How far into the future? An aircraft that launches from a runway and enters low

[djellison]

Whilst Skylon clearly needs a RCS, not gyros - it's worth mentioning - many spacecraft in LEO don't have RCS at all. They have gyros, and use magnetorquers to desaturate the gyros when required.

Hubble, for example, has no thrusters at all.

[Antice]

Whilst Skylon clearly needs a RCS, not gyros - it's worth mentioning - many spacecraft in LEO don't have RCS at all. They have gyros, and use magnetorquers to desaturate the gyros when required.

Hubble, for example, has no thrusters at all.

Ah-ha. Never heard of magnetorquers before. Had to google it up. Learning something new every day. interesting method for maintaining the orientation of satellites with the help of the earth's magnetic field there.
Isnt there yet another method employingn the gravitational gradient as well?

[cjameshuff]

Isnt there yet another method employingn the gravitational gradient as well?

http://en.wikipedia.org/wiki/Gravity..._stabilization

[publiusr]

Now Skylon is to be rather long and slim, so would that work for gravity gradient?

Its long slim build is one way for an airframe to hold a lot of low density hydrogen: Here is the other:
http://www.boeing.com/Features/2012/..._06_04_12.html
That's one porker of a UAV.

O/T

The ATO concept
http://www.theregister.co.uk/2011/11/02/space_airships/

[aquitaine]

Now Skylon is to be rather long and slim, so would that work for gravity gradient?

Its long slim build is one way for an airframe to hold a lot of low density hydrogen: Here is the other:
http://www.boeing.com/Features/2012/..._06_04_12.html
That's one porker of a UAV.

The Skylon has to be slim because it's designed to fly at hypersonic speeds.

[Antice]

The Skylon has to be slim because it's designed to fly at hypersonic speeds.

well.. I dunno if slim is the right word to describe skylon's shape. it's going to be 0,5m wider than a Boeing 747-300, and about 10 meters longer.
The appearance of looking slim is from the shortness of the wings i guess... they are half as long as the 747-300 wingspan (almost 60m compared to skylons 25,4m)

Comparing skylon to a real world familiar entity like the 747-300 really drives home the point of just how large the thing has to be to reach orbit. it's the curse of the SSTO. now imagine how big it would have had to be in order to reach orbit with a 15 tonne payload without the benefit of air breathing to mach 5.

[NEOWatcher]

well.. I dunno if slim is the right word to describe skylon's shape. it's going to be 0,5m wider than a Boeing 747-300, and about 10 meters longer.

I'm curious as to where you got your numbers. I couldn't easily find the 300 specs, but found some relative links (400, 800(8)). Certainly, the 800 is going to get the aspect ratio closer.
Skylon:
The currently proposed Skylon model C2 will be a physically large vehicle, with a length of 82 metres (269 ft) and a diameter of 6.3 metres (21 ft).

747-400 Combi:
Length 231 feet 10 inches (70.66 m)
Fuselage Width (external) 21 feet 4 inches (6.5 m)

747-800 (747-8):
250 ft 2 in (76.25 m)
20.1 ft (6.1 m) (cabin - not fuselage)

Even using the 800(8) number for length
or 6.5 x 76.25 vs 6.3 x 82. Both narrower and longer than a 747 (from what I can find)

The appearance of looking slim is from the shortness of the wings i guess... they are half as long as the 747-300 wingspan (almost 60m compared to skylons 25,4m)

For my own personal opinion, I think the look is also slimmer due to Skylon tapering a lot more, and the 747 fuselage not being round. (much taller, at least toward the front).

Comparing skylon to a real world familiar entity like the 747-300 really drives home the point of just how large the thing has to be to reach orbit. it's the curse of the SSTO.

Details aside, that is true.

[djellison]

Its long slim build is one way for an airframe to hold a lot of low density hydrogen: Here is the other:
http://www.boeing.com/Features/2012/..._06_04_12.html
That's one porker of a UAV.

What does that have to do with the subject in hand, exactly?

[Antice]

@NEOWatcher

I just picked one of the middle range models of the 747 at random from the main wikipedia article for the 747 series.
While there is little doubt that skylon indeed occupies a smaller volume than the 747 vehicles. due to among other things the differences you noted in overall fuselage shape, the main point was that while skylon appears to be very slim, it's really not that much slimmer than a common airliner like the 747 is compared to it's length.
Actually. when looking at the skylon animations it is easy to see the skylon as not much larger than a fighter jet unless one knows beforehand that it is indeed comparable to a 747 in overall size.
The same tends to happen when looking at rocket launches. them rockets are not just big fireworks. they are often giant constructs in their own right, something that is easy to forget when you never actually get to see them up close and personal.

[NEOWatcher]

...the main point was that while skylon appears to be very slim, it's really not that much slimmer than a common airliner like the 747 is compared to it's length.

Point taken and acknowledged with my post. I just thought the numbers were funny, so I decided to put them out there and found some discrepencies with your statement.

...Actually. when looking at the skylon animations it is easy to see the skylon as not much larger than a fighter jet unless one knows beforehand that it is indeed comparable to a 747 in overall size.

Yes; I see that problem with illustrations and animations for a lot of objects. I was approaching it from knowing that it's "big".

...The same tends to happen when looking at rocket launches. them rockets are not just big fireworks. they are often giant constructs in their own right, something that is easy to forget when you never actually get to see them up close and personal.

True; You just need to stand next to an F1 on display and imagine how big the whole thing must be. Just like the museum at the Statue of Liberty has a mold of a toe.