Was Operation Pedestal a greater Axis air attack than any faced by the USN in 1942?

[ThomasP]

AFIK The metal ailerons for the Spitfire were introduced on the Mk V production during the second half of 1941. But I am not sure how quickly or completely the metal ailerons replaced the fabric covered ones.

 

[Clayton Magnet]

Perhaps I am misremembering, but I thought the fabric control surfaces were found to "balloon" at high speeds, and were quickly retrofitted with metal skinned versions during the BOB. Maybe the Mk.V was the first to have them as standard from the factory?

 

[Wild_Bill_Kelso]

Here's another interesting graph from America's Hundred Thousand, showing the difference between early Hawk 81 P-40 and later Hawk 87 type

 

[PAT303]

FWIW the Hurricane and Bf109G were considered (by pilots that flew both) to have about the same roll rates at the same stick forces, but the Hurricane's maximum roll rate occurred at about 30 mph IAS less than the Bf109G's.

I think it was Winkle Brown who said the seating position and cramped cockpit of the 109 limited how much force could be placed on the stick, there wasn't enough elbow room.

 

[PAT303]

Perhaps I am misremembering, but I thought the fabric control surfaces were found to "balloon" at high speeds, and were quickly retrofitted with metal skinned versions during the BOB. Maybe the Mk.V was the first to have them as standard from the factory?

Lots of improvements were made just before the BoB like metal control surfaces, CS props, additional pilot armor, what made the biggest difference to high speed control was changing the aileron profile.

 

[ThomasP]

re the high roll rate(s) attributed to the P-40

As mentioned in the excerpt from 'America's Hundred Thousand', the 135°/sec roll rate is for the pre-war P-40(ie either no suffix or maybe A as suffix, as in the model 81A). It is unlikely that any P-40(any suffix) airframe that saw combat was capable of this roll rate.

The P-40(no suffix) had only 2x .50 cal guns (along with the ammo) in the nose (ie no wing guns or ammo) and no armour or SSFT. The nose guns and ammo were located only about 1.5' to 2' off of aerodynamic centerline, resulting in a relatively low rolling moment of inertia that was in large part responsible for the high 135°/sec achievable roll rate.

The P-40F had 6x .50 cal in the wings (no nose guns) plus armour and SSFT. Since the 6x .50 cal guns were located about 6' (innermost guns) to about 8 ft (outermost guns) off of aerodynamic centerline (with all of the ammo in the wings outboard of the outermost guns) there was a much greater rolling moment of inertia - hence the significantly lower achievable roll rate of 95°/sec.

There may have been directional stability issues as well, although I do not know if this was the case. If there were cg or unbalanced dynamic force issues that could contribute to loss of directional control during the roll then there may have been practical restrictions on the usable safe rolling velocity. An example of this was the A-4 Skyhawk. I was told by an A-4 pilot that the Skyhawk had a max roll rate of ~720°/sec, but if you did more than 2 complete rolls at the max roll rate there was a good chance the aircraft would depart from controlled flight.

 

[Wild_Bill_Kelso]

re the high roll rate(s) attributed to the P-40

As mentioned in the excerpt from 'America's Hundred Thousand', the 135°/sec roll rate is for the pre-war P-40(ie either no suffix or maybe A as suffix, as in the model 81A). It is unlikely that any P-40(any suffix) airframe that saw combat was capable of this roll rate.

The P-40(no suffix) had only 2x .50 cal guns (along with the ammo) in the nose (ie no wing guns or ammo) and no armour or SSFT. The nose guns and ammo were located only about 1.5' to 2' off of aerodynamic centerline, resulting in a relatively low rolling moment of inertia that was in large part responsible for the high 135°/sec achievable roll rate.

The "Tomahawk" tested in the Australian document, which achieves about 105 degrees roll, was a IIC, with 4 .30 cal wing guns.

The P-40F had 6x .50 cal in the wings (no nose guns) plus armour and SSFT. Since the 6x .50 cal guns were located about 6' (innermost guns) to about 8 ft (outermost guns) off of aerodynamic centerline (with all of the ammo in the wings outboard of the outermost guns) there was a much greater rolling moment of inertia - hence the significantly lower achievable roll rate of 95°/sec.

Well, that's just one test with the P-40F, at a particular loading etc. In the field, P-40Fs, like all of the otherwise just about identical P-40Ls which came after it in the same Theater, routinely had four .50 cal guns and a bit less ammunition. Not for roll rate, which no P-40 pilot ever complained about that I know of, but for better altitude performance and climb rate for fighting Bf 109s and MC 202 / 205s. But four wing guns would probably have improved roll as well. The MC 202s sometimes had some or all of their wing guns removed for the same reason.

There may have been directional stability issues as well, although I do not know if this was the case. If there were cg or unbalanced dynamic force issues that could contribute to loss of directional control during the roll then there may have been practical restrictions on the usable safe rolling velocity. An example of this was the A-4 Skyhawk. I was told by an A-4 pilot that the Skyhawk had a max roll rate of ~720°/sec, but if you did more than 2 complete rolls at the max roll rate there was a good chance the aircraft would depart from controlled flight.

Early Hawk 87 P-40s had an issue with takeoff swing requiring the heavy use of rudder on takeoff, which caused a fair amount of wrecks especially with inexperienced pilots especially as the takeoff boost rating of the engines kept going up. This was corrected in the K first with a fin and then (second half of the run) with an extended tail 27" longer, which seemed to fix the problem. The second half of the P-40F run, and all of the L, M and N P-40s also had the same extended tail.

Again, in many interviews of P-40 pilots I've never heard anyone complaining about the roll rate. Very much to the contrary. They did note that in high speed dives, which were common escape maneuvers in combat, they had to use a lot of rudder and trim tabs. There was even a joke that you could distinguish P-40 pilots by one leg being thicker than the other. This was largely (though not completely) alleviated by the extended tail.

Even at 95 degrees roll, that puts the P-40F as the third best rolling fighter tested at greater than 250 mph, and if you extrapolate the curve it's probably the fastest rolling with ~80 degrees at 400+ mph except for the Mustang III / P-51B.