P-39 Airacobra and P-63 King Cobra

GTX · February 13, 2009, 12:56:39 PM

Been thinking recently - keep the P-39's existing performance re engine and altitude but have it as a dedicated anti-tank/CAS aircraft for North Africa and later Europe. Either keep the 37mm (maybe with AP ammo) or replace the nose gun with something more powerful (40mm S-gun?) and add some small bombs and later rockets under the wings. Also armour up the pilot a bit more?

Regards,

Greg

GTX · February 13, 2009, 03:57:48 PM

Bet you didn't know the P-39 was also Santa's replacement sled for the early '40s - powered by a special modified "Reindeer MkII" variant of the Allison:

Regards,

Greg

Sauragnmon · February 16, 2009, 03:25:17 PM

Mad Scientist at work:

You know, I caught myself up on this thread, and I came to an insane thought. You guys want to put a Saber or other such engine into this tinyback little fighter, I had an idea - fastback the fuselage, instead of the bubbletop - Shoulder the intakes so they're either side of the cockpit, or side-intake them below and in front of the exhaust manifolds. That's how you saber this puppy.

SR - the Pusher P-39... wow... it's like an Ascender, but sexy. Sweet job. Seriously.

I'll look into this madness once I get a few more builds out of the way, I wonder if there's a P-39 or 63 in 72... hmm.

dy031101 · February 16, 2009, 05:43:07 PM

The King Cobra got me wondering...... how would a tailless canard tractor-prop fighter look?

It would be a departure from what we're used to and in love with, but...... I kinda suspect that the King Cobra won't look too bad as a basis......

sotoolslinger · February 16, 2009, 05:56:41 PM

dy this is one of my favorite subjects and not to stomp on a good idea but if you put a prop on the front, a prop on the back , assuming guns in the wings......where do you put the gas

Look how big the Do -335 had to be

dy031101 · February 16, 2009, 07:10:06 PM

Quote from: sotoolslinger on February 16, 2009, 05:56:41 PM
dy this is one of my favorite subjects and not to stomp on a good idea but if you put a prop on the front, a prop on the back , assuming guns in the wings......where do you put the gas

No no no, I didn't mean to add another prop-engine to the plane. Just the original prop in front of the heavy gun and engine behind the pilot (the P-63 is still a tractor-prop plane despite of its engine placement, right?). Then replace the conventional wing arrangement with the tailless canard scheme.

Weaver · February 17, 2009, 09:32:47 AM

Actually, a 3-surface layout would make sense. When you've got a CofG that's further back than normal, the tailplane is on a shorter moment arm and therefore less effective. Adding a pair of canards with linked elevators forwards would be an interesting alternative to making the tailplane bigger.

Weaver · February 19, 2009, 01:18:11 AM

Nice one Apo, although I think the room in the booms would be beter used for MUCH longer undercarriage, otherwise the first flight is going to be cut short when he rotates for take-off, the rear prop hits the ground and disintegrates and the bits slice though the booms.......

sequoiaranger · February 19, 2009, 06:45:39 AM

>I think the room in the booms would be beter used for MUCH longer undercarriage, otherwise the first flight is going to be cut short when he rotates for take-off, the rear prop hits the ground and disintegrates and the bits slice though the boom<

But not MUCH longer. Though I realize that the pusher Kyushu Shinden had long, spindly legs, the Saab J-21 was very much like a pusher P-39 with booms. Lift-off will probably be on plane for a little while after unsticking, THEN the pilot will pull the stick back after the prop is well clear of the runway.

In the pic below, look at the length of the main landing gear relative to the people standing by--maybe only a foot longer u/c? If you look at the pic with "Santa", the guy in white's chest is even with the leading edge of the wing. In my pic here it would appear that if the people took a couple of steps back, the leading edge would hit them armpit high or possibly shoulder high--not a whole lot of difference. I think on the Shinden a person could walk under the wing without scraping it (note the probably very short woman walking right past the u/c under the wing).

kitnut617 · February 19, 2009, 08:03:03 AM

Couple of things though, the Saab's prop is the same diameter as a Me.109, whereas the prop on the Shinden is much bigger, also the thrust line on the Saab is quite a bit higher than that shown in the twin prop P-63

Weaver · February 19, 2009, 08:35:52 AM

Also, the Saab's prop is nearer the u/c legs: it's only just behind the trailing edge of the wing, whereas the "twin-cobra's" is much further back.

Weaver · February 19, 2009, 09:00:54 AM

Quote from: sequoiaranger on February 19, 2009, 06:45:39 AM

In the pic below, look at the length of the main landing gear relative to the people standing by--maybe only a foot longer u/c? If you look at the pic with "Santa", the guy in white's chest is even with the leading edge of the wing. In my pic here it would appear that if the people took a couple of steps back, the leading edge would hit them armpit high or possibly shoulder high--not a whole lot of difference. I think on the Shinden a person could walk under the wing without scraping it (note the probably very short woman walking right past the u/c under the wing).

I think that picture is deceptive: the J21's wing is taller than head height, as per this pic (the pilot dummy is full-size):

Lots more pics here:

http://www.ipmsstockholm.org/magazine/2000/02/stuff_eng_detail_j21.htm

sequoiaranger · February 19, 2009, 06:30:25 PM

Weaver:

>I think that picture is deceptive: the J21's wing is taller than head height, as per this pic (the pilot dummy is full-size):<

The color, closer-up pic of REAL PEOPLE by the Saab seem to me to indicate that if the guy facing the left turned around, he would smack his face into the lower crown of the roundel (at or slightly above wing level). It seems to me that although the caption says "full-size" for the dummy, we don't know what his height is really? Or are the guys in the other photo very tall?

From the pictures of the Saab j-21 on the site you linked, it is clear to me that indeed the twin-boom pusher Airacobra as depicted in the photo-shopped picture would need some more elevation so that the prop cleared properly on take-off. That, or a truncated propeller (and any adjuvant oddities in RPM's or thrust that might cause).

Mossie · February 20, 2009, 02:06:51 AM

It's not the dummy, he's the right size. The J-21 in Weaves pic is on jacks!

Weaver · February 20, 2009, 02:17:34 AM

Quote from: sequoiaranger on February 19, 2009, 06:30:25 PM

The color, closer-up pic of REAL PEOPLE by the Saab seem to me to indicate that if the guy facing the left turned around, he would smack his face into the lower crown of the roundel (at or slightly above wing level). It seems to me that although the caption says "full-size" for the dummy, we don't know what his height is really? Or are the guys in the other photo very tall?

Well what we're doing is photo-interpreting here: I'm looking at the same picture, and my impression is that the same guy's hat would hit the bottom crown, rather than his face. My impression is also that the pilot guy could almost walk under the wing without stooping. "Full-size" real people come in a range of heights from 5' to 7' with a large number of people between 5'4" and 6'4".

We coud argue it all day: the bottom line is that it has "very long" undercarriage for prop-clearance, which is the point I was trying to make.