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Whatu

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Looks very nice, though probably it means I need to get the engines meshes redone.
The front cone closes when switching to internal lox, right?
 

Urwumpe

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Looks very nice, though probably it means I need to get the engines meshes redone.
The front cone closes when switching to internal lox, right?

Yes, and like on the SR-71, move depending on AOA and Mach number.
 

Urwumpe

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Indeed, and why does the engine body have that curvature?

The plane flies most of the time with a specific high AOA. As the SABRE engine requires the shocks to arrive as axial as possible to the inlet cone, for maximum efficiency, it is good (and normal also for other planes) to optimize for a special AOA.
 

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The AOA I can understand, its the physical shape of the engine downstream I don't.

N.
 

Urwumpe

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The AOA I can understand, its the physical shape of the engine downstream I don't.

N.

It has to do something with supersonic compression, I don't yet know how to explain this simple. You have two kinds of shockwaves.

ramth.gif


One kind, oblique shock, changes the direction of travel of the air, while it remains supersonic, the other normal shock slows it down below the speed of sound. By using many oblique shocks before you get a normal shock, you can build engines which don't choke already at Mach 1.6.

For the SABRE, you need to use the inlet cone for bringing the first shockwave (from the cone) at the lip of the inlet, so the following reflections of the shockwave compress and direct the air.
 

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You imply that the physical structure of this engine, has to have a curve to operate? The speed range, and fuel system dictates this, for this design?

N.
 

Urwumpe

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You imply that the physical structure of this engine, has to have a curve to operate? The speed range, and fuel system dictates this, for this design?

Yes - exactly. The curve is mostly for having the thrust in the right direction.
 

Scrooge McDuck

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Somehow I'm wondering if the Skylon plane could actually fly, at lower airspeeds; It seems to be lacking a horizontal stabilizer.
I know some planes don't have them, delta-wing like planes like the shuttle or concorde. But the Skylon seems to have relatively small main wings, and not at the back of the fuselage. Noticed it has tiny horizontal stabilizers at the front (canard), but would it actually work at low airspeeds for this wing configuration? Normally with canard stabilizers (at the nose), the main wings are placed more to the back end of the fuselage. Watching the animation, the design just 'feels' wrong or very unstable in reality.
Anyway, they must have calculated/tested/proved that this design is possible, otherwise ESA won't give the $$$ :)

regards,
mcduck
 

Urwumpe

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Canards are effective even at much lower airspeeds than normal stabilizers, as they get the air flow less disturbed, but they are also more instable because of their location - small movements, can cause big torques.
 

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May News

http://www.reactionengines.co.uk/news_may09.html

N.

---------- Post added at 10:13 ---------- Previous post was Yesterday at 22:28 ----------

Just watched the interviews, and Alan Bond(M.D.) seems quite upbeat. Interesting comment toward the end. He says when the current generation of expendable rockets need to be replaced, there would have to be good reasons for not using Skylon/Sabre technology. I assume he means the Arianne series, wonder if he's told ESA yet...

From some of the comments:-
Why a curved nacelle? The front points slightly down so the intake is square into the airflow when the vehicle is flying supersonically with a angle of attack. The back points down so the rocket nozzles point through the centre of mass for control when outside the atmosphere.

N.
 
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