[_VR_Aristo]

109 good diver? its compresses at high speeds.

my top 5 i can think off:

p47
j2m3/5
FW190(incuding ta)
mc205
p40

grant

How come the j2m3 is in second place... heck how come it is on the list in the first place?
Edit: Ok after testing the plane, I'll say it's not bad at all, although at bit slow on initial dive, it's very good at zoom climb. But still, second place?

dont forget the Spitfire either. It had one of the highest mach numbers recorded in a dive during the war..

That particular Spitfire reached 0.89 Mach, which was an experimental model that had the nose case ripped from the engine and the wings were laminar flow as well as being bent slightly backwards.


I'll quote vanir from another forum on the subject:
In actual service trim the highest official recording of compressibility during dive was for the Mustang at 0.8 Mach, any 'stang could do it and that was exceptional.
It was Charles Lindbergh who put the cap on the Thunderbolt dive. The Republic corporation had used test pilots on the company payroll to set the safe dive speed at 550mph indicated. Following a series of accidents in the New York region among training squadrons equipped with the new type, Lindbergh was asked to give an independent appraisal by the DoD(Department of Defence). He flew the P-47C and rated it as unstable in the dive at speeds exceeding 450mph indicated at 18,000 feet IIRC. By unstable he stated clearly the aircraft would likely kill the pilot in uncontrolled dives from extreme altitude and he was lucky to survive the test flight by attempting to achieve the manufacturer safe op guidelines.

It was noted by the DoD and NACA at the time (I can source references) that aircraft manufacturers in the US were routinely massaging listed performance specifications using paid test pilots rather than independent profiling of actual safe service operation (presumably in the competition to secure large contracts). Lindbergh was asked to test fly a wide variety of service aircraft for the DoD, there were others doing this job too. They travelled as civilians on the defence payroll even to field airstrips and tested aircraft under actual service conditions and trim for local revisions of operating procedures. I remember reading of a combat encounter by Lindbergh on one of these field test flights as a civilian contractor, apparently the combat zone had moved somewhat recently and the maps hadn't been adjusted. I don't think he was ever actually engaged by enemy aircraft though.

The phenomenal dive performance of the Thunderbolt is largely a myth, though the reality is still an extremely impressive dive performance. It's just that aircraft like the Messerschmitt, Focke Wulf, Tempest MkV and Griffon Spit could all match it. In fact the best divers according to British testing was the Griffon Spit and Tempest MkV in a power-on dive, although the Me-109G-2 they tested against them could still match initial dive acceleration (but not sustained power-on dives).

I've listened to the Luftwaffe aces in interviews being specifically asked about the P-47's dive performance, (Gunther) Rall for one, who comparatively tested these models as well as fought them in aerial combat had no idea it was even supposed to be quite so superior as the legend dictates. It had a good dive he said, nothing special. He liked the Mustang. To one persistant audience member, who asked what would you do if bounced by a Thunderbolt diving from altitude, he said well shoot it down of course. He did specify the P-47 had a great zoom, you couldn't follow it in the dive and get anywhere near the same altitude recovery afterwards, it was a severe mistake to try, that was the only notable thing about it he mentioned.
Anecdotal I realise.

109 good diver? its compresses at high speeds.

A part of a report about Bf-109 by test pilot Captain Eric Brown(who happens to flown more types of aircraft than anyone else in history):

"Diving - structural rigidity of 109 in dives

The Me 109 was dived to Mach 0.79 in instrumented tests. Slightly modified, it was even dived to Mach 0.80, and the problems experimented there weren't due to compressibility, but due to aileron overbalancing. P-51 and Fw 190 achieved about Mach 0.80. The P-47 had the lowest permissible Mach number of these aircraft. Test pilot Eric Brown observed it became uncontrollable at Mach 0.73, and "analysis showed that a dive to M=0.74 would almost certainly be a 'graveyard dive'."
Source: Radinger/Otto/Schick: "Messerschmitt Me 109", volumes 1 and 2, Eric Brown: "Testing for Combat".


To conclude; the reports are consistent that the P-47 wasn't as good at power-dive as it was publicized, in fact it was worse in respect to it's maximum safe dive speed than it's contemporaries by a considerable margin. Although being heavy, very good at accelerating on initial dive.

Hopefully that should clear the matter a little bit,

Aristo