Why do people place small nosecones on the back of their RAPIER engines?

[Thegamer211]

I see it sometimes in spaceplanes made by other players.

Does it benefit anything, or it just looks nicer?

Edited October 5, 2015 by Thegamer211

[Alshain]

It isn't a nosecone, it is a Toroidal Aerospike engine. It's sort of a hackish way of getting more engine power without using more space. They place the two engines on top of each other and clip them into one another.

[moogoob]

It isn't a nosecone, it is a Toroidal Aerospike engine. It's sort of a hackish way of getting more engine power without using more space. They place the two engines on top of each other and clip them into one another.

I've seen it actually done with the small nosecone, though. The explanation is that it won't block thrust if clipped slightly inside, and severely decreases the drag that the RAPIER causes due to the way that KSP treats drag on the rear of the space/aircraft.

EDIT: Actually forgot that I tested this myself - it does work. It's not that big a difference but could conceivably make it easier to hit super/hypersonic velocities.

[Red Iron Crown]

It's for drag reduction, as moogoob says. A small nosecone or a shock cone intake on the back of the engine reduces its drag significantly. Tested and publicized by Levelord here.

[legoclone09]

Shock Cone Intakes are the second best, the Tail Connector A is the best one. Nobody uses it was one, however. Too long.

[ForScience6686]

So, I don't like the clipping of a nose cone into an engine, but lets say you had some radical mounted engines that you would not use until orbit. Would it be worth the extra weight to add a decoupler and nose cone while going through the atmosphere? What kind of savings as you looking at?

[Red Iron Crown]

Would it be worth the extra weight to add a decoupler and nose cone while going through the atmosphere?

Yes, I did some testing of exactly that here: http://forum.kerbalspaceprogram.com/threads/125544-Anyone-have-data-or-observations-regarding-capping-unused-rocket-engines-on-space-planes?p=2020480&viewfull=1#post2020480

What kind of savings as you looking at?

That depends on ascent profile, the savings are lower for a conventional rocket that gets out of atmosphere quickly and higher for an airbreathing design that spends more time in atmo at high speeds.

[Mastikator]

It's for drag reduction, as moogoob says. A small nosecone or a shock cone intake on the back of the engine reduces its drag significantly. Tested and publicized by Levelord here.

Is this realistic? Is it cheating? (I know, single player game, simulation game, nothing is cheating yada yada, but if we for a moment consider realism as a test for cheating)

Is this a pseudo aerospike engine?

[Red Iron Crown]

It is realistic in the sense that a tapered tail end reduces drag, that is very much true in real life. It is a bit unrealistic in that the positioning of such a part puts it close enough to the exhaust that it would likely cook off if tried in reality. FWIW I use the tail spikes because they are more efficient and aesthetically pleasing; others might find the suspension of disbelief too much.

Not really related to aerospikes at all, those aren't about drag reduction but more about keeping a rocket engine relatively efficient over varying atmospheric pressures.

[Kerbart]

Is this realistic? Is it cheating? (I know, single player game, simulation game, nothing is cheating yada yada, but if we for a moment consider realism as a test for cheating)

Is this a pseudo aerospike engine?

An aerospike isâ€â€as far as I knowâ€â€constructed to keep performance in vacuum and in atmospheric conditions level. Better than a vacuum optimized engine in the atmosphere, better than an atmosphere optimized engine in vacuum.

This, on the other hand, is purely to reduce drag. It will be considered "cheating" by some, and "getting even with a broken model" by others.

[SpeedDaemon]

It is a bit unrealistic in that the positioning of such a part puts it close enough to the exhaust that it would likely cook off if tried in reality.

Wait, then what's this:

Granted, not a hybrid rocket engine...

[Red Iron Crown]

That is not a rocket, with exhaust temperatures that are much, much lower.

[KerikBalm]

However, when you've got high pressure exhaust coming out in the case of a rocket, the gas being expelled acts like an aero-nosecone... active rocket angines should behave like the rear node is occluded.

(though this is slightly different than in that case above, as the high pressure air comes out from a ring, and not a point/circle)

Anyway, if the nozzles can take the heat, the reverse cone should be able to take the heat (assuming similar material)

[Red Iron Crown]

No argument there, as I understand it there is no difference in the game between a running rocket engine and an idle one aerodynamically speaking.

Though I would point out that rocket engine nozzles can't stand the exhaust heat, they need either regenerative cooling or ablation to keep them from melting.

[Teilnehmer]

I see it sometimes in spaceplanes made by other players.

Does it benefit anything, or it just looks nicer?

It’s RapierSpike  Levelord’s invention.

The nosecones are for lowering the drag. They do not occlude the engine exhaust.

Edited October 5, 2015 by Teilnehmer

[Thegamer211]

It isn't a nosecone, it is a Toroidal Aerospike engine. It's sort of a hackish way of getting more engine power without using more space. They place the two engines on top of each other and clip them into one another.

No, it is a RAPIER with nosecones.

Photo:

It’s RapierSpike  Levelord’s invention.

The nosecones are for lowering the drag. They do not occlude the engine exhaust.

Yes! I knew I saw them in some thread.