Author Topic: Zeke compression (Read 667 times)

calan · « **on:** November 08, 2006, 03:48:19 AM »

I was testing the zekes for compression (climb to 20k... level off at 200 IAS... then push over into a relatively steep dive). After several consistent runs with both planes, I found that the A6M2 never really becomes uncontrollable, but begins to break up at around 500 IAS.

The A6M5 on the other hand, becomes completely uncontrollable at about 395 IAS, and ends up in an unrecoverable spin.

Why such a big difference? Aren't they essentially the same airframe?

Angus · « **Reply #1 on:** November 09, 2006, 07:08:17 AM »

Definately needs looking into

Goth · « **Reply #2 on:** November 09, 2006, 10:40:46 AM »

Maybe the fixed gear of the 2 provides enough stability. I think the 2 was in all probability lighter as well.

Benny Moore · « **Reply #3 on:** November 09, 2006, 12:26:16 PM »

Fixed gear? Neither of those Zekes had fixed gear. The only Zeke that had fixed gear was the float plane version, as far as I know. At any rate, it's common knowledge that the Zeke could not outmaneuver anything over two hundred and fifty miles per hour due to the "barn door" control surfaces.

Widewing · « **Reply #4 on:** November 09, 2006, 07:08:19 PM »

There are some noticable differences between the two in a dive. I have filmed both and you can determine the exact speed that things happen. It should be noted that both AH2 Zeros can survive much higher speeds and G loadings than the real Zeros could.

Here's the films.

A6M5

A6M2

My regards,

Widewing

Saxman · « **Reply #5 on:** November 09, 2006, 11:26:42 PM »

That seems to go for MANY planes. I've dragged Spits past 600 mph in my F4U with hard pullout at the edge of a blackout and watched them stay with me every inch with no ill-effect, when by all accounts they should be fluttering to the ground in pieces.

Squire · « **Reply #6 on:** November 10, 2006, 01:19:31 AM »

The P-51B/D, Spitfire XVI and F4U all had critical mach #s in the 0.8-ish range, so I dont know what data you are reffering too Saxman. Spitfires could dive with almost any WW2 prop fighter. Im not saying outdive, but they could keep up. In fact the manual for the Spit XVI indicates a crit mach of 0.85 for it (S.L. to 20k) or around 520mph TAS.

I have tried the Spit XVI in a dive in AH and above @550mph TAS it is uncontrollable.

They were not "British Zeros".

Angus · « **Reply #7 on:** November 10, 2006, 07:04:27 AM »

Quote

Originally posted by Saxman
That seems to go for MANY planes. I've dragged Spits past 600 mph in my F4U with hard pullout at the edge of a blackout and watched them stay with me every inch with no ill-effect, when by all accounts they should be fluttering to the ground in pieces.

The Spitty probably had the best elevator efficiency at high speeds of all WW2 prop fighters, so I'm not sure what you're getting at there.
They also hold the WW2 prop diving speed record.
Some Mk V's did break up when entering a self increasing pritch at high speeds, due to the combination of a delicate C.o.G. and very sensitive and effective elevators. The problem was solved by making the controls heavier through bob weights. The forces that broke Spitfires left a dead pilot, so there is no exact data on how heavy they were, but some say more than 12G or even 15, which is enough to break just about any WW2 fighter.

Squire · « **Reply #8 on:** November 10, 2006, 10:24:39 AM »

...Back to the original point, the best way to test dive performance is by filming using "alt-r" and then review the footage. Also, dont use combat trim.

Both Zeros get very stiff after @450 TAS, and break up at @530 TAS. Either the A6M5 should be better in a dive, or the A6M2 should be weaker.

calan · « **Reply #9 on:** November 10, 2006, 02:39:08 PM »

Quote

Originally posted by Squire
Either the A6M5 should be better in a dive, or the A6M2 should be weaker.

That's what I would have thought, but it doesn't seem that way.