Shortround6
Major General
There were two original XP-39Es plus a static airframe.
The first XP-39E (with a single stage Allison?) crashed about a month after the first flight. The 2nd air frame was intended from the start to use the two stage engine and be used for performance tests while the 1st was to be used in determining handling qualities, armament tests and maneuvers.
According to some accounts the static test airframe was brought up to flight standard. In any case a 3rd airframe was flown. The Performance was better than a standard P-39, but only at higher altitudes.
Bell chief test pilot Bob Stanley in a Bell company report from May of 1942.
" At 393 miles per hour at approximately 24,000ft the XP-39E is definitely faster than the P-39D. Only in speed, however, does it surpass the latter airplane, the XP-39E is inferior to the P-39D in regards to takeoff distance, landing speed, rate of climb, ceiling and general handling qualities."
Since the plane grossed over 9,000lbs with no real change in power until the higher (teens and low 20s ) altitudes were reached this is not surprising.
The engine in the 2nd and 3rd XP-39Es did have an auxiliary supercharger (2nd stage) it just wasn't very good and did not have the hydraulic variable speed drive.
26 flights had been made with the 2nd prototype by May 11th 1942. A connecting rod failed on the 27th flight and it took until June to repair the plane and flying started again in July.
Most of the flying from July to October of 1942 was concerned with propeller tests, in large part to support the P-63 program. The two remaining XP-39Es served as test beds for the two stage Allisons.
While 4000 had been on order at one point the contracts were canceled or rewritten to P-63 contracts because the XP-39E was not living up to expectations/promises (where have we heard that before
The XP-39E used the some P-39D parts and assemblies like the gun bay, landing gear parts and cabin sub assembly.
The first XP-39E (with a single stage Allison?) crashed about a month after the first flight. The 2nd air frame was intended from the start to use the two stage engine and be used for performance tests while the 1st was to be used in determining handling qualities, armament tests and maneuvers.
According to some accounts the static test airframe was brought up to flight standard. In any case a 3rd airframe was flown. The Performance was better than a standard P-39, but only at higher altitudes.
Bell chief test pilot Bob Stanley in a Bell company report from May of 1942.
" At 393 miles per hour at approximately 24,000ft the XP-39E is definitely faster than the P-39D. Only in speed, however, does it surpass the latter airplane, the XP-39E is inferior to the P-39D in regards to takeoff distance, landing speed, rate of climb, ceiling and general handling qualities."
Since the plane grossed over 9,000lbs with no real change in power until the higher (teens and low 20s ) altitudes were reached this is not surprising.
The engine in the 2nd and 3rd XP-39Es did have an auxiliary supercharger (2nd stage) it just wasn't very good and did not have the hydraulic variable speed drive.
26 flights had been made with the 2nd prototype by May 11th 1942. A connecting rod failed on the 27th flight and it took until June to repair the plane and flying started again in July.
Most of the flying from July to October of 1942 was concerned with propeller tests, in large part to support the P-63 program. The two remaining XP-39Es served as test beds for the two stage Allisons.
While 4000 had been on order at one point the contracts were canceled or rewritten to P-63 contracts because the XP-39E was not living up to expectations/promises (where have we heard that before
The XP-39E used the some P-39D parts and assemblies like the gun bay, landing gear parts and cabin sub assembly.