Bell P-39/P-400 Airacobra

The Bell P-39 Airacobra was an all-metal monoplane Pursuit aircraft with an inline engine mounted aft of the cockpit, a side opening door into the cockpit, tricycle landing gear, a cannon firing through the propellor hub, and additional machiine guns, mounted in the nose and wing.  The P-400 was an export variant, also known initially as the Caribou.  Per reference [8] it took its first flight on 6 April 1938, and entered operational service in 1941.  The P-39 was built in many variants, with the primary variants analyzed at this website being:

• the P-39D
• the P-39D-2
• the P-39Q-1
• the P-400

Also data is available from Reference [7] for a plane identified only as a P-39, with no other variant information given.

In addition to service with the USAAC, variants also served with the UK, Australia, the USSR, Potugal, Poland, Italy, and France  Per reference [8] a total of 9,588 of this type aircraft of all variants were procured.  

As shown in the images below distinguishing features of this aircraft including;

• an inline engine, mounted aft of the cockpit
• cannon firing through the propeller hub
• side opening door into the cockpit
  
• a low mounted wing 
• retractable tricycle landing gear

[Image Sources: Public Domain via Ref [8] - as annotated by this site]

                                                [Source: Ref [14b] - US Government/Public Domain]

                           [Source: Ref [4] - Public Domain]

In order to try and better develop weight estimating relationships an effort has been made to estimate the length of the fuselage aft of the firewall, and the length of the engine section forward of the firewall based off scaled drawings.  Together these two distances add to a term called the "structural length" and do not consider any portion of the engine or propeller shaft the extend foward of the fuselage/cowling, or any empennage that extends aft of the fuselage structure.  The drawing below shows the current best estimate of these dimensions obtained from available drawings of the airplane and will be updated with any real world data that becomes available.  For any aircraft with an inclined firewall, an attempt has been made to locate an approximate center of this location.

 
                                                           Source References [1] [2] [3] & [16]

In the above images, dimensions in Black come from the source material while dimesions in Red have been approximated from the data available.

The table below summarizes the current data collected on this type aircraft, identifying sources for the data

		P-39	P-39D	P-39D	P-39D-2	P-39Q-1	P-400	Secondary Source	Notes
Primary Source		4	1	2	1	1	1
No of Crew		1	1	1	1	1	1
Engine:
Qty		1	1	1	1	1	1
Model		V-1710	V-1710-35	V-1710-35	V-1710-63	V-1710-85 (E19)	V-1710-E4 (-35)	5
Displacement	(cu in)	1710	1710	1710	1710	1710	1710	5
Power
Military	(HP)		1150	1150	1150	1125	1150	5
War Emergency	(HP)		1490	1490	1580	1410	1490	5
Normal	(HP)
Take Off	(HP)		1150	1150	1325	1200	1150	5
Eng Dims
Length	(ft)
Width/Dia	(ft)
Height	(ft)
Base Engine Wt	(lb)		1375	1375	1435	1452	1375	5
Propeller
# Blades			3	3	3	3	3
Dia	(ft)		10.375	10.375	10.375	11.58	10.375
Manufacturer
Type		Const Speed	Const Speed	Const Speed	Const Speed	Const Speed	Const Speed
Wing
Span	(ft)	34	34	34
Root Thickness	(%)		15.0%	15.0%
	(in)	14.75	15.8	15.8
Total Area	(sq ft)		213.22	213.22	213.22	213.22	213.22
Wing (less Ailerons & Flaps)	(sq ft)	197.7
Ailerons	(sq ft)	15.46	11.82	11.82
Flaps	(sq ft)		26.2	26.2
Tail Area	(sq ft)		59.05	59.05	60.21	59.01	59.01	3
V Tail Area	(sq ft)		19.01	19.01	19.01	18.97	18.97	3
Fin	(sq ft)		7.94	7.94
Rudder	(sq ft)		11.07	11.07
H Tail Area	(sq ft)		40.04	40.04	41.2	40.04	40.04	3
Stabilizer	(sq ft)		23.9	23.9
Elevator	(sq ft)		16.14	16.14
Total Control Surf Area	(sq ft)		65.23	65.23
Length
Overall	(ft)	30.17	30.13	30.13	30.13	30.13	30.13
Fuselage	(ft)		26.3	26.3
Body	(ft)		30.38	30.38	30.38	30.38	30.38
Body Depth	(ft)	5.89
Body Width	(ft)	2.90
Fuel Tank Volume	(gal)	120
Wing Tanks	(gal)	120
FuselageTanks	(gal)
Oil Tank Volume	(gal)	13.8	11.7	11.7
Water Injection Fluid Tank Volume	(gal)
Wetted Area (sqf)	(sq ft)
Pwr Ldng	(lb/HP)			6.44
Wing Ldng	(lb/sq ft)			34.73
Struct. Des. GW	(lb)	7496	7406	7406
Ultimate Load Factor	(G's)	12	12	12
Design Speed	(mph)			530
Not to Exceed Speed	(mph)
Total Struct Weight		2185.5	1567.2	2157	1565		1558.8
Total Wing		934.6	934.6	924	934.2		930
Wing		872.6
Ailerons		36
Flaps		26
Fuselage Carry-Through
Tail		116	116	114	116		114
H Tail		79		78
Stabilizer		46
Elevator		33
V Tail		37		36
Fin		14.3
Rudder		22.7
Body + Eng Section + LG
Body + LG			516.6	1119	514.8		514.8
Body		618.3		608
Fuselage
Engine Section
Landing Gear		516.6	516.6	511	514.8		514.8
Mn Landing Gr		391.5		386
Tail/Nose Aux LG		125.1		125
Tail Hook
Booms
Nacelles
Total Propulsion Weight		2663.4	2663.4	2565	2709.6		2647.2
Engine w/ Accessories		1524.1	1524.1	1514	1554.2		1516.2
Engine(s) as Installed		1408.5	1408.5	1399	1435		1397
Accessories		115.6	115.6	115	119.2		119.2
Turbocharger(s)
Controls		30.3	30.3	30	30.3		30.3
Propeller(s)		398	398	398	399.3		399.3
2-Blade
3-Blade		398	398	398	399.3		399.3
4-Blade
Starting System		43.6	43.6	44	47.2		47.2
Water Injection System
Tanks
Piping Etc
Cooling System		322	322	322	323.3		326.3
Lube System		56.2	56.2	56	63.6		60.6
Tanks		13
Piping Etc		43.2
Fuel System		289.2	289.2	201	291.7		267.3
Tanks		240
Piping Etc		49.2
Total Sys. & Eqpmt.		674.3	674.1	641	755.6		721.1
Instruments		60.3	60.3	48	57.5		45.6
Surface Controls		108	108	106	115		110
Hydraulics			-		-		-
Electrical Equip		225.2	225	226	274.6		278
Electronics (Purple means incl in Furn/Gray in Useful Ld)		62	62	60	80.2		35
Arm Prov/Equipment & Armor		177.2	177.2	158	146.6		204.9
Furnishings		41.6	41.6	43	50.7		47.6
Anti-Ice (If not in Furn)
Other /Misc			-		31		-
Hoisting Gear
Floatation Gear
Armor Plate
Empty Wt		5523.2	4904.7	5363	5030.2		4927.1
Basic Mission Useful Load		1880.3		2042
Crew		160		200
Equipment
Oil		55.5		71
Fuel		624		720
Fuel & Oil Trapped in Systems
Water Solution for Engine Injection
Bombs/Torp Etc
Radio (if Not Included in Empty Wt)
Nav Equipment
Oxygen System
Armament		1025.8		887
Guns & Ammo		759.2		887
Guns		492.2		447
Ammo		267		440
Pyrotechnics
Camera
Other		266.6
Other Useful Load		15		164
Basic Mission GW		7403.5		7405

Notes: This website has been developed with a number of low cost or free programs including Hot Metal Pro, KompoZer, MicroSoft Designer and Da Button Factory.com

Rev 4-12-26

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