How does the shuttle hang on to its carrier plane?

April 18, 2012 2:21 PM

How is the space shuttle actually attached to its carrier plane?

As you can see from these two photos, the mounts are rounded and fit into the bottom of the shuttle. But what actually keeps the shuttle attached? Is there some kind of lock or magnetization? Or am I missing something else?

posted by BradNelson to technology (13 answers total)

The tops of those balls are cut away and there are connecting bolts that run through them into the shuttle. I had to poke around for a while to get a decent view of them, since the attachment points are usually covered in pictures.

It looks like some additional covers are in place there over the normal umbilical attachment points, etc., likely to protect them during the flight.
posted by introp at 2:38 PM on April 18, 2012 [1 favorite]

Oops. This was the link I meant.
posted by introp at 2:39 PM on April 18, 2012

As a kid I watched this on TV. A test of the shuttle detaching from the 747 and then later landing on its own. I guess in the normal ferry operations of the 747 they probably didn't make it possible to pull a knob and eject the shuttle. (or as in Moonraker, bad guy stealing the shuttle while in transit)
posted by birdherder at 3:10 PM on April 18, 2012

The mounting points on the Shuttle when being carried this way are the same ones used to support the external fuel tank during launch.
posted by Chocolate Pickle at 3:26 PM on April 18, 2012 [4 favorites]

I am pretty sure CP has it.

And any 'bolts' would need to be 'explosive', as I am sure that no-one would, and neither would it be allowed to, fly that 747 without a way of jettisoning the shuttle if the need arose.
posted by GeeEmm at 3:34 PM on April 18, 2012

I would be very, very surprised if they used exploding bolts when ferrying the shuttle on that 747.
posted by Chocolate Pickle at 4:05 PM on April 18, 2012

Chocolate Pickle: That makes sense. But still begs the question: how does it really work? So the domed cover is removed from the mounting bracket just before attaching? And then the shuttle contains bolts that secure it to the mounting bracket?
posted by BradNelson at 4:31 PM on April 18, 2012

I'm sure they're using non-explosive bolts to hold it on. There's no reason to use anything fancy.

The mounting points on the Shuttle orbiter are very strong, since they have to support the weight of the fuel tank during launch at 3G acceleration.

The 747 was custom built for that job, and the structure that holds the shuttle up is heavily reinforced and well integrated into the 747's frame.
posted by Chocolate Pickle at 4:38 PM on April 18, 2012

Using a little engineering inference, the dome mates to a socket in the shuttle which is also spherical. Meeting in a spherical joint like this ensures that there are no weird moment (twisting) forces between any two mounting points (kinda like how most overpasses aren't hard-mounted to their support structures, but rather sit on little rockers or pins). The bolt that keeps the sphere and spherical socket together looks huge - it's the diameter of the "sheared off" top of the ball.

The shuttle is likely mounted so that the lift it generates (delta wing) at speed is exactly equal to its weight. That way the only forces in steady, level flight are horizontal, and the bolts don't even take any load.
posted by notsnot at 5:48 PM on April 18, 2012

IF you go to the intrepids website you might be able to find out how. Just a couple of days ago i was at the intrepids website and it explained the brackets that attached the shuttle to the 747. I cannot find the section now.
posted by majortom1981 at 5:54 PM on April 18, 2012

The shuttle is likely mounted so that the lift it generates (delta wing) at speed is exactly equal to its weight.

No, the wing isn't nearly that good. It's much too small, for one thing.
posted by Chocolate Pickle at 6:25 PM on April 18, 2012

Drag minimisation would be the priority I imagine - note the big fairing on the rear of the shuttle.

My comments about the 'bolts' were generic - whatever the fastening method, it needs to be able to be reversed in flight to jettison the shuttle if this is required. If that were the case, the shuttle would need to be in a nose high attitude, generating as much lift and drag as airspeed of the 747 allowed. It would then lift off its mounts, rise up and fall behind the 747, fall being the operative word, but allowing the 747 to fly safely free of the load.
posted by GeeEmm at 8:49 PM on April 18, 2012

I don't agree. I see no situation in which they would want to do that (jettison the orbiter).

Also, when they were originally using the shuttle Enterprise to do landing tests, the way they got it off the back of the 747 while in flight was for the 747 to go into a pretty steep dive. It wasn't possible to get the shuttle off the back of the 747 safely while in level flight.

The shuttle wings are very small relative to the mass of the fusilage. As gliders go, the shuttle ranks as "piss poor". It has a glide ratio of 1:1. Which is to say that it "glides" at a 45 degree angle. For every meter forward it moves, it drops a meter. (If it's going at a constant speed.)

When they made their final approach to land, they went into a really, really STEEP dive to build up speed just before reaching the runway. That's why they were able to glide reasonably level for their touchdown. They were losing speed like mad.
posted by Chocolate Pickle at 10:14 PM on April 18, 2012 [2 favorites]