Space Exploration Stack Exchange
Space Exploration Stack Exchange

Questions tagged [engines]

Questions regarding equipment used to propel a spacecraft or a rocket. Questions about attitude control jets should be tagged "attitude".

502 questions
19
votes
1 answer

What is so hard about making a throttleable large rocket engine?

In the old days, most rocket engines weren't throttleable. I think the first one was actually the Apollo Lunar Module descent engine. But I'm interested in large, turbopump-fed engines using RP-1/LOX or LH2/LOX. Why is it so hard to makes these…
DrZ214
  • 4,566
  • 2
  • 29
  • 57
10
votes
1 answer

How common have the various orbital launchers' rocket engines been?

A fleeting thought on my sentiments about the disposability of RS-25s (rare! Only 47 made before the RS-25E/F contracts? Few remain! Complain about them being expended for SLS!) versus Raptors (one made every day or more? 39 blown up on Starship…
Erin Anne
  • 11,202
  • 1
  • 40
  • 76
10
votes
1 answer

What is the heaviest part of a rocket engine?

I'm trying to understand how much different parts of a rocket engine weigh. For example, according to Wikipedia, Merlin engine weighs 470 kg, of which 70 kg is the turbopump. How is the remaining 400 kg break out? I'm guessing the broad categories…
irakliy
  • 615
  • 4
  • 11
10
votes
2 answers

Planned usage of F-1 rocket engine in 1955?

The F-1 engine used for the first stage of the Saturn V is still the most powerful liquid fuel rocket engine. The development of the F-1 was started very early in 1955 by the US Air Force. In 1958 the Air Force eventually halted development of the…
Uwe
  • 48,975
  • 4
  • 121
  • 206
5
votes
2 answers

What is the thrust of Momentus' thrusters?

I understand that they have an interesting method of using microwaves to produce plasma from water. They claim to have a "high" thrust and "high" specific impulse. Their Isp numbers are published, but apparently not thrust. Has there been…
Michael Stachowsky
  • 6,250
  • 1
  • 21
  • 40
5
votes
1 answer

Space rocket engines performance and technology: SSME vs. RD-0120

Between this two LH2/LOX rocket engines the SSME(RS-25 different) of the Space Shuttle rocket and RD-0120 of the Energia rocket, which one has higher performance and better technology to launch space rockets in low earth orbit?
Mark777
  • 2,145
  • 1
  • 15
  • 33
3
votes
0 answers

Why are hydrogen pumps much more powerful than oxygen pumps in rocket engines?

In many rocket engines I've seen, hydrogen pumps seem to be 3 - 4 times more powerful than oxygen pumps while pumping about 5 times less mass. Why is that? Part of this is probably driven by relative density of oxygen vs. hydrogen. Is there a simple…
irakliy
  • 615
  • 4
  • 11
3
votes
1 answer

OSIRIS-REx engines location

I'm trying to locate all the OSIRIS-REx engines. Here: http://spaceflight101.com/osiris-rex/osiris-rex-spacecraft-overview/ (Propulsion System) I read that there are: 4 x 275 N, 6 x 22 N, 16 x 4.5 N and 2 x 80 mN. My biggest doubt is about the four…
Cristiano
  • 1,760
  • 7
  • 18
3
votes
1 answer

Is the behavior of the Bussard ramjet as described in Poul Anderson's novel Tau Zero accurate?

The ramjet in the novel "Tau Zero" required a separate decelerator which, spoilers, breaks, and causes the ship to career endlessly through the universe. Is this accurate from a real-world engineering standpoint? Could they not simply have adjusted…
Chris B. Behrens
  • 2,267
  • 15
  • 36
3
votes
3 answers

Is fuel and oxygen burnt in a gas generator?

If I understand correctly, a liquid propellant rocket engine combustion chamber is fed with fuel and oxygen from a turbopump. Those turbopumps are driven by a gas generator. The gas generator is fed with fuel and oxygen; but I cannot find if fuel is…
Manu H
  • 3,780
  • 1
  • 19
  • 48
2
votes
2 answers

Outsourced rocket engines for medium and small launchers

Is there any company selling rocket engines that work for small and medium orbital launchers other than Ursa Major Technologies? Looks like a good model: the company developing a rocket can save a lot of time and money not having to spend for…
Joe Jobs
  • 2,620
  • 17
  • 52
2
votes
1 answer

What is the efficiency of liquid-liquid vs liquid-gas vs gas-gas engines?

I've read somewhere that gas-gas engines (engines where both the fuel and the oxidizer enter the combustion chamber as gases) have greater efficiency of combustion as compared to liquid-liquid or gas-liquid engines. This is due to better mixing. So,…
irakliy
  • 615
  • 4
  • 11
2
votes
3 answers

Why does air get sucked in for a moment before engine start?

We have commonly observed that before engine start at T minus zero, for a very small moment before the exhaust gases gush out of the nozzle, the air around the nozzle is pulled in. For what reason can that be? Please explain in detail, relating to…
Jay
  • 361
  • 1
  • 10
1
vote
0 answers

Calculating thrust using only weight

How do you calculate minimum thrust for a rocket ship using just the weight of the rocket? How do you chose what engine you need to use for your rocket?
Varun W.
  • 129
  • 2
-8
votes
1 answer

Mathematical inconsistences in rocket fuel

Saturn v is 2882 tons. Fuel is 30gj a tons. Escape velocity (11 km/s). 350 TJ of KE. The fuel is 85 TJ. The Saturn v has 3 times less fuel than it would need to escape gravity.
D J Sims
  • 1
  • 1
  • 7