Space shuttle thrust

[signals]

The space shuttle uses two solid fuel boosters, giant fireworks that produce 2,800,000 pounds of force each. At liftoff, each produces 12,500,000 newtons and continue to burn for 124 seconds. The spacecraft's own engines produce a combined 12,000 pounds of force (54.4 kN), and accelerate and decelerate as the shuttle goes through different launch phases, to reduce shock.

http://gizmodo.com/#!5776438/this-is-w...ower-looks-like

So the shuttle itself only has 12k lbs of thrust? Seems like some of the engines in jets have a higher output...or am I missing something?

[frankv74]

The Booster rockets are what push the Shuttle up and out of the Atmosphyer. Once the booster's separate the shuttle is already in space. The Engine's on the shuttle don't need to be as powerfull in space since there is no gravity and no friction. With Earth's rotation and the thrusters the shuttle can do the speed it need... 17'000 mile per hour. It does not need to go any faster than that.

[MattC]

IIRC, does the Orbiter not rely solely on its own engines only when out of the atmosphere and out of Orbit?

In which case, the "low" thrust is not an issue.

Atmospheric flight needs a lot of thrust, if you double airspeed, you increase drag by a factor of 4, so in a conventional aircraft, flying at Mach 2 requires 4 times as much thrust as Mach 1 for a given airframe, height, air pressure etc.

But once out in a vacuum, drag isn't an issue, thus, neither is thrust.

[aim9xray]

The quoted thrust sounds like the rating for the primary engines in the OMS (Orbital Maneuvering System) pods - about 6000 pounds each for a total of about 12000 pounds. These are sometimes fired in addition to the SSMEs (Space Shuttle Main Engines) during ascent after the SRBs (Solid Rocket Boosters) have been jettisoned - when a heavy payload is carried or a difficult orbit inclination or altitude is attempted.

The OMS [large] engines were originally designed for orbital maneuvering - plane changes and/or orbit circularization. The many small OMS thrusters are intended for Orbiter attitude control and fine rendezvous maneuvering.

The SSMEs are not usable after ascent; the fuel for them is carried solely in the ET (External Tank) - no fuel for the SSMEs is carried in the Orbiter.

Edited March 4, 2011 by aim9xray

[Neptune48]

The space shuttle uses two solid fuel boosters, giant fireworks that produce 2,800,000 pounds of force each. At liftoff, each produces 12,500,000 newtons and continue to burn for 124 seconds. The spacecraft's own engines produce a combined 12,000 pounds of force (54.4 kN), and accelerate and decelerate as the shuttle goes through different launch phases, to reduce shock.

http://gizmodo.com/#!5776438/this-is-w...ower-looks-like

So the shuttle itself only has 12k lbs of thrust? Seems like some of the engines in jets have a higher output...or am I missing something?

My recollection from covering the first 14 missions was that the SRBs were 2.8M lbs thrust and the 3 main engines in the orbiter produced 400k lbs each. I think the other poster was correct that the 12k lbs was for the OMS (Orbital Maneuvering System) pods, which, along with the reaction control gets, are the only motors that can be used once the SRBs and the external tank are jettisoned.

The OMS motors are used to boost or stabilize the orbit, and for the de-orbit burn.

Regards,

Bruce

Edited March 4, 2011 by Neptune48

[SimFixer]

SSMEs produce a combined 1.125 milion pounds of thrust at sea level (3 x 375,000). Each SRB give you 3.3 million pounds at sea level (6.6 million total). Add 'em up and ya get nearly 8 million pounds.

http://en.wikipedia.org/wiki/Space_Shuttle_main_engine (see the Introduction paragraph)

Edited March 4, 2011 by SimFixer

[MiG31]

Each of the Space Shuttle Main Engines (SSMEs) produce up to 400,000 pounds of thrust at sea level, according to the wiki page. This approaches 500,000 pounds in a vacuum. So at liftoff, the orbiter's three SSMEs together produce up to 1,200,000 pounds of thrust. Nearer orbit, that goes up towards 1,500,000 pounds.

The OMS [large] engines were originally designed for orbital maneuvering - plane changes and/or orbit circularization. The many small OMS thrusters are intended for Orbiter attitude control and fine rendezvous maneuvering.

You're confusing the terminology. The large pods on either side of the orbiter's tail are the OMS pods. Each has one OMS engine rated at 6000 pounds thrust (not sure if that's at sea level or in a vacuum). The smaller thrusters are the Reaction Control System (RCS) thrusters, of which there are 24 on the ends of the OMS pods, and fourteen in the nose, along with six smaller vernier thrusters for fine control in orbit. Both the OMS and RCS engines utilize the same fuel and oxidizer.

EDIT: Beaten on the wiki link.

Edited March 4, 2011 by MiG31