SpaceX's Dragon

[XpertKerbalKSP]

Hello Fellow Kerbonauts!

I was on spacex.com recently and I was looking on the Dragon section. I noticed that the dragon (both V.I and V.II) didn't have service module engines. This really puzzled me because, how does a spacecraft adjust it's orbit without engines?

So does anyone know how the Dragon spacecraft maneuvers?

Thanks!

[DonaldPK51]

The Draco thrusters are quite powerful, it doesn't need a service engine for LEO.

[Scotius]

Yes. Aside from the trunk for solar panels, everything important is contained inside Dragon's main body.

[Bill Phil]

It's more self contained. There's a cargo module, but no real service module.

Also, orbital adjustments don't require big engines. RCS is usually good for the types used while going to the ISS.

[Streetwind]

On 28.3.2016 at 2:12 AM, XpertKerbalKSP said:

So does anyone know how the Dragon spacecraft maneuvers?

It maneuvers extremely little. A dozen m/s perhaps to rendezvous with the ISS, a lot less than that to leave it again. The biggest single maneuver is the deorbit burn. All of these are executed by the Draco RCS system.

It's important here to remember that the original Dragon capsule is a purpose-built system. It has no application beyond going to the ISS. And in the process of going to the ISS, it is placed exactly where it needs to be by its carrier rocket. As a result of this, the need for orbital maneuvering is almost nonexistent. A spacecraft like Apollo or the STS orbiters, by comparison, had to be able to execute a much wider, less well defined field of tasks. As such, they were outfitted accordingly (though the shuttle kinda cut it close, only carrying about 300 m/s).

The crew Dragon, too, is built to go to the ISS. Now, it's designed to be a little more general purpose than that, to the extent where people have thought about sending it to Mars (see: Red Dragon concept). The increased versatility comes courtesy of the SuperDraco launch abort system, which the capsule keeps carrying with it once successfully reaching orbit (as opposed to ejecting it on the way there like classical launch abort towers are). While not required for the ISS profile, if you really wanted to have a Dragon that could maneuver in space and didn't mind a slightly rough landing under parachutes (or don't plan to return the capsule at all), the SuperDracos can provide about 400 m/s extra dV in addition to whatever is contained in the normal Draco RCS system. And that's merely the stock configuration. Due to the easily stored propellants, you could theoretically build a special purpose Dragon V2 that sacrifices some (or all) of its interior volume to hold extra fuel tanks. You can get a lot of dV that way - enough to capture into Mars orbit, pick your landing site with precision, and land there fully propulsively while carrying a small Earth return vehicle as cargo.

 

Edited March 29, 2016 by Streetwind

[fredinno]

8 hours ago, Streetwind said:

The crew Dragon, too, is built to go to the ISS. Now, it's designed to be a little more general purpose than that, to the extent where people have thought about sending it to Mars (see: Red Dragon concept). The increased versatility comes courtesy of the SuperDraco launch abort system, which the capsule keeps carrying with it once successfully reaching orbit (as opposed to ejecting it on the way there like classical launch abort towers are). While not required for the ISS profile, if you really wanted to have a Dragon that could maneuver in space and didn't mind a slightly rough landing under parachutes (or don't plan to return the capsule at all), the SuperDracos can provide about 400 m/s extra dV in addition to whatever is contained in the normal Draco RCS system. And that's merely the stock configuration. Due to the easily stored propellants, you could theoretically build a special purpose Dragon V2 that sacrifices some (or all) of its interior volume to hold extra fuel tanks. You can get a lot of dV that way - enough to capture into Mars orbit, pick your landing site with precision, and land there fully propulsively while carrying a small Earth return vehicle as cargo.

Yeah, and a vehicle like that would be mass-inefficient and too heavily modified to make it worth it.

NASA rejected the Red Dragon Concept for a good reason.

[Streetwind]

8 minutes ago, fredinno said:

Yeah, and a vehicle like that would be mass-inefficient and too heavily modified to make it worth it.

That's not really the point, though. He asked about engine capabilities on the Dragon capsules, which is what I described.

[fredinno]

59 minutes ago, Streetwind said:

That's not really the point, though. He asked about engine capabilities on the Dragon capsules, which is what I described.

The Dragon V2's engines are intended to be used for LAS and landings. However, it is too low of a LWR for a good LAS, but too high of a TWR for everything else, which is a serious problem.
But you can use a nozzle extension to increase ISP and Delta V if you really wanted to.

 

[Streetwind]

...Look, I'm not sure what you're trying to do here, but please stop. It does not make you look all that well informed on the topics you address - particularly with linking that particular "proposal", which I'll spare you my thoughts on - and serves little purpose other than generating animosity in a thread where none existed previously.

I also remain with my stance that none of this has anything to do with my original reply above, which simply listed the modes of orbital maneuvering available to a crew Dragon. And hence, I'm not going to discuss it further.

[fredinno]

35 minutes ago, Streetwind said:

...Look, I'm not sure what you're trying to do here, but please stop. It does not make you look all that well informed on the topics you address - particularly with linking that particular "proposal", which I'll spare you my thoughts on - and serves little purpose other than generating animosity in a thread where none existed previously.

I also remain with my stance that none of this has anything to do with my original reply above, which simply listed the modes of orbital maneuvering available to a crew Dragon. And hence, I'm not going to discuss it further.

That was not my proposal tho.

[XpertKerbalKSP]

2 hours ago, fredinno said:

The Dragon V2's engines are intended to be used for LAS and landings. However, it is too low of a LWR for a good LAS, but too high of a TWR for everything else, which is a serious problem.
But you can use a nozzle extension to increase ISP and Delta V if you really wanted to.

 

Look, I'm asking about the capabilities of the Dragon, not about which company rejected or proposed it. I was asking the question " So does anyone know how the Dragon spacecraft maneuvers". So if you're gonna pop into my thread and look at the comments just to prove someone wrong, you can shut up, thanks.