Author Topic: P-51h (Read 1120 times)

AquaShrimp · « **on:** December 08, 2007, 04:47:01 AM »

Was the P-51H really only rated for 5.3 g's? I was reading that the weight loss from the P-51D to the P-51H was due to the de-strengthening of the airframe from a max of 8.3g's (U.S. norm) to 5.3. If so, it seems to me that this would have hampered the P-51H in combat.

AquaShrimp · « **Reply #1 on:** December 08, 2007, 07:44:27 AM »

I did a little bit of research, the P-51H really was rated at 5.3g's. There are actually numerous accounts of P-51D's breaking up in mid-air due to high g-forces. One example occurred in the 1945 over the Pacific. A P-51D began dogfighting a KI-84, and the tail of the P-51 snapped off in a turn.

Mustangs also suffered from wing loss in high speed dives, usually due to the gear doors getting caught in the windstream, and opening. I just can't understand why the 51H was de-strengthened. Seems like that would be exacerbating a design flaw. I believe even Hub Zemke went down when the wings of his mustang came off.

moot · « **Reply #2 on:** December 08, 2007, 08:38:45 AM »

Sounds like just a G limit, not an aerodynamic one. Wheel doors are unrelated to G forces as far as I understand. The H might have been a completely flawless aerodynamic specimen that just didn't require more than 5.3 G for its purpose.

Guppy35 · « **Reply #3 on:** December 08, 2007, 01:01:24 PM »

Quote

Originally posted by AquaShrimp
I did a little bit of research, the P-51H really was rated at 5.3g's. There are actually numerous accounts of P-51D's breaking up in mid-air due to high g-forces. One example occurred in the 1945 over the Pacific. A P-51D began dogfighting a KI-84, and the tail of the P-51 snapped off in a turn.

Mustangs also suffered from wing loss in high speed dives, usually due to the gear doors getting caught in the windstream, and opening. I just can't understand why the 51H was de-strengthened. Seems like that would be exacerbating a design flaw. I believe even Hub Zemke went down when the wings of his mustang came off.

Zemke went down in a storm

Most wartime birds went through times where they had structural issues. One of the concerns with the 51 was they didn't lengthen the fuselage when they added the extra horsepower of the Merlin.

Note the larger rudder on later Spits as the power increased. P40s got longer, 190s added to the fuselage etc.

Tiffies had tails come off. 109Fs had tails come off and wings.

It was not limited to 51s. You push the envelope on stuff, in particular in wartime and things will break.

Furball · « **Reply #4 on:** December 08, 2007, 01:42:40 PM »

Quote

Originally posted by Guppy35

Tiffies had tails come off.

Adding to what Guppy said, the early Typhoons had a problem with the tail coming off (due to elevator flutter), so they added metal plates across the tail joint which strengthened the tail before they figured out what was causing the problem - don't think they ever had a problem with them coming off after that. The wings certainly didn't have a problem snapping off, they are about as thick as they are wide

From here: http://www.aircraftresourcecenter.com/AWA1/301-400/walk327_Typhoon/walk327.htm

Wonder if the 109F had a problem because they removed the bracing struts which were on the E?

Guppy35 · « **Reply #5 on:** December 08, 2007, 02:58:56 PM »

Something like that. 109F ended up with bracing much like the Tiffie for a while I think.

Widewing · « **Reply #6 on:** December 08, 2007, 04:23:11 PM »

I believe that the G restriction applied to max weight configuration. There were restrictions on the P-51D at max weight too.

However, speaking about the P-51H, check out the climb rate of that little monster!

My regards,

Widewing

Widewing · « **Reply #7 on:** December 08, 2007, 04:26:31 PM »

How about speed? Yikes!!!

My regards,

Widewing

Treize69 · « **Reply #8 on:** December 14, 2007, 06:04:34 PM »

Quote

Originally posted by Guppy35
Something like that. 109F ended up with bracing much like the Tiffie for a while I think.

A pair of metal slats on each side actually, it would break off at the joint between the tailplane and main fuselage structure. The account I've heard most often was that the cantilever tail structure would flutter at high speed and high-G and snap the internal structures, but that could be as accurate as the whole P-38 "tail buffet" thing for all I know.

Krusty · « **Reply #9 on:** December 14, 2007, 06:18:15 PM »

You'll notice those on some of my 109F skins. I think I simply didn't think of it for the early ones, but I know it's on Marseille's and the 10/JG2 skin. Can't recall about the others.

Treize69 · « **Reply #10 on:** December 14, 2007, 06:34:26 PM »

I think it was only factory standard from the start of the F4 run on. Retrofitted to the F2 when possible, and not around yet for the F0.

AquaShrimp · « **Reply #11 on:** December 14, 2007, 06:48:37 PM »

No one's brought forth any data to show if the P-51H would have been capable of combat. The 51D suffered from various unrelated problems that could cause catastrophic airframe failure in flight. Then they went and destrengthened the airframe and put a bigger engine in it, and called it a P-51H!

Years ago there was a big thread about the P-51D, and its various airframe defects. If anyone could find it, I would be eternally grateful.

Treize69 · « **Reply #12 on:** December 14, 2007, 07:56:38 PM »

The lighter airframe might have actually not been as much of a detriment as it sounds, as a lighter aircraft means less stress on it during maneuvering and at speed. I don't know enough about aircraft design to say whether it would have balanced it out in action or not, but still...

Guppy35 · « **Reply #13 on:** December 14, 2007, 08:31:58 PM »

Quote

Originally posted by AquaShrimp
No one's brought forth any data to show if the P-51H would have been capable of combat. The 51D suffered from various unrelated problems that could cause catastrophic airframe failure in flight. Then they went and destrengthened the airframe and put a bigger engine in it, and called it a P-51H!

Years ago there was a big thread about the P-51D, and its various airframe defects. If anyone could find it, I would be eternally grateful.

Are you looking for something specific?

Considering it's success, I'm hard pressed to figure out what it's 'defects' were.

It had teething problems like any fighter design. Revising it's history after the fact?

As for the H. Considering it was obsolete by the time it got into production due to the introduction of jets, talking about it's use in combat or lack therof, serves little purpose. Obviously the 51D was sent to Korea because of it's loiter and fighter bomber abilities where the H remained with the Guard units

Back to the Merlin 51.

-Motor mounts were a problem early on
-plug fouling
-prop seals
-gun jams and freezing on the B
-some concerns with the airframe not being lengthened to accomodate the added torque of the Merlin
-P51K had problems with vibration in the hollow Aeroproducts propeller
-Some loss of directional stability with the addition of the Bubble canopy. This was fixed by adding the additional fin fillet.
etc etc

Stoney74 · « **Reply #14 on:** December 15, 2007, 01:06:07 AM »

Quote

Originally posted by AquaShrimp
No one's brought forth any data to show if the P-51H would have been capable of combat. The 51D suffered from various unrelated problems that could cause catastrophic airframe failure in flight.

Your first point...

Well, its kind of like the F7F, P-72, F8F, etc. We'll never know because they never saw combat. Certainly the USAAF and North American thought they would, otherwise they would have never designed the thing...

Your second point...

Source please...