The Bristol X.2 project of 1912 featured a hydroped undercarriage designed by Sir Dennistoun Burney. This consisted of three legs carrying a series of hydrofoils and a water propeller.

At rest, the X.2 floated on its boat-shaped hull. For take-off its engine first drove the water propellor. As it gathered speed, the hydroped undercarriage was supposed to raise te hull clear of the water, until the pilot could switch to the flying propeller and take-off.

When towed behind a destroyer, the X.2 became airborne like a kite, before crashing.