Shuttle question

[slidelock]

Just wondering, could the shuttle make an emergency landing if a MECO occurred just as the Liquid fuel tank was discarded? I had a dream about that, seemed they couldn't make orbit and couldn't return safely. I dont remember how it ended. Regardless , at what points are the greatest risk for loss of thrust during launch? Thanks

 

[nacnud]

Greatest risk would be to loose the right SRB 1" off the pad, that could end up with the stack hitting the VAB. <br /><br />Oh and MECO occurs well before the ET is discarded.

 

[ve7rkt]

What Nacund said. The ET contains the fuel for the Main Engines (the ME in MECO). ET separation is going to cause MECO one way or another. The right way, MECO happens before ET separation, you leave a little bit of unused fuel in the ET but who cares. The wrong way, the ET separates, the main engines shut down from starvation, but more importantly, the ME's turbopumps run dry. Imagine driving your car down the highway with the pedal to the floor, then suddenly kicking into neutral. Except instead of overheating and pulling to the side of the interstate, the turbine flies apart and tears up the tail of your spaceship.<br /><br />That's why on the last shuttle launch they had to keep swapping the external tank. There are sensors in the tank to tell you when the tank is just about empty, so that if you haven't reached MECO yet, it forces a kind-of-safe early MECO instead of a very-not-safe pump explosion. Some of those sensors were faulty.

 

[vogon13]

As was mentioned, the main engines shut down prior to ET sep.<br /><br />During the latter parts of the main engines firing you have several options in the event of a single engine failure.<br /><br />The other two engines can burn a little longer to make up for the short fall (there is a little extra fuel in the tank for this. Very close to cut off, you could lose 2 engines and probably do the same.<br /><br />You could settle for a lower orbit (not so good if you wanted to go to the space station). This is the abort to orbit option.<br /><br />You can also abort once around. This means you don't circularize the orbit at its high point, and you re-enter about 90 minutes later and use the large cross range capability of the shuttle and you land back at KSC.<br /><br />Seems like there could be be some combinations of these techniques for some of the more exotic trajectories (once) planned for the shuttle. (like the polar orbit from the Vandeberg facility).<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>