Hi Gang!

Was watching a program on the "History Channel" about the F4U Corsair. One of the "old vets" mentioned that the Zero became an easy victim because it could not make a right hand turn with a Corsair.

Any truth to this? Or was this just an "old vets" tale.

What do you think? I would be interested in knowing if there is any truth to this.

 

My understanding of this flaw was that it was the Zero's carberator that would cut out in a hard pushover turn and dive to the right. This flaw as far as I am aware was never corrected and remained a weakness of the A6M all the way to the wars end.

Cruiser K

 

A pretty reliable book list this information. Apparently something was happening to allow allied pilots to consecutively dive and roll right to easily ecape A6M. How was this proven as a myth? Well I did read this in a book on the A6M and Boyington was qouted as making the statement. I will check to find it.

Cruiser K

 

Speaking of physics and Pappy Boyington...as we speak I'm watching a repeat of the old Black Sheep series. Just happen to notice that the motor seems to turn to the right.

If we use use the torque theory as put forth earlier that would seem to make the Corsair or similar engined fighters more responsive while making right hand manuevers. Combine that with US fighters superior diving capabilities...voila...flaw meets strength.

Well its just a theory

 

No, the carburator cut-out under neg-G was a myth. I don't know how it got started, maybe Koga's zero got put back together wrong, but the designers and pilots of the zero all said that the carburator was specifically designed to allow for neg-G conditions, and worked fine.

That the corsair could outroll a zero is no myth. The corsair is one of the sweetest rollers of all WWII fighters, and the zero is lousy at it, especially at 250+.

Micah

 

The Spitfire Is DID have a carbeurator that cut out in Neg-G maneuvers. During the BoB, 109e pilots apparently used this to their advantage by pushing straight down when they got a spit on their tail. The spit would have to roll and pull down, this would give the 109 pilot a brief little advantage. They put in a new carb for later models of the Spitfire.

Micah

 

It is always difficult to turn and/or roll to the direction of the propeller due to reaction of the propeller on a/c. It is shared by all a/c though some a/c has less of this problem due to their wing, control surface design.

The larger the wing gets the harder it is to roll. And the relation is logarithmic rather than linear. For instance a clipped wing Spit IX could roll about 1.5 times faster than a original wing one.

Zero was no Roller though it was a very good turner. I imagine Japanese pilots prefer to turn left unless forced otherwise because initial rolling to the right was usually slower than enemy it encountered. Thats probably what is meant in the documentary.

On the other hand turning tight does not necesarily mean being safe, a wider turning a/c can still shoot down a tight turning one providing that it has better rate of turn (in degrees per second rather than min radius) and enough lead for a deflection shot.

 

No zero could ROLL with a corsair, except at speeds below the Corsair's combat range. TURNing is different. A zero could outturn a corsair any day of the week and twice on sundays. But what corsair pilots would do is get up to 250+, and just roll away. The zero at high speeds had a horrendously slow roll rate, whereas the F4U had great roll rates at medium and high speeds.

 

Hi,
that means that Zero's wing was affected of excessive deformation in torsion under high aerodinamic load. Since the Zero's maneuvrability was due to its reduced weight this was the price to pay!.

Best Regards
Mario

 

Mario:

I am not an aero-engineer and I don't know much about this, but the Zero's stick became very stiff and hard to bank, especially to the right. I had been under the impression the Zero's aerodynamic envelope was for low-speed, and that the washout in the wings was what made the ailerons stiffer at high speeds.

Please educate me, as your explanation seems to explain it better...

Are you saying that the wings deformed at higher speeds and the ailerons became less aerodynamic as a result of this deformation? If yes, I can certainly agree that the Zero's structure was VERY light and its wings (as with all aircraft) would deform when close to their limits (everything deforms prior to breaking).

Also, if yes, are you saying the wing would sweep back a little, or would it warp a little, or something else?

Thanks for the info.

--Rob Graham

 

Hi Mario and Rob;

Essentially, I believe Mario's explanation is correct, but one other factor could/should be mentioned in this aero-elasticity study.

When the wing torques/twists/ bends due to the aileron deflection, the "effective" control linkage is changed: if cables, they stretch, adding pressure and friction to the pulleys and bearings; if push-pull rods, they bend and twist, again increasing friction and mechanical resistance in the bearings.

In either case, the result is more force required at the control stick. or less control deflection for a given force input. At some point the pilot simply runs out of strength.

In extreme cases, this could lead to "aileron reversal" - namely beyond a certain speed and aileron deflection and expected rigth roll becomes a left roll!

Aero control designers make sure this point is significantally above the max speed the a/c can obtain. Is it just possible that the Zero, with its light structure was approaching this phenomona at say something above 325 mph?

In any event, all of these things, occurring at the same time, begin to explain the Zero's control loading problems above 250 mph.

cheers,

Amos

 

In addition to the two reasons brought up by Mario & Amos, there is another factor that non pilots may not be aware of. Airplane controls stiffen with speed. Designers can reduce this effect with aerodynamic counterbalances, but they dare not go too far lest other problems crop up. Indeed, sloppy controls are one of the warning signs to a pilot that his airplane is approaching a stall.