which rocket engine uses unsymmetrical dimethylhydrazine and has a thrust in vacuum that is not greater than 872200.0?
(AND spaceflight.bipropellant_rocket_engine (AND (lt spaceflight.rocket_engine.thrust_vacuum 872200.0^^http://www.w3.org/2001/XMLSchema#float) (JOIN (R spaceflight.rocket_engine_fuel.rocket_engines) m.017q1y)))