Hot Rod Job For SpaceShipOne

rwven writes "MSNBC is reporting that the engine on SpaceShipOne has been modified to provide more thrust, for a longer amount of time. Mainly, the Nitrous Oxide tank has increased in size to lengthen the amount of time before the dropoff of thrust when it goes from a liquid to a gas. Also reporting is Space.com."

Comments

Re:Wasting precious resources

[AndroidCat]

The nitrous oxide is the oxidizer, they use rubber for fuel.

SpaceShipOne uses a hybrid rocket engine that uses both liquid and solid propellant to propel it into space. The complete system consists of a liquid nitrous oxide (or laughing gas) oxidizer and a solid form of rubber fuel, which are burned together for about 76 seconds during an average flight, Benson said.

They really are burning rubber into space.

Re:OT: how does NOx work in cars?

[Sooner Boomer]

" Can somebody tell me what nitrous oxide does in a car engine? It's not a flammable gas, is it?"

In a word, oxygen - nitrous contains more oxygen than air and is in a highly dense liquid form. In a car engine, nitrous, along with additional fuel is squirted into the intake. In the hybrid rocket engine, a large cylinder of rubber is the fuel; the nitrous is the oxidizer.

Re:OT: how does NOx work in cars?

[CreateWindowEx]

Since combustion of one unit of gasoline requires more than ten units of air (containing oxygen), most car engines are limited by how much air they can get into the cylinders--it's fairly easy to just squirt more fuel, but to get more air in you have to either force it in with a turbocharger or a supercharger or reduce sources of friction on the way in (lower-restriction air intakes, etc) or fool with cam timing. Nitrous oxide is a cheap and easy way of adding more oxygen for a short period of time, plus it has the added benefit of helping to cool the cylinders, preventing "knocking" (premature ignition of the fuel by "hot spots" in the engine == $$$ if left unchecked).

Usually nitrous oxide systems are set up to inject extra fuel along with the nitrous oxide to keep the correct fuel/oxygen ratio.

As an aside, F&F fans should realize that NOS (Nawz) is the logo of Nitrous Oxide Systems, not a chemical abreviation for nitrious oxide, although they spend a lot of money trying to get their name associated with it.

Re:Wasting precious resources

[interiot]

More here.

• SpaceShipOne burns ... HTPB, a common ingredient in tire rubber.

• In conventional rockets, propellant can be pre-mixed -- as in the solid rocket boosters (SRBs) used NASA space shuttle -- or sit in tanks that are filled just prior to launch, like liquid oxygen and hydrogen rockets. In both engine configurations, the are highly volatile and can be toxic to handle.

  "The fact that the oxidizer and fuel are not molecularly mixed in these [hybrid] engines, makes them non-explosive," explained Greg Zilliac, a hybrid engine researcher at NASA's Ames Research Center in Moffett Field, California. "We've actually shipped fuel grains by UPS in the past."

Re:OT: how does NOx work in cars?

[OldJohnno]

The oxygen component actually provides only a small part of the power increase. NO2 has an extremely high latent heat of vapourisation - in other words it absorbs massive amounts of heat when it is injected and vapourises. This tremendous cooling effect allows a much denser cylinder charge and requires (a lot) more fuel be injected along with the NO2 to maintain the correct fuel/air ratio.

Re:Just say N2O

[deimtee]

And just because it's noble doesn't mean it doesn't get involved with other atoms sometimes,

Actually that pretty much IS what noble means.
Chemists have to work fairly hard and use some rather extreme conditions to get noble gases to react with anything.

Changes made to improve flight profile

[hpulley]

What has not yet been mentioned in this /. discussion is briefly, though not directly, mentioned in the aforementioned space.com article. The changes to the engine were made at least partly to offset the previous glitch encountered during the previous flight. "...the increased liquid nitrous oxide should delay that drop off and provide more thrust earlier in the flight, when SpaceShipOne's control surfaces can still bite into the Earth's atmosphere for steering." They hope this will allow them to reach their target altitude this time (almost missed the space altitude last time) without having to resort to secondary guidance systems.