P-47 Actions 29 Mar 44 near Berlin

[Franek Grabowski]

Originally Posted by Six Nifty .50s

Then we have to wonder where you learned about 'physics' and earth science.

All six of you?

The 'simple laws of physics' does not suggest that the maximum speed of a Spitfire XI flying at treetop height is exactly the same as it was at 25,000 feet. The 'simple laws of physics' does not tell us that that air resistance is the same, regardless of height.

That is why Mach number is used.

These speeds were achieved at what heights?

It does not matter, due to nature of Mach.

You'll have to take that up with Eric Morgan.

What page?

Perhaps Eric Morgan made another error when he claimed that a Spitfire reached 600 mph. And we have no way of knowing that instrument readings were always accurate.

If it was an instrument speed it would be called IAS and not TAS. Otherwise nobody used ASI to such measurements!

The report also clearly states that the FW 190A-3 also dived at higher speeds than the Spitfire V and the Spitfire IX. This is because the Spitfire had inferior dive acceleration. The opposite was true in USAAF tactical trials pitting the P-47 against the FW 190 where the Focke-Wulf had initial advantage but the Thunderbolt soon closed the gap.

That means that Fw 190 was worser even from Thunderbolt, nothing more.

Whatever Spitfire test pilots claimed to have achieved in very high altitude dives was certainly not borne out in combat, or in the RAF tactical trials versus German fighters.

This was simply realised in 1943, when it was a little bit too late. Had it been found earlier, no doubt Spit pilots would have been encouraged to chase their enemies.

When trying to escape, acceleration in the dive was far more important than maximum theoretical speed, which for the Spitfire had to be built up over a long period -- and essentially useless to the RAF pilots flying tactical trials.

Acceleration is one thing, speed is another, and yet another is air combat. No aircraft could escape Spitfire by simple diving because Spitfire is the fastest piston aircraft ever known.

[odybvig]

Spitfire is the fastest single engine piston plane ever known..............

Ehhhhhhhh NOT

The record for the fastest single-engined piston plane is held by a modified Grumman F8F Bearcat
545.07 mph (876.47 km/h) in 1969
Before that a Messerschmitt Bf 209 hold the speed record for 30 years.
469.22 mph on April 26, 1939

Olve Dybvig

[Franek Grabowski]

Olve, are you trying to prove 545 mph is more than 600 mph?

[odybvig]

ha ha funny Franek
Well, No spitfire hold the world record of the fastest aircraft.
Perheps the Spit is awsome in dive, but since the current record holder is not tested in the same condition, the frase: Spitfire is the fastest piston aircraft ever known, has no value

remains me of the old add; Wolkswagen Beetle, no one faster in free dive

Best
Olve Dybvig

[drgondog]

Franek - Iim pretty sure the fastest production fighter in level flight is the P-51H which flew at 487mph at 25,000 feet. I think the Do-335 was the fastest German fighter at 474mph and I recall that one variant of the Spitfire attained 479mph. They never flew against each other obviously.

The fastest experimental P-51 was the XP-51G at 495mph and the fastest experimental P-47 was the P-47J at 507mph. All of these were achieved at high altitude in level flight.

I am not aware of any 'official' faster speeds for un-modified ships in level flight.

It should be noted that the Reno racer Bearcats and Mustangs (HIGHLY modified) flew at 528 mph world speed records on the deck but were never tested for max speed at optimal altitude and presumably would have been faster in 20-25,000 range if the contrast between P-51 on the deck and altitude were used as a thought guideline. I recall (but could be wrong) taht the only non Bearcat/Mustang a/c that exceeded 500mph on the deck was the highly modified Sea Fury..

Offhand what true airspeeds were recorded and validated (accurate TAS) in either the Luftwaffe or RAF dive tests for the Spit, the P-47, the Fw 190 and the P-51? For example the Mach crit number for the 51 airfoil was around .82 but the mach limitation in a dive was .76 before bad things happened - a reflection of the entire a/c not just the wing.

What was a comparable critical mach for the Spit in a dive?

[Kutscha]

You do relize that on the deck at Reno is around 5000ft.

Did Franek say the fastest in level flight?

[odybvig]

He said: Spitfire is the fastest piston aircraft ever known.
And since official speed records are done in level flight, we have to use that

Olve

[drgondog]

Yes - I do know what the 'altitude' of the deck is at Reno. The rules however stipulate that the speed records be established 300 feet AGL not sea level.

No - He stated fastest fighter (presumably piston) but I must admit I have serious doubts that a Spitfire ever came close to 600mph in a dive but willing to examine the facts (and the data).

The 262 reached a verified and validated .86 Mach in a dive - no way the Spit exceeded that and kept it's tail on.

[Kutscha]

Nice data on the Spit's dive performance
http://www.spitfireperformance.com/sd2011.jpg

[Six Nifty .50s]

Originally Posted by Franek Grabowski

It does not matter, due to nature of Mach.

Another strange notion not sustained by facts. RAF test pilots were first to admit the maximum speed of the Spitfire declined rapidly when diving into denser air -- reduced to about .67 Mach at heights just below 20,000 feet. Not very impressive, and probably overoptimistic for anyone but highly experienced pilots. That explains why the 109s and 190s could out-accelerate Merlin-powered Spitfires if the dive was started from heights below 30,000 feet.

Originally Posted by Franek Grabowski

This was simply realised in 1943, when it was a little bit too late. Had it been found earlier, no doubt Spit pilots would have been encouraged to chase their enemies.

The laws of physics did not change in 1943. The only way Spitfire pilots could increase dive acceleration was to add more horsepower and more weight. Unfortunately for the RAF, the Germans did the same.

In RAF diving trials, the Griffon-powered Spitfire XIV could just barely out-accelerate a worn out Fw 190A-3 and Bf 109G-6. That advantage was short-lived, thanks to the Bf 109G-10, Bf 109K and Fw 190D.