WWII Gunnery Target Engine Technical Analysis
Part 7. Conclusion
by Tom Fey
Published 19 Jun 2017


Contents

Part 1. Background and General Configuration
Part 2. The Righter 2-GS-17 (O-15-1) in Detail
Part 3. The Righter O-15-3 Engine
Part 4. Performance and Efficiency Comparison between O-15-1 and O-15-3 Engines
Part 5. The O-45-1 and Kiekhaefer O-45-35
Part 6. Performance and Efficiency Comparison between O-45-1 and O-45-35 Engines
Part 7. Conclusion

Summary

While neither a manned nor armed aircraft, the WWII Radioplane gunnery drones served the training needs of the US Army and Navy to the tune of almost 15,000 sub-scale target aircraft during the war years. This summed production tally is greater than the Boeing B-17 Flying Fortress, Curtiss P-40 Warhawk, Grumman F6F Hellcat, or Lockheed P-38 Lightning. The technologys of their airframes, guidance, launch, and recovery systems, as well as their engines, are subjects worthy of study, admiration, and documentation for posterity. It is my hope this treatise does justice to the latter, and I thank all those that helped me with this task.

Acknowledgements

Special thanks to Ted Koch, Kevin Russen, and Laurie Videle who kindly photographed and measured their engines and parts, Kim McCutcheon who unearthed the type test reports, Sam Ferguson, Calum Douglas, and a dozen others that kindly responded to my numerous requests for photographs, documents, and measurements.

Full Tables

Table 7.1. Comparative Engine Data — Capacity, Volumes
(Dimensional Data Refers to Cylinders Unless "Engine" Appears)
Engine and Cylinder Engine Swept
Displacement
(in³ (cc))
Bore
(inches)
Stroke
(inches)
Dynamic
Stroke
(inches)
Company
Nominal
Comp Ratio
Static
Comp Ratio
Dynamic
Comp Ratio
Clearance
Volume
(in³ (cc))
Static
Volume
(in³ (cc))
Dynamic
Volume
(in³ (cc))
Engine
Dynamic
Volume
(in³ (cc))
0-15-1 Sand Cast #6212
Rectangular Port
16.9 (277)2.252.1251.426 to 15.5 to 14.0 to 11.89 (30.9)10.3 (169)7.5 (123)15.0 (246)
0-15-1 Sand Cast H-6212
Round Port
16.9 (277)2.252.1251.426 to 15.5 to 14.0 to 11.89 (30.9)10.3 (169)7.5 (123)15.0 (246)
 
0-15-3 Die Cast Square Port16.9 (277)2.252.1251.317 to 16.2 to 14.2 to 11.64 (26.8)10.1 (165)6.9 (112)13.7 (225)
0-15-3 Die Cast Round Port16.9 (277)2.252.1251.317 to 16.2 to 1 4.2 to 1 1.64 (26.8) 10.1 (165) 6.9 (112) 13.7 (225)
 
Kiekhaefer
0-45-1
45.6 (747 )3.252.751.887 to 17.3 to 15.3 to 13.6 (59)26.4 (433)19.2 (314)38.4 (629)
Righter
0-45-1
45.6 (747 )3.252.751.887 to 17.3 to 15.3 to 1 3.6 (59)26.4 (433)19.2 (314)38.4 (629)
 
0-45-3545.6 (747 )3.252.751.86?8.6 to 16.2 to 13.0 (49) 25.8 (423)18.5 (302)36.9 (605)

 

Table 7.2. Comparative Engine Data — Cooling Fin Area
(Dimensional Data Refers to Cylinders Unless "Engine" Appears)
Engine and Cylinder Engine Cooling Fin Area
(in²(ft²))
Cooling Fin Tip Gap
(inches)
Cooling Fin Base Gap
(inches)
Cooling Fin Tip Thickness
(inches)
Typical Barrel Fin Depth
(inches)
Outside Diameter
(inches)
Exhaust Stack External Area
(in²)
Weight
(grams)
0-15-1 Sand Cast #6212 Rectangular Port402.3 (2.79)0.1750.120.070.3754.015.051247
0-15-1 Sand Cast H-6212
Round Port
402.3 (2.79)???????
 
0-15-3 Die Cast Square Port368.4 (2.56)0.190.1660.0550.664.015.051056
0-15-3 Die Cast Round Port?0.185?0.055??15.051134
 
Kiekhaefer
0-45-1
614.4 (4.27)0.180.12Head=0.060
Body=0.065
0.645.02.82364
Righter
0-45-1
? 0.26 0.10 Head=0.098
Body=0.078
0.55 5.0 12.64?
 
0-45-35687.2 (4.77)0.1450.0880.0450.885.451.696 2370

 

Table 7.3. Comparative Engine Data — Induction and Transfer, Part 1
(Dimensional Data Refers to Cylinders Unless "Engine" Appears)
Engine and Cylinder Engine Crankshaft Length
(inches)*
Piston Ring Number and Thickness
(inches)
Rear Case Inlet Port Area
(in²)
Rear Case Inlet Port Arc
(degrees)
Intake Transfer Trunk Dimensions
(inches)
Cylinder Transfer Trunk Area
(in²)
Rotary Valve Cut Out Area
(in²)
Rotary Valve Cut Out
(degrees)
Rotary Valve Diameter
(inches)
Rotary Intake Open
(° ABC)
Rotary Intake Open
(° BTC)
Rotary Intake Close
(° ATC)
0-15-1 Sand Cast #6212
Rectangular Port
15.52 x 0.1512.48901.375 x 0.610.8361.686045512530
0-15-1 Sand Cast H-6212
Round Port
15.52 x 0.1512.48901.375 x 0.610.8361.686045512530
 
0-15-3 Die Cast Square Port10.672 x 0.0852.48901.375 x 0.610.8361.686045512530
0-15-3 Die Cast Round Port 10.67 2 x 0.085 2.48901.375 x 0.610.8361.686045512530
 
Kiekhaefer
0-45-1
14.02 x 0.0923.15687(1.92 to 1.97) x 0.8251.5842.44614.755812227
Righter
0-45-1
14.0 2 x 0.092 3.15687(1.92 to 1.97) x 0.8251.5842.44614.755812227
 
0-45-3513.5
(approximate)
3 x 0.0854.41100(2.09 to 2.12) x 0.8441.703.88553514530

 

Table 7.4. Comparative Engine Data — Induction and Transfer, Part 2
(Dimensional Data Refers to Cylinders Unless "Engine" Appears)
Engine and Cylinder Cylinder Transfer Port Area
(in²)
Exhaust Port Area
(in²)
Carb Deck Throat Diameter
(inches)
Intake Duration
(degrees)
Transfer and Exhaust Port Height Difference
(inches)*
Exhaust Port Open
(° ATC)
Transfer Port Open
(° ATC)
Transfer Port Close
(°ATC)
Exhaust Port Close
(°ATC)
Exhaust Port close
(°ABC)
Transfer Duration
(degrees)
Exhaust Duration
(degrees)
Exhaust Port Height
(inches)
Exhaust Port Arc Width
(inches)
Exhaust Port Area
(in²)
0-15-1 Sand Cast #6212
Rectangular Port
1.0440.9281.1751550.12107122247258781251510.580.4020.933
0-15-1 Sand Cast H-6212
Round Port
1.0440.9281.1751550.12107122247258781251510.438 dia. X 40.440 dia. X40.605
 
0-15-3 Die Cast Square Port1.0441.1141.1751550.12111116249258781331470.580.4841.122
0-15-3 Die Cast Round Port0.610.611.1751550.125???????0.438 dia. X 40.440 dia. X4 0.604
 
Kiekhaefer
0-45-1
1.2441.2441.781490.122102110251262821411600.7 x 2
+
0.57 x 2
0.706 x 2
+
0.573 x 2
1.244
Righter
0-45-1
1.5371.5371.781490.122102110251262821411600.694 dia. X 44 x 0.6991.537
 
0-45-351.271.272.261800.1993112248257771361640.7 x 2
+
0.58 x 2
0.706 x 2
+
0.583 x 2
1.298
* From Direct Cylinder Measurement

 

Table 7.5. Comparative Engine Data — Heat Rejection, Performance, SFC, Dimensions
(Dimensional Data Refers to Cylinders Unless "Engine" Appears)
Engine and Cylinder Engine Fin Area
(in²(ft²))
Fin Area per HP
(in²)
Fin Area per HP
(ft²)
Connecting Rod Length
(inches)
Rod Length to Stroke Ratio Rated HP @ RPM Engine Torque
(lb/ft)
Engine HP/Dynamic Volume Best Fuel Consumption
(gph)
Fuel Consumption
(gal/hp/hr)
Engine Specific Fuel Consumption
(lb/hp/hr)
Oil Ratio Engine Dry Weight
(lb)
Engine Specific Weight
(hp/lb)
Engine Length
(inches)
Engine Width with Plugs
(inches)
0-15-1 Sand Cast #6212
Rectangular Port
402.3 (2.79)61.80.434.252.006.25 @ 38008.60.401.600.261.308 to 125.50.2516.519.5
0-15-1 Sand Cast H-6212
Round Port
402.3 (2.79)61.80.434.252.006.6 @ 38009.10.431.600.241.408 to 125.50.2616.519.5
 
0-15-3 Die Cast Square Port368.4 (2.56)460.324.3752.068.0 @ 3800 11.10.581.400.181.086 to 119.30.4112.019.875
0-15-3 Die Cast Round Port368.4 (2.56) 460.324.3752.068.0 @ 3800 11.10.581.400.181.086 to 119.30.4112.019.875
 
Kiekhaefer
0-45-1
614.4 (4.27)30.70.205.01.8220 @ 3650
(22 @ 4000)
28.8 (28.9)0.52 (0.57)3.200.150.906 to 134.50.6416.37524.0
Righter
0-45-1
???5.01.8220 @ 3650
(22 @ 4000)
28.8 (28.9)0.52 (0.57)3.200.150.906 to 134.50.6416.37524.0
 
0-45-35687.2 (4.77)9.8 0.14 5.01.8235 @ 425043.3 0.9550.140.886 to 1 35.0 114.625 23.312

 

References

1946 National Air Races, Cleveland, Ohio. Periscope Films. https://www.youtube.com/watch?v=m5jgGxLoxTE
Botzum, Richard A. Fifty Years of Target Drone Aircraft . Northrop Ventura Division, 1985.
Dunkin, James E. Dennymites, Drones, and More. Dugout Publications, 2008.
Engine Manual Righter 2-GS-17 Series 41 and 42. WRA 7228 Fort Monroe 2-3-43-1000. 3-Feb-43.
Handbook of Instructions with Parts Catalog for Radio Controlled Airplane Target AAF Type OQ-14 Naval Model TDD-3. Technical Order 28-10C-4. 20-May-45.
Operation and Maintenance O-15-1 Engine. Technical Order 02-80AA. 10-Nov-42.
Operation and Maintenance O-45-35 Engine with Parts List. AN-28-10C-9. Undated, likley 1945/1946.
Operation and Maintenance Instructions OQ-2A Airplane Target and Catapult. Technical Order 11-55AA. 1-May-43
OQ-3 Handbook of Instructions with Parts. AN-28-10C-2. 25-Sep-44.
OQ-3 Operation, Service, Overhaul, and Parts. AN-28-10C-2. 30-Jun-45.
OQ-3 Operation, Service, Overhaul, and Parts. Technical Order 28-10C-4 REVISION. 6-Mar-46
Parts Catalog OQ-2A Radioplane. Technical Order 02-80AA-4. 20-Feb-43.
Parts Catalog OQ-2A Radioplane. Technical Order 11-55AA-4. 25-Feb-43.
Righter 2-GS-17 Engine Instructions. Righter Manufacturing Corporation, Burbank, CA. Undated.
Walter H. Righter and Radioplane Website. http://www.ctie.monash.edu.au/hargrave/denny.html