Question Sea Dragon engines

[T.Neo]

I am in the process of modelling the Sea Dragon rocket for Orbiter.

I have very limited info on it, other then a few images.
In these images I see a number of small engines on the outside, halfway around the rocket. I am geussing that these are sep motors, but what fuels them, and what are they attached to? Also, did the the Sea Dragon have a seperating interstage or did the interstage stay connected to either stage?

 

[Urwumpe]

They look like solid propellant ullage engines. Also I find no indication of the interstage being separate, it remains attached to the first stage.

 

[T.Neo]

Now I am confused, see here:
http://neverworld.net/truax/Sea_Dragon_Stage_I_Propulsion_System_Layout.jpg
It shows the first stage without any interstage attached, unless the interstage is just not shown

See also http://neverworld.net/truax/seadragon.jpg
It calls the little engines "TVC" engines and says that there are four of them. It assigns the tanks next to the "TVC" engines as LOX tanks supplying them

 

[Urwumpe]

Well, I did not have the drawing, but if they are called TVC engines, then they are used for controlling the second stage flight, similar to the smaller nozzles on the Soyuz launcher.

In the second drawing is also no true interstage visible, just a interstage assembly which is between second stage body and the expendable nozzle of the second stage.

 

[T.Neo]

Here are my models, first and second stages:

Am I doing anything blatantly wrong?

 

[Urwumpe]

Yes. The expandable noozle of the second stage surrounds a large part of the first stage.

Also, you don't need to model the whole TVC engine tanks, just the outside hemisphere or even less would be enough, as they seem to be enclosed in the interstage assembly, with only small holes opening directly around the thruster after the aerodynamic covers are jettisoned.

BTW:
http://ntrs.nasa.gov/search.jsp?N=0&Ntk=all&Ntx=mode matchall&Ntt=Sea+Dragon+Concept

I attached the flight profile from the first report, maybe it helps understanding how it was meant to work.

 

[T.Neo]

That drawing was very enlightening.

I see in the schematics that there is a "payload tank" at the top of the second stage. Any idea as to what this is for and what is was supposed to contain?

 

[Urwumpe]

That drawing was very enlightening.

I see in the schematics that there is a "payload tank" at the top of the second stage. Any idea as to what this is for and what is was supposed to contain?

Likely to contain the payload. Which could be fuel for refueling other missions, as far as I can tell from the mission profile.

 

[T.Neo]

Likely to contain the payload. Which could be fuel for refueling other missions, as far as I can tell from the mission profile.

So should I include a version without the payload tank and just a conventional fairing for any Orbinauts who want to launch custom payloads?

 

[Urwumpe]

So should I include a version without the payload tank and just a conventional fairing for any Orbinauts who want to launch custom payloads?

You will need a tank anyway I think - the tank seems to be a water tight payload fairing.

 

[T.Neo]

You will need a tank anyway I think - the tank seems to be a water tight payload fairing.

But how would the tank seperate to expose the payload?

 

[Urwumpe]

But how would the tank seperate to expose the payload?

Have not found it inside the documents. It is a very generic object.

 

[T.Neo]

I have now got the rocket sorted.

Almost.

I have the main tank cylinder LON divisions set at 24. Is this too much? Would half the divisions suffice?

 

[Urwumpe]

I have now got the rocket sorted.

Almost.

I have the main tank cylinder LON divisions set at 24. Is this too much? Would half the divisions suffice?

Keep them at 24, if you have not too many divisions on LAT. You will have a large object which could otherwise look very edgy from close.

 

[Urwumpe]

Any updates on this project?

 

[T.Neo]

Uh, yeah, sort of. I recently I had all my models set up the wrong way in anim8or, so I had to reorientate them. Once I have that done, I may try a bit of texturing...

EDIT:
I think I've rotated all the models. Now I need a swim :hotcool:.