The P-40 hates me (mysterious stalling behavior)

[Cobra516]

The P-40 certainly has some interesting flight characteristics that present themselves in the low speed/high AOA area of the flight envelope.  From my experience the onset of the stall is relatively predictable with a moderate break.  It does snap/spin quickly though if you're ham fisting it, especially if uncoordinated - but seems to be easily recoverable in most situations.  It seems that it often wants to fall flat or tail first if you let it, seems as if it has a very aft center of gravity.  All that is usually coupled with considerable yawing moment as well, depending on how you enter the stall/spin and the rudder becomes very sluggish to stop the slow/lazy lateral oscillations of the nose.  The nose certainly wallers around at slow speed and demands a lot of rudder input to keep it coordinated and keep the stall departures under control.  I usually use full flaps when stall fighting. 

Overall I think it's a relatively easy airplane to fly on the edge/stall fight, just have to keep it coordinated.  It has a lot of adverse yaw at slow speeds if not coordinated and that really aggravates the departure/stall.  Yawing moment is the major ingredient in the stall/spin equation, and when not flown properly the P-40 certainly produces a lot of it.

[Widewing]

I'm pretty sure the P-40 has split flaps.  They tend to be next-to-worthless for combat in aircraft with such a poor thrust:drag ratio.  In the tests I've done the P-40's turn rate decreases with the use of flaps.

Every fighter's turn rate decreases with flap use....


My regards,

Widewing

[Anaxogoras]

Every fighter's turn rate decreases with flap use....


My regards,

Widewing

Have you tested that assumption?  I have.

[Widewing]

Have you tested that assumption?  I have.

Does the Pope know Latin?   

Any time you reduce speed below corner velocity, your turn rate suffers. With the exception of the P-47s, P-51s and P-40s, every aircraft that deploys even one notch of flaps will be below corner velocity, or below corner velocity an instant later. The above mentioned will be below corner in about two seconds if pulling more than 3g. The vast majority of fighters can't begin to lower flaps until below corner velocity. So, their turn rate is already below optimum.

To determine corner velocity and the effect flaps have on turn rate and radius, you need Badboy's Bootstrap Calculator found here: http://www.badz.pwp.blueyonder.co.uk/Academy/AH_BootStrap.zip

Then, you need to record speed and time when turning the tightest circles you can manage. I recommend doing no less than 3 circles, taking the average of time and speed. Plug this data into Badboy's calculator and you'll have the data you require. Do it for clean and for each flap position. You will notice that sustained turn rate is much, much less than that at corner velocity. Adding flaps further reduces speed, and turn rate follows it down.

Once you grasp what Badboy's calculator is telling you, you'll see that flap usage is something you'll want to manage very carefully.


My regards,

Widewing

[SmokinLoon]

I'm pretty sure the P-40 has split flaps.  They tend to be next-to-worthless for combat in aircraft with such a poor thrust:drag ratio.  In the tests I've done the P-40's turn rate decreases with the use of flaps.

The turn rate **DECREASES** with flaps???  I want to make sure I read that... DECREASES?  Then what I have known to be true with the P40E for over a year is bogus.  Why oh Why!?      I've been lowering 1 notch for quite some time while turn fighting, seems to help. 

The one thing I ask is.. how many turn OFF the combat trim while dogfighting in the P40E?  If I am able to get it 250mph+, I turn it off.  It seems to stall out quicker when on and menouvering at low speed,... or is it just me?

[Anaxogoras]

The turn rate **DECREASES** with flaps???  I want to make sure I read that... DECREASES?  Then what I have known to be true with the P40E for over a year is bogus.  Why oh Why!?      I've been lowering 1 notch for quite some time while turn fighting, seems to help. 

The one thing I ask is.. how many turn OFF the combat trim while dogfighting in the P40E?  If I am able to get it 250mph+, I turn it off.  It seems to stall out quicker when on and menouvering at low speed,... or is it just me?

Read the thread.  One notch or two does seem to help the P-40, but for many other aircraft that have split flaps they do not help.

[Murdr]

The turn rate **DECREASES** with flaps???  I want to make sure I read that... DECREASES?  Then what I have known to be true with the P40E for over a year is bogus.  Why oh Why!?      I've been lowering 1 notch for quite some time while turn fighting, seems to help. 

The one thing I ask is.. how many turn OFF the combat trim while dogfighting in the P40E?  If I am able to get it 250mph+, I turn it off.  It seems to stall out quicker when on and menouvering at low speed,... or is it just me?

As Widewing said, best turn rate is a corner velocity (which can't be sustained without altitude loss, and is typically above flap deployment speed).  If we're talking sustained rate of turn, the effect of flaps varies from plane to plane, but for the p40E, the best sustained rate is at one notch.

[SmokinLoon]

As Widewing said, best turn rate is a corner velocity (which can't be sustained without altitude loss, and is typically above flap deployment speed).  If we're talking sustained rate of turn, the effect of flaps varies from plane to plane, but for the p40E, the best sustained rate is at one notch.

I've been using one notch only in tight turns and it seems to make the difference, at least for me, in lasting a bit longer in a dog fight.   

I need to learn some of the other lesser known tricks, because as soon as I lose the advantage I lose the fight since receovering is up to the other guy making a mistake.

[FYB]

Hello all,

Recently I've taken quite a shine to the P-40 in all it's iterations- the speed is somewhat lacking but it's roll rate is excellent and it seems capable of handling pretty much anything well (as long as you can sucker that FW-190 into a turn fight, that is.) There's just one little thing that has been driving me absolutely nuts.

The P-40 has an alarming tenancy to flip over and faceplant right into terra firma for no reason at all. This happens generally as I'm making a rather smooth (and not hard) turn, at around 150 MPH, or as I'm pulling out of a loop, at speeds of up to 200 MPH. She seems to want to roll left and stall, making me think it's an effect of torque, but sometimes she's okay with jerking around to the right, too. For reference, the P-40's stall speed is 90 MPH, and this phenomena is constantly observed at modest angles of attack- or no angle at all.

Naturally, this likes to strike just as I've won the rolling scissors or the like, and will unceremoniously flip my bird over and SLAM it into the earth just as I try to gently and smoothly take up a leisurely lag pursuit. As you may imagine, this makes me so mad I can barely breathe sometimes. Now, I've noticed this behavior consistently in both Aces High and IL-2 Sturmovik, so clearly I'm doing something wrong. I just can't imagine what. Do I need to give her some rudder opposite the direction of torque when undertaking maneuvers? Is torque in this bird worse then normal?

I can agree with it having an addiction to rolling when you make a tight turn at around 120 - 200mph, its mostly cause you might be pulling your stick back toward yourself to hard; otherwise, im not sure.

-FYB