The Rocketdyne AR-2 is fitted above and aft of the J79 engine in the Lockheed NF-104A. To attain a 25 mile altitude the 6000 lb thrust engine burns a mixture of JP-4 jet fuel and hydrogen peroxide.
The AR-2 is throttleable from 50 to 100% power. The NF-104A provides spaceflight experience at a fraction of X-15 operating costs.
All Aero 