Fleetwings BT-12 Sophomore

The Fleetwings BT-12 Sophomore was a monoplane Basic Trainer with seating for an instructor and trainee, under a greenhouse canopy, and had fixed landing gear.   It was constructed primarily of stainless steel and was fitted with a 450 HP Pratt & Whitney R-985 radial engine.  

Per reference [8] a prototype BT-12 took its first flight in 1939 but didn't enter service with the US armed forces until1942.  Eventually only 25 of this type aircraft were built out of a construction contract for 176.  

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

• radial engine
  
• inline cockpits for the instructor and trainee ounder a greenhouse canopy
• low mounted wing
• fixed landing gear
  

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

[Image Sources: US Government/Public Domain via Ref [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.



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

		BT-12	Secondary Sources	Notes
Primary Source		7
No of Crew		2
Engine:
Qty		1
Model		R-985-NA-1	5
Displacement	(cu in)	985	5
Power
Military	(HP)
War Emergency	(HP)
Normal	(HP)	450	5
Take Off	(HP)	450	5
Eng Dims
Length	(ft)	3.85	5
Width/Dia	(ft)	3.59	5
Height	(ft)
Base Engine Wt	(lb)	674	5
Propeller
# Blades		2
Dia	(ft)	8.75
Manufacturer		Two-Speed
Type		Hamitlon Std
Wing
Span	(ft)	40.33
Root Thickness	(%)	16
	(in)
Total Area	(sq ft)	240.42
Wing (less Ailerons & Flaps)	(sq ft)
Ailerons	(sq ft)
Flaps	(sq ft)
Tail Area	(sq ft)	63.0
V Tail Area	(sq ft)	21.33
Fin	(sq ft)	8.39
Rudder	(sq ft)	12.94
H Tail Area	(sq ft)	43.68
Stabilizer	(sq ft)	22.74
Elevator	(sq ft)	20.94
Total Control Surf Area	(sq ft)
Length
Overall	(ft)	29.16
Fuselage	(ft)
Body	(ft)
Body Depth	(ft)
Body Width	(ft)
Fuel Tank Volume	(gal)
Wing Tanks	(gal)
FuselageTanks	(gal)
Oil Tank Volume	(gal)
Water Injection Fluid Tank Volume	(gal)
Wetted Area (sqf)	(sq ft)
Pwr Ldng	(lb/HP)	10.42
Wing Ldng	(lb/sq ft)	19.51
Struct. Des. GW	(lb)
Ultimate Load Factor	(G's)	5.67
Design Speed	(mph)	250
Not to Exceed Speed	(mph)
Total Struct Weight		1923.61
Total Wing		737.75
Wing		665.88
Ailerons		28.54
Flaps		43.33
Fuselage Carry-Through
Tail		128.03
H Tail		85.54
Stabilizer		54.31
Elevator		31.23
V Tail		42.49
Fin		22.96
Rudder		19.53
Body + Eng Section + LG
Body + LG		813
Body		539
Fuselage
Engine Section
Landing Gear		274
Mn Landing Gr		236
Tail/Nose Aux LG		38
Tail Hook
Booms
Nacelles
Total Propulsion Weight		1047.01
Engine w/ Accessories		735.16
Engine(s) as Installed		659.43
Accessories		75.73
Turbocharger(s)
Controls		16.57
Propeller(s)		163.57
2-Blade		163.57
3-Blade
4-Blade
Starting System		46.51
Water Injection System
Tanks
Piping Etc
Cooling System
Lube System		52.09
Tanks		12.5
Piping Etc		38.59
Fuel System		33.11
Tanks		7.8
Piping Etc		25.31
Total Sys. & Eqpmt.		576.05
Instruments		62.75
Surface Controls		104.14
Hydraulics
Electrical Equip		196.62
Electronics (Purple means incl in Furn/Gray in Useful Ld)		72.74
Arm Prov/Equipment & Armor
Furnishings		123.09
Anti-Ice (If not in Furn)		3.96
Other /Misc		12.75
Hoisting Gear
Floatation Gear
Armor Plate
Empty Wt		3546.67
Basic Mission Useful Load		1210
Crew		400
Equipment
Oil		90
Fuel		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
Guns & Ammo
Guns
Ammo
Pyrotechnics
Camera
Other
Other Useful Load
Basic Mission GW		4691

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 3-22-26

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