Boeing4ever From , joined Dec 1969, posts, RR: Posted (12 years 2 weeks 5 days 14 hours ago) and read 2974 times:
Ok, I've been tinkering with an idea in my head for a while now. My apologies to all those a.net "vets" who consider even the slightest new idea or suggestion of such wretchedly low quality that I should be stoned to death, but here it is.
As we already know, the Space Shuttle is launched like a rocket. But it can glide like an airplane. I've also noticed that the first shuttle, the aerodynamic prototype Enterprise was tested by ferrying it up on the NASA 747 shuttle carrier and then releasing it. I also remember that recently a satellite was put into orbit after being launched from an airplane. Let's not forget the X-15 tests from the NASA B-52. So I figured, why not ditch the SRBs and that gigantic fuel tank and just launch the shuttles from the NASA 747SCs? (is that an acceptable designation for the 747 shuttle carrier?) I do know that the Shuttles have covers on their engines while riding piggy back on the 747s but that photo I saw of the Enterprise being released showed it didn't have that cover on. So the way I see it, fuel the shuttle, mate it to the 747SC, get the Astronauts on board, take off, get up to a high altitude (thus saving some fuel and costs necessary to get the Shuttle up from ground level) enter a slight dive, release the shuttle so it will glide on its own, fly the 747SC out of the way, and light up the engines of the shuttle. Then use the elevons to aim upward and get into orbit. Afterwards, the shuttle can roll over, and turn tail first like it always does.
The way I see it, if I'm not mistaken, is that this would save money and provide some advantages. The shuttle would have a bit more fuel left since its main engines are ignited and run for less time, and a bit less work as the shuttle is already traveling at a certain speed. Thus you could use the momentum of the shuttle. Second, the launch window wouldn't be so narrow, I assume at least, since the shuttle would be launched above the clouds and any potential storms, and the shuttle's launching area would be anywhere. (much like with the Sea Launch system) Third, with more fuel, the shuttle would have enough to work its way up to a higher orbit to mate with the ISS if an emergency should occur. For example, if a camera was mounted to the hump of the 747SC, it could be used for one final inspection of the shuttle's underside to make sure all the tiles are still there. (and no foam insulation falling from the 747SC either) If something is found wrong, the shuttle could dock with the ISS and a solution could be worked out. Perhaps repairs to the underside of the shuttle (I understand a space walk is near impossible on the smooth underside as there is nothing to grab onto, but I remember reading that the ISS recently got a robotic arm installed, so maybe an astronaut and his needed repair gear could hop a ride on it and be positioned by the shuttle's underside).
Maybe I'm nuts, or maybe I got the right idea. I don't know. What do you think?
FltMech9 From United States of America, joined May 2001, 57 posts, RR: 0
Reply 1, posted (12 years 2 weeks 5 days 14 hours ago) and read 2949 times:
Good idea, but the fuel for the shuttle's main engines comes from the external tank. Even with a 40,000 foot head start, those engines are very thirsty. Air launching a space vehicle could have some real advantages. Launches could be conducted over the equator to shorten the distance to space, saving even more fuel. Who knows where the future of space travel will take us.
Flyf15 From , joined Dec 1969, posts, RR:
Reply 2, posted (12 years 2 weeks 5 days 14 hours ago) and read 2944 times:
You still have to get the object to 17,500mph (I think about that?) and many many of miles above the Earth. Launching from an airplane over the equator gives you a ~1500mph (airplane speed plus rotation speed of the earth) as well as a 7 mile up head start. Significant, but nowhere near the entire energy required.
Cloudy From , joined Dec 1969, posts, RR:
Reply 8, posted (12 years 2 weeks 5 days 13 hours ago) and read 2908 times:
There have been some serious proposals to launch space vehicles from aircraft.
The three that come to mind are....
1. Lockheed's (Or was it Boeing's?) Space Launch Initiative candidate. This would use a very large flying wing to bring an orbital vehicle to launch altitude and speed. The flying wing would be purpose-designed and be MUCH larger than current commercial jets. And the orbiter would still be smaller than the current space shuttle.
2. Pioneer's air refueling concept. A small vehicle the size of a fighter jet would refuel from a widebody (mostly it would take on O2) and do a suborbital flight. A second stage would be needed to cary a small payload into orbit.
3. Eclipse's tow-launch concept. A suborbital spaceplane would be towed behing a commercial widebody and then be cut loose and ignite its rockets. A second stage would be needed to carry a small payload into orbit.
Notice that only one of these plans use an orbital vehicle, and that plan requires a purpose-built plane much larger than the 747. The others use much smaller planes that are not even intended to reach orbit anyway. Even so, both the Pioneer and Eclipse plans require 747 or MD11 size planes loaded to the limit.
The idea of launching anything near the size of the space shuttle from the back of a 747 is a non-starter. The 747 couldn't carry anything near the size and weight of the external tank and SRB's, and would not give you nearly enough speed (speed is the main thing here, not altitude) to compensate. The shortfall is not something thing small that can be overcome with clever engineering. It is HUGE. My SWAG is that it is a factor of 10 or more. It is doubtfull you could even leave the sensible atmosphere with such a beast, much less reach orbital speed.
BTW...The shuttle carrier aircraft is very limited in performance because it requires extra, heavy supports in the fusalage to carry a shuttle. This is because commercial 747's are not designed to carry anything on top. The combined weight of the EMPTY shuttle and these supports just about max out the 747's load-carrying capacity. The space shuttle hurts the carrier aircraft's aerodynamic performance overall, the extra lift is counteracted by interferance with other lifting surfaces and by other factors. I believe the carrier aircraft's range with the shuttle attached is less than 1500 miles and there is a severe altitude restriction as well. Perhaps someone can correct me on the specific figures, but I'm pretty sure the general point is valid.
Jhooper From United States of America, joined Dec 2001, 6206 posts, RR: 11
Reply 10, posted (12 years 2 weeks 5 days 12 hours ago) and read 2892 times:
This wouldn't work with the currect vehicle. Assuming you're just launching the orbiter, where would you get the fuel to power the main engines to orbit? (That's what the ET is for). So unless we find a very efficient method of powering the spacecraft, it wouldn't happen. Nuclear power? Actually, I think the way to go is to implement the National Aerospace Plane, an idea that was going around about a decade or so ago. It simply takes off like a normal airplane and climbs to altitude under it's own power and then launches to orbit. That's probably a more viable idea than using a 747.
Last year 1,944 New Yorkers saw something and said something.
Positive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 11, posted (12 years 2 weeks 5 days 12 hours ago) and read 2887 times:
The 747 idea would work if you were after a Sub-Orbital flight, but not an Orbital flight! That is the idea Burt Rutan is working on, launching a small spaceplane from the back of a specially developed carrier aircraft. The spaceplane could reach an altitude of 80km or so using this method but could NEVER attain orbit. An alternative to the carrier idea is the towrope method. Hook up a small spaceplane to an F4 Phantom towplane or another similar sized jet and it could tow you to 50,000ft or so where you could release and light up your engines. Again this is only useful for SUB-ORBITAL flights however.
707cmf From France, joined Mar 2002, 4885 posts, RR: 28
Reply 12, posted (12 years 2 weeks 5 days 2 hours ago) and read 2825 times:
If I may add to this debate :
I think one of the main problems to this theory is the fact that the shuttle's wings do not provide enough lift to make it fly a level flight, and there is no way it could climb using only lift+engine.
That's why there is such a great angle of attack upon landing (the greater the AOA, the greater the lift), and that is also why there is no option to go around in the unlikely event of a missed approach.
As Woody said, the SShuttle does not fly, it "falls with style"
Dw747400 From United States of America, joined Aug 2001, 1266 posts, RR: 1
Reply 15, posted (12 years 2 weeks 4 days ago) and read 2593 times:
About the Shuttle Carrier: I remember hearing that it was limited to FL260 and mach .60 with or without the shuttle onboard. That limits it even more as an air-launch platform.
Boeing was (is?) working on a design to launch satellites from a 747, but I think that they were limited to 15,000 pounds of payload to low earth orbit, and 5,000 or so to geostationary orbit. This is substantially less than a shuttle with payload, crew, and other support systems.