O.S. FS72-a Ringed 4-Stroke .72 Airplane Engine

Tower Stock# LXWHW8  •  Manufacturer Stock# 34720
O.S. FS72-a Ringed 4-Stroke .72 Airplane Engine (large view)
Notes from our tech department:
This is the glow powered O.S. FS72-a 4-Stroke Aircraft Engine.


Ideal powerplant for 56 size aircraft-provides extra power for
hovering and 3-D type manuevers, also provides torque for turning
larger diameter props for more realistic scale filght
Broad power band suitable for Scale as well as Sport models
Same mounting bolt pattern as the FL-70 and FS-70 Ultimate
New 61N carburetor with extended intake tube eliminates reverse flow
tendency of air/fuel mixture, carb is reversible 180
Blow-by internal oil system eliminates the need for a crankcase
breather fitting
Adjustable exhaust outlet direction and exhaust port to muffler
Same muffler as the O.S. 81FS-a offers a pleasant exhaust sound with
a lower sound level
Two year limited warranty


O.S. FS72-a 4-Stroke Aircraft Engine with muffler, header, type F
glow plug and manual


Fuel: 10%-20% nitromethane with 18% lubricant. Synthetic, castor, or
a synthetic/castor lubricant blend may be used.
NOTE: Certain four-cycle fuels cannot be used due to low oil content.
However, SOME four-cycle fuels such as the Wildcat 4-Cycle 15%
(CATP9109) may be used due to its 18% oil content.
When choosing fuels for this engine, be sure to select a fuel with
at least an 18% lubricant content.
Propeller: Sport and aerobatic scale 12x7, 13x6-8, 14x6-7


Displacement: 0.72 cu in (11.79cc)
Bore: 1.063" (27.0mm)
Stroke: 0.822" (20.6mm)
Weight: Engine, 16.79oz (476g)
with Silencer & Manifold, 18.7oz (530g)
Power output: 1.2 PS, 1.18 HP/11,000 RPM
Practical RPM: 2,400-12,500
Crankshaft Thread Size: 1/4 x 28
Height from Bottom of Mounting Tab to Top of Crankcase: 3.5" (90mm)
Width of Crankcase below Mounting Tabs: 1.4" (36mm)
Center of Mounting Holes Same Side: .79" (20mm)
Center of Mounting Holes Opposite Side: 1.8" (45mm)
Center of Front Mounting Hole to Drive Washer: 1.9" (49.5mm)
Center of Rear Mounting Hole to Drive Washer: 2.7" (69.5mm)
Center of Crankcase to Center of Needle Assembly: 0.83" (21.3mm)
Center of Crankcase to Outer Edge of Needle Assembly: 1.3" (33.7mm)
Muffler Angle in Relation to Engine: 11

Needle Settings: High Speed: 2.5 - 3 turns out from fully closed
Mixture Control (low speed): 2 turns out from fully

jxs 01/20/09
updt lmm 4/6/09
updt jxs 01/13/11
updt jml 02.04.11

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