st_dysan

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Sorry if this is the wrong forum but no one seems to look at the classifieds wanted section so I thought I would try here. Does anyone have a crashed Hangar 9 P-40 that has the Horizontal stab in one piece?

I bought a P-40 from a user here and when it arrived the horizontal stab was broken on both sides of fuse. If anyone can help I would really appreciate it. There's no way to fix and strengthen it so that I would be comfortable flying it. Also Horizon and various online stores don't carry the discontinued parts anymore. any help would be greatly appreciated.

dasintex

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What about a Replacement part from another manufacturer like Nitro Models?

LDM

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I would make a new one the originals were not that strong anyway

chuck993

I had a H9 P-40 and if you want to rebuild the tail you can do it easily and make it extremely strong. Remove the covering on the bottom and cover the whole bottom with thin ply(fix any broken wood inside first by gluing the parts together or replacing), then paint the ply with epoxy and recover. It will be thicker, but it is solid as a rock. I did the same thing with mine once, it works.

st_dysan

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Thanks for all the replies. I was trying for the easy way out but it looks like I'm going to end up pulling the covering off and doing that way. I was thinking about using a couple of small carbon rods but I like the idea of the lite ply on the bottom. Thanks for the all the ideas.

chuck993

I know this works, I had to do it myself, I ordered one through RCU and the tail got broken in shipment, so I put it on a stand, removed the covering, fixed the wood inside by regluing, etc...put the ply on (I used some small screws in corners to help hold it) 30 min epoxy to glue the ply on, clothes pins all around to get a good fit, After it dried I mixed 30 min epoxy with a small amount of alchohol to thin it, then painted the ply which makes it strong. After everything dried, I then a dremeled and hand sandied to make it the same shape as the top and edges. Iron the covering on and it was strong as an ox. Recheck the balance, mine gained some weight, but not a big deal in a warbird as long as you balance it, it is not that hard to do really and cheap.

da Rock

Repairing it is the way to go.

But there really isn't a need to overkill the strengthening. Regluing the broken places is necessary of course, but you'll actually strengthen way more than adequately with balsa sheeting. Run the grain spanwise and it'll provide way more stiffness than needed. Keep the amount of glue down as well. Simply apply wood glue like Elmers etc to the frame and lightly clamp the balsa. Any strength clamping will press the balsa into contact with the frame. Sanding to blend is very easy with balsa to balsa.

If you do choose to use plywood, find the EXTREMELY thin stuff. And consider cutting out fairly large lightening holes. Also, epoxy is quite heavy and does nothing good if smeared where it's not glueing things together. Consider only putting it on the framework if you do choose to use it.

There is a wing sheeting hardwood that used to be sold in hobby shops back when modelers were building their own models and sheeting foam wings. It's about the thickest plywood you'd want back there. It can actually be cut with scissors. The measurements back there are such that thin balsa really strengthens in combination with the existing structure. The existing structure just needed better wood selection or a couple of support spars (or thin balsa sheeting) and it'd stood the test.

Remember that you're building an airplane, not an automobile.

chuck993

The ply I used is extremely thin and can be cut with scissors, it is designed for this, I get it at my LHS, not plywood from the hardware store, but if you paint on Epoxy it will strengthen it.

da Rock

There are a couple of things that should be considered.

How heavy is the piece of wood, whether it's ply or balsa? Skinning a structure like a stab will increase it's stiffness greatly, way more than it needs to resist flutter. Balsa by itself has been used for years, as thin as 1/32 on 35size models. It's been used without the paint coat of epoxy. So consider that whatever wood you use, a coat of epoxy painted on it is massive overkill when in fact the plywood is way more than strong enough without help.

The couple of things to consider is weight and strength.

The existing structure in the stab of the H9 P40 has been adequate for the vast majority of those models. It is reasonable to assume that more than a slight imporvement in stiffness is all that's needed. With any airplane, weight in the tail is critical and should not be increased unreasonably. Think about what would be appropriate back there.

LDM

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Look up a product called fliteskin , I use it on many planes , a simple $35 purchase will last you on many many models for small applications .
Its amazeing stuff , light weight , you sand it to make it more porous and can use CA to attach .
I used it on my H9 corsair for the rudder reinforcement , its a great product

chuck993

at my field there are tons of warbirds and I would say most of them are overweight, fixed many times and weight seems to be the least of their worries...LOL

LDM

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Hey Chuck , I get to Norfolk all the time for a corporate call on Dollar TRee , how far is the field from The Chesapeak area ?

da Rock

Which is why they needed fixing many times.

LDM

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Ya , agree but seem like the weight argument gets people worked up . I have had the same conversation with Alec from KMP/ YN . He is a good guy but goes on about how well the planes fly regardless of the calculated wing loading .

I am bashing a CMP FW190 , I have done everything possible in the build to advoid adding weight . I rebuild the servo boxes in the wing turned sideway and ahead of the CG.
Both batterys are house in the fuse right behind the firewall , one the G26 ei and the other for the radio . All use servos are ahead of the CG ect ect .
I am determined not to add weight to achieve the CG

I like building light and not adding dead weight

da Rock

And this thread is about the tailfeathers of the H9 P-40 warhawk. That someone suggested grossly over strengthening. Sounds like your CMP FW190 build should work for you. BTW, Alec is talking about planes that're built and balanced. Yeah, they might still fly well, but would undoubtedly fly better had unnecessary weight been kept out, like grossly overstrengthening things like the stab. Want the best possible? Don't overdo it.

chuck993

reference No this thread started out with a guy that had the same plane and the same problem I did, which is a Hangar 9 P40 asking for suggestions. Did you own a Hangar 9 P40 with a broken tail? I am sure you didn't.
Since I had a Hangar 9 P40 with the same exact problem and I fixed it without adding tons of weight, I suggested a way to fix it for basically a couple of bucks and the thing is solid. This is a technique that other people flying and building airplanes for 20+ years have told me how to do[:-]

LDM

My Feedback: (15)

Well back on subject ( I think lol ) I do have the two H9 corsair , (one was lost ) any way the tail fin had a weak attachment /incertion point into the fuse .
On a few nose overers , and I do mean few , the fin was worked loose .
I removed it , reinforced it with flight skin , very little weight gain (not enought to impact original CG) and the plane never had a fin problem again .

Some refer to the product as G10 , I can speak for that description but know that the product sold by Fliteskin comes in differant sizes and thicknesses , some even great for a flap foundation waiting for rib application .

da Rock

st_dysan started the thread in post #1 looking for a replacement for his broken H9 P40 tail, and post #3 mentioned the epoxy coated plywood addition to the stabs.

I'm very sorry that my advice is that an epoxy painted plywood addition is grossly over strengthening but it is my opinion it is. I actually own two P-40s. One is a Kyosho that fluttered it's stab. That was braced internally and has lasted ever since. My H9 has not had a problem yet. Of course, there might be a good reason for that.

Your technique will most certainly strengthen what is basically a balsawood framework that is a perfectly adequate design with proper wood selection and construction. (Something not under our control with ARFs) Your technique will certainly be strong as epoxy covered plywood can be. However, having built model airplanes since the 50s, my experience is that solution is massive overkill. Excess weight is to be avoided when building or repairing model airplanes. Your advisors should have given you better advice.

chuck993