Elevator trim during Combat

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Improper aileron adjustment plus a faulty engine is what caused the poor turn performance at wright field buzzard. The high elevator forces are suspect as-well as the 190 featured perhaps some the lightest control forces of any a/c of WW2.

A good example of when the ailerons were properly adjusted are the British tests with a heavy Jabo version, this a/c despite being heavier less aerodynamically clean and running at low power was able to turn just as well the P-51 Mustang Mk.III. This a/c did also, unlike the others with improper aileron adjustment, give the pilot warning of the approaching stall with a slight buffet. (Just like vet Fw-190 pilots note it did)
 

If I could restate their problem (P-38). The transonic issues created a lot of turbulent flow between the engines/fuse wing body -----> leading to masking of the horizontal tail. That alone would tend to an 'pitch down' problem.

From my perspective the wing dive brakes created enough drag that the P-38 that it kept the airspeed in a controllable flight regime ~ .65-70 Mach in a dive and below the compressibility effect - in effect a 'governor' .

That's my story and I'm sticking to it - I have been wrong before.
 
I think the dive flaps did both, obviously adding a lot of drag (35 degree deployment), but they also caused a pitch up (with the elevator neutral or inoperable). (the shock wave dispersion thing was totally wrong though)

Hence the reason the P-80 was fitted with BOTH a belly mounted air brake and wing root mounted dive recovery flaps.
 
Wikipedia seems to have gotten it right:



Also buffetting was entirely separate problem which, unlike the compressibility problems, was completely solved:

 
drgondog,

I'm glad you like the 'jewel' It did seem that it might have some possible relevance to the point of contention, altho' with my rudimentary knowledge of aerodynamics, I wasn't sure. I should also mention that Tank said that the tail surfaces were also increased in proportion to the enlarged wing.

Tank's goal was to build a 'Dienstpferd'; a cavalry horse, not a racehorse, and he over-designed the '190 for future weight gain. Perhaps the basic wing design was considered strong enough to handle the extra area without subtantial modification of the basic structure, and this contributed to higher than expected deformation under the increased tip load. Understand that this is pure conjecture on my part. I know little beyond the basics of aero theory.

As to the P-38...As a big fan of the P-38, I've read numerous accounts of the compressibility problems, its causes, and the rationale behind the solution. They consistantly mirror what I and KK89 have posted.

JL
 
kool kitty89 said:
Hence the reason the P-80 was fitted with BOTH a belly mounted air brake and wing root mounted dive recovery flaps.
Click to expand...
Wing root dive recovery flap? You sure about that? It's been about 8 years since I last flew in a T-33 and I could tell you there were flaps and speed brakes, don't recall no wing root mounted dive recovery flaps....
I think early P-80s and leading edge brakes on the bottom of the wings that were subsequently removed in later models (and on the T-33) as the dive brake was all that was needed "to stay out of trouble."
 
That info was from a NASA article on WWII jets, referring to the P-80A.

ch11-2

the P-80 had a small dive-recovery flap near the leading edge of the lower surface of the wing. Again like later versions of the P-38, the P-80 had power-operated ailerons.
Click to expand...
 
Yep - saw that. It mentions the "leading edge of the lower surface of the wing," not "wing root mounted dive recovery flaps" as mentioned in your earlier post. In either case I think it's wrong, at least on production aircraft. In our tech library there is an F-80 flight manual - it makes reference to the wing flaps and dive flaps only. There is no other reference of a "fence type" dive brake on the aircraft as used on the P-38.

On page 23 of the -1 it gives instructions when a dive in excess of .75 - .8 Mach is encountered. On page 25 it gives part of the landing checklist and it states "wing Flaps down under 200MPH, dive flaps down if required." In the after landing check list on page 26 it says to bring the flaps and dive flaps up prior to taxi. Through out the entire -1 there is no other speed control device mentioned. On page 10B there is a picture of the actual switch.

I also have part of a CAF T-33 maintenance manual volume. The electrical system doesn't seem to show any other electrical augmentation of any other type of dive brake (now called speed brakes) within the system.

http://www.ww2aircraft.net/forum/other-mechanical-systems-tech/lockheed-p-80-shooting-star-9666.html

....
 
Ok I don't know why, for some reason when I read that it made me think the 'dive flaps' were located just outboard of the wing root.

But continuing that, do you know where on the LE of the wings the dive flaps were located?
 
kool kitty89 said:
Ok I don't know why, for some reason when I read that it made me think the 'dive flaps' were located just outboard of the wing root.

But continuing that, do you know where on the LE of the wings the dive flaps were located?
Click to expand...

I would guess they'd be on the lower inboard wing close to a main spar similar to a p-38.
 
They have a side-view cut-away diagram that shows the dive flaps on that manual you linked to.


What did you mean by "fence type" airbrakes on the P-38? I thought it was only fitted with dive flaps.


I don't see any disagreement with that NASA article and the P-80 manual.
 
There are "Dive Brakes" AKA Speed Brakes and wing flaps, no wing root mounted dive recovery flaps.

Here's the P-38 dive recovery flaps I'm talking about...

 
When I said wing root "dive flaps", I was referring to the P-80. (only on early models and different from the belly mounted speed brake)

I know the P-38's "dive flaps" were located just outboard of the engine nacelles.

look at the discussion with buzzard and me on pg #3 of the thread:




buzzard said:
As to the P-38...As a big fan of the P-38, I've read numerous accounts of the compressibility problems, its causes, and the rationale behind the solution. They consistantly mirror what I and KK89 have posted.

JL
Click to expand...
 
kool kitty89 said:
When I said wing root "dive flaps", I was referring to the P-80. (only on early models and different from the belly mounted speed brake).
Click to expand...
And again I'm saying the P-80 never had "wing root dive flaps." They have always been on the belly, from the P-80A to the C and those A's and B's modified to C's as well, and as far as I could see in photos it was that way on the XP-80 as well.

"Hence the reason the P-80 was fitted with BOTH a belly mounted air brake and wing root mounted dive recovery flaps."

Bottom line, there were wing flaps (on the wings, used during landings) and speed brakes (dive brakes, dive flaps) on the belly - nothing else...
 
Then what were you talking about here?

I think early P-80s and leading edge brakes on the bottom of the wings that were subsequently removed in later models (and on the T-33) as the dive brake was all that was needed "to stay out of trouble."
Click to expand...

Which agrees with the NASA site I linked to:



One interesting note is that the Meteor was fitted with "fence type" air brakes (opening to ~90 degrees, and slotted, opening above and below the wing) brakes were provided on the upper and lower surfaces of the wing between the nacelles and the sides of the fuselage.

 
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