A society lives on geostationary platforms at some vast height above the ground. The platforms themselves are not affected by gravity, wind, etc. Their technology has only just reached the point where they can construct biplanes about equivalent to a Sopwith Camel. Unfortunately, they do not have the knowledge or resources to expand their platform enough to build a suitable runway, so they resort to a different technique: steering the plane off of the edge of the platform.
Is this feasible? And if so, from how high would the plane have to fall to safely clear the ground and attain level flight? Would the pilot still be conscious by the time the plane reached this point in order to fly it?
On a side note, would such a plane be able to land again by stalling its engine and steering down like a glider? (again, because of the lack of a runway).