Those steam catapults got bombed out of existence before they saw much use. That's why they switched to the much smaller rocket assisted take off ramps, and air launch.1:144 V-1 Launch Ramp Starter Kit
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Looks like Germany put some thought into the V-1 steam catapult system. Modular (i.e. similiar to army bridging equipment) so sections could arrive by truck and quickly assembled on site. Should be capable of launching German fighter aircraft.