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Old Mar 02, 2002, 06:14 PM
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Cincinnati
Joined Feb 2002
18 Posts
Speed 400 Class P-39

At a slow time during a basketball game today, I was in a discussion about a P-39 project. However, preliminary examination of three view drawings reveal a very short tail moment and small tail surfaces. Does anyone have any experience with such a scale model at about a 30" span? Any ideas on what percent increase in horizontal stab would be appropriate? Any other suggestions before I cut wood? Paul Siegel
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Old Mar 02, 2002, 07:46 PM
Registered User
Keremeos, BC, Canada
Joined Dec 1996
632 Posts
P39

There are threads about the HOB kits, one of which used to be the P39, apparently out of production. If you can find the kit plans (I will fight you for a full kit!), it may be worth while to at least start there. It had the full molded turtle deck/canopy, but you shoud be able to bs that out with a Sig canopy, etc. From personal experience, I know that the HOB kit flew nicely, once you learned how to launch it (same applies to any of these kits). Once in the air, just gorgeous...
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Old Mar 02, 2002, 07:54 PM
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Jim Ryan's Avatar
Cincinnati, OH USA
Joined Oct 2000
1,956 Posts
Re: Speed 400 Class P-39

Originally posted by pfsiegel
At a slow time during a basketball game today, I was in a discussion about a P-39 project.

It was a great game, but when the Muskies pulled away, we didn't have John Calipari to talk to, so we were reduced to designing airplanes instead.

However, preliminary examination of three view drawings reveal a very short tail moment and small tail surfaces. Does anyone have any experience with such a scale model at about a 30" span? Any ideas on what percent increase in horizontal stab would be appropriate? Any other suggestions before I cut wood? Paul Siegel

I'm hoping Tex will surface and let us know what the areas are like on his modified Top Flite kit. I do know that Keith Shaw had an "interesting" experience test flying some guy's P-39 many years ago. The Airacobra is sure a great looking machine though....there has to be a way!

Jim
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Old Mar 02, 2002, 08:26 PM
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Granby, CT, USA
Joined Jan 2001
939 Posts
HOB airplanes

I think the HOB kits all used the same wing, and I suspect similar moments. Not particularly scale, so making conclusions off that series of airplanes might not be valid. They might all fly the same. My only contact with P-39's is that I made an 'Airabonita' out of a Jack Stafford P-39 kit for a friend. He says it never flew steadily, but hunted around a bunch and could never figure out why. Surely not a construction-related problem. That, too, is a model airplane, so I don't know what can be generalized off that either. Most warbirds have short-ish tails compared to aerobatic airplanes, and I'd guess would be less than sterling aerobats because of that.
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Old Mar 03, 2002, 09:57 AM
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Canada
Joined Nov 2000
6,873 Posts
I believe the HOB 1/2A kits all used the same design and modified the wingtips, canopy molding and tail group outlines for their variants.
Still have a HOB p39 kit .. never got around to building it after the my P51 and Me109 ones were done.. impressions after 20 years.. V nice instruction book..but a seriously overbuilt kit and the wood selection is poor, canopy molding is acceptable but not great.. amazing as to how far the goalposts have moved since then ;-)
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Old Mar 03, 2002, 07:55 PM
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Keremeos, BC, Canada
Joined Dec 1996
632 Posts
P39

Yeah, Bare, and I guess yer keepin it too, eh?

Right about moments, etc; the P39 is fairly close, but my buddy's FW190 plan has the ing about 1" back from scale. If one was to run electric, the wing could be moved ahead without penalty by moving batts, etc. I saw a 109 with the wing in scale position, and it flew fine(hot 1cc diesel power); no nasty surprises and it flew out of your hand (I launched) with a mild breeze.
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Old Mar 03, 2002, 09:22 PM
Mike Swan
Oroville, California, United States
Joined Oct 2000
372 Posts
Heres a Earl Stahl freefight p-39,if you look at the tail surfaces you can compare the differant outlines.http://www.theplanpage.com/esp/p39/airacobra.zip (447kb)
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Old Mar 04, 2002, 08:15 AM
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Winnipeg, MB Canada
Joined Jan 2000
2,419 Posts
TF P-39

Jim and all: My 'Cobra is a real tiger with the power on, yet a pussy-cat when it comes to vices. There dosen't seem to be any bad habits. I've slowed it down, banked and yanked and all I get is a bit of mushing. It's rock steady in high speed flight and it slows to a crawl on landing. I don't know just how scale the tail surfaces are, but they appear to be adequate. Wing area is touted as 850'ish I think, so wing loading is squat at 8lbs flying weight. Tex.
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Old Mar 04, 2002, 07:28 PM
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Keremeos, BC, Canada
Joined Dec 1996
632 Posts
P39

Yup, my experience too; flies like a MUCH larger model.

Favourite trick (particularly when the left-circuit club guys were at the field) was to run out the last of the power in a climb; nearly a dot. When the model stalled from no thrust, it would snap into a dive, and I would start yelling "deadstick! deadstick!" as the model came screaming down vertically. Then I would proceed (while the club guys hid under pickups) to do a couple of big, fat loops, a series of rolls, and inverted downwind, and slide the model onto the grass a few feet away... A truly lovely model...
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