From Great Expectations: North American's Exotic Advanced X-15 Concepts Part 1 by Dave Stern
American Aviation Historical Society Journal, Spring 2011.
Sub-orbital and fully Orbital X-15 programme.
Step I Standard generic X-15 31,250 pounds plus 1,500 pound payload.
Engine: XLR-99-RMI-1 fuel Flourine – Hydrogen
Pinnacle mounting atop single G-26 booster.
Downrange capability 1,115 nautical miles.
Step II Modified X-15A 34,850 pounds gross weight - advanced structural metals.
Pinnacle mounting atop middle booster of tri-parallel G-38 booster.
Two variants – Research package or photo reconnaissance.
Downrange capability 1,741 nautical miles.
Step III super advanced X-15B one man (two man also offered) low Earth orbital military missions.
Single seat 40,200 pounds gross weight. Modified Rocketdyne S-4 liquid fluorine-hydrogen.
Pinnacle mounting atop middle booster of tri-parallel G-38 booster.
Take off from Cape Canaveral pre-programmed to land (crash – pilot to parachute down) at Eglin Proving Ground Reservation.
In the article is a cutaway side view of presumably the Step III but this has Fluorine and Hydrazine in its tanks?! Also has in the middle 2 down and slightly outward pointing solid rocket motors presumably for de-orbit?
Regards,
Barry