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View Full Version : Playing test pilot, P-39 spin recovery



erco415
12-07-2006, 11:33 AM
I'm probably the only one who didn't know this, but here goes anyway!

The P-39 is well known for it's poor spin characteristics, and after augering in in a 39D-1 on what was otherwise an enjoyable flight, I set myself to finding a workable recovery technique.

The standard spin recovery calls for rudder opposite the rotation, stick forward and ailerons neutral. This of course produces no results in the 'Cobra. I tried pro-spin inputs, various combinations of control inputs, the Beggs-Meuller technique, and even the P-39 Flight Manual procedure (In Bell Aircraft's defense, perhaps I didn't perform their recovery technique properly. They do note in the manual that failure to follow the procedure closely may result in an unrecoverable spin) without result. What did work was to extend the landing gear and full (landing) flaps.

I did four spins, both left and right, with entry altitudes ranging from 16400 feet to 8450 feet. The aircraft was a P-39D1 with 50% fuel and full ammo. In each case, extending the gear and flaps in combination with standard spin recovery control input effected a recovery of the spin. Minimum altitude lost in recovery was 6200 feet, maximum was 10850 feet in a botched recovery (gear/flaps retracted too soon and controls relaxed). If anyone is interested, I have the track but don't know how to post it.

I think that recoveries with less altitude loss are possible with practice, but for now I'm confident that any P-39 spin entered at 6500' AGL or higher is recoverable with this technique (I have not tested the recovery with external stores/full fuel, so that may be another matter). I am interested in hearing about any other ways to recover the P-39 spin that you may know about.

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SlickStick
12-07-2006, 11:38 AM
The P-39s have a "bit" more spin characteristics modelled in-game than other planes and that severe flat spin of the P-39 is the hardest to recover from in my experience.

As you wrote, it takes a lot of altitude sometimes, especially to recover from that nasty, nasty flat spin, but you've summarized the recovery techniques fairly well above.

I would just add that I also chop throttle during recovery attempts with opposite rudder, neutral ailerons, full flaps (sometimes working them up and down), gear at times, and pushing forward on the stick.<div class="ev_tpc_signature">

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Worf101
12-07-2006, 12:44 PM
You guys read my mind. I wound up in a flat spin the other day in an offline campaign at about 10,000 feet, still couldn't get out of it. I couldn't get the damn nose to go down. I'm wondering now if I "trimmed down" would that help of not in that there's no air going "over" the tail surfaces?

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erco415
12-07-2006, 12:57 PM
SlickStick, is the altitude lost with your recovery about the same as what I'm doing? I just set configuration/input and wait until it comes out.

Worf101, I don't know (havn't tried) what trim might do for the recovery. I havn't touched it in my experiments. You'd have made it out ok with gear and flaps and normal recovery technique. The problem I see with excessive trim (one way or the other) is that when you do recover you'll likely be going quite fast and find yourself faced with a powerfull out of trim situation.

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scootertgm
12-07-2006, 02:12 PM
I found in the 39 if I start off with a chopped throttle, dump flaps and gear and push my stick down and into the turn, then go to full throttle untill I'm rolling rather than spinning, I have a pretty good sucess rate for recovery.

SlickStick
12-07-2006, 02:36 PM
Originally posted by erco415:
SlickStick, is the altitude lost with your recovery about the same as what I'm doing? I just set configuration/input and wait until it comes out.

Although, I keep my Speedbar in Metric (since the beginning, as it was the only unit available at one time and I got used to the readings versus in-game performance), I'd have to say I can lose anywhere from 1500m to 2500m of altitude when recovering from the really bad flat spin (if I recover at all).

God help me if I start to spin in a P-39 at anything below 1500m, as the chances of recovery before SPLAT! are slim and none....and Slim is usally out of town. http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif<div class="ev_tpc_signature">

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erco415
12-07-2006, 05:04 PM
Thanks guys!

It looks like the altitude loss is pretty similar between us SlickStick, though 1500M (4900' feet) is better than I've acchieved so far.

scootertgm, you describe what I'm doing, and the result, perfectly. Except that I've been leaving power on throughout. I'm gonna try and leave the power off initially and see if that improves the result. Interestingly enough, the flight manual spin recovery starts with the power at idle. Something else that I found kinda funny: when you get into that high-rate roll you'd think you were recovered but not quite. I find that I need to stay in that for a few seconds and let the speeed build before I take the spin recovery inputs out or it's back to the spin.

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SlickStick
12-07-2006, 06:31 PM
I'm expecting that 1500m may not have been the "Death Spin". It's been awhile since I thought about it.<div class="ev_tpc_signature">

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BillyTheKid_22
12-07-2006, 10:41 PM
Howdy all!! LOL!! P-39! Good time!! http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif I know hard P-39!!!<div class="ev_tpc_signature">

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Fork-N-spoon
12-08-2006, 01:48 AM
RE: P-39 spins

I believe that this is just another case of pilot rumors and or myths put into reading and then perpetuated and hyped up by forum readers over the past ten years. The basis for this is due to reading the NACA data on P-39 spins. They found that the P-39 didn???t have any more or less tendency to spin than other aircraft or was it any more difficult to get out of a spin. If I remember correctly, in their tests of the P-39 and P-63, they found that if gun pods were installed and or no ammunition ballast was carried, the P-39/P-63 had a tendency to enter a spin easier and that it would be more violent under these conditions.

From all my readings, it was common practice to ???rat race??? home from the target range. I imagine the ???tumble and spin and soon auger in??? most likely came from pilots engaging in mock combat or rat races after shooting all their ammunition off at the target range. Under normal conditions, the NACA is pretty explicit that the P-39 had normal tendencies to spin and that spin recovery was pretty straight forward.

Something interesting that most people never consider, the P-51 Mustang had similar problems if its rear fuel tank was full. I???ve always found it odd how the P-39 is so infamous about this problem while little is said about the Mustang???s problems. The other mindset on this topic is that it???s perfectly acceptable for the Mustang to have this problem because it was corrected once the fuel was burned off, but the problem is still unacceptable in the P-39 even though its problems were very similar, e.g. a change in MAC due to fuel/ammunition usage.<div class="ev_tpc_signature">

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Heliopause
12-08-2006, 02:23 AM
I thought it had something to do with the engine being mid-ship...<div class="ev_tpc_signature">

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A few weeks later the same thing happened to me.
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erco415
12-08-2006, 08:26 AM
Good stuff!

Fork-N-spoon, I've found that any aircraft with a reputation has it for a reason, though, like you, I think that it gets exaggerated over time - especially by those who don't have first hand experience with the machine in question. I've found a few references to the P-51's shaky handling with the fuselage full. But I wonder what North American has to say about it's spin recovery (not having that flight manual). Bell's spin recovery procedure suggests to me that not all was kosher with the 39's spin characteristics. The procedure states (in part): "Wait until rudder effect is noticeable, then apply full forward stick and ailerons against the spin regardless of ammunition load in the wings" and "If the procedure above is followed, the airplane will recover in one-half turn. If the procedures is not followed closely, the airplane may not recover." This suggests to me that all is not straightforward with the spin, but I don't have any of the 39's contemporarie's flight manuals to compare.

I've also recently read Edwards Park's 'Nanette', which paints a pretty intimate picture of flying the P-39/400 and it suggests that the 39 could be a real handful. But, I do agree with you that what we have in sim with the 39 (and in popular lore) is probably somewhat exaggerated. But that's what we've got and we have at least one way to get the 'Iron Dog' out of a spin.

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FlatSpinMan
12-08-2006, 08:52 AM
What did I do???????!!!!
Slick stick wrote:

nasty, nasty flat spin

DaWorfster wrote:
[quote]I wound up in a flat spin the other day <span class="ev_code_RED">He lies! It never happened, honestly!</span>...couldn't get out of it. I couldn't get the damn nose to go down<span class="ev_code_RED">Well can you blame me? Wash more!</span>. I'm wondering now if I "trimmed down" would that help<span class="ev_code_RED">I'm not THAT kinky, you pervert!</span>...in that there's no air going "over" the tail[quote]

I strongly resent and reject this insinuation,sir!!!<div class="ev_tpc_signature">

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SlickStick
12-08-2006, 09:20 AM
Originally posted by FlatSpinMan:
What did I do???????!!!!
Slick stick wrote:
[QUOTE]nasty, nasty flat spin

DaWorfster wrote:

I wound up in a flat spin the other day <span class="ev_code_RED">He lies! It never happened, honestly!</span>...couldn't get out of it. I couldn't get the damn nose to go down<span class="ev_code_RED">Well can you blame me? Wash more!</span>. I'm wondering now if I "trimmed down" would that help<span class="ev_code_RED">I'm not THAT kinky, you pervert!</span>...in that there's no air going "over" the tail[quote]

I strongly resent and reject this insinuation,sir!!!

http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif Great sense of humor, FSM!!! "I wound up in a flat spin the other day..." hehehe

Actually, when I saw your name in the "Last Post" column and reviewed the thread title, I thought, "Ooh, with a name like FlatSpinMan, he should have some great advice." Well, unless your first name is "NeverRecovering". http://forums.ubi.com/images/smilies/winky.gif<div class="ev_tpc_signature">

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GAU-8
12-08-2006, 09:35 AM
depends on which version ya fly. if you get it right.....its a loong spirally death way down, feels like hours. you will see later on.the P-39 will shake off its masters inputs, when master thinks "i am master!".

ive learned. you wont get out of them all, nor will every spin be the same, some you will control, some you wont.

best advice...dont get into the spin cycle firsthand. http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

FlatSpinMan
12-08-2006, 10:46 AM
http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gifThis is the plane that gave rise to my avatar name. Playing the Il2 Demo I just couldn't keep the thing steady. Still haven't lost my touch.<div class="ev_tpc_signature">

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shahram177
12-08-2006, 12:56 PM
what up with the P-51's and their flat spin!
My god I've gone into turns at well over 300mph and still have flat spun like a leaf!
The P-39 as fugly as it is I've never had any real problems with flat spins. But maybe I've just been very lucky!

slo_1_2_3
12-08-2006, 05:15 PM
Whoa..... You are gonnna get so banned




(hopefully you'll note my sarcasm)<div class="ev_tpc_signature">

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Chuck_Older
12-08-2006, 05:19 PM
Damn skippy I beware old naked ladies. In fact I steer clear entirely, Tony.<div class="ev_tpc_signature">

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BrotherVoodoo
12-08-2006, 08:14 PM
Very naughty indeed. http://forums.ubi.com/images/smilies/crackwhip.gif<div class="ev_tpc_signature">

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Thanatos833
12-08-2006, 09:31 PM
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Wow! That is disgusting.<div class="ev_tpc_signature">

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Hanglands
12-09-2006, 03:00 AM
I was unsure if I should reply to this post, I think it might be incriminating http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Great link, Great pictures, thanks a lot http://forums.ubi.com/images/smilies/25.gif<div class="ev_tpc_signature">

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John_Pimlott
12-09-2006, 08:08 AM
That lady would look good in whatever she wore. Thanks for sharing this.
Best wishes.
John.
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Jagdgeschwader2
12-09-2006, 08:18 AM
I'll bet that costs a pretty penny. Will they

erco415
12-09-2006, 08:31 AM
Originally posted by GAU-8:
depends on which version ya fly. if you get it right.....its a loong spirally death way down, feels like hours. you will see later on.the P-39 will shake off its masters inputs, when master thinks "i am master!".

ive learned. you wont get out of them all, nor will every spin be the same, some you will control, some you wont.

best advice...dont get into the spin cycle firsthand. http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

I certainly havn't done every entry/spin combo out there, but I havn't found one (so far) that doesn't respond to, that is, recover with, gear and full flaps. The troubling thing is the excessive altitude loss. At least I have a hard deck now for taking chances at low speed. But, like you said, best never to get into one in the first place.

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