N33RB Update from 2000

Source: 2000 Beartracks, Bob Barrows

The second BEARHAWK is now up and flying and doing very well.

Construction on this BEARHAWK was started in October 1996. The final F.A.A. inspection was October 19, 1999. Taking out the time spent on the Alaska trip and Sun N’ Fun and Oshkosh trips, building time was about 2 1/2 years. I attempted to do most of the work myself but did require Mike’s help about 5% of the time for operations requiring two people.

I did not keep a good track of the hours spent but averaged about 3 hours a day 5 days a week, which is about 2000 hours. This includes building the engine and the time spent on the propeller.

Cost is not relative since many of the materials were on hand from my shop supplies.

This BEARHAWK, N33RB, is set up with the Lycoming 0-540 260 HP engine, turning a three blade Hoffman prop with non-standard blades. The airframe is built to plans with the utility door system option. No back seats are currently installed as I plan to mostly use this aircraft for cargo hauling of engines and engine parts. I did install the thicker 3 /16″ windshield.

Test flying to date, Jan 5,2000, a total of 18 hours is as follows:

Speeds to 160 MPH

Stalls with little or no power. Stalls seem to be normal at all C.G. range placements. Breaks are straight ahead with no wing drop off.

Longitudinal stability is positive at forward C.G. and drops off to neutral at max rear C.G. loading.

Yaw stability seems normal with minimum adverse yaw and good strong rudder authority for slips.

Indicated Airspeeds to date are charted below.

RPM	MANIFOLD PRESSURE	AIRSPEED (MPH)
1800	18″	116
1900	19″	122
2000	20″	128
2100	21″	135
2200	22″	142
2300	23″	148
2400	24″	155

Tests were conducted at 3000′. Temperature range was 50-60 degrees Fahrenheit.

Landing speed indicated at touch down is under 40 MPH with 20 gallons of fuel and a pilot. Take-Off speed as above is at 40 MPH indicated. Take-Off distance is about 200 feet on grass and quite a bit less on a hard surface.

Thrust test shows 1200 lbs. at 27″ and 2700 RPM.

Landings have been made on both grass and blacktop with good control characteristics in all conditions to date.

I am using a tail wheel of the same construction that I designed and built for the prototype with a few modifications to use a 10″ O.D. tire in place of the standard 8″ size.

The landing gear was built to the drawings and causes the nose to set up somewhat higher than the prototype. This reduces the taxi visibility over the nose some but gives more prop clearance for larger diameter propellers. This also increases the angle of attack of the wing for take-off and three point landings. Over the nose visibility is as good as the prototype during flight.

Tests indicate that the engine thrust line (crankshaft center line) could be lowered 2″ parallel to the aircraft centerline if desired.

With the aircraft level as related to the lower longeron datum, the 80″ diameter prop has 15″ of ground clearance. 12″ is considered nominal for tailwheel aircraft of this size.

Bob Barrows and his two BEARHAWKS at Barrows Airfield.

The 260 HP BEARHAWK continues to fly very well. I am experiencing very smooth operation at 1900 RPM and 19-20 inches MP (lean). This seems to be the power setting that gives the best economy and reasonable cruise speed at 120 – 125 MPH. fuel consumption is about 1 – 2 gallons an hour more at the same airspeed in the Prototype.

1999 Builder Updates

Source: 1999 Beartracks

These two shots are from Kevin Deutscher #272 in Phoenix, AZ. He reports that he has finished his rib construction and is just about to finish up with his spars. He is about to move on to the wing assembly stage.

Kevin has invented the Multi Purpose Universal BEARHAWK Rib, Spar and Paint Booth Workbench called the MPUBRSPBWB for short – we might have to have a contest for the best attempt at pronunciation!

The wing to the left is Pat Fagan’s #232 Pearblossom, CA. He reports that he has one wing in the jig ready for skinning. He has his gas tanks finished and the other one ready to put in the jig.

Photo sent in by Wil Graft #365 of Wadsworth, OH. Wil has the left and right wings assembled and ready to put in the skinning jig. He has been busy acquiring and making tools. This is a shot of his deep throat riveter hard at work. He has also built a six inch wide heavy duty brake for the 4130 steel parts and a four foot sheet metal brake for much of his aluminum work.

The photo to the right – George and Velva Jensen #26 Frederic, MI sent in this great shot of their wing in the skinning jig. The Jensen’s are installing the extended range tanks in their wing. George reports that he has already fired up the wood furnace for winter work.

The two photos below are from Walt Draxler #82 Arlington Heights, IL. He is working on the ailerons and flaps. His work bench was big enough to do all four at the same time and keep the lefts left and the rights right.

Photo from Del Rawlins #316 Cordova, AK. This is a photo of the die that Del made to form the flap and aileron hinges in the hydraulic press. He patterned it after one that was in an earlier issue of Bear-Tracks.

Bearhawk Proto 2 Progress as of 1999

Source: 1999 Beartracks, Bob Barrows

To the left is a photo of the second Bearhawk that Bob is building. By the time you read this it will be through its first coat of color. Bob is going to paint this the same as the prototype.

1999 Beartracks Mailbag, Q&A with Bob Barrows

Source: 1999 Beartracks, Bob Barrows

Bob,

Thanks for the note of 10/17 and yes, the struts arrived safely this time. The outer wrap had a small tear that didn’t penetrate to the metal.

I usually work on the Bearhawk between 10 am and 6 pm with the odd interruption to run into Kent (South of Seattle) to Boeing Surplus, a good resource for used tools, new aluminum and such. I just picked up a 61″ x 151″ x .125 sheet of 2024T3 for $185. I am cutting main spar caps, splice and filler plates and attachment plates from this. The savings more than justify the 225 mile round trip.

I have joined the local 430 EAA chapter, but have not yet met the tech counselor. I will have to get them over here soon as I am close to completion of ribs. The spar blanks are ready, caps, slices, and other necessary parts should be cut this week-end so that riveting can begin. The 1/2″ x 1/2″ angles need cutting to length and riveting too.

I took time out to turn a set of punches and dies out of firewood (Alder, Maple, Madrona) to form lighting hole flanges. The photos show a couple of them and the drill press used as an arbor press.

I am ready to order the remaining aluminum needed and the 4130 tubing. I want to talk to some of the other builders in the state to see if my buying plan is viable. I bought the first batch from Airparts in KS and enjoyed their rapid and professional response. Cost are reasonable too, in my judgement.

Enclosed is my check for next years Bear-Tracks, an enjoyable and necessary adjunct to the plans. I am having FUN! Mostly because of the loving support of my wife, not to mention Dan Donovan of All Form Welding, who has given me free run of his shop and Joe Ritter, who has made his shop (2 doors away) available as a good neighbor! Now – if I could just line up a good bucker. Best Regards,

Jack Piggott – #347 – Sequim, WA

Dear Bob and Mike,

Enclosed is my renewal check for Bear-Tracks and a photo of my Pile-O-Ribs. After finishing the ribs, stiffeners, attach angles I got got tired of forming aluminum and have been having a good time making some of the flat 4130 pieces for the wing hardware. I am hoping to run out of my last order of material about the same time I start my flying lessons in early ’99.

I do have one question for you – I’ve looked over the plans and newsletters and can’t seem to find any detail on the tail spring anywhere, other than how to attach it. Did you make the spring, or is it a salvage unit from a production aircraft? The reason I am asking so far in advance of needing one, is if time allows I plan on doing some parts scrounging while I am in the states and have been making a list of items to be on the lookout for.

After further examination of the new struts and the revised drawing, I think an additional thank-you is in order for making them available to your builders. I really was not looking forward to making and attaching the original design fittings. I’ve constructed a substantial crate to store my struts in so that they should be safe until I need them.

Del Rawlings – # 316 – Cordova, AK

Del,

Thanks for the photos of your wing ribs, they look nice. Regarding the tail spring, I used some that were found at the airport here. It depends some what on the tail wheel you use. Also if you can’t find one that will work – you can have it made at a local auto spring fabrication shop. I will be providing more information on this subject in future newsletters.

Also we are now testing a homebuilt tailwheel assembly we designed and built. If it continues to work as good as it has been we will provide drawings for same with spring details.

~Bob

NOTICE: In an effort to get builders to send in photos of their projects we have decided to try and bribe you guys! Starting with the October issue if you send in a photo of your project your name will be put in the running for a very nice BEARHAWK HAT! We do not care what stage of construction you are currently at – we would just like to see your progress. Even if all you have done is your wing rib form block send in a photo!

Bob, Well after many other projects finally out of the way #235 is under way! The shop is heated and finished, my first shipment of aluminum is here and I have started cutting out nose ribs. The aluminum sure is a lot cheaper when I buy it through work at wholesale prices. It is less than half what I’ve seen advertised for. Sorry that I missed you at Oshkosh last year, I was only there for 10 hours on a charter flight. I did speak to Mike briefly, sounds like it was a great trip to Alaska. If you decide to come look at some land up here (your dollar is still valuable) drop me a line. I’ve enclosed an international money order for the newsletter renewal.

Mike Guthrie #235 – Ontario – CANADA

Hi Bob, I have a question about building the control surfaces I hope that you can answer. What kind of a jig did you use while assembling them? I am trying to build the ailerons, but keep having to start over, trying to keep everything straight and aligned. Any kind kind of suggestion you can provide would be appreciated. We are almost done riveting the skin on the left wing.

Pat Fagan #232 – Pearblosson, CA

Pat, Good to hear that you are progressing smoothly on your wing skinning. We did not build a jig to align the flaps and spars. Find a perfectly level – flat table to assemble the flaps and ailerons. Start out by skip riveting the nose skins along the spar every 4 – 5 holes to keep the movement of the parts to a minimum. Check the fit to the wing and drill out rivets on the top side of the skin and re-cleco and c-clamp as needed. continue to skip rivet and rechecking fit until all rivets are in place. The pull rivers are to go in last. I think that you will find this method to work best with minimum re-dos on the rivets.

From the Internet:

On drawing 20 1 had not closely looked at the tube sizes. I thought that a larger tube slid over the front horizontal stab tube and was welded to it. Now I realize it is two 7/8″ tubes of different thicknesses butt spliced together. Is this the intent? For slightly less than 1 pound extra weight, I will make the entire tube out of the .049 material. This will have the added advantage of being more resistant to rock strikes. I had some nasty dings to patch there on the Maule that I rebuilt. Drawing 16 shows the airfoil shaped trim made out of 1/2 by 1/2 .032 channel, I am wondering what method you use to get a smooth bend around the nose of the airfoil? I have access to a shear and a 12′ brake at work now so I brought a 72″ x 18″ sheet of .032 4130 with me to make all the T25 channel pieces with. They gave me a bit of a hassle about checking it on as luggage on the company 737 but I got it here. In a fit of insanity I agreed to an extra week of overtime, so I am imprisoned at Prudhoe for 3 weeks this time.

Rod Smith #246 – Wasilla, AK

Rod, For the more punishing environment that you will be flying in it is OK to bump up the tubing thickness to .049 – the thicker tubing will be a bit harder to work with and you are adding weight back. Since you plan on a electrical system though the weight penalty should be negligible. As for the airfoil shaped trim piece, it is made out of 1/2 inch channel. Numerous “V” shaped cuts were made to make the bend for the airfoil shape. The notches were then welded together. This trim piece and allows for a tight fit of the windscreen so it is OK to file the welds flush. ~Bob

Bob & Mike, Enclosed is a renewal check for Bear-Tracks and the landing gear shock strut seal and snap ring kit. I enjoyed meeting both of you at Arlington and I am glad to hear that the whole Alaska trip went well. The opportunity arose for me to buy all the tooling and miscellaneous hardware from an RV builder who became ill and won’t be building any more airplanes. I also picked up a Scott tailwheel and other miscellaneous items. I’m real anxious to finish my shop and classic car projects so I can work on the BEARHAWK only.

Wayne Halliburg #266 – Centralia, WA

Hello Bob, Another year has come and gone and more BEARHAWK parts are being made. After a short slow down to add on to the house and other “little” things I am now back at work on my project. I spent 8 hours on a Bridgeport milling machine last week squaring and cutting to length all the web supports (1/8 x & 1/4″) for both main spars and next week I will do the same for the rear spar. We squared up the inner front attach plates and I laid them out and they went together easy, the jigs for the spars should be simple. I ordered the fiberglass wing tips from T.Q. Fiberglass.

April 12th will be 2 years into this project, but I’ve only got about 330 hours into it to this point. As for powering my BEARHAWK I’m leaning towards the Franklin 205 HP engine, everyone that I’ve talked to seems to think a lot of them.
I was glad to hear your trip to Alaska was a success and I enjoyed reading about your adventures in the newsletter.

Sonny Cilley #234 – Royalton, VT

Sonny, Good to hear that everything is going together so well. It looks as if you are keeping a good record of your build time and you seem to be right on track hour-wise to a 2000 hour build time. If you just find a couple of hours every day you will get more done than trying to work on it 8 hours on one day.
We found the T. Q. Fiberglass wingtips to be of first class quality and hope that you do to. Let us know how you like the quality and the service that you received. -Bob.

Howdy:

Just set up the jig for my wings today. Took the whole day to get everything square and level. Will spend next weekend finishing and fitting the fuel tank and determining where the holes for the lines will go and double checking the fit of the tank straps and then, finally, I will put the 1st wing in the jig.

I had, as did others, a problem with the aileron cable at the pulley located at the web splice that takes the cable down the wing strut. I solved the problem by clamping the bracket to a solid work bench with 2 LARGE c-clamps. Then I tapped the top of the bracket with a hammer just a bit in the direction that was needed. When I reinstalled the bracket and pulley, to my amazement it lined up dead on. It only took a small tap as the misalignment is very small.

Tim Neil – # 209 – Uniontown, PA

Tim: Thanks for the update on your wing construction – you should really enjoy the skinning process as it progresses.

Regarding the pulley/cable line up. I have investigated this problem and found that the bracket as drawn on the prints is not located properly. This condition has been in use on the prototype and has not shown a wear problem yet. Your fix sounds like a simple effective way to modify the bracket for the builders who have already made this part.

I will be working up an engineering notice on the bracket in the next issue of BearTracks. ~Bob

Mike and Bob,

Would like to thank you for taking the time to show me the BEARHAWK. I’m sending you the info I have on procuring alodine. You can order the crystals from a chemical supply house for approximately 30 dollars. It will probably last you a life time or divide up cost among people you know. Alodine is chromic acid and you can normally get it in clear or yellowing. I use the yellowing to verify coverage. I believe I found this info in Sport Aviation (August 96). 1 tore out the page and I’m no longer sure which aviation mag it was out of. If you have problems locating supplier drop me a line. Best of Luck

Chester Abbott Ocean Springs, MS

To BEARHAWK dreamers and doers,

I had the pleasure of spending the holidays with Russ (Erbman) and his family. I also had the distinct pleasure of helping with the riveting procedure on the rib stiffeners and the wing spars.

You must realize that I was trained (50 years ago) to SPRAY EVERYTHING WITH ZINC CHROMATE primer. I have seen the development of epoxy primers. In both cases solvents are needed for cleanup. I don’t care what anyone else says, I DO NOT want aircraft solvents around a house that my grand children (and their mother) live in.

I had difficulty reminding myself that the white parts were primed and not top coated. They were not green.

I may be prejudiced, but Russ did a beautiful job of spraying the parts. I was impressed with the working life of the primer when we were brushing a coat of primer on the mating surfaces and then riveting. The sealing of the edges between the cap strips was excellent for the initial seal.

In case you did not catch on, I think the Poly Fiber Primer is Terrific. I forecast that within 5 years after the commercial release of the primer, it will be the most specified primer on new designs in the aircraft industry.

Lee H. Erb, P.E.

Wow – Give you guys a little incentive and you really come through. We had about 10 entries for the BEARHAWK hat drawing. If you sent in a photo – your name got tossed in the hat (the very one that you could win). Mike drew the winning name on Oct. 12. The winner’s name is on the last page of this issue. We will do this again for the January 2000 issue – so send in those photos.

Bob, As per our phone conversation the other day I am sending you these questions as you asked to include in the newsletter.

1) There seems to be a 1 1/2″ – 2″ gap between the wings and the fuselage and I wondered how you went about covering it?

2) With the rear window frame, do you have the outside of the frame flush with the door frame and if so how do you get the window in?

3) On the plans it looks like the aluminum fairing on the landing gear legs only covers to the rear leg. Is the front section covered with fabric? Do you run your brake lines inside the fairing?

4) Could you give me the details of the tail spring, length of spring and height of fuselage from the ground?

5) Do you have your rudder cables run along the lower inside of the fuselage with fairleads and do you use a turnbuckle on each side?

6) How do you attach elevator and trim levers inside the the fuselage when it is covered?

7) How many inspection holes do you have in the wings and what areas and size?

8) By the photo it looks like you have a fairing around the top of the landing gear to fuselage, also top and bottom of the wing strut, are these all fiberglass?

9) With the strut at the front of the rear stabilizer is the top just flattened or is there a piece welded to it?

10) The lead balance weight in the elevator, did you mold the lead piece in place or mold separately and attach later?

Merv Hargraves – #362 – Queensland, Australia

Merv – Thanks for sending in the questions, and the photos of your project. In regard to your questions:

1) I used .025 2024 T3 aluminum to cover this gap. It is similar to the fairing used on a Piper Tri-Pacer or Pacer. Attach to the wing with screws.

2) The rear window frame is just slightly outside of flush to allow the window to slide in.

3) The gear legs are covered with fabric and the brake line is inside mounted on tabs to the rear leg.

4) The tail spring is similar to those used on Maule aircraft. 3 or 4 sections 1 1/2″ wide 1/4″ thick, with the two main sections about 16″ long. The fuselage is 18″ off the ground.

5) Rudder cables run inside fuselage until about 19″ in front of tail post, where they exit the fabric to connect with the rudder horn. I used four fairleads located at Sta C, D, F & H to support the cable.

6) Make an access cover 9″ x 8″ on each side of the fuselage at a location centered on the top longeron and about 2″ in front of the tailpost.

7) 1 used 6 inspection holes in each wing one at each pulley, aileron bellcrank, flap spring attach points, flap arms and the strut attach fitting on the front of the spar.

8) The fairing at the top of the landing gear is .025 2024 T3 aluminum attached to the T25 channel and the .032 fairing support with screws, use rubber edge material around the top of the fairing so as not to damage the fuselage fabric as the gear moves. The fairings at the bottom of the struts are fiberglass (see ad in the back of this newsletter to order).

9) The strut is just flattened, bent and welded around the edge.

10) I molded separately and cut to fit but it could be molded in place if you like.

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 V_ne, 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 V_ne 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

1997 Beartracks Mailbag, Q&A with Bob

Source: 1997 Beartracks, Bob Barrows

The mailbag has been stuffed the last few months. A lot of good progress has been made by several builders who want to pass along information. A lot of questions about different powerplants are being raised about everything from Fords to Chevys to turbines and everything in between.

Bob,

I’ve been thinking of using a Turbo-Prop engine in my BEARHAWK. Turbomach T62 t401c1 (Solar) of 225 SHP available new surplus @$4750. However I need to find a matching gear reduction unit (PRSU) for approximately 2.5 or 3 to 1 reduction and constant speed prop unit. I haven’t been able to work out the details yet but I will make engine and cost comparisons this winter and work on the installation problems too.

I am somewhat familiar with turbine engine conversions as I assisted in a COX TURBINE OTTER conversion in Seattle, WA and have 30 years experience as an aeronautical engineer with Boeing.

My hope is that a turbine combination will result in lowest empty weight for maximum performance at similar cost compared to the Franklin 220 and Lycoming choices.

Paul Hubble – #126 – Deer Park, WA

A letter off the net –

I finished building a Murphy rebel in April of this year. I now have 60 hours on it and it flies real nice. Out here in the west (Barstow, CA) density altitude is a problem. I decided to build the BEARHAWK to get a little more room and also a larger engine. Right now I am leaning toward an auto conversion by Belted Air Power, of Las Vegas. They use brand new Chevy V6 engines and sell a complete firewall forward package for the RV-6 for $8000. We looked at it at Copperstate and liked it. It puts out 225 hp and uses a belt drive reduction. Bob Barrows was right in one of the newsletters when he said not to worry about the engine until it is necessary. I learned that from the Rebel, I rushed into buying a Lycoming O-235 and now everyone is using O-320’s.

I have started building ailerons and flaps. I got to the point where I needed
spars. There has been some concern lately about purchasing spars and I thought you all might like to know what I did. We have a heating/sheet metal shop in town. I took two sets of .032 blanks to the shop with the spar drawings and described what I needed. I now have four spars and the trailing edges all for $80 in labor. They did a nice job but I had to educate them in using 2024-T3. No sharp bends or scratches. I had them look at the information in the newsletter on bending the spar webs and trailing edges. I think it would be worth looking in to for other builders.

Rich Bartman- #18 – Newberry Springs, CA

Bob,

Could you give me the phone number and address for the manufacturer/supplier of the square section coiled springs for the undercarriage.

Also included are a few photos taken a little while ago. I am now preparing to skin the starboard wing.

Ray Thurston – New Zealand

Ray,

Thanks for the letter and the photographs of your wing and fuel tanks. They both look real good.

The springs for the landing gear are made by three different U.S. companies that I know of. Dayton, Dieco, and Danly. Use the Dayton spring if you can, the part number is EH 200-800.

Dayton Progress Corp – 500 Progress Rd – Dayton, 0H 45449-0039 – USA Ph-513/859-5111.

The springs should be about $40 each.

All builders are invited to send in photos of your progress for publication in Bear-Tracks. – Bob.

Bob,

Enclosed please find a check for another year of Bear-Tracks. I show one more issue left on my current subscription. I have begun construction on my BEARHAWK and I have a few questions I am hoping you could address. How critical are minor scratches in aluminum parts? Is there a way to fix this? Do you recommend priming all parts before assembly? What is the best way to measure rivet spacing on ribs (for fluting purposes). And one last question, what method is recommended for cutting aluminum plate? Thanks for a great design and all of your help.

Kirk Urbanczy – #166 – Palm Springs, CA

Kirk,

Thank you for your newsletter renewal, please note that subscriptions for the newsletter run from year to year, not the date of purchase of the plans. Regarding your questions:

Keep the aluminum as scratch free as you can. Scratches you can feel with your fingernail should be sanded with 400 grit sandpaper till smooth. Priming all aluminum parts separate is best but you need only to prime the spar pieces before riveting together. Measure rivet spacing according to information on the drawings and flute half way between each rivet. Once one rib is done it can be used as a template for the others. Cut aluminum plate .062 and thicker by sawing or shearing, .050 and thinner can be cut with large duck bill tin snips.

Bob

Bob,

I like your advice on things like cargo doors and more fuel tanks, I will opt to do none of them. I am plans #198 and have all of my ribs just about finished. Thanks for a great set of plans.

Larry Mader – #198- Spearfish, SD

Bob,

Don’t feel bad about not providing a materials list. John Thorp didn’t provide one for the T-18 and he finally told the builders that all of his time was spent on designing, drawings, etc. and it was something he couldn’t get to. So you see – life repeats itself right?

I have to build a house before I start my BEARHAWK but I will do a list if someone doesn’t do it first.

Here’s a tip from the book The All Metal Airplane perhaps you might want to pass it along to the builders. “When working on sheets of aluminum
staple corrugated cardboard to the surface of your bench. The little aluminum particles will fall into the corrugations and will not scratch your sheets. ”

Donald Schindler A&P – #68- Madison, WI

Bob,

Last week I sold my French wood project Yodel DR315. I had to work really hard to sell it so I have not done much on my BEARHAWK. I am trying to sort out some paperwork before I pay and ask Swedish EAA chapter about the building licence. I have to ask you some questions:

1- What about the formblocks for ribs that go inside the spar (see drawing) should I take away a little bit on formblock?

2- For welding in Sweden EAA chapter 222 we have to test for it, then we get a license for 6 months. I have spoke to one boy who has got a license and it looks not easy, even if you have got experience. Do you know anything about the ready build frames for the BEARHAWK? Quality on welds, price and so on?

Thanks for interesting Newsletters and hang on with God Speed and Quality Bob!

Sune Larsson – #172 – Gislaved, SWEDEN

Sune,

Thank you for your letter, regarding your questions,

The rib shape at the spar interface does require some modification to your formblock. I have put a jog in the rib flange as shown in the drawings by slightly undercutting the formblock as you stated.

I am currently building up another set of wings to see if the wing skins will fit up well without the jog. So far everything looks good. Look for more information in upcoming newsletters.

It is best that you weld your airframe together, as the U.S.A. suppliers are not set up yet. A&E is no longer offering BEARHAWK parts as he is trying to get out of the business. One option you might explore is to tack weld your fuselage together and pay someone, skilled in aircraft welding, to come in and weld it up for you. If you have the airplane tack welded together it should take no more than 30 – 40 hours for a skilled welder to do it for you. Check with your EAA chapter to see if this is legal in your country.

Bob

Bob,

First of all belated “Happy New Year” to you and yours. I hope yours was a most blessed Christmas. Ours was! Among other things, we were blessed with over 8 feet of snow! You have probably heard of the roofs caving in from lack of shovelling.

Said shovelling is what has occupied most of my fall and winter. Aside from a terminally short memory, it is my only excuse for not having renewed my subscription. Enclosed herewith is the required U.S. funds along with a request to bring me up to date.

Progress with this project has only been fair. I have all the rigs made, stiffened, primed with angles riveted in place. A tip for others is offered: Selecting appropriately sized short ends of pipe and bevelling in a lathe made the punch to press the edges of lighting holes into the matching recesses cut into the wood rib former resulting in a very smooth, stiffened rib. I cut the recess in the rib form with the same circle cutter in the drill press but used a specially sharpened tool bit. Keeping everything concentric was easy using the same sized 3/16″ jig pin hole into which torx drive screwdrivers (for one thing) fit perfectly for alignment! For pressing, I used a Dake arbor press with a clamped down work piece. The rings used to clamp the rib flat around the outside of the circle were large ball bearing races that are fairly common.

I encountered considerable disappointment with my first spar. I am now awaiting new material to build another (as I unwittingly only ordered half enough the first time). For a first time builder I could have used a lot more tips to avoid a lot of mistakes. I found that the cap strips moved considerably as I progressively riveted them on. The result was a lot of clean-up drilling of holes and too many epitrochoidal shaped holes reminiscent of a rotary Wankel engine! The killer was a preacher friend who lives some 90 miles away but who has experience building an RV-6. His critique was devastating and I nearly gave up. Fortunately I have some very loving and supportive family members who encouraged me onward. One was a sweet 20 year old step-daughter (Miss Creston 1993) who said “Don’t give up, I want to fly that thing when you’ve got it done.” Hey, how could I quit, eh?

I have all the steel I need and lots to do, but other loved ones need attention too. One in his rush to meet the growing demand for gas-heat and another who decided to build a new house in August. He is moving in this weekend. So it has been a busy but blessed time. My friend in Arizona calls every now and again to tell me how nice it is down there. I think he still has his Stearman and is nearly finished with his MonoCoach fuselage that I worked on with him last winter down there. He is still contemplating a BEARHAWK but can’t seem to justify a fifth aircraft to his wife. I told him to be more assertive. She about threw me out!

With the snow having caved in a local hanger on a 182, 1 just might have a line on a engine, some avionics and some other parts. We are dickering! Have a Great year!

Rod Dressel – #190 Creston,BC, Canada

Rod,

Thanks for the interesting update on your project. I hope the construction of the BEARHAWK is going more smoothly for you now. You are lucky to have such a supportive family during your building process.

I just built another set of spars and do not remember any problems with the holes, but I decided to revisit that in this issue of BEAR-TRACKS in case any other builders are having problems.

Our banks charge $12 to cash a foreign bank check even if it is in US funds like you sent. Please send an international money order or cash in the future.

BOB

Bob,

Moving right along beating out ribs on #164. 1 have a few questions that I could not find the answer to after studying the drawings.

What is the thickness of the material for ribs 3 and 4 (the short ones behind the fuel tank)? .032
What is the thickness of the material for the flap ribs? .025
What is the thickness of the material for the aileron ribs? .025

Thanks,

Russ Erb – #164 – Edwards, CA

Russ,

Sorry that info was not on the plans. I have now added that information to the plans. Thanks for your questions.

BOB

Bob,

I have just been doing a cable run check in the wings prior to putting them to one side to start on the fuselage.

I had previously checked the aileron cables before skinning but I did not have the flaps in place at that stage. Now I find that the flap push rod in about mid-position just makes contact with the cable in this area.

1) Could a fairlead be positioned in this area to give, say, 1/4″ cable clearance with the push rod? The cable should not be more than 2° – 3° from straight.

2) One other thing is the flap actuating lever attached to the 3/4″ torque tube at rib #1, 1 have positioned this lever as per your drawing N. 14, it would seem that the aileron cable passing through the fairlead at rib #1 may touch the end of this arm.

Would you please advise me on these points so that I may proceed with the project.

Regards,

Ray Thurston #005 – NEW ZEALAND

Ray,

I hope the wing building process went well for you, I think you will really enjoy building the fuselage as you will have something that will look like an airplane soon!

Regarding your questions, 1) The aileron cable touching the flap push rod is not serious, the fairlead in this area would be a good idea though, I have noticed this same situation in the prototype. I am considering installation of a plastic sleeve on either the push rod or along 8″ of the cable to stop a metal to metal rub on the prototype.

2) The actuating arm at the end of the torque tube may be shortened enough to eliminate any interference with the aileron cable.

Good Luck – Bob

Tom Yeomans #75 – Richland MI gave us a call at the shop to order the new strut material and report that he has his wings just about done and his basic fuselage welded up ready for its gear.

Hello Bob,

Hope this finds you and your family well!

S/N 52 and 53 going together slow but sure. We will be skinning wings in a few weeks.

Sorry, but I let my Bear-Tracks lapse – my last issue was October 1996. Could you please start me up at the next one after that? Thanks! Please send me a set of the Disogrin Rings. Check enclosed to cover the newsletter and rings.

I have a few questions :

1) Where do you pick up your static pressure for instruments?

2) Is the bottom skin (tip to #5 rib) .025 or .032? It is not on the plans but I had a bug that it was .032?

3) From the newsletter illustrating skinning was not clear as to which way the step on the bottom of the front spar goes, bottom skin on top or vice versa?

4) Do you know of any adverse characteristics of using A-10 warthog style wing tips?

Thanks, Be Well,

Douglas Jasper #53 – Corona, Ca.

Douglas,

Your newsletters to date and Disogrin rings are on their way. In answer to your questions,

1) I did not run a separate static line to the outside, take a look at production aircraft similar to the BEARHAWK (Maule, Cessna 180, Super Cub) to get an idea as to where to place one. You may also check out Tony’s books for more information on this subject.

2) The skin you mention is. 025 thick in that area.

3) You can attach the skin either way but the best sequence is as I have illustrated (in sketch #2 note the riveting sequence for ease of bucking rivets):

4)That style of wingtip should be OK – keep it light!

Good Luck – Bob

Bob, I have a few questions you may be able to answer before you head for Oshkosh:

1) Stringers; Your drawings show 1″ x 1/4″ x .032. All I can find here at present is 5/8″ x 5/16″ x .032. Would they be strong enough?

2) Are there any pulleys or fairleads required in the trim cable system?

3) How do you access the trim shaft bearings in the tailplane for lubrication after the fabric is on?

4) Do you bother drilling the airframe tubing to flush linseed oil through after welding?

5) The rudder horn for the tailwheel chain/SPring have no details given, just match up with the horn on the tailwheel?

6) The streamline tube strut stabilizer to fuselage, how do you provide for adjustment if the angle of incidence requires altering?

Regards – Ray Thurston #005 – NEW ZEALAND

Ray,

I am starting to get a lot of questions about the fuselage now. I assume lot of the builders are done with their wings and tail feathers and are starting on the fuselages. Regarding your questions

1) The stringer material that you spec out is OK as long as you use extra stand offs as needed. 1 x 1/4″ wood is OK also.

2) I am using two fair leads on fuselage center-line top at station M and station J.

3) No access on the prototype, shafts and bushings. I epoxy painted and greased on assembly. No problems to date.

4) No. Keep tubes welded airtight or protect inside of tubes. You may drill as you described if you want.

5) Builders choice to match with tail wheel used.

6) Rework end of streamline tubing as needed for fit.

Thanks for your questions and keep in touch. ~Bob

Hi Bob, Construction has started on #238. The newsletters are a priceless complement to the drawings. I’m starting as recommended with the wings. I have some questions maybe you could help me with, so that when I get to these points, I don’t have to sit around and ponder.

1) I have access to some 2024T3 .040. I was thinking of using this for the main spar web. I tried bending some test pieces in a brake and found that a 3/8″ radius provides a very nice bend. I realize it will make the spar slightly heavier but, maybe a bit stronger. Eventually I plan to put my BEARHAWK on floats. Having flown hundreds of hours on floats I know what kind of punishment an airframe can be subjected to! Would .040 2024T3 be acceptable for the main spar web?

2) From what I can see in the plans and the newsletters, the lightening holes in the spar web do not have flanges, is this correct?

3) Spar strips (cap strips) in the plans call for 1/8″ 2024T3. I can get 1/8″ x 1 1/2″angle 2024T351 to cut up. “T3” is heat treated and then cold worked. I am uncertain what the “51” stands for. Is this material OK?

Having studied the blueprints closely I find there should be very little to stumble on. You’ve done a very nice job. This is going to be a fun project!!

Dave Hiebert #238 – Alberta, CANADA

Dave,

Thank you for you kind comments about the plans. I think you will really enjoy building the BEARHAWK. Regarding your questions

1) .040 for the spar web will work fine but a minimum .140 bend radius is required in order to not stress the material to cracking.

2) Yes – no flanges are required.

3) The 2024T351 will work fine in this area. “T351” = solution heat treated, stress relieved, stretched, cold worked. Where is your supplier and what is the cost? Other builders may be interested in your area. Good luck and keep us updated as to your progress! ~ Bob

Mr. Barrows,

I want to thank you for your hospitality and the time that you took to show me “The BEARHAWK”. Having the opportunity to see the aircraft both finished and under construction was a great help. Being able to see the straight forward approach to fabrication of detail parts and the uncomplicated assembly set me at ease that everything was indeed as advertised and well thought out.

I have begun to to fabricate all the form blocks for the wing components and have found the plans to be very clear and accurate. On the few occasions that something seemed out of place all I had to do was study the plans a little closer to find out why and then correct the error in my ways. I have helped others with “Kit Aircraft” and found the plans not accurate or clear.

Again, my thanks.

I will want the wing struts when available. Updates to follow as I progress.

Kevin Deutscher #272 – Phoenix, AZ

Bob,

Thank you for letting my wife and I come down and look at the BEARHAWK. I learned quite a bit and realized that it is even more of the aircraft that I want, than I thought it was by looking at the plans. Now I just need to get busy and finish the house so I can start on it. I have a 48′ x 60′ hanger beside my house and I need to get it insulated before winter so I can work on my BEARHAWK full time this winter.

If you know anyone that would be interested in my 1956 Cessna 172, give them my phone number – it will help finance my BEARHAWK.

I am really looking forward to the next issue of the newsletter – which I think is excellent.

Dan Riffee #267 – Elizabeth, WV 304/275-0976

Bob,

While visiting you a month or so ago you showed me a device that you used to insure correct alignment of the nose ribs. Could you send me a sketch of that device? That method seems a lot easier than the running a wire through the ribs. I also have some questions.

1) On drawing #14 no attachment method is shown for connecting the 1/8″ flap cable to the inboard flap lever. Could you suggest a suitable method?

2) When connecting the 1/8″ cables to the bellcranks (drawing #11) is a clevis pin through the shackle and turnbuckle OK or should a bolt be used?

3) Also could you confirm that in drawing #14 that the flap lever is shown in the position full up flaps?

Thank you

Tim Neal #209 – Uniontown, PA

Tim,

Below is a sketch of the device that I used on the latest set of BEARHAWK wings that I am building.

Regarding your questions,

1) Use a cable shackle

2) Clevis pin or bolt is OK.

3) The drawing shows the flaps in the full up position.

Keep in touch. ~Bob

Builder Update

Below is a photo of #075 – Tom Yeomans’ project. As you can see he has his wings done as well as most of his fuselage! Thanks for the photo Tom!

The Story of Larry Sullivan’s New Bearhawk

Source: 2015 Q3 Beartracks, Larry Sullivan
Kit number 98 arrived from Texas in November 2007 and we set up shop in the hangar at HXF in Hartford WI. My building partner Tom Brown, was a pilot for Midwest Airlines out of Milwaukee and he had identified the Bearhawk as a plane worthy of our investment of time and money. He has a hanger at HXF where he kept his father’s Cessna 421 and it was and ideal location. (60’ x 60’ with heat and a toilet). Little did I know the marathon I was beginning.
Neither Tom nor I had any building experience although I had worked on some cars and motorcycles and built a couple of houses and furniture for my kids. The first year was one of sporadic progress on the tailwheel, struts, floorboards, and tail feathers. Nothing requiring fabrication. By the end of 2008 the crash had occurred and Tom had been laid off by Midwest Airlines resulting in major life reassessment. We both had kids in elementary and High School and little progress was made.
Even in that first year, despite very little progress, I began to get the sense of the constant focus the project demanded. How it pulled at me every free moment and when falling asleep at night. From one small task to the next, each requiring a phone call, time on the web, or just visualization of how things go together, it was always on my mind.

Larry’s fuel line routing

Unfortunately life got in the way. My kids were finishing high school and I was on call most of the time. Tom got a sales job that took him away for most of the week. The project sat there for three years without any attention. I even put together a flier to sell the brand new Lycoming 390 engine we had purchased in late 2008. Then I acquired a partner and my call responsibilities were reduced. I had told so many people that I was building an airplane and I had had the dream in my head for so many years, I just didn’t want to give it up. I asked around the Hartford airport to see if there was anyone who might be willing to help me get started in earnest and guide me.
Fortunately, I met Marc Stamsta, a skilled craftsman who builds vintage wood airplane wings and spars for a living (www.maxaero.net) and he was willing to help me get the project going. I bought Tom’s share of the project and proceeded solo!
Marc met with me each Thursday and we tackled the wings first. I learned to squeeze and buck rivets and shape fuel and pitot lines. Despite having purchased the Wicks “hardware kit”, few of the bolts seemed to be the proper length and turnbuckles were not quite right half the time. This was one of the most frustrating aspects of the build. I had to hunt for the correct piece of hardware or thimble or cable. The “1,100 hour estimated build time” was quickly whizzing by.

Hanging the wings met with near disaster when the drill bit became jammed at the root when drilling the hole to final size. Fortunately we were able to free it without damage. As with each part of the kit, we were impressed with the precision and quality of the kit. Everything seemed to fit together well.
It was on to the fuselage and I took on the fuel lines first. I made a slight modification in the route, and Bob indicated he saw no problem. Instead of bringing the rear line all the way forward of the doorframe, I routed the forward line back to meet the rear line below the door about even with the front of the seats. This allowed me to put the selector valve more aft next to the flap handle, the gascolator is aft of that and is more easily accessible behind the left landing gear.

I chose to use a new fuel-injected Lycoming IO-390 EXP engine with 210 HP, and a Hartzell 80” constant speed prop. The hope was that it would provide an excellent balance of power and weight. I saved 100 pounds over the 540 and gained 30 HP over the 360. For the build itself, I’m thankful I went with the four cylinder as it provided a huge space between the engine and the firewall to fit things and route lines and cables. As a novice builder I think it would have been much more difficult with the 540. The one major disadvantage is that the #1 and #2 cylinder intake manifolds did not fit into the cowling, requiring modifications. Thus, the blisters on my cowl. I found some old Travel Air valve covers that worked very well. In retrospect, I probably would go with a standard 360 for simplicity.

I used a baffle kit purchased from Glasair, for use on their Sportsman model with the 390. Since my throttle body is horizontally mounted in front of the sump, the baffle kit goes down under the throttle body so that the entire area behind the nose bowl is pressurized. I have no alternate air or cowl flaps. My exit opening is less than the standard and although I put a lip on the opening, I’ve been trimming it back because even in 80 degree humid weather here in Wisconsin, my oil temps been 180-200 and CHT have been 325-350 max.
I used Vetterman’s crossover exhausts. Clint provided excellent sup-port, was easily available by phone and made some modifications at no charge until it was right. I needed to add their 4” extensions to direct the exhaust further down as it was really fouling my struts and underbelly without them. I have been told by others at HXF that the plane has a very distinctive (bad-ass!) sound.

For the panel I chose the Dynon Skyview 10” monitor with their transponder, ADSB, engine monitoring system, GPS, heated pitot with AOA, and backup-battery. I took a seminar put on by Dynon at EAA prior to installing the system. I’m learning as I go and have had excellent support. Everything has worked as advertised. Rather than individual fuses for my electrical system I chose the Composite Designs Radio Stack power panel, which included the Master and Alt switches, Radio/Nav/Strobe/Fuel Pump/Landing Light switches and 14 breakers. It made the wiring so much easier and Wayne went above and beyond to give me some overall wiring advice. I used the ICom IC-A210 radio, and PS Engineering PM-1000 II four-channel intercom.
I enjoyed the wiring aspect of the build. I’m proud that I had only two issues, easily fixed with entire electrical system, despite completing it without any interim testing. The D-pins in the ADHRS connector cable were loose and had to be pushed in, and with the transponder and ADSB, I connected the TX to TX rather than TX to RX and had to reverse them.

N460K is covered with the Polyfiber system. I also used it for my seat frame supports. I painted it in a paint booth at Tom’s hanger (where I was building) that he had used for a work-related project and allowed me to build out to fit the Bearhawk. I had hoped to have my three children participate in the build with me but you can lead a horse to water… My daughter Caroline did help by welding together two rotisseries for mounting the wings and fuselage for painting and covering. They worked beautifully. I could wheel the fuselage and wings into the booth and easily rotate them as needed.
I used PPG Aerospace Desothane topcoat and Desoprime epoxy primer. The EAP-12 Desogel non-chromate adhesion promoter was very easy to work with. Rather than using the toxic Alodine products, this just sprayed on with a spray bottle and then was dabbed with a cloth to cover the entire bare metal surface and was allowed to dry. No rinsing needed. The painting was laborious and since it was not perfect, frustrating. I learned as I went which isn’t the best plan when it’s the finished product! At one point there was a thin streak on the wing and I finally realized there was a strip of plastic still on the bare metal that I had not detected when scrubbing and prepping. I was able to fix it without any visible defect. The paint seems very tough and worked well on both the aluminum and fabric. I used the polyfiber silver UV-protector as the primer for the topcoat on the fabric.
My plane came in at 1387 pounds, achieving my goal of less than 1400. I can carry 400# in the front seats, 300# in the back seats, 165# of cargo and 50 gallons of fuel and still be at 22.5” aft CG.

N460K’s first flight was on May 16, by Tom Hegy, an experienced crop duster at HXF. No problems initially. I flew it a few days later and on my first landing the engine stalled as I was flaring. I had trouble re-starting and when it did start, the #4 cylinder was not firing. After about 10 hours of troubleshooting we determined that the flow divider was faulty. Precision Airmotive exchanged it for a new one and it has run smoothly since. I had taken transition training with Jared in February, which was critical for my confidence. Still I was anxious particularly about the ground handling and landing on pavement. Under the recent circulated FAA AC 90-116 (Additional Pilot Pro-gram for Phase I Flight Test) I was able to have several local instructors fly with me for the first 10 hours. By then I was getting comfortable and have put an additional 50 hours in so far. Going to Oshkosh and having N460K displayed at the Bearhawk Booth was a thrill and an honor.

With regard to performance, I’m cruising at about 125 mph at 21” MP, 2300 RPM, consuming 8.5 gph. It seems the top cruising TAS is about 140 mph at 24 squared but at only 2500 ft MSL. I haven’t really taken it up higher and pushed it. I did take it to my 40th high school reunion in South Bend Indiana last month, taking the route under the O’Hare airspace along the Chicago Skyline over Lake Michigan, which was a thrill, especially since my wife came with me! I’m enjoying the process of learning the Dynon’s capabilities and with only a little over 100 hours of total flight time I have a lot to learn as a pilot. I look forward to the next 10 years with N460K.

First Flight Report from Steve Harris

Source: 2015 Q3 Beartracks, Steve Harris
N144TH is a Bearhawk 4-Place Quick Build. I purchased the project from the original owner that had not had much of a chance to work on it. I picked up the project in California and was able (just barely) to fit the fuselage and wings into my 26’ enclosed trailer for the 8-hour drive up to Oregon. The wings were still in the original steel packing frames from Avipro, but the fuselage had the gear legs and tail wheel installed. The fuselage was just a little too tall on the gear to clear the trailer. We had to disconnect the struts and let the gear splay out a bit to lower the fuselage to fit into the trailer. The only damage sustained in the journey was upon reattaching the oleo struts there was a bit of miscommunication and we managed to put a dent in one of the struts. After consultation with Mark at Avipro, the oleo was not easily repairable and he was thankfully able to sell me a replacement.
I had previously built an RV-4 so the metal work, fiberglass (ugh), engine installation, and electrical were familiar skills to me. I had only done some minor fabric repairs on a Citabria and Tri-Pacer (previously owned) so that was a new set of skills to learn. My goal for the project was to build simple and light with good performance at relatively high density altitudes. The mission is backcountry flying primarily in Oregon, Washington & Idaho and I wanted something rugged and easy to repair.
Some details on the aircraft:

Avipro quick build kit.

Lycoming O-540 built by Bob Barrows. Set up to use premium mogas.

MT 3 blade propeller and MT governor.

Airfoil shaped strips (Avipro) on horizontal stab and rudder.

Odyssey PC680 Battery mounted on the firewall.

Dynon Skyview system with ADSB, TIS transponder, COM, and autopilot. The ADSB weather and traffic is amazing!

Exterior covered in Oratex fabric, more on that later.

Interior is mostly Kydex with some fabric around the left rear window.

Skylight above the front seats but the rest of the overhead I did not install any headliner to save weight, increase headroom and allow easy access for serviceability.

Seat bottoms are aluminum pans with simple temperfoam cushions; seat backs are covered in Oratex fabric.

Crow 5 point harnesses for front seats, simple lap belts in the rear.

Rear baggage bulkhead has an access door to a cargo net behind the bulkhead to carry sleeping bags, coats or other light and bulky items.

Extended floorboards and access through the rear bulkhead to carry skis or other long items. I can carry items a little over 8’ in length if needed.

Gear legs modified to allow larger tires.

Aux tanks.

LED wing mounted lights of my own design.

Wingtip Whelen strobe / nav light combinations.

Empty weight with oil is 1463 lbs.

I now have 29 hours of flight testing completed after receiving the pink slip on August 15th. I’m very happy with the performance and it is very much in line with the advertised specs. Squawks were a minor oil leak from a valve cover return line, alternator field fuse blowing, inaccurate magnetic heading direction from the Skyview, and CHT/Oil temps higher than I would like. The oil leak was easily resolved by adjusting a hose clamp. The alternator field fuse was blowing from an overvoltage crowbar protection module I had installed. The protection module is supposed to monitor bus voltage and if it exceeds about 16.5 volts, crowbar the field wire to the alternator and blow the fuse taking the runaway alternator offline. After some troubleshooting and reading online, it seems that some earlier modules had issues with false tripping. This was a part I had surplus from when I built my RV-4 back in 2001. I removed the protection module and all is well now. The CHT temps I resolved by cleaning up some small baffle leaks, enlarging the cowl exit, putting some louvers (Vans RV-10 part) and an “augmenter” lip on the cowl exit. It now runs about 375F at cruise and barely above 400F on climb out on a 90-degree day. The high oil temperatures are a little embarrassing – I have the oil cooler mounted on the firewall fed by a 4” scat tube from the engine baffles. I had put a piece of cardboard over the inlet to keep debris from falling down the scat tube. Turns out it cools a lot better when that cardboard is removed. The Skyview system uses an ADAHRS with integrated magnetometer. There is no great place to mount in a tube fuselage that isn’t susceptible to magnetic interference from the 4130 structure. I mounted the ADAHRS/magnetometer in the fuselage high and behind the baggage compartment. After numerous calibrations and attempts it was still showing about a 30 degree offset in direction. Dynon recently introduced a remote magnetometer so I purchased that and installed in the wingtip. After calibration, it was marginally better but was still showing at least a 15-20 degree offset from actual heading. I had been using my iPhone compass application to do the ground calibrations. After comparing to an aircraft compass I had in the surplus bin, I found the source of the error was the compass application in the phone. I haven’t gone back to see if the original ADAHRS would work, but suspect it would be pretty close.
Construction was 1375 hours over 2 years and 3 months – virtually all on weekends. I kept very accurate track of time spent, but didn’t track the $ – I don’t want to even know that number but expect it is about $100K all in.
Covering: As mentioned previously, I chose to use the Oratex covering for a number of reasons: 1) No painting required, 2) Easy repairs in the field, 3) lightweight 4) non toxic water based system, and did I mention no painting? Overall I am very happy with the process and results. Oratex doesn’t give you that super shiny show plane finish and the tape edges are not filled in as nicely due to no filler or painting steps. It is also almost translucent and the structure is visible underneath when backlit. The ad-vantage of the Oratex is that it is very tough, very light, and easy to repair. I actually kind of like the translucent look but it is definitely a personal choice. There is a learning curve with the system and there are some significant differences from the traditional covering systems. The Oratex material uses a water-based glue that is applied to both surfaces and allowed to air dry. The adhesive is heat activated. The activation temperature of the glue is below the shrinking temperature of the fabric so the fabric is attached and adhesive activated first and then later the final shrinking is done with an iron at a higher temperature or temperature controlled heat gun. I started with the seat frames for practice then went on to the ailerons and flaps because they don’t have any compound curves. After the ailerons and flaps I covered the tail feathers, which do have lots of curves. Covering the fuselage was definitely stressful due to the large and expensive pieces of fabric and the difficult curves – especially at the fuselage / vertical stabilizer intersection. It all worked out well and I didn’t have any real issues. I covered the left and right sides of the fuselage first and the bottom last upon advice from the Oratex representative. It was very good advice and allowed access from the bottom of the fuselage up until the last step of covering so I could get the tail feathers all installed and cables in place etc. Overall I am very happy with the system – it suits my mission well. I will paint the cowl and boot cowl to match, but intend to leave the wings bare and polish them.
First flight was early morning on August 16th and a relatively short 20 minutes or so. I did have to man-age power and climb due to the CHT and Oil temps. I had never flown a Bearhawk before, actually never have even seen another one. I do have about 800 hours in tail wheel aircraft, most of that in my RV-4 but also some Citabria time. First landing was probably the best one I have made to date. Takeoffs are impressive and very short due to the big Lycoming up front. Landings are very different than my RV-4. The combination of a constant speed 3 blade prop, huge flaps and a draggier airframe make for much steeper approaches and short rollouts. I’m still working on landing techniques but what seems to work pretty well for me is to carry a little power – about 1700 RPM and to use full or almost full flaps and target 65MPH. This gives a tight pattern with a steep approach – a little bit of power just as flaring helps cushion the touchdown. Control forces are heavy compared to the RV and the Bearhawk is a definite rudder airplane with a lot of adverse yaw. The trim is very effective, if you accidentally leave the trim wheel where it was on landing – the next takeoff will get your attention quickly with the large pitch up force. You probably won’t make that mistake again! Elevator forces are higher than I expected. I would like to compare at some point to another Bearhawk to see if they are normal. I have checked that cable tension is not too high and looked for any other sources of friction in the system.
The Bearhawk is a very nice aircraft that I can take into the backcountry strips in the Pacific Northwest. A perfect complement to my RV-4 that really isn’t well suited to that type of flying with wheel pants, low wing, and way too small of tires for some of the surfaces. I am located in Sisters, OR at the airport K6K5 and love to have visitors (especially another Bearhawk!). I am also happy to talk with other builders at any time. My thanks to my very patient wife and family that allowed me significant time to work on the project and helped any time I needed bucking rivets, stretching fabric, or bringing me dinner in the hangar. The N number I chose for my RV has my ini-tials (N144SH). The Bearhawk is the same except it has my wife’s initial instead of mine (N144TH) – so it is real-ly her plane! Also thanks to the previous builder who started the project, BetterAircraft fabric (Oratex dealer), Avipro and Bob Barrows. Lars at BetterAircraft fabric provided very good support on the covering. Mark at Avipro was very helpful and provided great kit support even though I wasn’t the original purchaser. I also purchased my MT prop through Mark. Bob built me a great engine and answered a few questions not to mention designing a wonderful airplane.

Sun-n-Fun 2015

Source: 2015 Q2 Beartracks

There were a few Bearhawk folks at the 2015 Sun-n-Fun fly-in at Lakeland, Florida. LSA builders Jerry Cornwell and Bill Stratton set up camp with appropriate decorations (pictured right). Scratch builder Mike Swain was tent camping with his especially adventurous and supportive wife, young daughter, and weeks-old infant son. Mike suggested an informal Bearhawk gathering, which happened on Friday evening at the Recreational Aviation Foundation’s fire ring. Tiffany Stephansen, 4-place scratch builder, stopped by after a shift of volunteer work at the avionics workshop. 4-place builder Jared Yates drove in for the gathering, already being in Florida on other business. Jerry and Bill brought a photo album full of LSA pictures. They are building two airplanes somewhat simultaneously, and have created some clever solutions to various minor building challenges. Hopefully some of those will make it into a Beartracks issue soon. Everyone had a great time looking through the pictures and hearing about their progress. Thanks to Mike for organizing initiative! It’s always fun to meet fellow Bearhawk folks.

Tim Babcock’s New Bearhawk 4-Place

Source: 2015 Q2 Beartracks, Tim Babcock
361 was purchased as a plans built project from Merle Rusnak on Oct 24, 1999. Along with the plans were the two wing strut extrusions that were the only available pre-manufactured parts at that time. The aircraft plans were published in 1995 and the prototype was flying the Oshkosh and Lakeland airshows. The numbers were impressive so the decision was made to proceed with the build. Spent several days going over the plans an making material lists for the steel and the aluminum. Ordered the aluminum from Copper and Brass sales in Edmonton (supplier of metal to Boeing in Seattle) and the steel from Dillsburg Aircraft Works in the USA. Subscribed to the newsletter along with acquiring all back issues. Also purchased the builders manual and photo set.
The plans were very good and the newsletters provided all the necessary information on the build table for the wings and fuselage along with the manufacture of jigs to keep everything true. Lots of time was spent on building quality jigs and in some cases it took days to build the jig and an hour to produce the parts.
The wings were started first because the designer said that if you “Finish the wings you will probably finish the airplane”. Bob was correct in that statement as he was in everything with this amazing airplane. Dies were made and wing ribs were produced. Many months of riveting followed and the pre-closing inspection on the wings was requested on Jun 18, 2002. Jack Johnson came over and inspected and passed the wing pre-closing, flap and aileron pre-closing. The wings were finished about two months later and put into storage.
Work was started on the modification of the wing build table to a Fuselage build table/jig and manufacture of the fuselage began. After two house moves and the building of a new hanger in Wetaskiwin, the fuselage was ready for the pre-cover inspection. During this time the panel was built up with the Dynon EFIS and EMS as primary instrumentation. Mechanical airspeed, turn and bank, and altitude back up instruments were installed. The panel was built as a modular type to be easily removed for service later on using Cannon plugs. Full radio and GPS stack also. All self-constructed and wired.
The wings, flaps, ailerons, horizontal stabilizer, rudder, elevator and trim system were installed and rigged. Jerry Mulder came out and inspected the fuselage in April 2013. Painting was finished up and the engine core was rebuilt with a new crankshaft and counter weights (now a 0540-A4A5) to accommodate the new Hartzell compact propeller. New and rebuilt cylinders were installed.
Engine and propeller were installed and wired with a Lightspeed dual mini sensor ignition system along with a back up battery emergency power system. New custom exhaust system purchase from Vetterman Exhaust just for the Bearhawk. Fuel system connected and pressure and leak tested. Engine and propeller run in as per Lycoming Break in procedure. Static system pressure tested and calibrated along with the Dynon EFIS and EMS. LED landing light installed with alternating flash system for approach and landing. All the seats were installed and retractable shoulder harness installed in front seats to allow for unrestricted access to flap handle and fuel selector valve on the floor.
The only modifications made were to the main landing gear which was changed to accommodate hydraulic wheel skis using the Cessna style inside axle stub mounting for the skis along with the reinforcement of the boot cowl safety cable mounts connecting to the upper motor mounts. Installed wheel controls for easier egress when on floats. Also installation of float fittings while fuselage was being built up along with the ventral fin mounts and water rudder cable runs.
Registration completed and decals installed the final inspection was called for on August 2014. Jerry Mulder returned and completed final inspection on November 6, 2014. This was a much harder project than my BD4, which I completed in four years. It was a Ray Ward conversion and also had the O-540 engine in it. First flight for C-GDVK was November 21, 1999. Of course the Bearhawk can be bought as a Quick Build Kit now. But certainly no regrets.
The first flight of C-GDBN was on January 17, 2015 with no major issues to report. Propeller over-speed on touch and goes (wrong alarm setting in the Dynon for that) and a very slight left wing heavy condition that was cured with the washers under the aileron mount trick. I thought my O-540 powered BD4 got off the ground quickly but the Bearhawk was flying and climbing at a surprising rate before I had time to raise the tail. It could have been easy to bust the overhanging class “C” airspace.
Over 15 hours on it now and it is a very stable airplane in all configurations, well maybe with the exception of the trim wheel system. But I am use to that now. Could be exciting again if I let someone else fly and don’t tell them. Empty weight is 1610 due to full interior and in-sulation for winter flying up here. Of course we can go up to 2500 lbs on wheels and skis and 2700 on floats here.
Tim Babcock, Edmonton, Alberta, Canada