From Science Fiction to Fact?

I’m looking forward to the new Revelation Space novel by Alastair Reynolds to be released by Gollancz in the summer. Of course I moseyed round to look at the cover on the publisher’s website.

My first reaction? That spacecraft looks awfully like the Skylon spaceplane, a spaceplane concept developed by the British firm, Reaction engines Limited (REL) – picture below:

Then the engineer in me took over. Couldn’t help it. It’s instinctive in me.

The main difference is that the novel’s cover shows the plane in space. It does not have to fly in atmospheres. The Skylon does. But let us assume for now that both planes have to fly through the air.

The major differences are the Inhibitor plane has wing tips on top of the engines (used to reduce drag in subsonic flight), has what appears to be intakes in the nose and the fuselage is sqarish with aerodynamic cornering. On the other hand the Skylon has canards (those controls at the nose) and a rudder..

The comparison leaves me wondering two main things. How does the Inhibitor plane control its flight through the air? (Skylon does this via the rudder and canards.) And why doesn’t the Inhibitor plane maximise its internal volume to skin ratio, which reduces the amount of skin heating in atmospheric flight to a minimum for the amount of cargo or number of people on board.

Let us deal with the latter question first. If the Inhibitor plane is small (we’ll have to see if that is the case once the novel is published), then it may have to fit around the shapes of specified objects such as human sitting in a cockpit. So we have what is called a constrained minimum of fuselage surface area.

But there may be another reason why the fuselage is squarish. The whole body could be acting as a rudder to control the horizontal turning in the air. O.K., let us take this idea a step further. The Inhibitor plane could be using its horizontal surfaces as the equivalent of a vertical rudder. That is all well and good, but how would both the horizontal and vertical rudder be controlled I hear you ask?

Remember those nose intakes? If there is a control to vary the amount of air taken on board through them, it will create a differential pressure, which means the space plane will turn. It’s a kind of short term instability like fly by wire, but this affects the engine fuel supply instead.

But I hear you say, there are only two nose intakes, so the atmospheric control can only be in one plane. That is true if the nose intakes only take in air. What about pushing out air in an aerodynamically controllable way, especially in the vertical direction? See those strange ridges on the back of the plane? They could be out-takes. Now we are talking.

Clearly up to now I’ve been talking about atmospheric flight. Spaceflight is another matter and would have to rely on directional vector controls within the engines. This could always act as a back-up in atmospheric flight. So now we have two systems in air – good safety feature here. Equally in space, the air ejection controls could help manoeuvre the space plane. Also a good safety feature here. I’m beginning to really like this design.

Of course there are a lot of features in common between the two plane designs – for the purposes of supersonic flight – black material for atmospheric heating control, long noses for sending the supersonic booms into ultrasonics so that people do not hear them and engines set close to the centre for good aerodynamic control.

Of there is a lot more engineering to this than I have discussed here. My next step would be to look at the centre gravity position relative to the centre of aerodynamic pressure – which incidentally can be controlled by moving the fuel around the plane. This was used successfully in Concorde – yes this particular technology goes all the way back to the 1960s. The real technological development would the internal engine, intake, out-take and fuel co-ordination, especially reducing the reaction times to commands and changes in the external environment. This is data heavy, but it can be done with the appropriate amount of development work.

See what I’ve done with the artist’s design of the Inhibitor plane? Identified what the good points are and how they might work in reality. And sometimes humanity needs the artists to come up with suggestions for the scientists and engineers to look at to see if they are feasible.

This is one of the reasons that science fiction exists and is popular in certain circles.

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