Do plans exist for scale Aircobra/Kingcobra replica?

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Peterson

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Just wondering if anyone has scaled down either the Bell Aircobra or Kingcobra. I can't afford to build one, but love the uniqueness of the design. I wouldn't know how to scale a set of plans down either.
 

thump

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When you say scaled down plans do you mean RC plans? If so try the palmer plans this is for a 92'' wingspan model and it's a beauty.
Here's the link Precision Cut Kits.
 

Tiger Tim

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Probably not scaled that far down. I bet Peterson was thinking more like 75%. Big enough to carry someone but small enough to be a sport plane.

I've been thinking a bit lately about how neat a scaled Airacobra would be. I was thinking all metal construction, probably built like a T-51 to dumb things down; a side-hinged canopy because I bet you'd never cram through a 3/4 scale door, and rotary power up front to keep the pointy nose profile without having to resign yourself to all sorts of gearbox and drive shaft issues. Plus, if you put the engine in the middle like the original you'd need a 28mm canon in the nose for balance.
 

thump

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if you put the engine in the middle like the original you'd need a 28mm canon in the nose for balance.




I disagree, It would be a .50 cal at most ;)
 
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Peterson

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It should be big enough to fly an adult sized human. Digging the rotary power, not sure I need any kind of heavy gun : an M 240B would do the trick !
 

ScaleBirdsScott

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There's been some thought of using the core design from the Hellcat project for doing a P-39 someday. Our frame would be a viable platform for it, though it'd be hard to implement the side-door as it really was.

I agree on the rotaries as mentioned, or maybe the D-motor?
 

Peterson

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There's been some thought of using the core design from the Hellcat project for doing a P-39 someday. Our frame would be a viable platform for it, though it'd be hard to implement the side-door as it really was.

I agree on the rotaries as mentioned, or maybe the D-motor?

If you end up rendering a set of plans, please PM me!
 

fiftycal

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i have a real P-39 Airacobra on ebay, its a project if interested, i also have listed a full set of engineering drawings, maybe you can scale them down
 

Jerry Lytle

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An 80% scaled P-39 cockpit would be the right size for one of the little people.
I recall that there was a limited height for P-39 pilots of around 5'8".
Any 4'6" pilots out there? :)
 

Riggerrob

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In a few more years, electric motors will make Airacobra and Kingcobra replicas feasible, without that pesky drive shaft. Just mount the electric motor and propeller in the nose and mount the battery-pack or petroleum-powered generator behind the pilly. Add automatic weapons to the nose until it balances.
 

ScaleBirdsScott

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Very true. Also there was a nifty motor st the Oshkosh innovation Station tent which is real small and could theoretically make a great prinary driver or also just a good source for driving the Electrical Pixie Motivator
 

Topaz

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If you want to do a scale P-39, pull the driveline from a Stemme S-10 motorglider, which is mid-engine with a nose-mounted prop just like the P-39. Myself, I think it would be heresy to gut a Stemme like this, but it does have all the parts you'd need for the driveline.
 

Tiger Tim

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I've never taken one art to check but doesn't the S-10 route the drive shaft through the middle of the cockpit? Easy enough to run it between side-by-side seats but may be uncomfortable going through the pilot's chest in a single seater.
 

TFF

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Although a big airplane by homebuilt standards, it was probably one of the smaller fighters of WW2. Minus the tall gear about Bf109 size. Scaling the airplane puts the unscalable pilot in more of a bind to look right. The plus I see is for the V8 guys. The lump is not firewall forward, so the extra weight of an auto conversion does not have the same penalties as if you hung it off the front. Driveshaft? Oh well. Tri gear makes ground handling good for a commoner. There was a real one at Oshkosh; the only flier I have ever seen. I looked at it a while.
 

Tiger Tim

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The P-39/63 design is in many ways doomed from the start as a scaled down replica if you're not willing to make some significant concessions. If you want to see some significant flight time either as one airplane or as a fleet I think you'll have to ditch the mid-engine and move it to the nose which means either a low-profile power plant, or cylinders sticking out beyond the Cobra's otherwise streamlined nose profile. Maybe an inline engine could be almost hidden in the nose contours if you made a scaled Airabonita, the tailwheel carrier prototype.
 

steveair2

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Tim, that's a great picture of the XFL-1. I had to squint so hard at the Blue Yonder airplane that I couldn't see anything.
I wonder if there's any P-39's left in Russia?
 

cluttonfred

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Airacobra-Cross-section.jpg bell_p-39.jpg

Picking up an old thread as I was digging around myself for any reduced-scale P-39 replicas out there. This cross section shows that a reduced-scale Airacobra could, in fact, accommodate a full-scale pilot if it weren't for that pesky driveshaft.

One one hand, I can dream about a real little P-39 with a rear-mounted engine, maybe a Suzuki conversion, and retractable gear, but since I wouldn't have a 37mm cannon and two .50 cal machine guns in the nose I don't see how you could get the CG right without a lot of ballast.

On the other hand, the cockpit is quite far forward so if you went with a nose-mounted engine it would have to be very light to avoid needing ballast in the tail. I wouldn't bother with such a project if I had to use a two-stroke, a WWII fighter replica that sounded like a chain would just be annoying.

The Stemme hybrid approach is interesting but quite expensive. I wonder if a direct hybrid with no batteries at all, just a rear-mounted generator powering the nose-mounted electric motor to avoid the shaft and gearbox, would be feasible? You wouldn't need infinite throttle settings, just four or five set points from idle to full power.

One approach that might work is moving a nose-mounted engine back towards the pilot as far as possible, perhaps even putting the rudder pedals on either side and straddling it, but I don't know if you could put a long enough prop extension on a Raven or Aeromomentum Suzuki conversion or maybe even a Mikron without causing other problems.

With any nose-mounted engine it would be fun to route the exhaust to simulated manifolds behind the cockpit if you could do it safely.

Any other ideas?
 

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