P-51D overmodelled!

[gofaster]

As I suspected, the 51D isn't modeled properly.  I was looking for P-51B paint schemes and came across this account of a P-51 ace who flew Spitfire Vs, P-51Bs, and P-51Ds.

He states:

My flight chased 12 109s south of Vienna. They climbed and we followed, unable to close on them. At 38,000 feet I fired a long burst at one of them from at least a 1000 yards, and saw some strikes. It rolled over and dived and I followed but soon reached compressibility with severe buffeting of the tail and loss of elevator control. I slowed my plane and regained control, but the 109 got away.

On two other occasions ME 109s got away from me because the P 51d could not stay with them in a high-speed dive. At 525-550 mph the plane would start to porpoise uncontrollably and had to be slowed to regain control. The P 51 was redlined at 505 mph, meaning that this speed should not be exceeded. But when chasing 109s or 190s in a dive from 25-26,000 it often was exceeded, if you wanted to keep up with those enemy planes. The P 51b, and c, could stay with those planes in a dive. The P 51d had a thicker wing and a bubble canopy which changed the airflow and brought on compressibility at lower speeds.

So there you have it.  109 pilots and 51B fans should take to the streets and demand a correction to the HTC model!

[dedalos]

Originally posted by gofaster
As I suspected, the 51D isn't modeled properly.  

Yep, how else would Steve be able to kill me every single time?

[Widewing]

Well, the veteran pilot who wrote the account was misinformed. There was no difference in the wing thickness between the P-51B/C and the P-51D. All versions had the same VnE limits, including the Allison engine models. North American thought the USAAF VnE limit of 505 mph TAS was too conservative. It was easily exceeded and if G loading was not excessive, it wasn't dangerous to push to 550 mph TAS. You can be damn sure the 109 was shaking like a wet dog as well.

Most aggressive Mustang pilots would pursue 109s in a dive without a second thought. My opinion is that this guy was just afraid of getting into even a mild compression buffet, and there was no lack of overly nervous pilots like him in WWII.

My regards,

Widewing

[Steve]

I think p51 turning ability is UNDERmodelled.


Hi Ded.  

[Siaf__csf]

Got to admire the confidence widew has in smashing the opinnion of someone who actually flew the thing in combat

Kinda like playing Formula1 on playstation and then saying Schumacher is misinformed about the Ferrari he drives - it shouldnt run that fast.

[moot]

might've been alesi rather than schumi.
can't deny that he was wrong about the technical fact he based himself on.

[Tumor]

What model 109's?

[Adogg]

OMG! Look the only way we'll ever settle this over-modelled whine is if we all up P51s (B and D) and fly 'em - oh wait...

...who here has access to those planes? Let alone is able to fly one? My guess almost no one who speaks in the forum "authoritatively" about aircraft being under or overmodelled. Technical specs are a best guess, there are all sorts of happy or unhappy performance "surprises" that don't end up in the manuals.

Anyone who has test-flown a plane can tell you that like any mechanical system each one has nuances and variances that make it more or less than what the manufacturer states it is.

Heck each production block is different.

Let's see what the AH2 models turn out like before anyone starts painting plackards and signing petitions.

[SunTracker]

Two P-51s per week were being lost due to structural failures in the ETO.

[BUG_EAF322]

With all respect to the veteran pilots
but just imagine not to many experience  and trown into a battle.

they had a lot to worry about
with their very own lives

I can imagine that might make u a bit timid
anyhow u can't model planes on some statement.

and yes like that 109  didn't shake at those speeds
it had a thicker wing as the p51 i guess

I guess another attempt from a wabble to make the planes more UBER

[Sable]

Originally posted by SunTracker
Two P-51s per week were being lost due to structural failures in the ETO.

And this is out of how many sorties flown?  Thousands?  It certainly isn't too hard to pull a wing off your P-51 in AH if you start a dive at 25,000ft and don't pull the power back.  

I've found that the 109G-10 can usually keep up with the P-51D in a dive, if not catch it outright.  The trick with the P-51 is to make a sharp 90 degree turn, and then a sharp 180 back the other way once you are over about 450mph indicated .... the 109s ailerons will be too stiff to follow you.

Kinnol

[Widewing]

Originally posted by Siaf__csf
Got to admire the confidence widew has in smashing the opinnion of someone who actually flew the thing in combat

Well, does over 2300 hours military time add some credence? That includes time in everything from amphibians, thru the TA-4J and even caught a few rides in the F-4J Phantom II.

I have friends who own (or owned) and fly P-51Ds, I've had a chance to fly in a two-seat conversion as well. I've interviewed many P-51 veterans in the course of reseaching articles.

Finally, you would be surprised how many veterans DON'T know basic facts about their own hardware. One does not need to be a P-51 combat vet to crack the pilot's manual or any technical volume on the type. Just like every GI in the ETO identified every German tank as a Tiger and every artillery round as an "88", pilots have misconceptions and flat-out bad memories. The toughest part about writing history is separating error from fact and poor memory from actual documents.

The guy who wrote that little ditty has either forgotten, or simply doesn't know what he should know about the Mustang. Talk to other Mustang vets and they will confirm that this guy had or has issues unrelated to the aircraft's performance, but more in line with his own performance.

What I stated was dead-nuts accurate. All P-51s that saw combat had the same VnE, because they had the same wing design. 505 mph TAS was the VnE for every model from the P-51A thru the P-51K. That does not reflect maximum speed capability, just that of a very conservative USAAF. Severe buffeting does not begin until well beyond Mach 0.80, with things getting especially violent at 0.86 Mach. The USAAF Flight Test Section tested the P-51D at speeds up to 0.86 Mach as a matter of routine. Major Fred Borsodi ran the Wright Field P-51D test program, and worked with Gus Lundstrum and NAA's George Welch. All of these guys pushed the P-51 way past the official VnE on a daily basis. It was no more prone to compressibility than any other P-51 model.  Borsodi and Welch had more P-51 time than entire squadrons in the ETO (about 2,000 hours each).

My regards,

Widewing

[Batz]

Co e,  co alt the 109 would accellerate faster in the initial part of the dive and both planes have similiar critical mach. The deciding factor would be which pilot has the balls to push it the limit.

In AH folks have no qualm about pushing it, so what if they die they reup.

[Staga]

Originally posted by Widewing
North American thought the USAAF VnE limit of 505 mph TAS was too conservative. It was easily exceeded and if G loading was not excessive, it wasn't dangerous to push to 550 mph TAS. You can be damn sure the 109 was shaking like a wet dog as well.

Do you have any proofs that 109 "shaked like a wet dog" at 500mph?

Finnish Bf109 ace Kyösti Karhila:

The Messerschmitt became stiff to steer not until the speed exceeded 700kmh. I once went into vertical dive and the speed was far more than 800 kmh. The plane did not vibrate but as I pulled the stick it did not move[/url].

800kmh = 500mph

[Angus]

I have seen one account about 109's smashing into the sea, being unable to pull from a high speed dive. Those were E models.
But the General conception of many old pilots I've read from, or heard eye-to-eye was that both the P51 and the P48 would dive better than a 109, also having better control in the dive,