Sign in / up

back to article Brit Skylon spaceplane moves closer to lift-off

The European Space Agency (ESA) has chipped in €1m to study the viability of the Skylon spaceplane concept - a radical single stage to orbit (SSTO) vehicle whose motors use "a synthesis of elements from rocket and gas turbine technology". Artist's representation of the Skylon. Pic: Reaction Engines The Skylon According to …

COMMENTS

House rules Send corrections
This topic is closed for new posts.

Page:

    1. Richard 12 Silver badge
      Reply Icon

      Re: I forsee a teensy problemette...

      Not necessarily.

      The Skylon would be suborbital, dropping off the transfer craft and then descending back to Earth of its own accord.

      The transfer craft then burns to put the sat into the proper orbit.

      To recover the transfer craft, wait until the next Skylon launch and play swopsies - transfer B is launched, and transfer A is recovered around apogee.

      The delta-v needed for that isn't too bad - though the timing is well beyond my meagre Kerbal Space Program abilities!

      1 1
      1. DropBear
        Reply Icon

        Re: I forsee a teensy problemette...

        The only teensy problem with that is that the article _explicitly_ mentions the aircraft being propelled to mach 25, which happens to be the exact orbital velocity for a full low earth orbit - not suborbital stuff. Granted, I'm all ears about where this thing keeps its reentry heat shield.

        1 0
        1. Richard 12 Silver badge
          Reply Icon
          Facepalm

          Re: I forsee a teensy problemette...

          So it does, I'd got that confused with the Mach 5.5 bit.

          That makes the re-use of the transfer tug considerably easier as it could be retrieved in the same mission, assuming the Skylon can stay on-orbit for long enough.

          They intend to use the aeroshell itself as the heatshield, coupled with refrigeration using the last bit of cryogenic hydrogen.

          1 0
  2. Anonymous Coward
    Anonymous Coward

    Frisbee time

    While I certainly hope this all works, I do have a problem with the layout of the vehicle. Engines on the ends of the wings present some interesting structural and aerodynamic problems. First, the wing has to be stronger, and is going to be quite complicated with all the fuel lines, engine control systems, etc., running through it. More important is this - in this configuration, an engine-out is going to make a frisbee out of the vehicle, there isn't enough rudder or vectorable thrust available to keep going straight.

    The engines really need to be mounted closer together, on the tail, think DC-9 or Lear Jet, and there needs to be some way to maintain directional stability in yaw despite the VERY asymmetrical thrust resulting from an engine-out event. Remember that the higher the performance and power output, the closer you are to the bleeding edge of technology. In this device, an engine-out situation is likely to be catastrophic.

    Make the engines work, redesign the airframe, and THEN try it.

    0 3
    1. Richard 12 Silver badge
      Reply Icon
      Boffin

      Re: Frisbee time

      I disagree.

      The engines become the heaviest part of the craft very quickly after launch, and by the time it's coming in for landing the fuselage is an empty tube.

      Unless the engines are in the middle it's going to be ungodly unstable, likely impossible to control once back in atmosphere.

      I'll take "screwed if engine flames out" over "screwed on every approach"

      Also, if an engine flames out it may still be possible to safely abort and rescue the craft and payload, if it's going fast enough.

      2 0
      1. John Smith 19 Gold badge
        Reply Icon

        Re: Frisbee time

        "The engines become the heaviest part of the craft very quickly after launch, and by the time it's coming in for landing the fuselage is an empty tube."

        Correct.

        That engines-at-the back was one of the things that killed HOTOL. SOP for rockets but they realizes once you put wings on the structure the whole game changes. Realizing that putting the engines in the middle (with the payload pay in fact) were key features in turning HOTOL into Skylon.

        Engines-at-the back at the back is also why no human pilot could directly fly the Shuttle.

        Actually Skylon is designed to be statically stable. That's important because like Shuttle it will make a glide landing. Even REL could not come up with a way to do a powered landing, although given the craft will be at least 78% lighter on landing (more given a successful payload deployment) it should not be far off carrying enough LH2 for a 2nd pass.

        1 0
      2. Anonymous Coward
        Reply Icon
        Anonymous Coward

        Re: Frisbee time

        Thanks for mentioning that. If the weight distribution is like a dumbbell, this is said to be "having a high polar moment of rotation", which means that once spinning - frisbee style - it is going to be almost impossible to stop.

        This means the craft as shown in the artist's renderings has TWO major problems.

        1) Huge asymmetrical thrust in an engine-out event, instant frisbee (yaw) and uncorrectable by any aerodynamic means (i.e instant disaster). While there will need to be attitude thrusters for out-of-atmosphere pitch, roll, and yaw changes, they won't be able to compensate for a main engine failure, and that tiny little vertical stabilizer/rudder is far too inadequate even at lower altitudes.

        These are very powerful engines, and if one of them fails, the remaining engine's thrust at the end of a long arm is going to whip the craft around instantly and very vigorously, so yes, we're all going to die. Relax, it will be quick. Very quick.

        2) Engines at the rear, as in DC-9 and Lear might result in an aft CG at zero fuel, and I do remember that most aircraft are not "empty tubes" but are full of people and things so the CG doesn't shift drastically - but in this case, if most of the fuselage is fuel tank, the aft CG will be a problem.

        Lets put the engines close together, mounted near the CG of the aircraft, probably over (Honda jet) or under (ME-262) the wings. We don't want them so close together that a failure in one will propagate to the other (as in TU-144 and B-70), but we do want them as close as possible to the longitudinal center line of the aircraft so we don't wind up with the asymmetrical thrust problem.

        All aircraft are a collection of compromises flying in formation. This particular drawing seems to have been done by a publicist, any aeronautical engineer would reject this configuration in a heartbeat.

        I do support this project and hope they are ultimately successful, but I doubt the final aircraft is going to look very much like the picture.

        0 3
        1. Anonymous Coward
          Reply Icon
          Anonymous Coward

          Re: Frisbee time

          Or alternatively, we can assume that the project team are aware of all those issues and have an understanding of aerodynamics and have chosen this layout as the best compromise.

          2 0
  3. Nya

    Why things going up?

    Surely if they prove this works with the prototype, forget the cheapass way to launch satellites, surely selling the mach 5+ bomber might be more open to buyers no?

    0 0

Page:

This topic is closed for new posts.