P-40E Weight Reduction, in April 1942

[oldcrowcv63]

Ferguson and Pascalis, cite in their history of the 49th Fighter Group that George Kiser flew in a modified P-40E with his two outboard 0.50 cal guns removed and fought with a reduced ammo load.

Removing two 50's probably reduced the weight of the P-40E by ~160 lbs. Deleting the two guns ammo (235 rpg) provides a further reduction of 141 lbs for a total reduction of probably ~300 lbs.

Basic fuel load for the P-40E was probably 148 gallons (at ~6#/gal) or 888 lbs.

According to: P-40 Performance Tests

P-40E weighing 8,011 lbs (No belly tank) took 19.42 minutes time-to-climb to 25,000 ft

(Note that AHT lists 8,290 lbs for apparently the same configuration)

while

P-40D weighing 7,740 lbs (No belly tank) took 15.9 minutes time-to-climb to 25,000 ft

P-40E Service ceiling is listed as 30,000', although other sources list 29,000'. Practically, in the tropics, I can't find an instance of a P-40E getting above 27,000'.

P-40D Service ceiling is listed as 30,600'.

McDowell (In Action) claims an 0.5" ammo load out for a P-40D was 615 rpg or 2460 total rounds for a total weight of ~738 lbs.

That just doesn't seem likely because it would push the P-40D gross weight above that of the P-40E. The cited tests report seems to confirm a difference of the order of about 300 lbs lighter for the D, as would be expected by deletion of the two 50's and the ammo.

If the weight of .50" ammo is about 30 lbs per hundred count, further reducing the ammo load from 235 rpg to 190 rpg may drop the weight by nearly 50 lbs. There is no mention of Kiser reducing his fuel load but reason to believe he did, as AAF tests starting in June state that a fuel load of 87 gallons was standard or about 366 lbs less than the fully loaded P-40E. In such a case, total weight reduction is over 700 lbs.

I expect such a modified P-40E to have a higher service ceiling and a time to climb exceeding the 15.9 minute to 25,000' of the D version.

It appears that on April 27, 1942, Kiser was launched to intercept a formation of escorted G4Ms and bagged two of the raiders (his 6th 7th victories) and an escort just before they reached the Darwin target area. I believe Gordon Birkett wrote the following description found at:

Defence of Darwin April 42 | ArmyAirForces

"Blue flight, 8th Pursuit Squadron, led by Capt George Kiser in #57 caught up to the enemy bombers just as they were about to cross the west shore of Darwin. Kiser flew his P-40E with only 4 machine guns in place, and with reduced ammunition load.
P-40E #57 as flown by Captain George Kiser, Blue Fight, 8thPursuit Squadron, 27/04/42 An ADF-Serial.com first, I have authenticated the Serial as 41-5622. One of 4 P-40E/E-1s displayed for the Press at RAAF Darwin in April 1942 along with #51, #36 and #94. This aircraft was later named “Squirlbate” GRB
This improved the roll rate and performance at high altitude. A lesson he learnt from operating in Java with the 17th Pursuit Squadron (Provisional)."

Seems to me Kiser or any pilot of such a performance enhanced aircraft would have wanted to fly with a similarly configured wingman. How many of such flight elements were modified is a mystery but I have seen a number of 49th group photos that seem to be censored with the P-40 wings leading edge obscured.

 

[davebender]

A note of caution.

Early war P-40Es (at least in Philippines) had many problems with machinegun jams. I would fix the weapon problem(s) first. Otherwise a P-40E armed with four machineguns might have only one or two that work during combat.

 

[oldcrowcv63]

A note of caution.

Early war P-40Es (at least in Philippines) had many problems with machinegun jams. I would fix the weapon problem(s) first. Otherwise a P-40E armed with four machineguns might have only one or two that work during combat.

Point taken, although their mods seem to have worked out fairly well on an average basis as these guys were in pretty continuous combat over Darwin through the summer of '42.

I suspect the problems with the guns were solved as unit armorers became more experienced and proficient and pilots gained experience in both QAing the guns and handling the aircraft in flight... That being said, the problem did seem to persist for longer than I'd expect.