NASA Studies Problem With Shuttle Wings

[Chief]

http://www.newsvine.com/_news/2007/10/10/1016899-nasa-studies-problem-with-shuttle-wings

CAPE CANAVERAL — NASA is studying a possible problem with the thermal shielding on Discovery's wings that could force a delay in this month's launch.

Discovery's seven astronauts climbed aboard the shuttle at the launch pad Wednesday for a practice countdown. At the same time, shuttle managers discussed whether three of the 44 reinforced carbon panels that line the edges of Discovery's wings should be replaced.

The shuttle would have to be returned to the hangar for that kind of work, which would mean a launch delay. Discovery is scheduled to lift off Oct. 23 with a new live-in compartment for the international space station.

NASA spokesman Allard Beutel said the outer coating on three of the wing panels shows degradation, an issue that the NASA Engineering and Safety Center has been reviewing for the past several months.

The safety center recommended Wednesday that the three panels be replaced before Discovery flies. But the shuttle program is leaning toward leaving them alone, for now, and proceeding with the launch based on data from other engineers, Beutel said.

Beutel said engineers do not know what is causing this coating to weaken.

**SCHNIPP**

I don't see how they can possibly take a chance on this, especially in light of the Columbia disaster.

Back to the hangar, and soon I'll guess...

[Waterbuffalo]

Any decent little thing like the wings of the Shuttle will affect mostly the landing of the Shuttle.

Not sure if the wings have much effect on the shuttle if most of the shuttle is taken off the launchpad by booster rockets and fuel that has more energy output to direct thrust from all of the nozzles. than the planes of the wings.

[Chief]

The wings are subject to aerodynamic forces during launch, that usually peak in the time right before separation of the SRBs, when they throttle down the SME's while the shuttle assembly transitions through the sound barrier. Different parts of the stack go supersonic at different times, and generate many shockwaves, and as the shockwaves propogate aft along the vehicle, the ride can be pretty violent as the shock waves from the nosecones of the boosters hit the shock wave coming off the nose of the shuttle, and the shockwave coming off the tip of the external tank; all of those shock waves play over the wings of the shuttle as it passes through the sound barrier. Once it's supersonic and accellerating, the shockwaves traill off behind the vehicle and the forces smooth out. That's why you hear the call "Go at throttle-up" on launch, because they are throttling the main engines back up to 105%.

It's on reentry that the carbon leading edge panels are exposed to the high heat from atmospheic friction, along with hypersonic forces that the shuttle encounters the deeper it goes into the atmosphere. Orbital velocity is 17,500 MPH, and at entry interface, the point where the shuttle first touches the atmosphere, it's still going almost 17,000 MPH or MACH 12+, and those kinds of forces can cause a relatively minor flaw in that carbon fiber to fail catastrophically and down another shuttle.

Nothing to mess around with and that's why they will probably roll it back to the barn soon. Expensive to fix too...

[Waterbuffalo]

Replacing the skin or tiles, plus a couple day process to roll it back to the barn would generally be some thing I'd not want to be in charge of.

Your correct, I forgot after the booster and fuel tank are done, the shuttle has to have some sort of aerodynamical control. That's where the wings come in after this separation. Plus the flaw you described is most important to be corrected, because if its not done, there will be the problems you explained in the re-entry of the shuttle and we'll have another Columbia and Discovery down shuttle.

Don't think NASA can take another one of those Foobars..

[Chief]

On ascent, as the air thins out, the aerodynamic controls become less and less effective, and at high speeds, a control surface deflection causes more drag than control. That's why all three of the SMEs are gimbaled, along with the nozzles of the SRBs. The flight computers can better steer the shuttle on powered ascent by gimbaling the engines and changing the axis of thrust in relation to the centerline of the shuttle stack. Right before launch, they run the engines through their entire range of gimbal movement, then lock them into the initial ascent position; if you watch some launch video you can see the fairly large range of motion the engines have.

It's fascinating technology even though it's going on forty years old now. I spent many hours at the NASA shuttle website reading some of the technical data that they have available on the internet. What's really interesting to me is watching the live countdown and launch preparations on NASA TV. If you know enough about what is going on, you can better appreciate the limited dialog from Shuttle Launch Control in Florida up to and including the launch itself. It is so complex, it simply would not be possible to launch or even fly the shuttle without extensive computer support.

[Waterbuffalo]

About three years ago, I watched the Discovery come down and land at Edwards in the middle of the night. That was one of the most fascinating things for me.

NASA is one of the few Federal Government agencies I love to watch, though its probably a money pit just like the rest of them. (aka Voter pleaser..)

Better go see where I can more information on the new rover missions to mars..

[Chief]

Check the JPL website for that, since the Mars Rover missions are run through them.

[Waterbuffalo]

Should be going over there.. Forgot JPL runs the mysterious space mission to other mental capacities..

Will go over there when I can..

Any updates on the shuttle mission that was scrubbed?