Posted on 05/20/2004 2:18:52 PM PDT by tricky_k_1972
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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