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.

EFII Experience in the Bearhawk Patrol

Source: 2018 Q2 Beartracks, Ed Meyer – Bearhawk Patrol N101EP (Co-owned with Paul Nowaske)
As promised on the Bearhawk Forum after a few requests, here is a write-up of our experience with the Electronic Fuel Injection and Ignition (EFII) system.
Why EFII
As a bit of background, I had a couple years of experience beginning 1969 where I worked in an FAA repair station overhauling Lycoming and Continental engines. My job was to overhaul accessories which included carburetors and magnetos. During this time I gained good understanding how they work and always thought that a carburetor in particular was a pretty crude way to get fuel into an engine. The one plus is that it is very simple. Later, in the ‘80s, automobiles transitioned almost exclusively to using electronic fuel injection and ignition and I observed that the reliability of our cars went up significantly without the frequent attention that the temperamental old systems required. We wanted something more modern for a new airplane.
The EFII system seemed to fill the bill. We opted for the dual system with many redundant components for reliability. We have two of most of the components in the system so that no single component failure will stop the engine. There are two crank position sensors, two MAP sensors, etc. driving two different ECUs. The ignition is driven by both systems much like dual mags where one set of plugs is fired by each. The injection is controlled by one system with a switch to change to the other if needed. This is always checked during run-up assure both are working properly.
Other considerations
The EFII system is 100% dependent on a steady supply of electricity for operation. Therefore we chose to install redundant electrical systems. We have the normal belt driven alternator plus a gear driven alternator on the vacuum pump pad. These each have an Earth-x battery. There is a main bus and an E-bus that each feed the redundant components of the EFII system. One of the optional components in the EFII system is a box called a Bus Manager that helps to insure power is always available. Given our dual electrical systems, the Bus Manager might not have been necessary but one feature included in it is automatic fuel pump switching if the main fails. I once had an engine failure in a low wing airplane which requires fuel pumping. After getting on the ground, luckily safely, and thinking about the events, I could not remember if the aux fuel pump had been turned on immediately. It was on after landing but I don’t know when it got turned on. Lots to think about when it got real quiet up front like where to land and such. The automatic switching appealed to me. This is checked at every engine start. When the system is first powered up, there is no fuel pressure so the Bus Manager switches to pump 2 automatically. Once the pressure comes up the selector switch can be set to number 2 then back to number 1, the main pump, it will stay on number one unless fuel pressure drops.
Installation
The EFII system has a good set of instructions for installation and we had little difficulty with following them. It required pulling the intake tubes from the engine and sending them in to have fittings welded on for the electronic injectors. (I understand the new System 32 EFII does not require this.) Also, the flywheel had to be sent to have a permanent magnet installed for the crankshaft position sensors to detect.
The EFII requires a fuel return line to be installed. We puzzled over this quite a bit to try and make this as simple as possible. Installation of a header tank was considered but rejected for a number of reasons. We finally decided to simply add a fuel fitting bung to each tank at about the center of the wing root rib lightening holes for easy access. A friend was a good aluminum TIG welder and did a first rate job on them. We opted for the duplex SPRL V4-4P fuel valve that includes left, right, both, and off settings for both the feed and return. Not knowing how much fuel returns, it seemed good to return it to the tank is comes from. I still do not know how much returns but I have since seen where some airplanes have return lines going to only one tank regardless of which is selected. This would be somewhat simpler than what we did but I would still want to know that the return volume is relatively small before I would opt for this.

We did have an issue installing the fuel valve. We had the lines all nicely run and hooked up and then during pressure testing it seemed the valve was not sealing as it should resulting in phone calls, emails, returning valve, etc. Turns out that we had installed it wrong! Somehow we had assumed the top section of the valve was the feed side and the bottom was the return. Not correct. After re-plumbing it was fine.
Our fuel system uses Bob’s design through the gascolator. Lines come from fore and aft of each tank to tee fittings inside the boot cowl then through the fuel selector valve to the gascolator. The EFII instructions state that a gascolator is “not required nor desired.” We chose to use it anyway for a couple reasons. It gives us a low point to sample the fuel for contaminants and it provides a screen ahead of the inline fuel filters that are supplied with the EFII system. One critique of inline fuel filters I have heard is that there is no way to tell if they are becoming plugged up. I think with the gascolator, if there were enough contaminants to be a problem they would show up there first.
After the gascolator, the fuel flows through the first inline filter then to the redundant fuel pumps which are under the floorboard near to the fuel valve. The pumps come mounted parallel in a manifold that has a single inlet and outlet. From there the fuel flows past the firewall to another large fine inline filter before going to the ‘rail’ which is hoses running to each injector in series. The picture below shows the secondary filter and fuel lines in-side fire sleeve running to #3 and #1 cylinders as well as the lower spark plug wires. From there a hose connects to the fuel pressure regulator which is mounted on the firewall. Then it returns to the fuel valve and finally back to the tank.

The ignition portion of the EFII installation is quite simple. The two coil packs need to be mounted and there were magneto cover plates provided that had mounting provisions for the coil packs. Crankshaft position sensors need to be installed near the flywheel on the front of the engine and the plug wires had to be made up to length but all the parts were provided. One of the advantages of the system is that it uses automotive spark plugs which are much less expensive than aviation plugs. Knowing we were going to use this system, we had Bob install cylinders set up for 14mm spark plugs when he built our engine. Even with the unshielded wires and plugs there is very little ignition noise in the radio. If I have the radio squelch open I can detect a small amount of noise that changes with the ignition checks during run-up.
Oxygen Sensor
One component that is separate from the EFII system but recommended is the installation of an O2 sensor and gauge for reading fuel/air mixture. In automobiles running unleaded fuel, the O2 sensor feeds back to the ECU so it can automatically adjust mixture for optimum. The EFII system does not use this feedback in order to maximize reliability since O2 sensors often fail, especially with leaded fuel. The sensor is mounted high in the exhaust only 3 or 4 inches from the cylinder head which is claimed to help it keep from fouling. So far so good on ours and I have heard of them going several hundred hours without problem. The mixture gauge, which gives a real time F/A ratio reading, is real nice to have especially when doing the initial setup of the system. In the picture at the right, the F/A mixture gauge is in the center above the EFII programmer with the mixture knob is to the right of it. The switch on the right is to select which ECU is controlling the injection with the 88 ECU normal. The key switch is left of the programmer.
Operation
The EFII system comes with a ‘programmer’ that provides the interface to adjust settings in the system. We opted to install the programmer in the instrument panel but it is not actually required during system operation. I have never changed any settings in flight and do not intend to. I have looked at some parameters occasionally but it is not easy to see in flight.
Before first engine runs, Robert Paisley, the man behind EFII, sent a set of values to update the default settings that were in the system. Robert spent 30 or 40 minutes on the phone with me describing what all the parameters are for and what settings I should change and what to be very careful of changing.
On first attempts at starting, it was somewhat slow to start. The system ECUs are identified and 71 and 88, which is a reference to the rotational reference of the crankshaft trigger sensors that drive them. It finally started by changing from 88, which is considered to main ECU, to 71 and adjusting the mixture knob richer. I later found that the selector switch was installed upside down, (amateur built you know) so it actually was on 88 when it started.

We ran it several times at various power settings looking at the mixture and adjusting until it was about right. This was done by setting the mixture knob until the mixture reading was about 12 to 1 then reading the percentage of knob adjustment on the programmer followed by changing mixture setting values for the various RPMs by an equivalent percentage and trying again to zero it in. This sounds like a lot of ground run time but it actually was not much.
I toyed with the idea of having someone with more recent experience than me make the first flight and there were volunteers willing. I opted to fly it myself mostly because of the EFII system being quite different and by now I un-derstood it better than anyone in the area. While flying I would carefully monitor mixture, adjust the mixture knob and then change settings back on the ground until it dialed in pretty well.
On early flights, the CHTs were a little high so we had to work on that. I think the biggest part of the fix was in-creasing the air outlet size at the bottom of the cowl and installing a lip. We also adjusted the baffles a little espe-cially right in front of #2 cylinder to allow more air to flow past the area that has very little cooling fins. One other change which seemed to help some was to change the timing a little at high power settings. This is also done from the programmer interface. I did not even open the cowling for this. It has settings that increase the timing up to 30 degrees before TDC above about 1500 RPMs. Additional settings retard it back a few degrees at high MAP. I in-creased these setting for a little more retard at high power. Especially for a new engine I would recommend that more retard is good at high power.
Normal Operations: Start-up begins with turn on of the fuel valve (the pump howls loudly if turned on before the fuel valve) followed by turning on the key (equivalent to master switch) which powers up the system. As previously mentioned fuel pump #2 comes on requiring the pump selector switch to be set to #2 then back to #1 which veri-fies the automatic switching function and verifies both pumps are operational. Once the EFIS boots up, I crack the throttle a bit and activate the starter switch. The starter can draw current from either battery or both and all this functionality came prewired with the Bus Manager. As it stands right now, when the engine is cold, I normally have to run the starter for a few seconds, pause a bit, and then activate the starter again and it fires right up. (I under-stand it is possible to update the firmware in order to be able to open the throttle a time or two the get the equiva-lent of an accelerator pump function providing a bit of prime.) If the engine has been run, even after several hours, it starts right away on the first try hot or cold. There are zero hot start issues.
Run-up includes an ignition check where power to each coil pack is turned off momentarily to ascertain that they are fully functional. There is no ‘mag’ drop when doing this. If anything there is a very slight increase in RPM. I suspect this might have something to do with flame propagation in the cylinders and the 1700 run-up RPMs. Also, momentarily switching from ECU 88 to ECU 71 during run-up verifies that ECU 71 system components all work properly. To shut down after flying: turn off the key. Just like a car. I normally turn off the fuel valve as well but having forgotten that a time or two created no issues other than some fuel migrating from one side to the other via the both setting of the fuel valve.
LOP Operation: With the EFII system it is easy to run well lean of peak. I am able to run it at about 16-17 to 1 and it still runs smooth. I can detect a slight power drop with it this lean but it stays smooth and CHTs drop about 20 degrees. According to Dynon, this is nearly 100 degrees LOP. I have thought about changing the settings for fuel flow to automatically lean like this at the RPMs I use for cruise which are generally anywhere from 2200 to 2400. I have been reluctant to do that because I am afraid that while increasing RPMs like starting takeoff, or going around, it might cause a stumble when going through these cruise RPMs. The benefit of this would be that the mix-ture knob could simply stay centered for all operations. Instead, for now at least, it is set to be equivalent to full rich when the knob is centered and when in cruise I can turn the knob to about the 10 o’clock position for LOP. This works easy and predictable. A good thing is that once set, it stays even when changing altitudes. A before landing checklist item is to reset the mixture knob back to center much like setting the mixture to rich for legacy systems.
Would I Recommend EFII? Yes. The engine runs very strong and smooth. I have no way of knowing how much power it is actually making but it feels strong and others have commented on the performance of the airplane. There is definitely a learning curve with the system. There is little doubt that it was somewhat more expensive than an old fashioned carburetor and magneto setup, especially with the addition of the second alternator and battery. Is it worth it? It was for us. I like it.
Robert Paisley adds: “Since Ed’s EFII installation, there has been a major update in the design of the EFII systems.
EFII is in the process of releasing all-new control electronics with many added features designed specifically for the needs of experimental aircraft. The updated EFII kit is called System32 – additional information can be found at www.flyefii.com.”

Exhaust Systems

The prototype Bearhawks had hand-fabricated exhaust systems made from thin wall, electrical conduit and have served the designer well for years. However, there are ready sources for custom Bearhawk exhaust systems, for those who want a stainless system and can’t, or don’t want to, fabricate it themselves.
Most builders have a system made by Clint Busenitz at http://www.vettermanexhaust.com/
Alternate suppliers:
Andre at Plane Xhaust in Fort Lauderdale, FL 866-312-4122 http://www.planexhaust.net/

New Stainless Exhaust Supplier

Source: 2015 Q4 Beartracks, Bob Barrows
These photos are of a stainless steel exhaust system copied after my de-sign, which I have been using with very good success on all of my proto-type Bearhawks. This set shown was built by Andre at Plane Xhaust in Fort Lauderdale, FL 866-312-4122 (they also have a website), for the Patrol built by Eric Newton, that I sold to Andy Corsetti in FL. The price is very good at $800.00/set. Thank you Andy for getting this done.15q4p

1998 Beartracks Mailbag, Q&A with Bob Barrows

Source: 1998 Beartracks, Bob Barrows

Dear Bob,

This is a formal invitation to come visit us in this area on your trip to Alaska. It is sure to be an exciting adventure and I am envious of you actually planning it. I often talk about going to see my old flying instructor (Ray Krumrey) in Old Harbor, Kodiak Island but haven’t got there yet. It is one of my flights of fancy to fly there in the Bearhawk and do a big impression on him. Ray is a great guy and we became good friends as a result of flying.

David Giles (#222) wants to meet you. He is an SDA Minister who flies an RV-6 he built and is barely started on the Bearhawk his son and he are doing. He is a really nice fellow – one of your fellow Countrymen originally – and he visits me fairly often. I’m sure that there are others who would like to meet you too. Another reason for coming is that you will be right on course for the “Rocky Mountain Trench” which will take you right to your destinations in Alaska. It will be a comfort to you to know that you will be flying over a lot of paved road (emergency landing strip). Be advised that GPS is definitely a good idea as there are very few other Nav aids in this North Country once you get 300 miles North of the Border. I haven’t actually been over but I am told it is great!

Progress on the Bearhawk is slow and steady. My Son has already dubbed it with the moniker “Times Two” since I have made so many things twice! I keep telling him that those were “test pieces”! However, the fuselage is largely done and I am working on the little bits and pieces necessary before I move it off the reference plane of the dead level and flat workbench I built from three 16ft TGI floor truss crops. Used 4×4 legs with adjustment bolts in bottoms. Covered top with 4×8 plywood with one foot overhang. Using other shipping plywood, I made shelves between the truss ledges. This works well as they slide out and is a handy place to store pieces of tube right under the bench top. Simple, strong and flat and it can be disassembled as I put the legs on with lag bolts and left about 4″ edge overhang!

Have all the wing pieces built but have not done any skinning of them. I got tired of pounding aluminum and switched to building the fuselage. This winter I hope to make the tanks and a lot of the hardware pieces like seats, controls, levers and such. The main idea for me was to have a project to keep me out of mischief! It has worked but I have also derived a great deal of enjoyment and satisfaction from building (to this point).

Bill and his wife spend their winters in Arizona. He got me onto this design of yours and has been a great resource with all his experience. He and another of his friends are building an RV-6 each. He likes to get upside down once in a while, he says! He sold his Stearman. The Airline driver who bought it had to get some old timer to fly it back East because he couldn’t handle it. After getting it home, the nerd wrecked it within a week! Wheel landed on wet grass area and hit some puddles of water. End of story! $50,000 later … ??? All the best,

Rod Dressell – *190 – Creston, B.C.


Dear Bob,

Do we need to consider increasing the vertical stabilizer/rudder size, or add a dorsal (ventral) fin for use with floats?

Thanks,

Bob Thomasson – #280 – Santa Rosa, CA

Bob,

The rudder will not have to be altered in size to accommodate floats. The vertical fin area may have to be increased to counter the side area of the floats. A dorsal fin bolted to the bottom of the fuselage will accomplish this. Weld in a bushing for a 5/16″ bolt at station G-K and use the tail spring attach fitting to bolt on the dorsal fin. I am not sure as to how much fin area is needed – you will need to experiment, and talk to other float pilots. Bob

Bob,

Keep up the good work, your newsletter is invaluable! … Still working on the wings.

Thanks

Brad Young – #229 – Spearfish, SD

Dear Bob,

Just a reminder that we wanted to be put on the list as one of those who would order struts from you. Fritz and I put the wings on last weekend. We had the fuselage setting sideways in my garage with one wing in and one wing outside of the garage. The door was covered with plastic sheet so we could heat the place. It took a day or so to get things squared up and the wings are off now and tucked away in their rack until next spring when we can paint them.

We hope to be done by the first of April ’98 if things go well.

Tom Lee – *98 – Winona, MN

Dear Bob,

Well, I’ve had your Bearhawk in the back of my mind since I read the Sport Aviation article 2 years ago. I poked around the airplane a OSH last year but never got to meet you or talk to you about it.

My RV-6 is almost rebuilt – after being run over by a Chevy, believe it or not – and I am contemplating a project where I can learn some new skills.

I work for Dick VanGrunsven and can get almost all the materials needed very reasonably along with access to all the metal forming equipment you could ever want.

So – what I’m thinking about is a minimal, light airplane – but with a battery and starter, hooked to the lightest six cylinder engine I can find. Say an 0-470? Do you think this is practical for a guy with minimal welding skills but good teachers?

Enclosed is a check for your flyer & – I hope – a collection of past newsletters. I write the one for Van’s, so I like to read other peoples! Addresses of Western OR or WA builders would be appreciated too. Thanks.

Ken Scutt – Hillsboro, OR

Ken,

Thank you for your letter and the request for information on the Bearhawk. It is interesting to hear that you work for Van’s Aircraft and write his newsletter.

Many builders of the Bearhawk are doing this airplane as a first time project and learning the skills as needed, from knowledgeable EAA members.

Please find enclosed a data sheet, photo, a selection of newsletters and a list of builders in your area.

Thank You – BOB

Dear Mr. R. Barrows,

I have received the drawings for the Bearhawk: The drawings are beautiful!

For your super excellent work – I send my graduation!

Yours Faithfully,

#209 Stefan Kjorcev-#308-Oberglatt SWITZERLAND

Tim Neal #209 sent in this photo of his project.




Bob,

A few questions as my fuselage is well on and I will need some answers to keep going.

1) For the rear door modification – you specify .032 alloy, would .025 be too light?

2) Will you be supplying a detail of the main doors in the newsletter?

3) What weight of alloy do you use for engine cowling – .020 or .025?

4) Routing of fuel lines from tanks and do you run separate line from the front and rear draw off points on tank and join to one in cabin or how do you do it?

5) Your method of attaching plastic sight tubes for fuel to alloy tank tubing?

6) Have you a fore and aft adjustable for front seats to seat long and short legs?

7) Some friends of mine at Oshkosh talked to you and took some good photos, a question on your exhaust system, by the photo: you appear to have 4 separate pipes, are they straight out and what is the noise like?

8) The trim system on your drawing #22; Do you need a friction disk or is there enough friction in the system? Is the trim chain a 1/4″ with a 12 tooth sprocket?

9) Positioning of wing attachment fittings on fuselage, the 32″ dimension is OK but the parallel dimension for both sides in relation to the spar fittings and lining everything up, my spar fittings are pilot drilled 3/16″, presumably the fuselage fittings should only be pilot drilled at this stage? These wings are quiet large compared to my Tailwind, so will you be giving a rundown on the fitting, lining up and setting dihedral, drilling and reaming holes to size, etc.?

10) Lift strut fittings, I have made up the wing end channel fittings, the double joggle in the fuselage end is somewhat more complex. What was your method of shaping? Also do you square cut the ends of the struts or angle cut to angle of wing and fuselage?

11) 1 know from a previous comment that you prefer a control stick and my Tailwind has a stick but I really want to have a yoke system with the Bearhawk. Much easier for females with a dress on and the floor remains relatively free of obstruction. Could I copy something?

12) Finally, the need for a fixed step up into the cabin like many aircraft have, my wife is not that tall.

Regards,

Ray Thurston – #5 – Blenheim NEW ZEALAND

Ray,

Good to hear from you again.

Regarding your questions:

1: .025 should be OK. 032 is better for the wear and tear resistance.

2: We will cover door construction in a upcoming issue of Bear-Tracks.

3: .025 is used. You may use .032 for the top.

4: The tubing is joined below lower front door frame with T section. (Upcoming newsletter)

5: Below is a sketch of what I recommend:

6: Yes – the same as a Piper Tri-Pacer. This system is nice in that as the seat moves forward it also rises lifting the shorter pilot up to see over the instrument panel, as it goes back the seat lowers giving the taller pilot more headroom.

7: I have 4 straight stacks out of the bottom of the cowling. I am told that they are loud but not unpleasant. I do wear earplugs.

8: No there is enough friction in the system.

9: See here.

10: I’ll cover the correct method for bending the end fittings in the next newsletter. Cut the strut ends square.

11: We do not plan to design such a system but you could copy the Tri-Pacer or a Cessna design.

12: A step is a builders option – check as designed on other tube fuselage aircraft.

Thanks for your letter and send us some photos of your project! ~ BOB

Bob,

I want to thank you again for your time and sharing techniques. I made another set of fluting pliers and they make a nicer crimp. I am also doing my rib lightning hole flanges a lot better, no warped ribs.

The idea of putting tape on the fluting pliers to keep from marking the aluminum really works. Thanks.

J.T. Newbegin – #284 – McAlpin, FL

Hi Bob & Mike,

Just got your newsletter, sounds like a lot of great activity with the builders. It also looks like you are getting close with Proto II.

I have enclosed a check for $250 for a pair of wing struts. I will be looking forward to getting them.

BEARHAWK 075 has fabric on it now. I am taping at this time and hope to have everything in silver in a couple of weeks.

The engine has not been installed yet, it will be a Ford Dura Tech 24 Valve 3.0 V6. I am converting the engine myself and have had to do a lot of searching to find an ignition/fuel injection computer system that I felt comfortable with. The original Ford system has too many extra input requirements and no adequate wiring diagrams.

After the engine is roughed in and the fuselage is on the gear I will send you some photos.

Have a great day!

Tom Yeomans – 075 – Richland, MI

Tom,
Sounds like you have made quite a bit of progress on your project. A lot of the builders may have an interest in more information about your Ford conversion. Keep us updated. ~ Mike

Chuck Frasier called the shop a few weeks back and had a question about the tail feathers. He was fitting up the elevator and found that the trim tab arm is rubbing the T-14 spar tubes on the horizontal stabilizer and the elevator.

To fix this you put a 10° – 15° bend in the trim tab arm under the elevator T-14 tube. You should clear the spars by a bit more than 1/4″.

Reference drawing #20.

Dear Bob,

Enclosed is a check for one pair of struts. I have finished a full review of the plans and worked out a material list. I bought all the .025 aluminum I’ll need and I am accumulating the other material.

Still trying to get my garage finished and other projects I had already started so I can start pounding out ribs. Is there enough strength requirement for using the 1/2″ X 1/2″ rib attach angles or can I make more than one forming block and bend up the end of ribs for attachment? I would rather make more forming blocks and save some weight unless the attach angles are required.

I have not seen in the October Sport Aviation article or in Bear-Tracks or in the plans any information on testing. Has the plane been flutter tested? Has the plane gone through flight testing such as dives to Vne, stalls at both ends of the envelope, light weight to gross?

Thanks for the help. Would sure like to see N6890R if you stop near Seattle on your way to Alaska this year. A visit to the Arlington fly-in would sure be nice for the west coast builders who can’t make it to Oshkosh but would like to see the BEARHAWK!

Wayne Hallburg – 266 – Centralia, WA

Wayne,
Thank you for the strut order – we will be shipping the struts (hopefully) before you read this. About your questions: Yes you can eliminate the angles if you wish but you must take into account the varying widths of the spars at different locations. The flutter testing was done during dives to Vne speed at 180 mph and stalls have been done at 1500 lb and 2400 lb gross with no unusual characteristics shown.

We are planning on attending the Arlington fly-in this year and hope to see you there. -Bob

Bob responds to a fax from Ray Thurston :

Ray,

In reference to your fax of 01/16/98 about the flap control assembly drawing #28: In checking the fit up on the BEARHAWK now under construction in my shop I did use the arm length as shown on drawing #28 but I offset it as shown below. In addition I moved the shock strut attach fitting (see drawing #24) up as high as I could and still have room for the rod ends HMX-76. This all gave me the clearance that I needed. ~Bob

Dear Bob,

Enclosed is a check for a pair of wing struts. I am also enclosing a photo for the newsletter. It is a picture of a die, made by Doug Jasper, for bending the flat plate pieces for the wing hardware.

It worked quite well and I think it is obvious how it works. He spaced the bars so that one side will bend .063 and the other side .080. I filed a radius on the edge of the male die, which is 3/4″ key stock, so one side does .063 and the other .080.

I just finished my steel wing hardware. I brought my flap and aileron mechanism to my EAA Chapter meeting last night and everyone commented on how nice they looked. Even had one person praise you for the engineering and how smoothly the mechanisms worked. I am now finally beginning to assemble my first wing. Slow but sure.

Pat Fagan – #232 – Pearblossorn CA



Dear Bob,

I am confused about the turnbuckles for the elevator where connecting to the bellcrank.

Drawing #26 says AN 135-32S Turnbuckle. I just ordered as specified and find on arrival when I was doing a trial fit that the pin eye is .25″ and yet the bellcrank says 3/16″.

The Cable eye likewise seems larger than required at .281″.

All parts are stamped and the turnbuckle is definitely AN135-32S. Would AN135-16S be more appropriate? Could you let me know?

Ray Thurston – #005 – New Zealand

Ray,

The AN 135-32S as called for in the plans is correct. You will need to make a bushing from 1/4 ” x .028 4130 tube, and use (2) AN960-416 washers as shown. ~Bob



While at Sun N’ Fun several builders brought pictures of their progress. Below is a photo of Larry Williams #184 project. Larry is using a Continental 0-470 for power. ~Bob


Bob,

I received the wing struts Saturday and the plans for the struts a few days later. Thank you. I received the cap strip material I ordered from Wicks last week and I bought some rivets to practice with over at the fly-in and flea market at Hampton Airfield on the coast of New Hampshire. I am a little nervous about starting the spars but I am sure that it will all go fine.

A friend of mine has landing gear and the gear shock struts that go on a 1947 108-2 and we were wondering if it would work on the Bearhawk. If so is it as strong as your design. What are your thoughts.

Sonny Cilley – #234 – Royalton, VT

Sonny,

I am sure that your spars will come out fine. It is just a matter of following the directions on the plans and in the newsletters.

The 108-2 landing gear system that you have is strong enough for the Bearhawk – but doing the engineering work to install them would be quite involved and time consuming. The time spent adapting the Bearhawk to accept the Stintson landing gear would be greater that just building the gear shown in the drawings. ~Bob

Bob & Mike,

It was great meeting both of you at Palmer, Alaska and I immediately dived into the plans and newsletters. Wish I had had the chance to study before going to Palmer but that is life in the frozen North.

As stated at Palmer, here is my check for a set of struts and drawings. I also want your wing construction and photo log, which will answer many procedural questions, I’m sure. May as well get the Disogrin ring set as I don’t want any delays for parts. While I have not yet ordered my 4130 and Aluminum, I have sent for all the books and catalogs recommended, made up a material list, made the wing rib form and acquired jig material (table) and a good shop to build in. All this since getting back from Alaska on August 12th. Being retired has its advantages.

I was in Alaska for about two months installing the water wheel power project for my friend. We are still evaluating the project, though the initial data
is quite favorable and slightly exceeds expectations after some modifications.

Hope all is well in Fincastle, do you think you might do Arlington again next year? I would like to have a list of Washington builders list and when available. In the meantime I will be attending the local EAA chapter meetings which I understand is loaded with talent.

Is there a drawing for the float hard points?

Just so I don’t miss any bets, please let me know your pricing for an 0-360. Thanks and looking forward to building.

Jack Piggott – #347 – Sequin, WA

Jack,

Thanks for the photos and letter. The struts have been mailed out along with the drawings and the o-ring seal kit. You should unwrap and oil down the struts when you receive them before putting them in storage. Mike has sent you a photo log that you should receive soon.

It sounds like you have really been chugging along on your project. Keep up a good head of steam because it is a long haul.

Regarding the float attach points, see the 1996 issue for rear float attach location, and use the front landing gear fitting for the forward attachment point. The fitting at the rear can be made just like the landing gear fitting if you like. We will work more with you on this area as needed. Do you have any idea what kind of floats you will be using? ~Bob

Mr Barrows,

Just a letter of introduction that is long over-due. I recently purchased plans s/n 188 from Mr Serge Valin the package also included the photo log and newsletters to October 1996. Enclosed is a check for all the back issue that I am missing and a subscription for 1999.

With any luck this winter will see me pounding out ribs. If there are any builders that are close to Detroit, I have access to a 10′ shear and brake for spars.

Mark Deacon- *188 – Brownstown, MI 734/789-1196

Mark

Your newsletters are on the way. I’ve included your phone number for builders in your area that may want to get in touch with you regarding the 10′ shear and brake. ~Bob

New Hot-Rod Bearhawk Patrol in Virginia

Source: 2014 Beartracks, Jared Yates
14q2oHatcher Ferguson and Don Aldridge have just completed their second Bearhawk Patrol, and it is a showcase of experience and ingenuity. The two built N22HD with performance in mind, and spared almost no expense. The fuselage is welded from a VR3 tubing kit, and the quick-build wings are from Bearhawk Aircraft. The engine started out as an ECI IO360, and now it flies as a fire-breathing 210HP example of “the best they could make it.”
Sky Dynamics of Moneta, Virginia modified the engine with a light-weight cold-air sump and induction system, lightweight flywheel, and 4-into-1 exhaust system. After the modifications Sky Dynamics ran the engine on their dyno to validate the performance gains. Two P-mags drive the electronic ignition system, and the fuel injection servo is from Don Rivera at Airflow Performance. Hatcher and Don Aldridge initially purchased a used Silverhawk fuel injection system on eBay, but the engine ran terribly with it. They took the servo down to Airflow Performance and found that it had been contaminated with water. Airflow Performance swapped out their servo for another, and now it runs beautifully. All of that power is turning an 80- inch carbon fiber Whirlwind prop, and Hatcher reports takeoff rolls consistently under 100 feet. Why did they install such a high performance engine? When I asked, the answer was along the lines of “to see if they could.”
Hatcher and Don know that the best way to further boost performance in an airplane with this type of hot-rod engine is to reduce weight. They considered weight savings in nearly every construction decision that they made. For example, they eliminated the skylight, rear seat throttle control and brakes, and the baggage door. They installed light-weight single puck brakes, used micro nutplates throughout, substituted #6 screws for #8 screws whenever possible, and minimized the size of welded tabs. The lightweight tailwheel assembly is Bob’s design, built by Eric at BHTailwheels.com. They redesigned the seats to reduce the width of the rear and increase the width of the front, and had a hot-rod shop shape the foam and sew the leather upholstery. The miniature Becker radio and transponder save a few pounds, as does the vacuum-pad alternator. The lithium battery saves approximately 15 pounds over a comparable Odyssey, but it still turns the engine over with plenty of gusto.14q2p
In some cases they added a little bit of weight to make the airplane more safe and functional. The LED lights and strobes give better inflight visibility to other airplanes, and allow for flights later into the evening when the flying is good. Hatcher says “they’re all LEDs, which hardly weigh or draw anything.” When that engine is running at full power and burning 17-18 gallons per hour, cooling is a concern. A cowl flap adds a little bit of weight but keeps temperatures normal. In the end, this airplane’s empty weight is 1168 pounds, 30 pounds lighter than their last.
A local expert helped fabricate a two-piece all fiberglass cowling. This doesn’t save any weight, but the new cowl is much easier to install and remove, and it has a more complex shape that reduces drag. The installed cowl is the third one made from the female mold. The first was two heavy, and they reduced the thickness of each of the next two. Hatcher speculates that they could save a few pounds by using carbon fiber instead of fiberglass, and fortunately they can use the same mold with carbon fiber to test that theory in the future.
What’s not to love about such an advanced flying machine? The paint, according to Don and Hatcher. Everything was going well as they applied the Polyfiber covering system to the powder-coated airframe. After they started painting top coats with the same Imron paint that they used on their blue Patrol, DuPont discontinued the product and they had to switch to the new “XL Pro.” The new product didn’t match the old product to their satisfaction, so they had to repaint several parts, at an estimated expense of 10-15 pounds. Hatcher says that he’s not satisfied with the way the paint turned out, but I’ve yet to meet an amateur airplane painter who will tell you he is. If the two fly it to Oshkosh next month as planned, I suspect that they won’t receive any complaints about it, especially if it is parked anywhere near mine!
The big question is, how does it fly? The specifics are still pending as they refine the calibration of their instruments. Hatcher reports that it handles just like their last Patrol, but has a much shorter takeoff, steeper climb, and faster cruise. They have only taken it on a few short trips, so they don’t have good cruise performance data yet. Hatcher says for local flights he uses about 13” MAP, 2300 RPM, and gets 100-110 miles per hour at 5.9 gallons per hour. If he runs the engine hard in level flight, his cruise speed begins to approach the realm of VNE, which is the main reason that their Patrol is a little bit slower than their RV10. Bob Barrows has flown the airplane and says that he likes the way it performs. Like most experimental airplanes, this new Patrol still has a few tweaks in the works. The static RPM is only around 2600, and Hatcher would like to gradually adjust it up to 2700. He would also like to fit a set of his giant wheel pants (for 6-8.50 tires) and build some fairings for the shock struts. I asked if they had kept track of how much they had spent on the project, and Don said “Yes, but we don’t discuss that!” with a laugh. Both are quite pleased with the way the airplane turned out, and I’m looking forward to seeing it in person!