When the shuttle lands at Edwards, it has to be ferried back to Florida on the back of a specially fitted 747. That’s a pretty heavy load, I imagine. But maybe not, compared to the weight of 200 (300?) some passengers and their luggage. I can’t find anything that would allow me to compare the weight of the shuttle with the weight that a loaded 747 carries. What would be a good estimate? xo, C.
I found a site that lists the weight of Enterprise as 144,000 lbs when it was on the back of a 747 for tests back in 1977.
http://www.edwards.af.mil/archive/2002/2002-archive-shuttle_milestone.html
Various sites list the 747 maximum payload as somewhere between 200,000 and 250,000 lbs depending on which model 747 they are talking about.
Different models of 747 can carry somewhere in the neighborhood of 400 passengers (I found one site that listed 374 passengers for a 747-200 and 420 passengers for a 737-400). If you figure about 400 passengers, each weighing about 200 lbs total (person plus luggage), you only end up with about 80,000 lbs.
Oops. That 737-400 should say 747-400.
I’m no engineer, but I would imagine that the Space Shuttle would create a significant amount of lift, so it wouldn’t be like loading up the interior of a 747 with 144,000 pounds of luggage.
Of course, the Shuttle also represents a considerable amount of drag as compared to passengers and baggage carried within the fuselage.
It’s also worth noting that some 747 models are designed for carrying cargo (they’re cool, they have a door in the nose that opens up kinda like the one on a C-5). I’d imagine a 747 loaded up with freight tends to be a good bit heavier than one loaded up with passengers (and of course, there are certain liberties you can take with payload, carrying more in exchange for less fuel, etc.).
The 747 that carries the shuttle almost certainly has structural reinforcements and maybe even uprated engines for the extra payload. Civilian cargo haulers and airliner airframes converted for military use recieve various structural reinforcements to support the weight of military vehicles and cargo (which includes trucks, armored vehicles, etc.) You’d be amazed how rugged you can make those airliner airframes. The Air Force has a cargo/refueler version of the DC-10 that, when unencumbered by extra fuel or cargo, can fly straight up (90 degrees from the ground) into the air after takeoff.
It’s also worth noting that the piggyback 747 also has an unusual tail assembly, probably designed to compensate for the disruption of airflow past the rudder and stabilizers that the shuttle would cause.
SDMB - ya gotta love this place
And for the actual answer
Heh, that reminds me of a random, kinda off-topic thing I just remembered. Teacher I had who flew B-52s in the Air Force said that it was fairly common to load a plane up with fuel past the maximum takeoff weight, because by the time a B-52, with it’s 8 turbofan engines, rolled on it’s way from the ramp to the end of the runway, it would burn more than enough fuel to get under the takeoff weight limit again. Then, once they took off, they’d immediately refuel to top off the tanks (seems the wings can support a lot more weight than the wheels)
(back to the topic at hand) looking at the numbers posted for NASA’s 747, it looks like they did indeed uprate the engines and airframe.
Once the aircraft is airborne, the wings only need support the fuselage rather than vice versa. And while I’m not familiar with the -52, on most large planes the main tankage is inside the wing structure, so the weight of the fuel is supported (more or less) directly by lift rather than structure.
Stranger
I have to ask for a cite on this. Few fighter planes can be configured for a greater than 1:1 thrus to weight ratio. I do not believe any cargo plane is capble of that even with a light load.
Gross takeoff weight is almost never a matter of structural limits and certainly not limits of BUF’s landing gear. It’s a matter of aerodynamics and power. A too heavy plane may be within strutrual limits but less able to safely maneuver at normal takoff speeds. In some cases a plane may be capable of flying with more weight than it is able to take off with.
It’s worth noting that many large planes can’t land with as much weight as they take off with as the weight of fuel in the tanks can cause structural damage as it sloshes.
Ummm…no. No way, no how can a KC-10 get to 90 degrees nose up.
Back on topic - I once flew a “pathfinder” mission for the NASA 747 with the shuttle on top. They were flying the shuttle west, from the KSC out to Edwards for some work.
They needed a pathfinder - us in our trusty C-141 - to fly ahead of the 747 (with a NASA guy in the jumpseat) to make sure there wasn’t any unexpected turbulence along the route. The 747 with the shuttle attached can only climb into the mid-teens (ie 13-16,000 feet), and it takes almost full power to maintain that altitude. Needless to say a 747 at 15,000 ft and full power burns a LOT more gas than usual, so their range is severely limited. They would typically fly 400-mile legs and then stop, refuel, check the weather, etc. I was only the pathfinder for two legs, but it was definitely one of my more memorable missions!
Very interesting. All theses years I envisioned it done as a straight run. This also explains why NASA hates to land the shuttle anywhere but Florida.
Yeah, I never would have thought it was such a logistical nightmare until I was involved in it.
Talking to the pilots of the 747 I found out that NASA would do almost anything to avoid having to piggy-back a shuttle on the 747. Between the short legs, refueling, changing plans, weather avoidance and crew rest it can take almost a week to move a shuttle across the country.
Of course being NASA, they take full advantage of every possible angle: we were welcomed in Salt Lake City by a full contingent of the local press corps. Tours were given to key city officials, and the 747/Shuttle led the news stories that night.
But even if NASA did nothing, I think they’d still have a ton of people show up at the airport. It’s just such a cool thing to see flying!
http://www.msfc.nasa.gov/news/news/releases/1998/98-189.html
I wasn’t in Nashville at the time, but people at work tell me they saw the shuttle on the 747 fly right between their building and downtown.
It is fairly standard to have a maximum ramp weight that is higher than the take-off weight. The take-off weight is generally limited by performance, specifically the aircraft’s performance in the case of an engine failure on take-off.
Hrm… now that I think about it, my dad told me about it after he had been to an air show. Just now occurs to me that he mighta been pulling my leg. :smack:
I DO know for a fact that a C-130 can do acrobatic maneuvers. If you strap about 20 rocket pods to it. 
The Blue Angels have a Hercules fitted with RATO (Rocket Assisted Take-Off) that can go nearly straight up after take-off. That’s probably what he was thinking of.
Well, it must be possible for some fighter planes to do that, because every year at the Chicago Air and Water show, planes do that for the folks - or at least they sure seem to. xo, C.