P-51D Stall Speed

[Tailspin45]

Re: "snap roll", the P-51 manual (the real one, but the DCS version which is mostly a word for word copy) says, "The aerodynamic characteristics of the P-51D are such that snap rolls cannot be satisfactorily performed. This has been proved by a long series of test flights."

 

But we all know that's not true of the beta version of the DCS '51. It'll snap in a heart beat, and in fact does it quite predictably and repeatably during an accelerated stall.

 

However, that's not the same as a wing drop in a power off level stall, as discussed earlier in this thread. I've done a few stalls as a passenger in a P-51, and oodles of them as either PIC or CFI in a Texan. They don't mush like modern aircraft, there is a distinct wing drop, and not a whole lot of warning. But its not sneaky, violent, uncontrollable, and it's most certainly not a snap roll. Release the back pressure, use opposite rudder to bring the wing up (NOT aileron) and you'll be on your way with a little power. Do nothing and it'll go over on it's back and into a spiral.

 

I've not just stalled but spun Texans, too, many times—I wouldn't let our pilots do aerobatics in it unless they could demonstrate power off, power on, accelerated, and crossed-contro stall/spin recovery. Dunno if it's true of the '51, but when you release the back pressure and add opposite rudder, in a fully developed (at least 3 turn) spin, the rotation actually speeds up for about a turn before it comes out in another 3/4 to full turn. That's scared more than one fledgling into trying something else with disastrous results.

 

But I digress. Based on almost no experience in the P-51 and a whole lot in a T6 I think the stall of the DCS Mustang, as it stands, is not accurate, and thus the landings are more difficult than they should be. Lots of people have told me, and I've read in plenty of places, that the P-51 is actually easier to land than a T6. Believe, me that's sure not true of this beta version.

 

But that begs the implied question, which was how to land. The way I do it (YMMV) is to come down final at 110, slow to 90 over the fence, keep a little power on, and let if settle in a three-point attitude (it's the same picture you see out front before takeoff or sitting on the ramp). When it touches pull the power slowly to idle and keep her going straight with the stick back and aileron into the wind. If it bounces a few feet, just hold what ya got and it'll come back down. If it bounces way up, gently GENTLY add power to cushion it and maybe reduce a tiny bit of back pressure. If you're going around, the only option if you really find yourself in huge bounce, is to slowly add power, reduce the angle of attack, keep it going straight and fly out of it—you might even touch the ground again, but reducing your angle of attack and getting airspeed is what will keep you from pulling off to the left, scaring the hell out of the people on the ramp, or worse rolling over on your back and doing a face plant.

 

If you're trying to make a wheel landing (I don't advocate it) for a host of reasons, a little trick than help keep you out of a PIO is to add a couple of good licks of nose down trim. When the wheels touch just relax the stick and she'll stay down. Trying to anticipate the touchdown and judge how much to push to peg her to the runway takes a deft touch. The forward trim does it for you.

 

And wheel landing or three pointer, don't tromp on the brakes or this will happen (especially in a soft field). That's a picture of the SNJ I'm talking about taken on Monday after some bad judgement by a pilot who was delivering it to a new owner. (We sold it 6 years ago to someone else. But it's still sad to see the ol' girl on her back with her legs in the air.) The other shot was is at a happier time and place.

Edited June 16, 2012 by Tailspin45

[effte]

Tom,

just wanted to let you know that I immensely appreciate your input in these forums!

 

Cc on the snap rolls - now I remember reading that. Different manual - I grabbed the one closest at the time which was the F-51 one. Thanks for pointing that bit out.

 

Sorry to hear about the plane. Doesn't look too badly damaged though? Do you know what happened? Emergency off-field landing I take it, as it doesn't look much like a runway?

 

I also found this interesting PIREP on flying mainly the SNJ and the Mustang.

 

In your blog, you point out the importance of aileron into the wind. Try that in DCS: P-51D, even in a 70 mph true crosswind gale, and you'll find yourself lifting the downwind wheel pretty soon and very abruptly - to the point of losing control (admittedly, I still have to put in some work there, it may be possible to get used to). Ailerons neutral works though. Anyone say beta? :)

 

Cheers,

Fred

Edited June 16, 2012 by effte

[JimMack]

Great post.

Our real P51 pilot agrees with you all have said - but remember - we are still tuning the flight model before final release and hope to address these problems.

Both P51 and T6 can do a snap roll but should be avoided at all costs, as they are unpredictable. In fact a T6 pilot in the UK was killed not so long ago as he ended up in a vertical dive after an inadvertent snap roll.

Only exception is that he agrees that a wheelie landing in a T6 is not a good idea, but is relatively easy in a P51.

 

 

 

Re: "snap roll", the P-51 manual (the real one, but the DCS version which is mostly a word for word copy) says, "The aerodynamic characteristics of the P-51D are such that snap rolls cannot be satisfactorily performed. This has been proved by a long series of test flights."

 

But we all know that's not true of the beta version of the DCS '51. It'll snap in a heart beat, and in fact does it quite predictably and repeatably during an accelerated stall.

 

However, that's not the same as a wing drop in a power off level stall, as discussed earlier in this thread. I've done a few stalls as a passenger in a P-51, and oodles of them as either PIC or CFI in a Texan. They don't mush like modern aircraft, there is a distinct wing drop, and not a whole lot of warning. But its not sneaky, violent, uncontrollable, and it's most certainly not a snap roll. Release the back pressure, use opposite rudder to bring the wing up (NOT aileron) and you'll be on your way with a little power. Do nothing and it'll go over on it's back and into a spiral.

 

I've not just stalled but spun Texans, too, many times—I wouldn't let our pilots do aerobatics in it unless they could demonstrate power off, power on, accelerated, and crossed-contro stall/spin recovery. Dunno if it's true of the '51, but when you release the back pressure and add opposite rudder, in a fully developed (at least 3 turn) spin, the rotation actually speeds up for about a turn before it comes out in another 3/4 to full turn. That's scared more than one fledgling into trying something else with disastrous results.

 

But I digress. Based on almost no experience in the P-51 and a whole lot in a T6 I think the stall of the DCS Mustang, as it stands, is not accurate, and thus the landings are more difficult than they should be. Lots of people have told me, and I've read in plenty of places, that the P-51 is actually easier to land than a T6. Believe, me that's sure not true of this beta version.

 

But that begs the implied question, which was how to land. The way I do it (YMMV) is to come down final at 110, slow to 90 over the fence, keep a little power on, and let if settle in a three-point attitude (it's the same picture you see out front before takeoff or sitting on the ramp). When it touches pull the power slowly to idle and keep her going straight with the stick back and aileron into the wind. If it bounces a few feet, just hold what ya got and it'll come back down. If it bounces way up, gently GENTLY add power to cushion it and maybe reduce a tiny bit of back pressure. If you're going around, the only option if you really find yourself in huge bounce, is to slowly add power, reduce the angle of attack, keep it going straight and fly out of it—you might even touch the ground again, but reducing your angle of attack and getting airspeed is what will keep you from pulling off to the left, scaring the hell out of the people on the ramp, or worse rolling over on your back and doing a face plant.

 

If you're trying to make a wheel landing (I don't advocate it) for a host of reasons, a little trick than help keep you out of a PIO is to add a couple of good licks of nose down trim. When the wheels touch just relax the stick and she'll stay down. Trying to anticipate the touchdown and judge how much to push to peg her to the runway takes a deft touch. The forward trim does it for you.

 

And wheel landing or three pointer, don't tromp on the brakes or this will happen (especially in a soft field). That's a picture of the SNJ I'm talking about taken on Monday after some bad judgement by a pilot who was delivering it to a new owner. (We sold it 6 years ago to someone else. But it's still sad to see the ol' girl on her back with her legs in the air.) The other shot was is at a happier time and place.

Edited June 17, 2012 by JimMack

[Tailspin45]

Do you know what happened? Emergency off-field landing I take it, as it doesn't look much like a runway?

 

New owner intends to restore the aircraft, and wanted to work on it in his barn/hangar. So he asked the pilot to land it in his farm field.

 

Video from news helicopter shows he landed between two dirt roads that were maybe 5-600 feet apart, using the wing span as a scale.

 

So I'm guessing he dragged it in over the approach end road, plopped it down and stood on the brakes to get stopped before the upwind road. Which it did.

 

Might have worked if the ground hadn't been so soft, but....

 

I also found this interesting PIREP on flying mainly the SNJ and the Mustang.

 

I've always loved Bud's writing -- only Gordon Baxter was better. This one is a real find! Thanks for sharing! His description of the SNJ was spot on, from my experience, so I think we can assume his description of the '51 is too. I'm delighted to hear JimMack confirm they're still tuning the flight model, as I knew they would.

Edited June 18, 2012 by Tailspin45

[JimMack]

A point about control very close to the stall speed. If you get a slight wing drop, correct with rudder and not aileron. The reason is that the increased drag with aileron on the wing can stall the wing. This not only applies to the P51D - the Phantom F4 was notorious in this respect, as a few crashes at Da Nang in Vietnam can testify.

 

This vid has been posted before -

Edited July 6, 2012 by JimMack

[Ramstein]

A point about control very close to the stall speed. If you get a slight wing drop, correct with rudder and not aileron. The reason is that the increased drag with aileron on the wing can stall the wing. This not only applies to the P51D - the Phantom F4 was notorious in this respect, as a few crashes at Da Nang in Vietnam can testify.

 

This vid has been posted before -

 

 

the wing surface area of the F-4 Phantom is very small... compared to the size of the aircraft... very thin too...:joystick:

Edited July 6, 2012 by Ramstein

[Ramstein]

I felt an adjustment to stall speed and like the new feel with the patch...

:thumbup:

[Lucky]

This is a great thread. Thanks to all the RL pilots who have contributed.