3/4th Scale Replica Bell P-39 Airacobra

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Derswede

Well-Known Member
The Lionheart? Now that is a great looking bird. If I had the , the time and a place to build something, that would be my bird. Love the Staggerwing, have had the pleasure to fly and fly in a couple. Much better handling than you would think by looking at the size.

Derswede

nicknack

Well-Known Member
How about ditching the driveshaft completely and use an electric motor(like the 350hp ones from siemens) to drive the propeller and another to act as a generator driven by a 400 to 500hp piston engine like an LS3.

In this case the drive shaft is the electric cable carrying the current from the generator to the motor... I bet we can save a bunch of weight from PRSU units and driveshaft dead weight.

pylon500

Well-Known Member
Scaled Airacobra...?
How about getting the tailwheel endorsement and having a crack at the Airabonita!
Although it turns out this has already been done
Very hard to find any info on this, and can't find the one photo I took of it when I discovered it in a hangar.
I think it had some alloy block V6 in it?

Lets just say it looked good from a distance.

wsimpso1

Super Moderator
Staff member
Log Member
No, it's not that simple. Dealing with torsional vibration issues in a long driveshaft is something that makes brave engineers weep. Getting a tailwheel endorsement would be a lot easier.
It won't make this one weep, but it will require some serious engineering. A shaft that long can easily have a low enough spring rate to properly isolate torsional vibe from the forward gearbox/prop. It will have critical speed issues to manage. A competent licensed professional in rotating machinery ought to be able to help, but it will cost money.

I second the others. Even I have a tailwheel endorsement, you can too. Then there are good options already proven in the market and in the air.

Billski

wsimpso1

Super Moderator
Staff member
Log Member
met some Tusgegee airmen a few years ago who flew the p-39 and p-51 they said the only thing the p-39 was good for was that you could roll the window down like in a car toss your scarf out and look cool, otherwise it was junk
The Russian pilots that flew them did not think they were given a dog. They shot down a lot of Luftwaffe aircraft with them...

mm4440

Well-Known Member
Diesel Electric drive works well for locomotives where it functions as a CVT and weight is good for adhesion. A drive shaft is 99+% efficient and a carbon one is light and about \$1000; a hybrid electric drive would be less efficient, likely heavier and much more expensive.

Dana

Super Moderator
Staff member
The Russian pilots that flew them did not think they were given a dog. They shot down a lot of Luftwaffe aircraft with them...
The Russians liked them for ground attack, mostly. With that big cannon they were very good for that.

TFF

Well-Known Member
The Eastern Front was mostly low level fighting. A couple of thousand feet AGL. The Allison with the single stage supercharger was not outclassed because of altitude. It also ran. Reliability compared to Russian made stuff was way better. Parts fit, parts could swap, parts available. Hard to fight without functional equipment. It’s actually an agile plane, relatively small, and a big gun. It’s glossed over but when the war stared and we showed up in Europe with P-39s and P-40s, the British started to feel sorry for us and Lend Leased us second hand Mk V Spirfires because we were getting blistered with our planes. Ground support P-39s would do fine, a top German ace in an aircraft a notch above was turkey shooting in the West.

nicknack

Well-Known Member
Scaled Airacobra...?
How about getting the tailwheel endorsement and having a crack at the Airabonita!
Although it turns out this has already been done
Very hard to find any info on this, and can't find the one photo I took of it when I discovered it in a hangar.
I think it had some alloy block V6 in it?
View attachment 106993
View attachment 106994
Lets just say it looked good from a distance.
I will prefer to convert it into tricycle gear....
Anyone ever made a replica Me309? Another tricycle that looks good too..

Speedboat100

Banned
I have R/C Kingcobra kit at the basement...how about that in 50% size....Bell P-63 KINGCOBRA ?

REVAN

Well-Known Member
My 2-cents:

If any WW-2 replica was destined to be scaled down and done with an electric propulsion, it would be the P-39. If your heart is set on the P-39, the synergy exists in doing it as an electric plane. By the time you are done designing and building the aircraft, the battery tech will be good enough to make it all come together.

Put an electric motor in the front, and engineer a large battery bay behind the pilot (the battery pack to be designed later when the plane is closer to being ready to fly).

galapoola

Well-Known Member
“By the time you are done designing and building the aircraft, the battery tech will be good enough to make it all come together.“

Reminds me of the movie Interstellar

vhhjr

Well-Known Member
HBA Supporter
Unless you are a person of minute stature a 50% P-39 won't work. I built a 70% mock-up and had to add 2 inches to the fuselage height to fit my 5' 10", 200 lb hulk. Even an original P-39 could be a little tight. I sat in one in an Australian museum. I also made the doors oversize and it was still difficult to get in and out of. My plan was to hinge the top of the canopy.

I ran across a P-39 project in Australia a few years ago and lost tract of it. This Airabonito may be it. The builder, Deuter Sedbauer, sent me some photos. He was planning on a nose mounted engine.

Vince Homer

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vhhjr

Well-Known Member
HBA Supporter
Here's al the photos Deuter sent me in 2005.

Vince Homer

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