P-38 issue, strange occurrence of the P-38 not being able to pull out of dive at low speed

[AKA_Ramstein]

If for any reason I find my P-38 at the higher angle of attack, says -45 to -90 degrees heading down in altitude (toward the ground). At speeds less than 200 mph, no weapons or with weapons, flaps at any angle, the aircraft loses controls and will not pull out and goes into the ground. The same issue that happens when you fly to fast and causes the infamous P-38 frozen controls by lack of air flow to the rear stabilizer. I have never had this issue before, just very recently. I know someone will say just don't point the nose down. Is it the same characteristic as for the over speeds it is famous for, or is it a bug?

[SCG_Tzigy]

Happened to me handful of times. Always thought I had flaps out and went over the DNE speed or was damaged by flak or EA. Always totally suprised (read shocked) by it.

[IckyATLAS]

Check the link below, for an answer.

 

 

 

[Lusekofte]

Trim it out of the dive

[Jaws2002]

Robin Olds said in one of his interviews that, in one of his fights, the canopy  disrupted the airflow over the elevators. He pulled on the stick and nothing happened.

Edited December 8, 2022 by Jaws2002

[SCG_Tzigy]

4 hours ago, Lusekofte said:

Trim it out of the dive

Did not work for me. Every single time it happened to me I was low and the event was violently fast...  Will experiment in higher altitude.

Edited December 8, 2022 by SCG_Tzigy

[Lusekofte]

It I s a known fact for earlier to mid models in over speed dive. This is not over speed dive as I can understand it. But there was something about using some sort of flaps speed brake on later versions 

[Stonehouse]

The dive recovery flap is modelled and from memory uses the dive brake control mapping. It works for high-speed dives not sure about your low-speed situation as it does cause a speed decrease when deployed.

[R33GZ]

Just out of curiosity, were you able verify that you actually had an elevator before impact?

 

I had this happen to me last week with a Bf 110 E. I nosed over at approx 400kph to continue my attack from about 1k altitude.when I initiated the recovery, I found I had no elevator control. When I hit pause and did a quick damage assessment, I found that the positive pressure on the elevator forced what was left of it to depart company. I had taken a 20mm flak hit just forward of the tailplane on the ingress and the damage to the elevator meant I shouldn't have pressed the attack.... and so ended another short lived Bf 110 E career ?

[DD_Arthur]

On the P38, set dive flaps and pull your prop-pitch right back when you enter a dive, not your throttle.

Edited December 8, 2022 by DD_Arthur

[AKA_Ramstein]

i am telling you guys, there is no recovery. it just sends you in with no chance of recovery, and no time to do anything. I see that some of you guys have experienced this very same thing. So, at least I know I am not the only one.

Edited December 8, 2022 by AKA_Ramstein

[69th_Mobile_BBQ]

If you've pulled the nose up to level from your -45 to -90 degree dive, or even managed to get the nose pointing upward but, are still going down towards the ground, you're probably "belly flopping" the plane into the airstream and disrupting the airflow over the top of the wing, killing lift.  Though it seems counter-intuitive, try relaxing how much you pull the elevator until the plane's trajectory catches up to its orientation.  It also helps to throttle back in the dive, but once the nose is at around -10 degrees going to 0, then positive degrees, push up the throttle smoothly. Don't be afraid to go full throttle if you need to. Most of the time, by the time the plane is going the direction you want, you've only used 10-15 seconds of combat timer before you can throttle back to nominal settings. 

4 minutes ago, 69th_Mobile_BBQ said:

If you've pulled the nose up to level from your -45 to -90 degree dive, or even managed to get the nose pointing upward but, are still going down towards the ground, you're probably "belly flopping" the plane into the airstream and disrupting the airflow over the top of the wing, killing lift.  Though it seems counter-intuitive, try relaxing how much you pull the elevator until the plane's trajectory catches up to its orientation.  It also helps to throttle back in the dive, but once the nose is at around -10 degrees going to 0, then positive degrees, push up the throttle smoothly. Don't be afraid to go full throttle if you need to. Most of the time, by the time the plane is going the direction you want, you've only used 10-15 seconds of combat timer before you can throttle back to nominal settings. 

 

edit:  If you look at the rpm indicators, there's a green band at around 2400rpm.  From what I can gather from pilot interviews, this setting gives the smoothest airflow over the wing for pulling out of dives or at very minimum, is the lowest setting that enables safely pulling out of the dive.  Anything lower is extremely dangerous.

Edited December 8, 2022 by 69th_Mobile_BBQ

[357th_KW]

21 hours ago, AKA_Ramstein said:

If for any reason I find my P-38 at the higher angle of attack, says -45 to -90 degrees heading down in altitude (toward the ground). At speeds less than 200 mph, no weapons or with weapons, flaps at any angle, the aircraft loses controls and will not pull out and goes into the ground. The same issue that happens when you fly to fast and causes the infamous P-38 frozen controls by lack of air flow to the rear stabilizer. I have never had this issue before, just very recently. I know someone will say just don't point the nose down. Is it the same characteristic as for the over speeds it is famous for, or is it a bug?

Try recording a track of what is happening.  At high dive speeds you run into compressibility and dive flaps can help you recover, but that would be way above 200mph.
 

I’ve seen low speed loss of control in the P-38, where too much forward elevator somehow causes a sort of tail stall, and the airplane just falls out of control with no possible recovery.  I’ve only seen this with flaps out at low speed and a hard forward push.

[ShamrockOneFive]

I think we need to see a track to try and help sort this out.

[RossMarBow]

If you are close to stall speed.
And pull back to hard trying to avoid hitting the ground.
You will stall into the ground.
All aircraft do this.

[SCG_Tzigy]

5 hours ago, 357th_KW said:

I’ve seen low speed loss of control in the P-38, where too much forward elevator somehow causes a sort of tail stall, and the airplane just falls out of control with no possible recovery.  I’ve only seen this with flaps out at low speed and a hard forward push.

 

Exactly this!

4 minutes ago, RossMarBow said:

If you are close to stall speed.
And pull back to hard trying to avoid hitting the ground.
You will stall into the ground.
All aircraft do this.

 

Dude. Really? I had no idea.

[Art-J]

At such low speeds, unless some sort of a flat spin is involved (which I suppose isn't in this case, judging from original post?), the horizontal stab should point the plane back into correct AoA range and make recovery possible, especially if OP tried various control inputs to do so (I'd hazard a guess he did?). That's what it's there for. There might be some FM bug here (would not be the first one in this sim after all), but the original description is too vague to make sense out of it. If (and that's a  big "if") the scenario can be reliably reproduced, posting a replay track from a short test flight would definitely help in troubleshooting.

Edited December 9, 2022 by Art-J

[69th_Mobile_BBQ]

4 hours ago, SCG_Tzigy said:

 

Dude. Really? I had no idea.

 

Yes. If the plane's flight path (trajectory) it too far out of line with the AoA of the wings, it disrupts the airflow over the top of the wing and kills lift.  You have to pull less strongly until trajectory and AoA come more into line.  

Using too much elevator can also cause airflow over the rear stabilizer to break up and either reduce effectiveness or cancel the purpose of the stabilizer.  It basically becomes like flying a plane that's lost its tail.

The next time you pull back on the stick and the plane starts to "shudder" try relaxing just a little bit until the shuddering goes away. That's pretty much the sweet spot you're looking for.  You should notice that your turns will even get a little tighter than trying to fight the plane while its shaking from the disrupted airflow.  You'll also experience less instances of pulling back on the stick only to have the plane suddenly snap out of control. 

[Jaegermeister]

19 hours ago, AKA_Ramstein said:

i am telling you guys, there is no recovery. it just sends you in with no chance of recovery, and no time to do anything. I see that some of you guys have experienced this very same thing. So, at least I know I am not the only one.

 

I tested the P-38 last night and had no problem recovering from slow speed dives, basically starting from a stall or just above and pulling out before 200mph. It's not a bug with the Lightning. I have a track, but I don't think it's needed.

 

Sounds like not having enough altitude to recover normally by building airspeed and easing out of the dive.

 

 

20 hours ago, Stonehouse said:

The dive recovery flap is modelled and from memory uses the dive brake control mapping. It works for high-speed dives not sure about your low-speed situation as it does cause a speed decrease when deployed.

 

Airbrakes on/off aka dive flaps and Dive Recovery System on/off aka dive recovery flaps are 2 different things. The dive recovery flaps are designed to shift the center of lift back on the wing to improve airflow and restore lift close to supersonic speed. They are not going to help at low speeds, they would lower the stall speed.

 

The Dive Flaps are basically a split flap in the middle of the lower wing, and the combat/takeoff/landing flaps are Fowler flaps

 

 

 

 

Edited December 9, 2022 by Jaegermeister

[AKA_Ramstein]

everyone else try it,, I have... that's why i said there was no fix for me.. maybe you guys. good luck.

 

btw. I am just going try and never let the front of the P-38 ever do that again. no matter what.

Edited December 9, 2022 by AKA_Ramstein

[SCG_Tzigy]

20 hours ago, 357th_KW said:

..low speed loss of control in the P-38, where too much forward elevator somehow causes a sort of tail stall, and the airplane just falls out of control with no possible recovery.  I’ve only seen this with flaps out at low speed and a hard forward push.

For me it is very similar to what KW says here. I realized and now remembering last few events, it was low speed, combat flaps, dogfight low level usually, I push the nose down briefly and here we go.. It has nothing to do with the usual slow or high speed stall...

This feels like the elevator stuck in a full down position or your tail completely shot off...

[Art-J]

@AKA_RamsteinI tried it with various flaps, power, dive brake combinations. The only way I can kinda replicate what you are describing at low speeds is by cutting the throttles and pushing the yoke towards the ground with flaps full (Fowlers, not dive ones). Flaps incur strong negative pitch moment at first, the plane starts flipping over to its back, stops at about -130 / -140 degrees, falls to the ground vertically and becomes impossible to recover despite various control inputs. Looks like a bug in FM I'd say, because:

a) at such AoA the whole wing is stalled and thus flaps should not produce negative pitch moment anymore. At the same time;

b) horizontal stab is not located in airflow disrupted by the wing and thus should have enough authority to push the plane towards lower AoA and recovery, especially with elevator up.

 

Maybe it would happen with combat or takeoff flaps as well, just a bit later. Haven't tried.

 

That being said, as soon as I retract the flaps fully, the FM does what it's supposed to do, the plane becomes longitudinally stable again and is easy to recover. There seems to be a bug, but otherwise FM works OK as long as you're not trying to nose over with some flaps out. Why would you do that, though?

 

Replay track attached.

Track.zip

Edited December 9, 2022 by Art-J

[Jaegermeister]

5 hours ago, Art-J said:

@AKA_RamsteinI tried it with various flaps, power, dive brake combinations. The only way I can kinda replicate what you are describing at low speeds is by cutting the throttles and pushing the yoke towards the ground with flaps full (Fowlers, not dive ones). Flaps incur strong negative pitch moment at first, the plane starts flipping over to its back, stops at about -130 / -140 degrees, falls to the ground vertically and becomes impossible to recover despite various control inputs. Looks like a bug in FM I'd say, because:

a) at such AoA the whole wing is stalled and thus flaps should not produce negative pitch moment anymore. At the same time;

b) horizontal stab is not located in airflow disrupted by the wing and thus should have enough authority to push the plane towards lower AoA and recovery, especially with elevator up.

 

Maybe it would happen with combat or takeoff flaps as well, just a bit later. Haven't tried.

 

That being said, as soon as I retract the flaps fully, the FM does what it's supposed to do, the plane becomes longitudinally stable again and is easy to recover. There seems to be a bug, but otherwise FM works OK as long as you're not trying to nose over with some flaps out. Why would you do that, though?

 

Replay track attached.

Track.zip 673.53 kB · 2 downloads

 

Well done. I watched your video and I agree that the flaps are preventing recovery from a reversed inverted flat stall attitude. How would any of us know if that is a bug or not? Also I 100% agree with asking the question "Why would you do that, though?"

 

Spoiler

 

Maybe the Devs have modeled you not being able to reach the controls because your head is slammed against the canopy, your feet aren't on the pedals, and the seat belts are paralyzing your arms. I think you guys have come up with how to put the Lightning into an inverted flat spin, which is generally considered unrecoverable.

 

Edited December 10, 2022 by Jaegermeister

[Art-J]

Nah, I wouldn't call it inverted spin, as there is no rotation around yaw axis (the only thing which could realistically keep it at such AoA), plus full elevator control is available, it just doesn't do anything. So I still think we've got a flight model issue here, but given the highly unusual and impractical scenario you have to put yourself into to experience it, I don't think developers will bother addressing it anytime soon. One would have to report it first in dedicated bugs section of the forum anyway.

 

In the test shown on the track I extended the flaps at close to stall speeds, but in other tests, when doing it later while nosing over I've noticed it doesn't take long to make the flaps jam in some extended position - which means game over. Maybe AKA_Ramstein found himself in such situation without realizing it, thinking that they're retracting when in reality they're not - thus problems with recovery.

[AKA_Ramstein]

it is a lawn dart. that's all it is when it happens. I can't emphasize that enough. There is no control anything. and it happens very fast. I don't understand why some people can't understand it! Some people fully do understand, so I know it isn't just me.

[Mysticpuma]

On 12/11/2022 at 1:50 AM, AKA_Ramstein said:

it is a lawn dart. that's all it is when it happens. I can't emphasize that enough. There is no control anything. and it happens very fast. I don't understand why some people can't understand it! Some people fully do understand, so I know it isn't just me.

But you still haven't posted a track showing this? 

[IckyATLAS]

I have made some test flights with the P38 at different altitudes (16000ft, 5000ft, 3000ft, and vertical dives, loops.

You can find the 4 tracks below. Unfortunately in the track you do not see the cockpit instrument bar. For that I need to do a video but have no time for it.

I started dives at around 200 to 250 MPH. As long as you stay below 400 MPH in your vertical dive there is no real issue, you will recover.

When you go above 400 MPH then controls become heavier as you go faster. But you can still recover if you are high enough, you loose a tremendous altitude but you save your ass. I do not know what are the exact G forces but in the video you see that you do not blackout, sometimes just colors are lost. So it is acceptable at least for the pilot.

One element to take into account in a dive, the P38 picks up speed very fast. It accelerates in a dive in an impressive way. So you must really watch your speed ina dive, it is a matter of life and death.

The moment you go over 450 or more you are dead because recovery becomes too slow as controls are extremely heavy, and you continue picking up speed past 500, you will never recover as controls will completely freeze an you go down like an arrow until you hit the farm.

Let me know  your comments.

Enjoy:

 

P38 Tracks.zip

 

 

Edited December 14, 2022 by IckyATLAS

[Art-J]

That's all nice of you, but is irrelevant to the problem OP asked about. He wanted to know why he lost control below 200 mph... and so would like to know the rest of us, because we can't replicate what he's describing.

[MisterSmith]

Please post tracks or I will have to close this as an unverified FM claim. Thusfar it is unrepeatable within the community.

 

Smith

[MisterSmith]

Locked for the above.

 

Smith