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P-40 Replica Project

Posted By:
Scott Bolster
Young Eagles Pilot or VolunteerHomebuilder or Craftsman
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5
#1 Posted: 12/11/2009 10:55:33

Hello, I've had my eyes on a warbird replica for going on 6 years now.  I started off with the Titan T-51 as a goal, visited their shops in Ohio (only about 2 hours away from where I grew up) and was very impressed by their hospitality.  I basically had the run of their shop with their test pilot and owner answering all my questions.  But they went and raised the price from $37,000 up to $50,000 and now it's more.  Well... there goes that idea.  :)

So after mulling around for a while, surfing the net I found the two replica websites:  WAR Replicas and Lohle (sp.?) The second was a bit tiny and slow for my vision and the first looked like a viable option with approx 150mph performance with an advertised +6/-6 aerobatic envelope.  The only thing was that there was only one other aircraft completed (the design aircraft in Austrailia) and one other set of plans sold.  So I took a chance and bought the plans $345.  Keeping in mind that I never tried anything like this before I saw the following:  They didn't come in a protective tube and they were chewed up at the edges a bit, then I opened them up and saw the drawings were pretty faded in places.  The wing blueprint sheets had a rib that had the spar sticking out the top of it and some other stuff.  Not having a baseline to guide my opinions, I consulted our local FAA inspector who had built about 5 wooden airplanes so far and was the head A/P instructor at the local university.  He wasn't too impressed either but he said they could work.  So I got a little sheepish.

Then I came up with the idea that I could probably design my own.  I'm a relatively smart guy with a good deal of self-taught aerodynamics knowledge.  With the right reference material and support, it could be viable.  I have some really knowledgeable people that I work with who are willing to help. As I mentioned earlier, the FAA rep is a great guy who's experience is vast and another friend who has already built a Breezy and is working on a Cub at the moment.  And with you fine people, I should be able to accomplish this pretty lofty goal.  Even if it puts me in the poor house on the way to the looney bin...

So here's where I'm at:  I've purchased some design books as well as a few others to get my feet wet:  Modern Aircraft Design by Martin Hollmann; The Sportplane Builder by Tony Bingelis; Airfoil Selection by Barnaby Wainfan; Construction of Tubular Steel Fuselages; GA Airfoils by Harry Riblett.  These are just to brainstorm and do some preliminary rough guesswork.  Simplified Aircraft Design for Homebuilders by Daniel Raymer is on my Christmas List for Santa... or my girlfriend... to get me.  So I at least have a starting point for research and, as I said, rough design guesswork to get basic dimensions.

I've also bought those engineering blueprints off E-bay for the P-40.  Really nice to have from a collector / enthusiast standpoint.  Some of the blueprints are unreadable, but I'm only using them for basic fuselage contours / wing layout / etc.  Just to give me some reference.

I've been searching these forums and came across the thread about the 82% Corsair and downloaded the Compufoil program to help a bit.  And I've found a few other ideas /  direction.

So I'm completely aware that this is not going to be a simple process and that it will take a lot of time and everything else that goes along with it.  But I am not trying to re-invent the wheel as I would like to use existing airfoils, basic fuselage / wing construction, etc.  I've also been in contact with the very nice guys over at Geared Drives for the engine / PSRU selection process.

I guess I'm right at the beginning, gathering as many pieces of information I can about the whole process.  But some of the first questions I have is that, from the blueprints of the aircraft, there's 16 fuselage bulkheads and about 12 or 13 wing ribs.  Is there some kind of guideline for the amount of these for a certain fuselage length or wingspan?  I'm wanting to start drawing out the wing and fuselage in ViaCAD to get some total weight estimates for the structures and I'm not positive if I should stick with the basic origional layout or if that happenned to be overkill since it was a warbird and was meant to be shot at... or was it underdesigned since, as with much in government spending, lowest bidder and such.  :)

This may be a long thread, as I'd like to keep all my questions in one place both for myself and anyone else looking to undertake something like this.

Any help, hints, tips, blessings, warnings, mantras would be greatly appreciated!



Neil Sidders
Homebuilder or Craftsman
50
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11
#2 Posted: 12/11/2009 23:31:06

I really can't help much with many of your questions.  However the first airplane I ever worked on was a P-40E.  As it happens I believe it is the same one on my postings, N1207V.  The airplane is in a museum out west somewhere now. 

The airframe is anything but under built.  As anyone who has worked on these Warbirds will tell you it is beautifully manufactured and when you consider when it was built and the purpose it was built for, the original work is truly astounding.

Eric Mingledorff ownd the "E" model and Kermitt Weeks had a "N" model durring the same time period and it was said that the "N" model flew a little better in part because the rudder hinge line was farther back than on the "E".  I think the "E" model was the best loooking of all the different models.  Of course that is opinion.

I wish you well in your endevor.



Pierre D'Entremont
Homebuilder or Craftsman
131
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#3 Posted: 12/12/2009 13:19:21

Would recomend consulting the I Ching...

You may be told you are crazy but this is misdiagnosed Excentric Addicted to Aircraft synDROMEitis....that occurrs from a synoptic overstimulation ....well you get the picture...   success is only 99% failure...so you might be very poor if not already arristcrat....or marry one who shares the passion...or sickness depending on veiwpoint.

you may not be re-inventing the wheel but I hope it has some...

It would be nice if the fusilage was addapted for the engine used in the Thunder Mustang as it would be kinda peppy , huh ?

I will be interrested as you do this Scott , and wish you healthy mindedness...as my Dad and God father ,Col. Sam Grashio had some time in P-40's ...Pops ended up in jugs in Oky at the end and Sam escaped with Ed Dyess after surviving Bataan March of Death and internment...  thus the painting by  Keith Ferris -To Little , Too Late....the Greenwitch Workshop had a video of theSymposium Fiftieth aniversary of Pearl and the Phillipines and  print signing that was very much worth seeing...

So if you are honest to the plane you may have some supernatural assistance from time to time...might even get a mantra....I just sing to myself , myself...like them ol drinkin hymes when I can remmember them....

One thing for sure....you'll know more about P-40's than you ever thought you wanted to know before it's all over...

happy dreams and good luck...

and fortune cookies are kind iffy ...but sometimes.....



Tooky or Pierre
Adam Smith
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#4 Posted: 12/12/2009 14:48:42

Scott, welcome to the forum!   Your post took me back to the late 1990s when I first got an internet connection and was dreaming with a friend of building a wooden Spitfire replica or at one point looking at buying the salvage of the legendary replica of Spitfire prototype K5054 built by Clive du Cros.

If you're building a replica warbird Clive's book "Birth of a Spitfire" is worth tracking down, it tells the story of his whole 10+ year journey to achieve his dream.  There are usually copies available on eBay and the like.

Have you looked at Marcel Jurca's MJ-12 plans for a 75% scale P-40?  http://www.jurcaplanswest.com/MJ-12.htm 

 



Pierre D'Entremont
Homebuilder or Craftsman
131
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#5 Posted: 12/13/2009 10:05:46

I'm BACK !!!!!!

You probably....most likely...undoubtatubly   already have gone to    Warbirdalley.com        ??? and hit the P-40 tab and found Rudy Fraska's 360 view of a cockpit ????   It's a place.....

If you are needing info on the documentary of the war symosium that had Gen Joe Moore, Col. Grashio and Ken Taylor's accounts you can get me at   tookytuu@yahoo.com   or 816 668 2436....

Pierre



Tooky or Pierre
Paul Rodriguez
Homebuilder or Craftsman
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2
#6 Posted: 12/14/2009 19:23:43

Welcome, Scott, to the world of the mentally unbalanced......I'm working on a Zenith 601,  but the voices in my head are shouting "P-40"  in my brain, too.  Call it monomania, but when I get the 601  done,.....................      What I have in mind, though, is a Light Sport, of sufficient performance to have fun, and maybe do a little cross-country.  My particular madness went something like this:    

 Guillow makes a 28-inch wingspan balsa model of the bird, with wonderfully detailed plans.  What I'm thinking of is to enlarge the plans via overhead projector, 12:1, and thereby have plans for a 28-foot wingspan model. That would make it roughly 70 to 75% scale.   Using the plans for their balsa bulkheads, I'm looking at making forming blocks for ONE SIDE of the bulkheads, with the addition of a 2 or 3 inch tab extending from each end of the halves. Tap a joggle on  one side, then rivet them together, and, voila, a bulkhead. String them on two tight cables, top and bottom. (the holes would have to be very carefully aligned) and stretched on about a 15 foot 2x4 frame, and they'd then be supported well enough to hold until placement of four longerons, tail to cockpit, and cockpit to firewall. I'm thinking of using one by one angles, eighth inch thick extrusions.  From the cockpit back, four skin sheets: bottom, sides, and top, with J-bends at the upper edges for strength, all done with Avex rivets. I doubt if I can English-Wheel accurate curves for the fuselage, so maybe multiple pieces of skin will have to do.

The Guillow plans have very good drawings of the ribs, too, although I'm not sure if they're really the right airfoil. Probably wouldn't be too hard to find out. Then, using somewhat the same construction system as Zenith's wings, an 8-foot center section, and two 10-foot outer panels in the P-40 planform ought to make it "P-40-ish"  Power? Whatever will give around 100 horses ought to get it up to 128 MPH max cruise, LSA parameters.  An old aluminum V-6, inverted, would give direct drive, and authentic looking exhausts.  Since LSA allows 1320 pounds, a one-seater could still make the weight. If LSA isn't a consideration, you could cram a lot more horsepower into it.

I think the horizontal and vertical stabilizers would need two spars for adequate strength.  The tips, as with the wingtips, would be a challenge, Maybe fiberglass over hand-sculpted molds.

I have no clue what to do for landing gear. I looked at  a P-40 at Oshkosh in July, and understand the gearing that makes them pivot, but don't have the faintest idea how to work them around the main spar. May have to settle for stiff legs.

I haven't checked with Loehle, but if they would part with a cowl, it should be an almost perfect scale fit. Anyway, that's what's been rattling around in my brain, My EAA chapter has enough guys with real talent to help get it done when (if) I finish the 601. 

Re your questions, the "lowest bidder" system probably didn't set in until later. I'd guess they meant it to take battle damage, and 12 or 13 ribs per wing  would be just fine to me.  Good luck in  your planning/building. I'd be interested to know how you come along with the project.  If you're not already a member, I'd encourage you to join the nearest EAA chapter. They have tons of experience, and are always ready to help.

Paul Rodriguez

 

 



Scott Bolster
Young Eagles Pilot or VolunteerHomebuilder or Craftsman
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#7 Posted: 12/15/2009 14:16:07

Thanks guys for all the replies!  One of the things I did was to get those engineering blueprints off a seller on E-bay that really went into detail on the gear and it's mechanisims to swivel them.  And I'm thinking they are secured to the front and back of the spar.  The strut actually doesn't go up all the way and it's supported by other arms.

But, actually, I went over to the link that Adam Smith provided above and have been talking to the guys and girl over at Jurca.  I'm going to get some photos of their 75% P-40 replica; but I think I have found my airplane.  They have a bunch of other plans including a 100% Spitfire powered by a V-12 Allison.  That tube structure is beefy to say the least and it's a beautiful reproduction.

But the P-40 is all wood and is glassed over, can take up to 400HP and then some (perfect for the firewall-forward LS-1 packages out there), and actually has two seats, which is pretty neat.  The russians actually modified a P-40 with a second seat at some point during the war.

It would have been a challenge to design my own P-40, but I do have other ideas in my head on designs.  But for now, I think I'll be buying these plans in the near future!  The guys over at Jurca said the plans are very good quality when I asked.  I was skeptical due to the W.A.R. plans being a little sub-par so I asked very specific questions.  He said they were printed from a graphic design printing agency (the plans are in PDF format for storage) and the paper is rather thick.  So I'm thinking they are of much better quality than the W.A.R.

So I'll be keeping in touch as the project continues!



Shannon Coleman
Homebuilder or Craftsman
69
Posts
27
#8 Posted: 12/17/2009 18:47:32

Please post your impression of the quality of the Jurca plans when they arrive.  I've considered the same project before, but the cost of the Jurca plans seemed high at the time.  If they are of as good a quality as they described to you, then they should be worth it. 



David Spinnett
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0
#9 Posted: 2/13/2010 10:33:48

I went down the same road exactly - books, Blueprints, War plans, only for the FW190. Stalled due to not sure what to do next. I got as far as having a plane on the gear, but decided I hate fiberglass and it was too small. I want to build all metal, and two place, but don't really know where to begin for the design. Its no problem to build the whole thing digitally, just have no idea how many bulkheads there should be, metal thicknesses etc.... Was thinking of cribbing the RV8 design (performance bogey) as a starting point, doing a digital build then having a pro review it.....



Nick Sheryka
Homebuilder or Craftsman
11
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#10 Posted: 2/16/2010 20:24:55

Anyone know how many have been built and / or are flying from the Jurca plans? I would love to build one someday.  The P-40 has always been my favorite, being what my grandfather (seen pictured in my avatar) flew.



building Waiex #142 www.milpon.com
Pierre D'Entremont
Homebuilder or Craftsman
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#11 Posted: 2/16/2010 22:36:49

It may have been cheaper to hang with the Titan....but if you proceed and end up with a real close P40 it will have been worth it   ...


toolittle.jpg



Tooky or Pierre
Bryan McGrath
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30
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#12 Posted: 2/19/2010 23:25:08
Scott Bolster wrote:

 


It would have been a challenge to design my own P-40, but I do have other ideas in my head on designs.  But for now, I think I'll be buying these plans in the near future!  The guys over at Jurca said the plans are very good quality when I asked.  I was skeptical due to the W.A.R. plans being a little sub-par so I asked very specific questions.  He said they were printed from a graphic design printing agency (the plans are in PDF format for storage) and the paper is rather thick.  So I'm thinking they are of much better quality than the W.A.R.


 

It will be interesting to hear what the plans are like. At least you know Marcel Jurca was a qualified and experienced aircraft designer. If you stick to his design at least you know it will fly. His sport designs are very popular in Europe and his original prototypes are still flying even after 30+ years.



Scott Bolster
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#13 Posted: 9/3/2010 03:10:56

I was re-visiting this idea just the other day.  I had been wrapped up in getting my instrument ticket and, with my finances more freed up, I was looking to get started.  So I went and checked the website... you know... to get the dreams of soaring in a P-40 going again.  And what I found actually left me speechless:  The plans had increased in price from $850 to a staggering $1850.  That's from February.

I have a lot of stuff rolling around in my brain right now that isn't too flattering about this.  I was ok with spending $850 on plans... even though they were the most expensive that I had found in my research.  I guess this was because his daughter, Pamela, said that the proceeds went to support his widow.  But I simply can't fathom what kind of justification a $1000 price hike can have.

We all know the spirit of the EAA is to bring the joy of creating and flying airplanes at a reasonable cost and somehow I just can't help my mind from wondering if that has been lost over there.  But I guess this post is both a venting of my frustration and a call for someone who had a better understanding of what might be going on to explain before I call these people and start asking questions.

Thanks.



Craig Williams
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#14 Posted: 9/3/2010 08:35:39

Scott

 

I commend you on your enthusiasm and share it for the Hawker Sea Fury.  I too had dreams of building my own but after helping my friend Tony a bit with his 82% Corsair (www.corsair82.com) I realized it was way to big a job for me and one airplane.  The WAR way of building the plane is the way I would do it.  Just scale it up to the size you want.  This is where talking to someone like Tony would be invaluable because you can't just scale up or scale down an airplane.  So with that said I will add my encouragement and it sounds like your doing your homework so .  Good Luck and keep us posted. 

 

Craig