Such dead ends might not be useless. Many Rotary rocket alumni went on to found XCOR where they're building a suborbital winged rocket plane. XCOR's also lined

Such dead ends might not be useless. Many Rotary rocket alumni went on to found XCOR where they're building a suborbital winged rocket plane. XCOR's also lined up to provide a piston pumped rocket engine for the ACES upper stage for ULA, which could mean very flexible in space operations (long coast times).