XCOR on track with workhorse rocket engine

http://www.avpress.com/n/21/1021_s7.hts ^ | Saturday, October 21, 2006 | ALLISON GATLIN

[BenLurkin]

XCOR Aerospace Friday announced a milestone in its development of a rocket engine to power the racing aircraft of the Rocket Racing League, a NASCAR-like series of aerial races planned to begin next year. The Mojave-based rocket-engine company completed testing the design of the 1,500 pound-thrust engine, powered by liquid oxygen and kerosene. The test-firings, using a test stand, were completed at XCOR's facility at the Mojave Airport.

"We have performed multiple runs of increasing duration," said XCOR CEO Jeff Greason. "The requirements are for a reliable and robust engine. We are on the right track with the workhorse engine for the Rocket Racing League."

With design verification complete, the testing process moves on to evaluating the engine's performance, XCOR spokesman James Busby said.

"Now we go until the engine is completely shaken out," he said.

Based on the testing completed so far, "we expect at this point to fire the engine up to 200 seconds," Busby said, which would allow the racer to climb to 50,000 feet altitude.

Derivatives of the Rocket Racing League engine will be used by XCOR to power its own future suborbital space vehicles.

XCOR is responsible not only for the engine design, but also its integration into the airframe and controls.

Test pilot and former space shuttle commander Rick Searfoss has been working with computer simulators to test the control panels and flying qualities expected in the racer, "to make sure the pilot is comfortable with the controls," Busby said.

XCOR's announcement at the Wirefly X Prize Cup in New Mexico followed the premiere there of the Mark 1 X-Racer design, dubbed "Thunderhawk."

Based on a Velocity Aircraft kit-plane airframe, the racers will be fielded by various teams to compete in a circuit of races, ending with finals at the X Prize Cup.

[r9etb]

Pretty cool, but I'm not entirely clear on the point of the Rocket Racing League. The rockets would have to become gliders at some point ... is the idea to go for distance or something?

[taxcontrol]

hmmmm, a 757 or like aircraft takes a rocket to say 30,000 and then put two of these engines on a frame and get it to say 100,000 feet, perhaps a booster rocket to kick a payload into low orbit????

[Dan Evans]

hmmmm, a 757 or like aircraft takes a rocket to say 30,000 and then put two of these engines on a frame and get it to say 100,000 feet, perhaps a booster rocket to kick a payload into low orbit????

That would have to be some booster rocket. It takes something like twenty times the energy to get an object up to orbital velocity as it does to get it to orbital altitude.

[diogenes ghost]

200 seconds ain't gonna make for much of a race. Gimmee a big ole Merlin or Allison any time. Thunder in the skies.

[JoeFromSidney]

I saw an interesting display on the Rocket Racing League at this year's World Science Fiction Convention. The idea is for the racers to follow a 3-dimensional course. Not only do they have to be fast, but they have to pass through certain "gates" defined in latitude, longitude and altitude, around a closed course. The intent is to bring back something like the Cleveland Air Races of the 1930s, where the planes had to fly a closed course defined by several pylons. I'm looking forward to seeing one of the races.

[GAB-1955]

It sounds like Diddy Kong Racing to me! Can I fire rockets at the planes ahead of me?

[taxcontrol]

I was under the impression that the greatest amount of fuel consumption was used in overcoming 3 major factors.

1) gravity
2) altitude
3) drag

200 km altitude requires about 7.8 km/sec velocity to sustain orbit. Granted, at 100,000 feet, to achieve an altitude of 200 km, you would still need to gain another 560,000 feet and like you said, the orbital velocity.... but, air drag would be significantly reduced at that altitude allowing a larger percent of the thrust to be used for either.

Anyway... I'm not a rocket scientist so likely my idea for a cheep means of getting something up to low orbit aren't actually feasible.

But we can all dream.

[Dan Evans]

Even ignoring air resistance, orbital insertion takes the vast majority of the energy. The energy to get to altitude in Mgh, where M is mass, g is gravitational acceleration (9.8 m/sec^2) and h is the altitude.

Consider an orbit at 125 miles. Altitude would be 200,000 m. So the energy to get to altitude would be Mgh = M x 9.8 x 200,000 or 1,960,000 joules per kg.

But the energy to insert into orbit would be 1/2 Mv^2. Using 7800 m/s for v. 1/2 x M x 7800 x 7800 = 30,420,000 joules per kg.

So 30,420,000 / 1,960,000 gives about 15.5 times as much energy to insert an object into a 125 mile orbit as it takes to get it to altitude.

I think that the future of orbital insertion will be things that pull from above. Orbital accelerators, orbital cannons that blast at parachute type devices or orbital skyhook gadgets a hundred miles long that grab a spacecraft at apogee and sling it into orbit.