Posted on 05/20/2004 2:18:52 PM PDT by tricky_k_1972
The May 13th flight of the privately-financed SpaceShipOne has verified that the craft and its operators are close to attempting suborbital flight. Their goal: Two consecutive missions, two weeks apart, aimed at winning the Ansari X Prize purse.
SpaceShipOne has undergone a series of 14 confidence-building missions -- air toted, gliding, and powered flights -- much to the satisfaction of SpaceShipOne’s builder, Scaled Composites of Mojave, California.
Another test hop is on the books, before trying to win the $10 million Ansari X Prize competition, according to sources close to the project.
Back-to-back flights
The quest by Scaled Composites to demonstrate non-government piloted space flight operations is led by aerospace innovator, Burt Rutan, who heads the company. Financial backer of the space plane project is Paul Allen, Microsoft co-founder and chief executive officer of Vulcan Inc.
The Ansari X Prize money is to be awarded to the first company or organization to launch a vehicle capable of carrying three people to a height of 62.5 miles (100 kilometers or some 330,000 feet), then return safely to Earth, and repeat the flight with the same vehicle within two weeks.
Teams from various nations have signed up for the Ansari X Prize competition, many of which are actively testing hardware in the hopes of beating Rutan in the suborbital race.
The purse is being offered by the X Prize Foundation of St. Louis, Missouri. The cash reward offer expires as of January 1, 2005.
Most demanding flight
Flight data from the May 13 test of the rocket plane – the most demanding on craft and pilot -- has been officially released by Scaled Composites.
After deployment from the White Knight carrier plane at 46,000 feet, SpaceShipOne fell for 10 seconds prior to motor light off.
SpaceShipOne’s hybrid rocket motor then blazed away for 55 seconds -- the longest burn-time yet for the propulsion system. An engine run time of over one-minute is expected to reach X Prize altitude.
The rocket plane’s first powered flight took place on December 17, 2003, with the motor firing for 15 seconds. A second powered trek occurred on April 8th of this year, with the engine burning for 40 seconds.
On the May 13 flight, the vehicle boosted itself smoothly to 150,000 feet and reached Mach 2.5 – or two-and-a-half times the speed of sound. After motor shutoff, momentum carried the craft to 211,400 feet altitude.
Smooth sailing
During a portion of SpaceShipOne’s boost, the flight director display did not function properly. Pilot Mike Melvill, however, continued the planned trajectory referencing the external horizon through cockpit windows.
Melvill used the ship’s reaction control system to reorient SpaceShipOne to entry attitude. The vehicle’s tail section was flipped up – called feather position -- converting SpaceShipOne to a high-drag configuration, permitting stable atmospheric entry.
The ship was “de-feathered” starting at 55,000 feet. As SpaceShipOne glided toward its runway touchdown, onboard avionics was rebooted. The craft made a smooth and uneventful landing at the Mojave Airport, according to Scaled Composites log data.
Suborbital history
The most recent test of SpaceShipOne is part of Scaled Composites’ “Tier One” program.
In unveiling the SpaceShipOne on April 18, 2003 at Mojave, California ceremonies, Rutan noted the history behind taming the suborbital heights.
Suborbital manned space flights have been done before using the Redstone rocket/Mercury space capsule combination in 1961 and by the B-52 carried X-15 rocket plane in 1963.
“Even though the experience, as described by Alan Shepard, Gus Grissom and Joe Walker was awe-inspiring, suborbital space flights were ignored for the next 40 years. The view from the apex of a suborbital flight is similar to being in orbit, but the cost and risk is far less,” Rutan explained.
“Our goal is to demonstrate that non-government manned space flight operations are not only feasible, but can be done at very low costs. Safety, of course is paramount, but minimum cost is critical,” Rutan said. “We look to the future, hopefully within ten years, when ordinary people, for the cost of a luxury cruise, can experience a rocket flight into the black sky above the Earth's atmosphere, enjoy a few minutes of weightless excitement, then feel the thunderous deceleration of the aerodynamic drag on entry.”
I'm not familiar with that technology. It must work, though ;-)
Was the oxidizer H2O2 or NO? Both have been mentioned.
bttt for later read.
no it is something real simple I recall like alcohol or hydogen peroxide. There is a way they are doing it that is really safe. Sorry cant remember but I will look for the article.
"During a portion of SpaceShipOne’s boost, the flight director display did not function properly. Pilot Mike Melvill, however, continued the planned trajectory referencing the external horizon through cockpit windows."
Nice bit of pilotage. VFR at 200,000 feet...talk about pucker factor!
The engine uses nitrous oxide (N2O2, or laughing gas) as an oxidizer and burns hydroxy-terminated polybutadiene, a synthetic rubber, as fuel. Both can be stored safely without special precautions and will not react even when mixed. It takes a significant heat source applied to the fuel and then adding the oxidizer to ignite them. Combustion products include water, carbon monoxide and dioxide, hydrogen, and nitrogen, which are relatively benign compared to by-products from other rocket fuels.The craft carries nitrous in a filament-wound tank that has much of its surface area bonded to the fuselage. This makes it a structural part of the spacecraft. The large bond area also reduces loading per square inch and isolates the airframe from engine vibrations. Nitrous is loaded onto SS1 prior to launch at 700 psi. This is enough to pressurize the oxidizer tank, so turbo pumps and complicated plumbing are not needed. The flight and rocket controls in SS1 are simple. The rocket, for example, has just two switches: one to arm it, and one to fire it. There are no throttle or fuel controls, though it can be shut down and restarted in flight. A screen displays critical motor parameters while a navigation unit guides the pilot along a preprogrammed flight path. The pilot uses a stick to control flight surfaces. Surfaces are manually controlled at subsonic speeds, electric trim actuators kick in at supersonic speeds, and for altitude control in outer space, the craft uses cold-gas, carbon-dioxide thrusters. Its three-person crew will experience about 10 sec of 5-g acceleration.
Reentry begins after the fuel is exhausted. SS1's twin-boom tail flips up 90°, providing a shuttlecock or "feathering" effect. It puts the craft in a stable, nose-up attitude that slows reentry and reduces aerodynamic heating. It should limit heating to about 1,000°F and let the designers get away with thermally protecting only 20% of the hull. The flip-up tail also reduces workload on the pilot, letting the SS1 glide down in a "hands-off" reentry, according to Rutan. The tails then flip down for a glide-in landing. SS1 should land about 90 min and 35 miles away from White Knight's take off.
No word on the attitude control thrusters...
It seems that the "feathering" tails were deployed during powered flight in that photo. Was that a fu**up?
Sometimes, seems like.
It might be that visible exhaust continues for a while even while the motor is essentially shut down. At that altitude, though, the control surfaces wouldn't be effective anyway.
...and the article above says those surfaces only deploy during re-entry.
Either the picture is a composite, or somebody screwed up.
No word on the attitude control thrusters...
I'll bet ten bucks that "altitude control" here is a typo for "attitude control", because "altitude" doesn't make a hell of a lot of sense in that context. Plus carbon-dioxide thrusters would be quite sensible for *attitude* control but not *altitude* control.
The problem, if there is one, would be that the structure might not be as robust in the feathered position, but since it is designed to withstand some decent reentry forces, it should be okay. The auto guidance failed and the pilot took over, so it might be that the pilot deployed the tail early and that normally the ship would wait until later. Until we see the flight plan, we won't know if this was intnetional or not. I wonder how quickly the motor stops thrusting when it is shut down.
Looks fine to me -- might you be misinterpreting the photos?
In the "engine on" picture, the tails are clearly swept straight back. In the "feathered" photos, the tails are swung up (down?) to almost a 90-degree angle from the craft's centerline.
Right, it is attitude control thrusters. The ship could probably reenter okay even if those fail, so long as the tail is feathered. If the tail does not feather, would the ship still fly, or would the passengers get a super rough ride?
I think you're right about the thrusters.
In an earlier photo, not in this set, the tail is feathered while there is visible exhaust. We are wondering if the tail was feathered during powered flight, or if power was essentially off or soon to be off while there was still motor exhaust.
I'm talking about #5. Am I not seeing what I think I am seeing?
The tail is not feathered in #5.
OK, I guess the shadow on the right fin threw me. I see that they are NOT deployed now.
Non-feathered:
Feathered (note that its two tail booms are raised like arms in a "stick-em-up" pose):
Transitioning from feathered-to-nonfeathered (note that the camera is on the tail itself, so while it looks as if the tail assembly is staying still and fuselage is rotating, it's actually the other way around):
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