The P-39Q was the last version of the Airacobra to roll off the production lines at Bell. It was also the version which was built in the largest numbers, 4905 P-39Qs being built before production finally ended.
The principal difference between the P-39Q and earlier version was in the fighter's armament--the four wing-mounted 0.30-inch machine guns were replaced by a single 0.50-inch machine gun mounted in a fairing underneath each wing. The ammunition capacity of the underwing guns was 300 rounds per gun. The two fuselage-mounted 0.50-inch machine guns with 200 rpg, plus the hub-mounted 37-mm cannon with 30 rounds, were retained. The replacement of the four wing guns was generally applauded by American pilots, most of whom thought that the 0-30-inch guns of the earlier versions were too light to be effective and it wasn't worth the extra fuel needed to carry the 4000 rounds of 0.30-inch ammunition. However, the Russians, who got most of the P-39Qs built, usually had the underwing gun pods removed.
The engine was the Allison V-1710-85 (E19) of 1200 hp, the same powerplant that was used in the P-39N.
There were several production blocks of the P-39Q:
P-39Q-1-BE: Retained the 72.4 Imp gallon fuel capacity of the P-39N-5 but returned to the original 231 pounds of armor of the P-39N-1.
P-39Q-2-BE: Five Q-1s were modified to carry cameras for photographic reconnaissance by adding K-24 and K-25 cameras in the aft fuselage. P-39Q-5-BE (Model 26Q-5): Reverted to the lighter armor fit of the P-39N-5 (193.4 pounds), as well as the use of the full wing fuel capacity (92.6 Imp gall) characteristic of the P-39M. Type A-1 bombsight adapters were added to the P-39Q-5-BEs at the Modification Center before delivery to operational units.
P-39Q-6-BE: 148 Q-5s were modified to carry cameras for photographic reconnaissance by adding K-24 and K-25 cameras in the aft fuselage.
P-39Q-10-BE (Model 26Q-10): Internal fuel capacity rose to 100 Imp gallons and armor weight went to 227.1 pounds. The throttle was linked to the propeller settings to provide automatic adjustments. There was additional winterization of the oil system, and there were rubber engine mounts installed. The first P-39Q-10-BEs were delivered to the USAAF by the end of July 1943. A total of 705 examples were built, but 995 more that were assigned serial numbers 42-21251/22245 were actually completed as P-63E-1 Kingcobras.
P-39Q-11-BE: Eight Q-10s were modified to carry cameras for photographic reconnaissance by adding K-24 and K-25 cameras in the aft fuselage.
P-39Q-15-BE (Model 26Q-15): Differed from the Q-10 in minor equipment variations. Among these was a reinforced inclined deck to prevent 0.50-inch machine gun tripod mounting cracking, bulkhead reinforcements to prevent rudder pedal wall cracking, a reinforced reduction gearbox bulkhead to prevent cowling former cracking, and repositioning of the battery solenoid. This example was delivered beginning in August of 1943. 1000 examples were built.
P-39Q-20-BE (Model 26Q-20): The underwing 0.50-inch machine gun pods were sometimes omitted in this version.
P-39Q-21-BE: Similar to P-39Q-20, but a four-bladed Aeroproducts propeller was fitted.
P-39Q-25-BE (Model 26Q-25): Similar to the Q-21 but with a reinforced aft-fuselage and horizontal stabilizer structure and a four-bladed Aeroproducts propeller. The wing guns were deleted from these aircraft, which were exported to the Soviet Union. 700 were built.
P-39Q-30-BE: Tests indicated that directional stability was materially worsened by the four-bladed propeller, and this version reverted to the three-bladed unit. This was the last production version of the P-39Q.
On July 25, 1944, all P-39 production ceased, with 9558 examples being produced.
A few P-39Qs were modified into two seaters with dual controls for use as advanced trainers under the designation RP-39Q (redesignated TP-39Q after 1944). All armament was removed. The second cockpit was sort of "grafted" in front of the original cockpit, and the pilot in this extra cockpit sat under a hinged canopy. The extra cockpit was fitted with only rudimentary controls. The original cockpit retained the same controls and instruments as the standard P-39Q. The instructor sat in front in the extra cockpit, the student in the original cockpit, and the two communicated via an intercom telephone. The tail fillet was enlarged and an additional shallow ventral fin was fitted under the rear fuselage. These modifications produced one of the most grotesque aircraft I have ever seen. :-). The first example, converted from P-39Q-5 42-20024, was rolled out for the first time on September 16, 1943. It was designated TP-39Q-5. 12 two-seater fighter trainers were converted from P-39Q-20s, and were designated RP-39Q-22. The ventral strake was somewhat different in shape from that of the ventral fin of the original TP-39Q-5. Serials were 44-3879, 3885/3887, 3889, 3895, 3897, 3905, 3906, 3908, 3917, and 3918.
The first P-39Qs were delivered to Eglin Field, Florida and Wright Field, Ohio for testing. The first P-39Qs were delivered to the Army Air force by the end of July of 1943.
Production of the P-39Q finally terminated in August of 1944. Most of the P-39Qs were delivered to the Soviet Union. Only a few ended up serving with American units. One of these was the 332nd Fighter Group which took on 75 P-39Qs in Italy in February 1944. After only two months, these Airacobras were replaced by P-47s, finally retiring the type from US service.
A P-39Q (serial number 44-3887) is on display at the WPAFB Museum. It is, however, marked as a P-39J serial number 41-7073, which served with the 57th FS on Adak Island.
P-39Q-15 serial number 44-2433 Galloping Gertie is currently in storage at the Paul Garber Storage and Restoration Facility in Suitland, Maryland.
Specifications of the P-39Q-5-BE:
One Allison V-1710-85 engine rated at 1200 hp at sea level and 1125 hp at 15,500 feet. Maximum speed 330 mph at 5000 feet, 357 mph at 10,000 feet, 376 mph at 15,000 feet. Climb to 5000 feet in 2.0 minutes. Climb to 20,000 feet in 8.5 minutes. Maximum range (clean) was 525 miles at 20,000 feet at 250 mph. With one 145.7 Imp gal drop tank, range was 1075 miles at 196 mph. Service ceiling was 35,000 feet. Weights were 5645 pounds empty, 7600 pounds normal loaded, 8300 pounds maximum loaded. Dimensions: Wingspan 34 feet 0 inches, length 30 feet 2 inches, height 12 feet 5 inches, wing area 213 square feet.
Serials of P-39Q Airacobra
42-19446/19595 Bell P-39Q-1 Airacobra 150 planes 19479/19483 to P-39Q-2-BE. 42-19596/20545 Bell P-39Q-5 Airacobra 950 planes 19608,19610,19612,19614,19616,19624,19626,19628,19636, 19640,19642,19644/19646, all even numbers 19648/19719, all odd numbers 19697/19719,19723,19725, odd numbers 19927/19975,19977/19979, 19981,19983,19985,19987, all odd numbers19989/20011,20013/20015,20017/20019, odd numbers 20021/20065,20067/20069,odd numbers 20071/10092,20095/20097,20099,20101,20103,20105 converted to P-39Q-6-BE 42-20546/21250 Bell P-39Q-10 Airacobra 705 planes 44-2001/3000 Bell P-39Q-15 Airacobra 1000 planes 44-3001/3850 Bell P-39Q-20 Airacobra 850 planes 44-3851/3858 Bell P-39Q-21 Airacobra 8 planes 44-3859/3860 Bell P-39Q-20 Airacobra 2 planes 44-3861/3864 Bell P-39Q-21 Airacobra 4 planes 44-3865/3870 Bell P-39Q-20 Airacobra 6 planes 44-3871/3874 Bell P-39Q-21 Airacobra 4 planes 44-3875/3880 Bell P-39Q-20 Airacobra 6 planes 44-3881/3884 Bell P-39Q-21 Airacobra 4 planes 44-3885/3890 Bell P-39Q-20 Airacobra 6 planes 44-3891/3894 Bell P-39Q-21 Airacobra 4 planes 44-3895/3900 Bell P-39Q-20 Airacobra 6 planes 44-3901/3904 Bell P-39Q-21 Airacobra 4 planes 44-3905/3910 Bell P-39Q-20 Airacobra 6 planes 44-3911/3914 Bell P-39Q-21 Airacobra 4 planes 44-3915/3919 Bell P-39Q-20 Airacobra 5 planes 44-3920/3936 Bell P-39Q-21 Airacobra 17 planes 44-3937/3940 Bell P-39Q-20 Airacobra 4 planes 44-3941/4000 Bell P-39Q-21 Airacobra 60 planes 44/32167/32666 Bell P-39Q-25 Airacobra 500 planes 44/70905/71104 Bell P-39Q-25 Airacobra 200 planes 44/71105/71504 Bell P-39Q-30 Airacobra 400 planes