Designation Compound launch
Bore 1 inch
Stroke 7/8 inch
Configuration Vertical twin cylinder compound
Height 5 1/2 inches
Length 5 1/4 inches
Extra equipment Drain cocks
Displacement lubricator
Reversing gear
Taps required 2, 5, 7 BA
5/32, 3/16 x 40 tpi
1/4 x 32 tpi
5/16 x 26 tpi
Notes Designed for model boats 54 to 72 inches long. The compound launch has a theoretical advantage in efficiency over the single expansion version, but at the expense of having dead centres making it non self-starting.