I just saw a film of a space shuttle piggyback on a 747 for about the billionth time and was struck with how really clever that idea was. Anybody here know how that came about?
Why didn’t I think of that? 
Now I’ll apologize for the shameless attention getter in the title.
Process of elimination? (How else you gonna move that thing without disassembling it?)
The original test flights of the shuttle were performed by piggybacking a shuttle to 20-odd-thousand feet and then cutting her loose. But you knew that, right?
I know there were planes piggy-backed on planes going back at least as far as WWII, but for different reasons. And one of them wasn’t supposed to land.
One of the ideas was to build a big enough runway to land the shuttle right back at Cape Canaveral, so it wouldn’t have to be transported back. I’m not sure why they went with Plan B. Maybe prevailing winds or other weather issues?
You piqued my curiosity. What’s the story with that picture?
The bottom plane was a flying bomb, laden with explosives. The program was called Mistral, and used several types of fighter/bomber lash-ups. The pilot was in the fighter on top, and had a release mechanism so he could return to base and the bottom plane would fly on and crash into its target. It wasn’t successful, and IIRC it was dropped when the Germans developed some genuine remote controlled glide bombs like the Henschel Hs 293. They were far more accurate as they could be guided right up to the moment of impact, and the Germans sank several ships with them.
They eventually did land them back at the Cape; saved them money and cut the turn-around time.
The first shuttle flights landed at Edwards Air Force Base, where there’s a huge dry lake bed. I remember the first flight landed on a painted-on runway, but there was room for error in every direction. If the glide ratio had been off by a little bit, they’d have been fine.
Even after the shuttle was approved to land at Cape Canaveral, they still had to be ready for contingencies that might mean moving the orbiter around. A couple fights got diverted to Edwards again because of weather in Florida. There were designated emergency landing sites if the shuttle had to abort during launch. And there were plans at one point to launch polar-orbit missions from Vandenburg Air Force Base. (Never happened, but it looks like Enterprise was taken there at least once to make sure everything fit right.)
But how did they cut her loose? They’d have to be going pretty fast for the shuttle (a “lifting body”*) to fly off. It has no real wings and relatively little lift. It falls at an angle and it lands at over 200mph with the nose way high.
*Betcha didn’t know that. 
The shuttle program was really cool, worth every penny.
The 747 does a pretty quick dive.
http://abcnews.go.com/Archives/video/aug-12-1977-shuttle-enterprise-test-9563114
Oh yeah! But the shuttle would be diving with it. It would have to climb, something it can’t do.
I think.
Is there an engineer in the house?
I’m an engineer!
(electrical, though, so not much help here)
Anyway, it seems to me that the 747 just needs to release the shuttle and then dive. The 747 has elevators so it is easily capable of diving more steeply than just following a parabolic arc. The shuttle, once released, would however continue to follow a parabolic arc even if it had all of the aerodynamics of a brick (which is how its pilots often described its performance).
Doesn’t seem difficult to me.
The unpowered shuttle, if the stick is pulled back, could climb a little or at least not sink very fast if the initial speed was high enough. Try a paper airplane with the back of the wings bent or curled up a bit - it will climb right after you throw it, until it loses airspeed.
The combo could have been making 400-500 kts (or more?) before separation. Stick back on the shuttle + stick forward on the 747 would do it.
I remember once the shuttle had to land at White Sands because Edwards was wet, and the runway at Kennedy wasn’t done.
Even if it’s not a huge amount relatively speaking, the shuttle’s wings do still produce lift, otherwise it would simply fall at the usual 9.8 m/s^2 rather than gliding. Even if the shuttle couldn’t climb at all, the 747 just has to be able to dive at an angle steeper than the shuttle’s glide angle for the angle of attack the two were flying at prior to release, which doesn’t seem to hard. (NB: I don’t have any performance data in front of me for either craft involved.)
All in all, engineer_comp_geek and tallcoldone have it right and the comparison to a paper airplane is a good one. The 747 just needs to release and pull away (downward) to throw the shuttle like a paper airplane (albeit a paper airplane that can acutally adjust its control surfaces in flight). The shuttle wouldn’t be able to sustain a climb without thrust but it could certainly climb a little when it’s released before setting its flaps in the positions it needs to glide in for a landing.
Lord Il Palazzo
BS Aerospace Engineering
In a case of fiction accurately predicting reality, G. Harry Stine, writing under the pseudonym Lee Correy, described a lift-off of the space shuttle Atlantis on a polar flight plan in the novel Shuttle Down. The engines prematurely cut off and the shuttle is forced to make an emergency landing on Easter Island. Problems faced by NASA include the crew not carrying any documentation, and the necessity of extending the runway at Easter Island’s sole airport to be able to allow a 747 to land and take off while carrying the equivalent weight of a space shuttle.
In real life, shortly after the book was published, NASA began issuing passports and traveler’s cheques to astronauts to carry with them in case of emergency landings and the U.S. paid the Chilean Government to improve the facilities at Mataveri International Airport on Rapa Nui in case of just such an emergency.
I found this list of landing sites for the shuttle, and I don’t see Easter Island on it. Maybe the list changed over the years.
I wouldn’t expect the landing of the 747 to be a problem (although I haven’t checked the numbers). The takeoff, with the orbiter attached, sounds like the limiting factor.
I wonder where the SCA (Shuttle Carrier Aircraft) would fly to from there, though. The NASA fact sheet for it says the range is typically 1,000 miles mated. (Lots of reasons for that; flies at a speed and altitude to minimize turbulence, etc.) Where’s the nearest place to Easter Island with a runway big enough to land, refuel, and take off again?
I recall in the novel that an in-flight refueling system was rigged to the 747. I don’t know how practical such a system would be in reality, though. Stone was an ex-NASA safety launch engineer, though, so he had the technical background to know what he was writing about.
Well, Air Force One is a modified Boeing 747, and it can be refueled in flight, so the parts of the technology are all there. It looks like the receptacle is is on the front of the plane, ahead of the flight deck, so it would still be accessible when the shuttle was attached. I don’t know if I’d want to try it unless I really had to, though. Seems like there’d be a lot of wake turbulence coming off the tanker aircraft and right into the shuttle.