Source: 2021 Q3 Beartracks, Stan Timmerman
Many years ago I started blacksmithing. The hobby involves playing with fire and hitting things with hammers. As with aviation, you meet a lot of unusual people. While at one of the local events, I listened to some old timers speculate about whether they could forge an airplane engine. At the time, I did not know that modern airplane engines are made of aluminum – not iron. I do not know if those guys could have done it, but that is not the point. To be a blacksmith requires an open mind as to what is possible. I learned a lot about working iron from that hobby. At first glance, it is not applicable to aviation. But, I use that experience to make my own tools. I will show an example with my pneumatic hammer revision 2.
I happened across a pneumatic chisel at Northern Tool, like their item number 154422. I think it was around $13 (now $18.99). I knew that it would be a high grade of steel and would be hardened. The first step is to anneal the chisel. This is done with a rosebud torch. I could have used a forge, but I wanted the end that fits in the rivet gun to maintain its hardness. By heating from the business end of the chisel, I will soften just the part that I want softened. The picture may not be in focus because the designer of the camera focusing system did not anticipate the camera user would be holding a torch while trying to photograph glowing metal with the other hand.
While still orange hot, I bury the chisel in my bucket of vermiculite. It will take a long time to cool.
The next day, I came back and drilled/tapped holes in the face of the chisel. Even with annealing, it is important to use a nice quality bit, either cobalt or titanium. The center hole is threaded (metric) to fit the quick-change soft-face hammer, (Harbor Freight sku 69093) hammer that sells for $6. It comes with multiple plastic faces with a metric thread stud.
I then drilled and threaded smaller holes that will be used to keep the plastic hammer head from unscrewing while in use.
This is the finished plastic-faced hammer that I can use for flow forming aluminum. As an aside, there are rivet guns and there are pneumatic hammers. A pneumatic hammer cannot be used for riveting, but they work just fine for flow forming.
Edge Rolling
This edge rolling technique is for use where the edge of one aluminum sheet lays flat on another piece of aluminum. Fuel tank covers, boot cowl, and cowling are places where this technique can make your sheet metal work nicer.
There are several tools available for this job, including the ones pictured to the right, available from Avery tools. Any of the varieties will work, including a sheet metal brake capable of the proper bend radius.
The idea is to roll the edge of the aluminum down just a little bit so that when you tighten it down, there will be a nice tight contact with the wing skin with no gaps.
The shape of the wheels do all the work. You can purchase other edge rolling tools similar to this from all of the aircraft supply stores. Make sure you do this BEFORE you dimple the holes or you will run into interference.
Forming Ribs with a Tent Stake Mallet
Source: 2001 Beartracks, Bob and Mike
One of the first tools that every builder is going to have to obtain is a rawhide or plastic mallet to form ribs with. One builder suggested the Coleman Tent Stake Hammer. We picked one up ($3.49 + tax) and found that with a little modification it is an excellent rib forming tool. The flat surface of the mallet face is fine for driving in stakes but not very good for forming aluminum. The striking face of the mallet needs to be given a slight concave surface with a bit of filing and sanding – this is a very simple task and you will find that the mallet is more than adequate for forming ribs. It is available at any department store that has a Camping Section.
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.
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.
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
Making the Wing Skin Stiffeners for the Fuel Tank Bay
Source: 1996 Beartracks, Bob Barrows
The Wing Skin Stiffeners used in the fuel tank area on the inside upper surface (2 per wing) need to be preformed to match the airfoil shape.
First cut the aluminum blank about 3″ longer than needed and bend up as shown using a sheet metal brake.
We did the contouring as follows:
Using the wing nib form block as a base attach the stiffener as shown below.
Screw the front end of the stiffener to the form block as shown and clamp the back end as shown.
We then heated the entire length with a torch (use a propane torch if you have one) being careful to heat evenly. If you heat too much in one place the stiffener will break at that point.
Check to see if enough heating has been done to cause the part to take a permanent set by loosening the front screw.
If any of you builders would like to set up a rolling fixture to make this part, give me a call.
Bob
1996 Beartracks Mailbag
Source: 1996 Beartracks
Bob – Thanks for the good talk we had yesterday – that was what was needed to push me over the edge. After nagging my wife for about six months, it wasn’t difficult to convince her that I needed to purchase the plans for the Beerhawk. Please find my check enclosed.
I’ve been on the Cozy e-mail list for several months and have really enjoyed it The list is a bunch of guys with e-mail access that share information with each other. I’m going to miss it I think the Internet is a great vehicle for the exchange of problems and solutions, as well as a source of encouragement for weary builders.
A similar e-mail list for the Bearhawk would be invaluable. I know that you are not set up to give such a service, and I’m not asking you to make an investment in that area. However, I manage a system on the Internet, and I have enough bandwidth to handle a lot of traffic. I intend to start such a forum, and perhaps document my trials and tribulations with this project for the whole world to see. What I would like to ask from you is that if you have any inquiries about e-mail or WEB pages, that you forward those interested people to me, and I will add them to my forum.
I do have some selfish motives here. Having never built an airplane before, I would love to have contact with people who have – especially those working on the same type of airplane. I also like to be kept up to date on new engines, etc.
Thanks for designing such a neat aircraft! I look forward to starting work on it. My wife looks forward to me getting this out of my system.
R Paul Beam (067)
Bob – #009 is underway and I am now thoroughly enjoying the project. I have some questions and want to pass along some experiences getting underway.
First the books by Tony Bingelis were disappointingly sketchy about the how-to’s of fluting and flanging. Regarding fluting, I discovered it is best to keep my plier tips back from the bend about 3/16″ and make the flues minimal in depth at first, especially an the longer straight parts of the wing ribs. Next the flutes are modified deeper as needed. Also, I’ve learned that flute modification may be necessary before the piece will lay flat an the bench. Before we discussed fluting by phone, the flutes I had made were every 1 1/2″ apart, spaced where the drawings indicate no rivets; I had not used two flutes within the space, nor skipped any. I then tried two as you suggested within the two front-most sections between rivets on the nose ribs (the maximum curve on the ribs) with good success. Also, the little scratches I got with my fluting pliers were inspected by an A&P mechanic at our local airport. He said they looked great and asked how we do the flanges an the lightening holes…so I showed him your little wooden tool! He was Impressed.
Would you discuss priming our parts as we proceed. I am in a very damp climate and expect this project to take a long while. Should I be priming as I go along? How do you clean your parts before priming? Do you use any ultra fine sanding before priming? What kind of primer specifically do you prefer? Would dipping be practical for small stuff? Now I’ll pass along a couple of my experiences and solutions to date (for better or worse!).
Flanging the lightening holes gave me fits on two counts: getting the tool to do its job and preventing and eliminating warpage of the ribs. The solutions were as follows: Wax the aluminum on both sides before running the tool around (as was suggested Winter ’95 ). Place the rib flat on a piece of cheap, short nap, foam backed carpet. The carpet “absorbs” the thickness of the tool edge so you run it around the lightening hole and prevents scratching as you turn the aluminum for best mechanical advantage. That reduced the warpage which I further took out as suggested by running the tool around the flange from the top (Winter ’95)…with another modification! I found the wood blocks idea a bit hard for myself to manage. Instead, I used a scrap of 5/8″ plywood to make a full sized pattern insert for each size rib, complete with holes large enough so as not to touch the flanged edged of the lightening holes (precision is not important here). I also made a separate wooden push tool instead of using the butt of the flanging tool. It has a T shaped handle which helps distribute the push forces across my hand, and a slight concave to the contact end to keep it from slipping.
I’ve joined our Tallahassee EAA and through the club have gotten in contact with three members who are building RV’s, and also the mechanic mentioned above who owns a shop at the airport and is helping them. So I have friends locally for some of my “novice-builder” needs. Still, I hope each of us will share our experiences as we progress on THE BEARHAWK.
Roy Nash (009)
Thanks for the neat ideas Roy. Regarding priming/painting –
Prime spars for sure. Other parts can be primed as you go – degrease and SCOTCH-BRITE before priming. I use zinc chromate but others like epoxy primer should be even better, although harder to work with. STEEL PARTS should be bead blasted, primed
and coated with polyurethane or epoxy enamel. See SPORT AVIATION page 86 Oct ’95 edition for more information.
Bob
Dear Bob,
Thanks for the inspiring phone conversation we had in December. My close friend Julian Henley and I have decided to start building our own BEARHAWK before any more time is wasted! So — I’ve enclosed a check for a set of plans. We hope to stop by and see you in April or May.
As I mentioned to you before, there is heavily congested airspace in the northeast with the “BIG THREE” New York airports, Bradley International in
Hartford, CT, and Boston Logan Airport in Boston, MA, as well as extensive general aviation traffic. I would like to put a skylight in the ceiling area that
would go from the windshield back to the trailing edge of the wing, very much like a Champion Citabria or Decathlon. Could you possibly sketch out your recommendation for this, as this is very important safety feature up here in the northeast, and would be greatly appreciated.
Steven Wieczorek – Branford, CT
Steve,
Your plans are on the way. Working with another person during construction should help speed things up a bit, just be sure to do a little something EVERY day.
The skylight will be OK in the BEARHAWK. You may not want to run it as far back as you mentioned though. Past the rear spar the fuselage is starting to narrow and the contour of the roof is starting to round out. I would recommend that you run the skylight from the top of the windshield to the rear spar. Look for more information about this option in an upcoming newsletter.
Bob
Dear Mr. Barrows,
I received the plans set just a few days ago, and so far I am delighted at the prospect of starting the building process.
In going through the plans, however, I noticed a difference between what is drawn and what I saw at Oshkosh. I noticed that there are no aileron trim tabs, shown in the drawings. Do you recommend the installation of separate aileron trim tabs or would it be better to install a system to trim the entire aileron? Is
aileron trim even necessary?
Second question: Since I am limited on building space (until I move to a new house) is it advisable to begin construction of the ailerons and flaps before beginning the wings? Primarily I am wondering if the wing is needed before the control surfaces for alignment purposes. I would also like to start on the “small parts” to learn to work with and rivet aluminum before tackling such important components as spars. When I do get to that point, however, I will be sure to employ the experience of local EAA members.
Thank you for your time and I look forward to building my BEARHAWK!
Bob Spetz – Tempe, AZ – #118
Bob,
The aileron tabs you saw a Oshkosh were servo tabs, not trim tabs. It was found that servos were not needed and were eliminated from the plans before they were offered for sale. The servos would only add complexity to the design and slow down construction. The ailerons are just as light without them.
You can proceed with building the ailerons and flaps first if you like. The wing is not needed for these assemblies to take place if you build wing to prints. Starting on the “small parts” is a good idea. You may want to make all the ribs first (wing, aileron, & flaps) and then make the steel parts for the wing. And don’t be afraid to ask for some help from your EAA friends when it comes time to bend up those spars.
Bob
Dear Bob,
Enclosed find an ad for the Bear-Tracker Trader. Also enclosed is a check for renewal of my subscription to Bear-Tracks when the time comes.
Our wings are coming along nicely but are on hold now since my partner Gene Nelson is away for the summer presumably to escape the heat.
I am working on the power plant and prop drive which is to be a 383 small block direct drive Chevy. I plan on a conservative 200 H.P. at 2800 R.P.M. using Airflow Performance Multi-Point Fuel Injection system. It is a very exciting project. I am looking forward to seeing you at Oshkosh.
Regards,
Bob Cleberg – 042 – Tucson, AZ
Bob,
Thanks for the update on your project. I suspect you are going to get a lot of calls from fellow BEARHAWK builders about your engine conversion. There is a story in the April ’96 issue of KITPLANES about a similar conversion in a P6E Hawk replica, although it seems to be a bit heavy and will need to be installed inverted to maintain thrust line. Keep us updated as to your progress. ~ BOB
Dear Bob;
Please find enclosed check for Bearhawk plans. Many thanks – the rest is up to me.
Sure looks (and reads) like the ideal bush plane for my needs. I’ve been flying an O-200 powered Protech in and out of the bush for the past two years and have learned more about the power of prayer and “seat-of-the-pants” flying during that short period than in the previous 23 years with 3 different aircraft.
Do you happen to know if high compression pistons are available for the O-200 Continental, because I could sure do with a bit of extra “oomph” up front while I build the “Bearhawk”!
Best Wishes,
Charlie Janes – 202 – New Zealand
Charlie:
I think that the Chevrolet small block 4.00 +.060 pistons have been used in O-200 race planes for higher compression. The Continental C-85 pistons will also increase the compression ratio for more power.
Bob
Hi Bob,
I have enclosed the engine prints for the Javelin Ford 3.8L V6 for you to look over. Please give me your expert opinion – Will this set-up work? Thank you for your time and I look forward to your reply.
Randal Clark – 207 – Mayville, WI
Thank you for the data on the Javelin Ford 230 V6. This is the first time I have been able to closely investigate the specifications on this particular engine. My initial reaction is that this engine is a bit heavy at 395 lb plus the weight of the radiator, coolant, pipes and oil. You may be able to lighten the package up with a little creative thinking.
The Javelin engine dimensions are not encouraging either. The depth of the Javelin engine from the prop center line to the bottom of the oil pan is 20 3/4″ whereas the Lycoming is about 12″. The height of the Lycoming is 6 7/8″ near the front and the Javelin is about 6″ in this area. The basic cowl lines of the Bearhawk would not fit this engine installation. A builder redesign of the cowling as well as the firewall may be needed to make the Javelin conversion work.
I find weight and horsepower claims of most automotive conversions doubtful. You should do your own investigating in this area.
The Bearhawk as with any other aircraft, is much more enjoyable to fly if you keep everything light.
Bob
Making Fluting Pliers
Source: 1995 Beartracks, Bob Barrows
Fluting Pliers – You can buy a set of fluting pliers (very expensive) or you can make your own. To make your own you will need a set of Large Pliers. Clamp the pliers in a vise and drill a 1/4″ hole between the jaws. It may help to soften the pliers first with a torch. Then braze a section of 3/16″ rod on one side of the pliers. File as needed to produce a nice smooth radius around the rod and along the rim of the jaws.
Using your fluting pliers, flute rib at approximately 1-1/2″ spacing to straighten out the rib after tapping flange over to a 90° angle.
These homemade fluting pliers seem to work better than the units sold on the market. The homemade pliers make a smaller crimp that is much easier to work into the rivet pattern.
Making the Nose Bowl and Wingtips out of Aluminum
Source: 2015 Q1 Beartracks, Eric Parks and Brent VanDervort
What do you get when you combine a team of two Bearhawk scratch-builders, when one is an expert metal fabricator who strongly dislikes fiberglass? An all-metal Bearhawk, of course. Here are a few pictures the formed aluminum nosebowl that Brent has made. Eric and Brent are building in south Charlotte, NC, and they also have completed a set of aluminum wing tips, which reportedly look like small canoes. Material is .062” 3003-H14.
The photos show several of the steps in the sequence. The nosebowl is not formed entirely from a flat sheet of aluminum. Brent made a few strategic cuts to remove material in the curviest sections, which he welded closed with an oxy-acetylene process. As he says, the parts look all wrong right up until they are done. In case you are wondering as I was, they are not planning to polish the parts. Brent is counting on a little bit of filler to produce a first-class final paint finish.