a lot of traffic. I intend to start such a forum, and perhaps document my trials and tribulations with this project for the whole world to see. What I would like to ask from you is that if you have any inquiries about e-mail or WEB pages, that you forward those interested people to me, and I will add them to my forum.
I do have some selfish motives here. Having never built an airplane before, I would love to have contact with people who have – especially those working on the same type of airplane. I also like to be kept up to date on new engines, etc.
Thanks for designing such a neat aircraft! I look forward to starting work on it. My wife looks forward to me getting this out of my system.
R Paul Beam (067)
Bob – #009 is underway and I am now thoroughly enjoying the project. I have some questions and want to pass along some experiences getting underway.
First the books by Tony Bingelis were disappointingly sketchy about the how-to’s of fluting and flanging. Regarding fluting, I discovered it is best to keep my plier tips back from the bend about 3/16″ and make the flues minimal in depth at first, especially an the longer straight parts of the wing ribs. Next the flutes are modified deeper as needed. Also, I’ve learned that flute modification may be necessary before the piece will lay flat an the bench. Before we discussed fluting by phone, the flutes I had made were every 1 1/2″ apart, spaced where the drawings indicate no rivets; I had not used two flutes within the space, nor skipped any. I then tried two as you suggested within the two front-most sections between rivets on the nose ribs (the maximum curve on the ribs) with good success. Also, the little scratches I got with my fluting pliers were inspected by an A&P mechanic at our local airport. He said they looked great and asked how we do the flanges an the lightening holes…so I showed him your little wooden tool! He was Impressed.
Would you discuss priming our parts as we proceed. I am in a very damp climate and expect this project to take a long while. Should I be priming as I go along? How do you clean your parts before priming? Do you use any ultra fine sanding before priming? What kind of primer specifically do you prefer? Would dipping be practical for small stuff? Now I’ll pass along a couple of my experiences and solutions to date (for better or worse!).
Flanging the lightening holes gave me fits on two counts: getting the tool to do its job and preventing and eliminating warpage of the ribs. The solutions were as follows: Wax the aluminum on both sides before running the tool around (as was suggested Winter ’95 ). Place the rib flat on a piece of cheap, short nap, foam backed carpet. The carpet “absorbs” the thickness of the tool edge so you run it around the lightening hole and prevents scratching as you turn the aluminum for best mechanical advantage. That reduced the warpage which I further took out as suggested by running the tool around the flange from the top (Winter ’95)…with another modification! I found the wood blocks idea a bit hard for myself to manage. Instead, I used a scrap of 5/8″ plywood to make a full sized pattern insert for each size rib, complete with holes large enough so as not to touch the flanged edged of the lightening holes (precision is not important here). I also made a separate wooden push tool instead of using the butt of the flanging tool. It has a T shaped handle which helps distribute the push forces across my hand, and a slight concave to the contact end to keep it from slipping.
I’ve joined our Tallahassee EAA and through the club have gotten in contact with three members who are building RV’s, and also the mechanic mentioned above who owns a shop at the airport and is helping them. So I have friends locally for some of my “novice-builder” needs. Still, I hope each of us will share our experiences as we progress on THE BEARHAWK.
Roy Nash (009)
Thanks for the neat ideas Roy. Regarding priming/painting –
Prime spars for sure. Other parts can be primed as you go – degrease and SCOTCH-BRITE before priming. I use zinc chromate but others like epoxy primer should be even better, although harder to work with. STEEL PARTS should be bead blasted, primed
and coated with polyurethane or epoxy enamel. See SPORT AVIATION page 86 Oct ’95 edition for more information.
Bob
Dear Bob,
Thanks for the inspiring phone conversation we had in December. My close friend Julian Henley and I have decided to start building our own BEARHAWK before any more time is wasted! So — I’ve enclosed a check for a set of plans. We hope to stop by and see you in April or May.
As I mentioned to you before, there is heavily congested airspace in the northeast with the “BIG THREE” New York airports, Bradley International in
Hartford, CT, and Boston Logan Airport in Boston, MA, as well as extensive general aviation traffic. I would like to put a skylight in the ceiling area that
would go from the windshield back to the trailing edge of the wing, very much like a Champion Citabria or Decathlon. Could you possibly sketch out your recommendation for this, as this is very important safety feature up here in the northeast, and would be greatly appreciated.
Steven Wieczorek – Branford, CT
Steve,
Your plans are on the way. Working with another person during construction should help speed things up a bit, just be sure to do a little something EVERY day.
The skylight will be OK in the BEARHAWK. You may not want to run it as far back as you mentioned though. Past the rear spar the fuselage is starting to narrow and the contour of the roof is starting to round out. I would recommend that you run the skylight from the top of the windshield to the rear spar. Look for more information about this option in an upcoming newsletter.
Bob
Dear Mr. Barrows,
I received the plans set just a few days ago, and so far I am delighted at the prospect of starting the building process.
In going through the plans, however, I noticed a difference between what is drawn and what I saw at Oshkosh. I noticed that there are no aileron trim tabs, shown in the drawings. Do you recommend the installation of separate aileron trim tabs or would it be better to install a system to trim the entire aileron? Is
aileron trim even necessary?
Second question: Since I am limited on building space (until I move to a new house) is it advisable to begin construction of the ailerons and flaps before beginning the wings? Primarily I am wondering if the wing is needed before the control surfaces for alignment purposes. I would also like to start on the “small parts” to learn to work with and rivet aluminum before tackling such important components as spars. When I do get to that point, however, I will be sure to employ the experience of local EAA members.
Thank you for your time and I look forward to building my BEARHAWK!
Bob Spetz – Tempe, AZ – #118
Bob,
The aileron tabs you saw a Oshkosh were servo tabs, not trim tabs. It was found that servos were not needed and were eliminated from the plans before they were offered for sale. The servos would only add complexity to the design and slow down construction. The ailerons are just as light without them.
You can proceed with building the ailerons and flaps first if you like. The wing is not needed for these assemblies to take place if you build wing to prints. Starting on the “small parts” is a good idea. You may want to make all the ribs first (wing, aileron, & flaps) and then make the steel parts for the wing. And don’t be afraid to ask for some help from your EAA friends when it comes time to bend up those spars.
Bob
Dear Bob,
Enclosed find an ad for the Bear-Tracker Trader. Also enclosed is a check for renewal of my subscription to Bear-Tracks when the time comes.
Our wings are coming along nicely but are on hold now since my partner Gene Nelson is away for the summer presumably to escape the heat.
I am working on the power plant and prop drive which is to be a 383 small block direct drive Chevy. I plan on a conservative 200 H.P. at 2800 R.P.M. using Airflow Performance Multi-Point Fuel Injection system. It is a very exciting project. I am looking forward to seeing you at Oshkosh.
Regards,
Bob Cleberg – 042 – Tucson, AZ
Bob,
Thanks for the update on your project. I suspect you are going to get a lot of calls from fellow BEARHAWK builders about your engine conversion. There is a story in the April ’96 issue of KITPLANES about a similar conversion in a P6E Hawk replica, although it seems to be a bit heavy and will need to be installed inverted to maintain thrust line. Keep us updated as to your progress. ~ BOB
Dear Bob;
Please find enclosed check for Bearhawk plans. Many thanks – the rest is up to me.
Sure looks (and reads) like the ideal bush plane for my needs. I’ve been flying an O-200 powered Protech in and out of the bush for the past two years and have learned more about the power of prayer and “seat-of-the-pants” flying during that short period than in the previous 23 years with 3 different aircraft.
Do you happen to know if high compression pistons are available for the O-200 Continental, because I could sure do with a bit of extra “oomph” up front while I build the “Bearhawk”!
Best Wishes,
Charlie Janes – 202 – New Zealand
Charlie:
I think that the Chevrolet small block 4.00 +.060 pistons have been used in O-200 race planes for higher compression. The Continental C-85 pistons will also increase the compression ratio for more power.
Bob
Hi Bob,
I have enclosed the engine prints for the Javelin Ford 3.8L V6 for you to look over. Please give me your expert opinion – Will this set-up work? Thank you for your time and I look forward to your reply.
Randal Clark – 207 – Mayville, WI
Thank you for the data on the Javelin Ford 230 V6. This is the first time I have been able to closely investigate the specifications on this particular engine. My initial reaction is that this engine is a bit heavy at 395 lb plus the weight of the radiator, coolant, pipes and oil. You may be able to lighten the package up with a little creative thinking.
The Javelin engine dimensions are not encouraging either. The depth of the Javelin engine from the prop center line to the bottom of the oil pan is 20 3/4″ whereas the Lycoming is about 12″. The height of the Lycoming is 6 7/8″ near the front and the Javelin is about 6″ in this area. The basic cowl lines of the Bearhawk would not fit this engine installation. A builder redesign of the cowling as well as the firewall may be needed to make the Javelin conversion work.
I find weight and horsepower claims of most automotive conversions doubtful. You should do your own investigating in this area.
The Bearhawk as with any other aircraft, is much more enjoyable to fly if you keep everything light.
Bob
Dan Shilling’s Subaru-Powered Bearhawk
Source: 2014 Q2 Beartracks, Jared Yates
On a recent visit to Alaska, I had the good fortune of meeting up with Dan Shilling at Merrill Field in Anchorage. Dan graciously spent a few hours showing me his airplane and talking about how he built it, and how he uses it in Alaska.
Dan built his Bearhawk from scratch, over 8 years and 3300 hours of build time. As of now it has around 260 hours of flight time spread over 6 years. Dan was born in Alaska and is a minister by trade, and has always been interested in flying. He took his first lessons while living in Colorado early in his career. When he built his Bearhawk, one of his first priorities was minimizing his out of pocket expense. This explains why he was able to have about half as much money invested in his project as I do, but also about twice as much build time. It seems as though the cost and time variables are often interchangeable, a relationship that conveniently allows a builder to chose his priorities and proceed accordingly.
Dan shares a trait that I have found in many Bearhawk builders that I have met: he’s an excellent scrounger and seems to get a thrill from bargain hunting. For example, here is the story of how he got his spinner. “I scrounged the spinner for free off of a wrecked Maule. The spinner is the only thing that remains from that Maule. It had wrecked on a beach landing, and it was being sling lifted out of the area by helicopter. It was a pretty heavy load for the helicopter being used, and a bad gust of wind got hold of the plane and was about to cause a second crash when the helo pilot punched it loose into the ocean. I don’t know why the spinner had been removed since it was also damaged, but it now is a modified BH spinner. I hammered and hammered on that bent up thing to straighten it out.” Anyone can call up Aircraft Spruce and order a spinner, but how many folks can tell a story like that?
From the firewall back, Dan’s Bearhawk is much like the others that I have seen. He used the Polyfiber covering process with Polytone on the fabric and Aerothane on the rest. In Alaska, hangar space is practically unobtainable, so his airplane sits outside all year. I couldn’t help but note the unfortunate irony that the majority of airplanes in Alaska are not hangared, even though the weather and exposure there are about as bad as they could be anywhere. He installs wing covers in the winter, though they are a little bit tricky to get over the vortex generators. The condition of his finish speaks to the durability of the Polyfiber system; while it is not perfect, I thought Dan’s was one of the better looking birds on the ramp.
Notable deviations from plans include straight-bottom front doors (no mouse doors) and a skylight. The front doors don’t open quite as wide as those with a mouse door, but as he points out, they open plenty wide enough for him to get in and out of the airplane. Dan also incorporated a lever-actuated elevator trim system that is similar to the Patrol, though the lever points forward instead of to the side. By choosing this arrangement, he was able to eliminate the hump in the center of the fuselage and use a single, flat piece of plastic for the skylight. He added a hoop of metal to the top of the flap handle that makes it much easier to reach when the flaps are fully retracted. Dan’s tailwheel assembly and spring are right off of a Cessna 180, or as Dan said, “Right off of that Cessna 180 parked right there.” Don’t be concerned, the owner of the 180 was involved in that decision. After all, Dan is a minister, remember? 
On the 180 the bolts that clamp the tailwheel to the stinger had worked loose and enlarged the holes (see the safety update in this issue for a similar concern on the Bearhawk). Dan drilled the holes to the next bolt size up and the setup works great, though he’d like to consider upgrading to a wider tire for soft ground operations. The smaller tire tends to plow in those conditions, and while a wider tire is available, it also requires a wider fork, which is an expensive upgrade.
On the day of our visit, Dan did not have the back seat installed. Since he usually flies solo or with one other passenger, he prefers to not carry around the extra weight of the seat. He keeps a survival kit and minimal camping gear in the back, and has had to stop for an impromptu overnight on at least one occasion. Dan uses his Bearhawk mostly for local flights around his part of Alaska, though he also uses it to visit is parents in a fairly remote area near Fairbanks. A trip that would require 10 hours of rough driving only takes a little more than two hours in his Bearhawk.
I was also impressed with Dan’s creative flight control lock. Control locks are certainly not something to take lightly– they should be designed well to mitigate the possibility of trying to fly with them installed. But for an airplane that sits outside all the time, they are a necessity. He uses large diameter (12 inches or so) externally-mounted padded disks to lock the flaps and rudder in place, but for the elevator and ailerons he devised a lock that clamps the control stick to the long carry-through tube that goes under the front seats. He said that if he were to do it again, he would change the design from its current pivoting arrangement. As it is now, he must remove the pivot pin for flight, since he’s concerned about interference in the full-aft stick position. He also realizes the very remote possibility that inflight turbulence could allow the lock to swing up into place and engage. His improved design would be to incorporate the same type of fitting on the rear two corners of the triangle that he used on the front of this one.
So what about the engine? Auto engine conversions are a polarizing topic in the homebuilding community. They often present an initially appealing price that can easily be overshadowed by a much longer build time and complicated research and development phase. Engines are the sort of thing that are designed for a specific use, and the designers of car engines certainly don’t have small airplanes in mind as they make design choices that balance power, weight, longevity, maintainability, fuel economy, and ease of mass production. It is not uncommon to hear about a builder who has started with an auto conversion and eventually replaced it with a Lycoming or Continental.
Someone must not have told Dan all of that, because his engine looks like it was supposed to be there, and it has been working great for the last 260 hours. When I asked him why he chose the Subaru over the Lycoming, he said that he was interested in minimizing cost, and that he was interested in the challenge of doing something different. He started with a junkyard engine, though he eventually replaced the junkyard engine with a newly-rebuilt engine of the same type. The cost of the rebuilt engine was on the order of $3500. It sits “backwards” compared to how it would sit in the car, with the belt-driven accessories on the back end. The new front end is connected to a New-Zealand made Autoflight PSRU that gears the prop down to about half of the engine RPM. The intake is on the top end, and he made a custom aluminum manifold that saved considerable weight and bulk over the original. The car exhaust manifolds were cast iron, so he removed those and fabricated a pair of muffled 3-into-1 pipes out of mild steel. The radiator sits parallel to the white engine mount tube in the right side of the picture, and he had it custom-made for this application. An oil cooler sits just in front of the radiator, with the small blue lines connected to it. The prop is a 3-blade 80-inch Ivo that has electrically-adjustable pitch. I looked at the prop hub and raised an eyebrow when he told me this, since the blades are clamped rigidly to the hub. It turns out that instead of rotating a rigid blade assembly like the Hartzell does, the Ivo contains a spanwise rod that warps the prop blade to change the pitch.
Dan doesn’t have any way to know exactly how much horsepower he is getting out of the Subaru. He knows that his static thrust is around the same as a Lycoming O360 Bearhawk, but that’s at full throttle and around 4400 of the 5400 static RPM that the engine could safely produce. This is an issue that he’s still tinkering with, and his next step will be to try trimming the prop blades to lighten the load on the engine and allow it to turn up to a higher RPM. Static thrust only tells part of the story anyway, so short of comparing climb rates, cruise speeds, and takeoff rolls, it’s hard to say exactly how the Subaru is performing. It is getting the airplane around Alaska just fine, which is certainly worth something. From my discussion with Dan, it sounds like his flight performance is on par with what I see in my 360-powered Bearhawk, though he notes that his firewall-forward weight is probably more comparable to a 540.
From the pilot’s perspective, operating the Subaru is a little bit different. For example, when Dan checks his oil level before each flight, he also checks his coolant level. In the cockpit, there is only one lever, which controls the throttle. The prop control is a three position switch just under the VSI. The left bank of switches includes an electrical master and two electric fuel pumps. This is certainly an electrically-dependent airplane, and Dan has designed the electrical architecture accordingly. He has two PC680 batteries under the front pilot seats. If his alternator quits working, he immediately gets active notification in the cockpit by means of a loud buzzer and flashing light. At that point he has around 45 minutes to find a place to land. The two electric fuel pumps deliver about 60 PSI for the injection system, which is controlled electronically by a system used in other aviation and racing applications. That system also controls ignition and ignition timing. The panel includes an extra gauge or two, such as coolant temperature and fuel mixture. The rheostat to the right of the prop switch is a mixture control that provides sort of a “trim” function to the computer.
Just to the right of the rheostat you can see the horizontal LED bar that shows the mixture condition. We prepared the airplane to fly, and I was impressed with Dan’s passenger briefing. He pointed out the location of his survival gear, a reminder of his prudent preparation for the remote areas that he flies over. So by now you must be thinking, how does it fly? I can’t tell you that, because we didn’t have a chance to fly it. Dan did start it up on the ground and ran it for a few minutes. It started readily, and ran very smoothly. The coolant flow is thermostatically controlled, so it comes up to temperature quickly.
Throttle response was very fast with the lightweight prop. We didn’t get to fly because the winds were very gusty and variable. Dan seemed very motivated to take me for a ride, but I was impressed to see that in spite of that motivation, he decided to stay on the ground when he realized how strong the winds were on the ATIS broadcast. I strive to live by the old adage “the superior pilot uses his superior judgment to avoid situations that demonstrate his superior skill.” In this regard Dan is certainly a superior pilot, and I suppose that one doesn’t fly for very long in a place like Alaska without having good judgment and respect for environmental conditions beyond his control.
I asked Dan about the reliability of his engine, since that has been one of the talking points in the argument against auto conversions. He recalled two situations where he had to land prematurely, but in both cases he was able to get the airplane safely on the ground at an airport. In one case he had a coolant line break soon after takeoff. His more-experienced pilot friend Mark (owner of the aforementioned Cessna 180) was at the controls during the early test hours and as the line broke he could smell the leaking coolant. He stayed in the traffic pattern and landed without incident. After finding the broken radiator hose, Dan recalled that he had probably scored the hose during fabrication. The second premature landing was a case of bad fuel. This manifested itself as a partial loss of power and a rough running engine, but Dan still had enough engine power to make it back to land. Honestly it seems to me like these sorts of problems can just as readily happen to any airplane, and I don’t think it would be fair to say that Dan’s powerplant has been any less reliable than a Lycoming or Continental.
In closing I would say that Dan has an excellent machine that fits his mission. While the auto engine added a year to his build, it also yielded a firewall-forward cost around $9,000, not counting the subsequent replacement engine. His airplane shows the flexibility of the Bearhawk, and how it allows builders to prioritize cost and effort to find just the right balance for each individual case. Auto engines are certainly not for everyone, but neither is scratch building! If you find yourself in Alaska, I’d suggest contacting Dan to try to get together for a visit. He’s an interesting fellow and loves to talk about the airplane that he has every reason to be proud of.
LSA Builder Update from Rolly Clark
Source: 2014 Q1 Beartracks, Rolly Clark
Mr. Barrows flew down to 52A back in October to make up an engine mount for production at AviPro’s factory. He would be using my fuselage as a jig. I was very eager to see Barrows in person and look his LSA prototype over. I could hear him coming for about 3 minutes before I could see him. I was curious as to what he would bring with him. He brought an O-200 case, three sticks of 4130 tubing about 30 inches long (guessing), four steel disks about an inch in diameter, and some aluminum disks to simulate the Lord mounts. He also brought an electric grinder and a hack saw! I had tried to set my fuselage up according to the LSA Book, with everything plumbed and square and the string that represents the thrust line pulled from the tail to the spot where the engine case would set. After greeting, he went to work setting up my fuselage for the job. He said, “you’ve the right idea but we need to change a few things.”
He then took measurements from plumb bobs (he let me help) and made marks on the floor of my hangar, and generally got things organized. He admired the C-170 that was also in my hangar and told me how he used to fly one picking up and delivering engines to customers. After an uncomfortable experience with it, he decided he need an airplane that was better suited to his purpose. I took that to mean it had more power and room and easier to load and un-load. The result of course was the 4-place Bearhawk.
It was interesting to watch him work – not much wasted motion. He said a fellow named William Wynne would be driving up from Florida to help and this fellow was a Corvair aero engine expert. Well, that really got my interest up as there is a very active EAA group in Carrolton, Georgia, where they have built a bunch of Peitenpols and put Corvair engines in them. I had flown over there about a year ago. I watched them fly and looked them over carefully. That Corvair engine is very impressive and it does a good job in the Piets! Incidentally, these Pietenpols were modified a little and were called “Big Petes”. The main change was to make the small cockpits big enough for the big Georgia boys to fit. About the time Mr. Barrows got everything all set and ready, Mr. Wynne drove up pulling a covered trailer that housed his Air Corvair equipment.
After greeting all around, he pulled out a ramp and unloaded what he needed. It consisted of his MIG welding rig (gasp!) and his Corvair case, and his Corvair complete engine. Six cylinders and 110 HP!
What a beauty! Those gentlemen worked that afternoon and the next day and had two prototype engine mounts for production purposes to show for their work. I tried to stay out of the way while watching what they were doing. I would also go out to the LSA, which was tied down on the ramp, and look at what I thought I might find interesting. When all the welding, etc., was finished, Mr. Barrows offered me a ride. I am a very experienced pilot and it does not take me long to evaluate an airplane. It is a good flying airplane with good control harmony.
Control response is just right all the way down to the bottom of the envelope. It slips well, which is good if you are high on final. Mr. Barrows airplane is very basic with only the minimum required instruments – no electrics, no nothing. When I was getting in the plane, he handed me some earplugs! They were needed! The airplane is loud. There are no mufflers and exhaust pipes are right under your feet.
I plan on mufflers, and an electrical system on my plane. I am next to the ATL Class B and feel the need. Mr. Wynne went next and I watched the take-off. Not much runway needed! Rapid climb. Looked good. When they got back, I helped them load their equipment. Mr. Barrows asked me to give him a prop, which I did and then off he went back to Virginia. Mr. Wynne and I visited some more while he was finishing preparing to leave. He gave me some interesting advice about electrical needs on my airplane.
I hope to get this airplane done and in the air in the next several years, but in the meantime I look forward to the learning experience of building this unique airplane.