even nasa uses boat-tails - Fuel Economy, Hypermiling, EcoModding News and Forum

Tourigjm · 12-11-2008, 10:32 AM

noticed this on the shuttle's rear end on the news yesterday.
shows that the tail doesn't have to be super long with respect to the body, however it should contour to a specified angle.

nasa basjoosed the shuttle

MazdaMatt · 12-11-2008, 10:40 AM

I'd bet that saved more fuel in one flight than i use in a year.

DifferentPointofView · 12-11-2008, 11:20 AM

that picture used more bandwidth than my grandpa uses in one year

well atleast they're catching on. doesn't really matter too much once you get into space, but then again like 90 percent of the fuel used is probably on lift off (or more)

MazdaMatt · 12-11-2008, 11:57 AM

Do they just let it blow off when it is time to go?

jamesqf · 12-11-2008, 12:33 PM

"Time to go"? You mean on launch? The tail cone is only for ferrying (and it's been used since the first drop tests back in the '70s). When it's launched, the aerodynamics are going to be vastly different, 'cause there's one heck of a lot of high temperature/pressure gas expanding out of that rear end.

MazdaMatt · 12-11-2008, 12:50 PM

Oh, i'm a doofus... clearly they don't launch into space from the top of a plane.

wyatt · 12-11-2008, 12:58 PM

Ok, not exactly sure where to start, I know lots of stuff about the Shuttle Transportation System (STS)...
1) That tail has been around since before the STS started flying (they had a prototype Orbiter model (the Enterprise) that they used for aero testing that they piggy-backed on a 747, perhaps this very plane), so most likely NASA didn't take the idea from a fellow EcoModder...

Here is a picture from (I think the 70's or early 80's) that is about the same as above. It shows some of the testing they had to do. In this test they would take the Orbiter up and release it so it could be landed. At the time I don't think they had a means of escaping if anything went wrong, so I guess you just hoped things worked.
2) The STS uses two types of fuel. The Orbiter uses a Liquid Oxygen / Liquid Hydrogen (LOX/LH2) mix, that burns at a more or less constant rate for about 1000 seconds. It also has Reusable Solid Rocket Boosters (RSRBs) that burn at a more or less constant rate for about 125 seconds. The STS uses a lot of fuel at lift off, but it uses that much fuel for a long time... If you really want, I can see about finding a graph that will show the fuel use over time...
3) The Pictures above don't show how the Shuttle takes off. It is just getting a ride back to Florida since it had to land in California due to weather issues. The Orbiter takes off on the back of the External Tank (ET) with two large RSRBs. The RSRB's drop off about 125 seconds into the total burn, and the Orbiter powers it's self and the ET into orbit, where it drops the ET, and the Orbiter continues on it's way to the International Space Station (ISS).

Here is a picture of the STS taking off. You can see the Orbiter piggy-backing on the red/orange ET with the white RSRBs on the side.

aerohead · 12-11-2008, 01:53 PM

It's better to see the tail from above.It basically respects the angles Mair came up with.When released over Edward's AFB,the boat-tail doubled the glide range.At the same time NASA was playing with the STS they were also out on Roger's Dry Lake riveting boat-tails onto Ford vans.