Take the 2-minute tour ×
Astronomy Stack Exchange is a question and answer site for astronomers and astrophysicists. It's 100% free, no registration required.

I searched on the subject, thinking it could probably be cheaper to fly the spacecraft aboard a plane and then launch it from altitude. The only thing I found was this Wikipedia page, but it only enumerates advantages over ground launch without saying why it's not the traditional way of doing things. Knowing the X-15 was tested in the 50s, if it was the better option, it would be known since that time.

I think one the reason may be limitations on the payload for the plane to takeoff and fly to a sufficient altitude, but it shouldn't be a problem when sending astronauts on the ISS, for example. Any idea on this?

share|improve this question
    
Look up the Pegasus. Basically, air-launched ICBMs are the maximum possible payload (albeit prohibited by treaties). The Burlak project by the Russians was a bit larger but unsuccessful. –  Deer Hunter May 31 at 5:39

2 Answers 2

up vote 2 down vote accepted

Because there is no plane that could do that. And even if there was one, you gain almost nothing from doing so.

The Saturn V rocket weighed almost 3 thousand tons before launch. The Space Shuttle weighed almost 2 thousand tons.

A Boeing 747 can "only" carry about 120 tons. That's something like 5% the weight of the space vehicles mentioned above. You'd need 20 Boeing planes to carry one fully fueled space vehicle.


But how about the altitude gain? The 747 could carry a payload up to 14 km altitude, or so.

By comparison, the orbit of the International Space Station is at 420 km. The Hubble Space Telescope is at 560 km altitude. There are no orbits below 160 km (because they would decay rapidly due to drag), and most are above 200 km. Geosynchronous satellites are at 40 thousand km above Earth.

The plane would only cover about 2...3% the orbital altitude, or even much less.

As you can see, the numbers just don't add up.


EDIT: The wiki page you mention refers to special designs, where the whole vehicle is made for takeoff as an airplane or balloon; the airplane is basically the first stage. But this is not a mainstream solution currently, for reasons indicated above. It may work for very small vehicles.

share|improve this answer
    
Doesn't deal with drag in the lower atmosphere. –  Deer Hunter Jun 1 at 3:25

SpaceShipOne

The picture above shows a picture of Space Ship One. on the jet powered 'carrier aircraft'/'mother ship' White Knight - that probably counts as an Aircraft.

However, I think these designs are only designed to reach low-earth orbit, not up high enough t carry a satellite, carry cargo to the ISS, etc

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.