28
votes
Accepted
Why did Crew Dragon switch to burst disks instead of multiple check valves?
It would be possible to design a check valve chain of high reliability of closing, but it would restrict flow and start to increase the risk of one valve sticking shut. You would probably also need ...
- 20.7k
12
votes
Could a modified Dragon reach Low Earth Orbit just using SuperDraco engines?
Dragon V2 (Crew Dragon) uses 8 SuperDraco engines with maximum of 73,000 N thrust each. So, in theory, it could produce enough thrust to lift about 50,000 kg off the pad at thrust-to-weight ratio (T/W)...
- 76.3k
9
votes
Accepted
Dragon 2 Propellant Capacity
That's 1,388 kg of propellant for the whole vehicle, not per engine.
Reading the original document referred to by Wikipedia, it says 3,060 pounds of propellant for the Crew Dragon capsule.
(It's on ...
- 5,168
8
votes
SuperDraco Dragon V2 vs Merlin 1D Falcon
The thrust of the engines (for any launcher or spacecraft, really) is nowhere near as important as the amount of fuel feeding them.
It takes about 9400-10000m/s of ∆v, depending on trajectory, to ...
- 165k
8
votes
Accepted
Why does the Superdraco exhaust seem so under-expanded in this photo?
In this photo, the exhaust doesn't expand so much. The nozzle looks to be a bit longer. So they've played with various nozzles.
(cropped and adjusted for visibility)
And the Ars Technica article ...
- 123k
7
votes
Accepted
How could SpaceX’s crew Dragon land with abort thrusters in case of emergencies?
PearsonArtPhoto answers why it isn't done - generally NASA's very conservative approach to spacecraft safety, and hurdles it would set to get it implemented.
But assuming a miraculous change in NASA ...
- 54.3k
6
votes
Does the Crew Dragon still have the launch abort fuel on board at landing?
Yes, fuel is still carried. Only 600 m before splashdown (2:12 in this video), "Dragon has safed all propulsion systems on board." https://www.space.com/spacex-crew-dragon-demo-2-...
- 11.2k
5
votes
How could SpaceX’s crew Dragon land with abort thrusters in case of emergencies?
There is no plan to do this, nor has there ever been an extensively studied plan. In theory it could be done, but NASA would want to certify it, and it is just better to spend more effort to make sure ...
- 121k
5
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Could the Crew Dragon be used to re-boost the ISS?
Theoretically, it could, but why use the larger, more expensive rocket engines when you could just use a less expensive, smaller draco engines?
Super Dracos are off axis, meaning that any thrust from ...
- 121k
5
votes
Accepted
What would happen during an inflight abort in a Falcon 9 if the booster engines did not shut down?
The abort system in the Falcon 9 removes the payload (Crew Dragon) from the second stage using the Super Draco engines. The second stage remains attached to the first stage. Mass of the fully loaded ...
- 441
5
votes
Accepted
Dragon capsule thrust requirements
Dragon 2 (Crew Dragon) has two separate types of engines: the powerful SuperDraco thrusters (currently planned only for use in launch escape) and the much smaller Draco thrusters used for attitude ...
- 1,532
5
votes
Accepted
SuperDraco Engines in Crew Dragon spacecraft
Firstly, available space for engines isn’t really a problem. A spacecraft can be made exactly as big as the needed cargo space plus engines. Capsules only look tiny because you usually see them next ...
- 2,257
5
votes
Accepted
How can SpaceX test SuperDracos whilst hanging off a crane?
Like any good descent engine, SuperDraco throttles deeply; Wikipedia says down to 20%.
Various speculative sources put the thrust angle anywhere between 25º and 35º, which determines cosine losses. ...
- 165k
5
votes
SuperDraco Dragon V2 vs Merlin 1D Falcon
The critical number for rocket engines is their specific impulse (Isp, a measure of how efficient the engine is).
The Merlin has an Isp of 311 s.
The SuperDraco Isp is estimated to be around 225 s (...
- 123k
4
votes
Can a SuperDraco engine help landing the SpaceX 1st stage?
There was discussion on using the Super Draco design to land the second stage, but SpaceX has mostly given up on second stage recovery for Falcon. (NOT for the BFR booster that will be the vehicle to ...
- 78.9k
3
votes
Why not Super-Draco in lunar lander?
To begin with, SpaceX bid Starship as their lunar lander. Starship used methalox as their propellant for their Raptor engines. However, Starship does need landing engines higher up on the hull for the ...
- 3,951
3
votes
Merlin 1D Engine
The Merlin Engine is a gas generator cycle engine which uses liquid Oxygen(LOX) and refined Kerosene(RP1) as its propellants.
The SuperDraco engine is a pressure fed cycle engine which uses mono-...
- 4,285
3
votes
Why does the Superdraco exhaust seem so under-expanded in this photo?
I think its clear the lack of a nozzle is the cause. As to the "why" I can think of a few reasons that might be partly responsible (other than it's just testing):
They are not designed to be used for ...
- 3,402
2
votes
SuperDraco Engines in Crew Dragon spacecraft
The SuperDraco engines themselves are quite compact. Liquid rocket engines consist of a relatively small combustion chamber and a nozzle which may be large or small in proportion depending on the ...
- 165k
2
votes
Why not Super-Draco in lunar lander?
First of all, the SuperDracos were designed from the start primarily as a launch escape system. Although using them for propulsive landing was explored extensively, it was never implemented.
For ...
- 1,532
1
vote
Dragon Superdracos: how much MMH/NTO propellant?
For the abort tests in early 2020, according to documents filed with the FAA over a year prior, the Dragon flew with 2565 kg of propellant (1590 kg of NTO and 975 kg of MMH), but only about half of ...
- 165k
1
vote
Does the Crew Dragon still have the launch abort fuel on board at landing?
Yes, the fuel for the launch abort system is kept during the duration of the flight, however it is not wasted.
The SuperDraco abort thrusters use the same combination of propellants (NTO and N2O2) ...
- 3,787
1
vote
Purpose of side holes on SuperDraco pods of DM-1 flight Dragon 2 capsule
I believe these are the flaps that open and close to reveal the openings for the SuperDracos. The SuperDracos allow Dragon 2 to separate from the rocket during aborts. I think they swivel so the ones ...
- 11
1
vote
Crew Dragon SuperDraco Engine Covers
The abort test was done several years ago. Quite a few changes have been made since. The covers on the Super Draco nozzles are quite recent, from what I've seen. The entire pod area now has a silver-...
- 723
1
vote
Dragon 2 Propellant Capacity
The Super Dracos are used for two purposes in the initial design.
Launch Abort System, and powered landing.
For LAS usage, they need to get away from an exploding booster, faster than the explosion ...
- 78.9k
1
vote
Could a modified Dragon reach Low Earth Orbit just using SuperDraco engines?
We've seen how high a Dragon can reach with its superdraco engines on its pad abort test, and it was about 5000 feet. If you filled it with propellant instead of cargo and passengers it might get a ...
- 19.2k
1
vote
How can SpaceX test SuperDracos whilst hanging off a crane?
Think of it like this: how would you test the vehicle without a crane? They are testing out the powered landing capabilities so the idea is to work with slow, smooth trajectories that may be mostly ...
- 4,340
1
vote
Can a SuperDraco engine help landing the SpaceX 1st stage?
As we saw in the last few launches, cold gas thrusters (the F9 first stage uses nitrogen for recovery maneuvers) seem to be sufficient to maneuver the stage before fins engage.
But yes, Superdracos ...
- 11
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