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When speaking of space shuttle landings, they always mention that it is "very poor glider, with one shot, no go-arounds."

Of course this is true; however, if the Shuttle found itself in a situation where it was a little short on delta-v to reach land/a runway (perhaps during an RTLS abort), would the OMS make any meaningful difference in extending gliding distance?

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Not all that useful - the OMS engines had 6,000 lbf of thrust each. For comparison, the Allison J35 (used in the F-84) produced 5,600 lbf of thrust.

Comparing weights, the shuttle weighted 165,000 pounds empty (reference) while the F-84G weighed 11,470 pounds empty. Since we have two OMS engines on the shuttle, we're double that to 22,940 pounds. So we have to push approximately 8 times the weight.

There are a few other considerations - The OMS engine only had enough fuel for 1,000 ft/sec of delta-V, fuel would be needed for entering orbit, and later 200 ft/sec for reentry, along with whatever else was used for maneuvering during the mission. Therefore there probably wasn't a whole lot of fuel remaining. Also in my comparison don't forget that the shuttle is not known for being very aerodynamic, so you might be able to manage small changes, but nothing of significance.

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  • $\begingroup$ I'm not sure about the aerodynamics being a problem, the production Buran was meant to have 2 jet engines, and it certainly took off on 4 during atmospheric testing. $\endgroup$ – ymb1 Sep 16 '18 at 14:38
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    $\begingroup$ Actually it's even worse. The thrust and delta V are for vacuum operations, at 1ATM it would be significantly smaller $\endgroup$ – Antzi Sep 16 '18 at 16:43
  • $\begingroup$ A vacuum engine at sea level won't just suffer loss of thrust/Isp, it might be damaged by the shock waves inside the nozzle bell. But I hadn't realized there was so little dV available from OMS -- I'd thought it was more like twice that figure. And 1/14 G in vacuum -- hardly enough to spill the coffee. $\endgroup$ – Zeiss Ikon Oct 3 at 15:53

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