North_American_Trainers.htm

North American BT-9, BC-1, AT-6 and SNJ

During the 1930's North American Aviation developed a series of trainer aircraft for a variety of USAAC, US Navy, and foreign trainer programs. The specific designs that are included in the aircraft analyzed at this website include:

the USAAC BT-9B Basic Trainer
the USAAC BC-1 Basic Combat Trainer
the USAAC AT-6A Advanced Trainer
the US Navy SNJ-5 Scout Trainer

Per Reference [8] the BT-9, which first flew in April 1936, was a low wing monoplane with fixed landing gear. Although it had metal wings the sides of the fuselage aft of the firewall and the wing and tail control surfaces were constructed of fabric panels over metal frames. The BT-9B was a slightly modified variant ot the base BT-9 aircraft.

The North American BC-1 was a monoplane Basic Combat Trainer for the USAAC. It was configured similar to the BT-9 design though it had retractable landing gear. Per Reference [8] an armed variant of the BC-1 with a semi-monococque external skin for its fuselage was also developed, designated the BC-1A. Various AT-6 variants would serve with the armed forces of Canada and the UK under the designation of Harvard type trainers, as well as with the US Navy as the SNJ Texan type trainers.

Per Reference [8] the base AT-6 was basically the same as the BC-1A variant of the BC-1, with some small modification. The AT-6A had a slightly different engine and modified wing fuel tanks. The US Navy's SNJ-5 was basically equaivalent to the USAAC's AT-6D variant, which had a slightly upgraded engine, a 24V electrical system (in place of the 12V system of earlier variants), and some structural and materials changes, over the earlier AT-6 variants. The AT-6D/SNJ-5 variant was also operatd by Canada and the UK as the Harvard Mk III.

The AT-6/SNJ/Harvard family of trainers would eventually serve with numerous air forces around the world both during WWII and after. After WWII, with the foundation of the US Air Force AT-6 trainers were redesignated as T-6 trainers.

As shown in the images below distinguishing features of the BT-9, BC-1, AT-6 and SNJ aircraft including;

radial engines
inline cockpits for the instructor and trainee under a greenhouse canopy
low mounted wings
fixed landing gear for the BT-9 or retractable landing gear on the BC-1, AT-6 and SNJ aircraft

[Image Sources: US Government/Public Domain via Ref [8] and Ref [9] - as annotated by this site]

BT-9 / BC-1 / AT-6A/SNJ - [Source: Ref [14a] - US Government/Public Domain]

BT-9 3-View [Source 8] AT-6 3-View [Source 8]

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.

BT9B Dims

Source References [2] [3] & [8]

BC1 Dims

Source References [2] & [8]

AT6A-SNJ Dims

Source References [2] & [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

		BT-9B	BC-1	AT-6A	SNJ-5	Secondary Sources	Notes
Primary Source		2	2	2	2
No of Crew		2	2	2	2
Engine:
Qty		1	1	1	1
Model		R-975-7	R-1340-47	R-1340-49	R-1340-AN-1	5, 8
Displacement	(cu in)	975	1340	1340	1340	5, 8
Power
Military	(HP)		600	600		5, 8
War Emergency	(HP)
Normal	(HP)	400	550	550	550	5, 8
Take Off	(HP)	400	600	600	600	5, 8
Eng Dims
Length	(ft)	3.54	3.58	3.58	4.00	5, 8
Width/Dia	(ft)	3.75	4.29	4.29	4.33	5, 8
Height	(ft)
Base Engine Wt	(lb)	695	854	854	865	5, 8
Propeller
# Blades		2	2	2	2
Dia	(ft)	8	9.08	9.00	9
Manufacturer		Two-Speed	Two-Speed	Const Spd	Const Spd
Type				Hamilton Std	Hamilton Std
Wing
Span	(ft)			42.60	42.02
Root Thickness	(%)
	(in)
Total Area	(sq ft)	248	225	258.1	253.73
Wing (less Ailerons & Flaps)	(sq ft)			218.18	213.47
Ailerons	(sq ft)			11.4	11.4
Flaps	(sq ft)			28.52	28.86
Tail Area	(sq ft)	59.23		87.19	87.19	3
V Tail Area	(sq ft)	19.03		18.54	18.54	3
Fin	(sq ft)			5.33	5.33
Rudder	(sq ft)			13.21	13.21
H Tail Area	(sq ft)	40.2		50.11	50.11	3
Stabilizer	(sq ft)			28.34	28.34
Elevator	(sq ft)			21.76	21.76
Total Control Surf Area	(sq ft)
Length
Overall	(ft)	28		28.99	28.99
Fuselage	(ft)	27.6	27.8	29
Body	(ft)	26.37		20.54	20.54
Body Depth	(ft)
Body Width	(ft)
Fuel Tank Volume	(gal)			178	110.4
Wing Tanks	(gal)
FuselageTanks	(gal)
Oil Tank Volume	(gal)			15.5	12.2
Water Injection Fluid Tank Volume	(gal)
Wetted Area (sqf)	(sq ft)
Pwr Ldng	(lb/HP)	11.11	8.70	8.69	8.78
Wing Ldng	(lb/sq ft)	17.91	23.20	20.19	20.75
Struct. Des. GW	(lb)			5246	5280
Ultimate Load Factor	(G's)				8.5
Design Speed	(mph)	170	207	210	251
Not to Exceed Speed	(mph)

Total Struct Weight		1621	1950	1995	1960
Total Wing		663	716	743	755
Wing
Ailerons
Flaps
Fuselage Carry-Through
Tail		96	112	119	119
H Tail		70	81	87	86
Stabilizer
Elevator
V Tail		26	31	32	33
Fin
Rudder
Body + Eng Section + LG
Body + LG		862	1122	1133	1086
Body		532	659	671	641
Fuselage
Engine Section
Landing Gear		330	463	462	445
Mn Landing Gr		299	427	425	403
Tail/Nose Aux LG		31	36	37	42
Tail Hook
Booms
Nacelles
Total Propulsion Weight		1082	1303	1333	1386
Engine w/ Accessories		740	919	939	945
Engine(s) as Installed		690	846	851	871
Accessories		50	73	88	74
Turbocharger(s)
Controls		15	22	22	12
Propeller(s)		161	176	176	184
2-Blade		161	176	176	184
3-Blade
4-Blade
Starting System		42	45	43	46
Water Injection System
Tanks
Piping Etc
Cooling System
Lube System		17	24	30	73
Tanks
Piping Etc
Fuel System		107	117	123	126
Tanks
Piping Etc
Total Sys. & Eqpmt.		611	793	710	744
Instruments		71	79	83	86
Surface Controls		92	101	100	110
Hydraulics				52	40
Electrical Equip		207	229	223	195
Electronics (Purple means incl in Furn/Gray in Useful Ld)
Arm Prov/Equipment & Armor				24	38
Furnishings		241	384	228	275
Anti-Ice (If not in Furn)
Other /Misc
Hoisting Gear
Floatation Gear
Armor Plate

Empty Wt		3314	4046	4038	4090
Basic Mission Useful Load		1128	1175	1174	1175
Crew		400	400	400	400
Equipment
Oil		72	77	76	77
Fuel		624	666	666	666
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
Guns & Ammo
Guns
Ammo
Pyrotechnics
Camera
Other
Other Useful Load		32	32	32	32
Basic Mission GW		4442	5221	5212	5265

For the filming of the movie "Tora, Tora, Tora" in 1970 several T-6 aircraft were converted to look like Japanese Mitsubishi Zero A6M fighter planes, some of which still appear in air shows.

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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