Skip to main content

Questions tagged [restartable-engine]

A rocket engine, or other impulse engine, which is designed to be fired more than once.

Filter by
Sorted by
Tagged with
5 votes
1 answer
171 views

Why would you want a low turbine temperature in an expander bleed cycle engine?

In a paper by Sippel et al. [1] the following statement is made on page 2: "Consequently the LE-5B turbine drive gas temperature has been successfully reduced [w.r.t. the LE-5A engine]." ...
Ruben's user avatar
  • 1,154
2 votes
1 answer
126 views

Decomposing HTP through regenerative cooling for use in closed expander cycle

HTP or high test peroxide has a long history as a low cost and high reliability oxidiser, and has had a lot of recent attention for its pseudo hypergolic nature when passed over a catalyst bed. ...
R. Hall's user avatar
  • 822
14 votes
2 answers
3k views

Can nuclear thermal engine designs be shutdown in such a way as to be restartable, in space?

Nuclear thermal rocket designs have a working temperature of 2000k or greater. Shutting such a reactor down won't stop that heat production instantly - it'll take quite some time to cool. Do current ...
user2702772's user avatar
  • 1,114
0 votes
0 answers
102 views

Preventing hard starts using varied propellant/ O/F ratio?

From what I've heard, hard-starts are a very common, particularly in less refined amateur rocket engines, and the only way to avoid them is to either start the engine on an extremely low flow rate or ...
R. Hall's user avatar
  • 822
8 votes
2 answers
317 views

Falcon 9: Why does F9 first stage always lose Video Link during Entry Burn?

Typically the F9 first stage and the drone ship each lose the video connection once during landing: F9 first stage during entry burn Drone ship during F9 first stage touch down (see here and here) ...
Dave's user avatar
  • 183
3 votes
1 answer
321 views

Why did the Agena-D leak oxidiser when starting its engine?

The Agena-D upper stage, although extremely reliable, had a tendency to leak some of its RFNA oxidiser when starting its Bell 8096 engine; although not a problem for a stock Agena-D, it did cause ...
Vikki's user avatar
  • 4,157
12 votes
1 answer
1k views

Why didn’t the space shuttle’s engine-out checklists include steps for attempting a relight?

Throughout much of a space shuttle ascent, even a single SSME failure would have left the mission’s intended orbit out of reach and forced some sort of abort; a two-SSME-out situation would have left ...
Vikki's user avatar
  • 4,157
1 vote
1 answer
67 views

How do you read an Engine Throttling specification of 3-5:1 in percent thrust load?

I was looking at the CECE engine by Aerojet, however I am not sure how to determine the trust range of percent thrust range of the engine. How I can translate the throttling spec into a percent load ...
user28833's user avatar
  • 499
3 votes
2 answers
153 views

Is there an upper stage main engine that is human ratable and may out perform the Common Extensible Cyrogenic Engine performance by Aerojet?

I am fasinated by Aerojet. The CECE, has a total qualified burn time of 10,000 seconds and with a total of 50 restarts. The LOX/LH2 engines have a great performance with a specific impulse of > 445. ...
user28833's user avatar
  • 499
4 votes
0 answers
72 views

Chilling during restart of Spacex first stage engine [duplicate]

As I know that all the liquid rocket engines go through chilling process for different components (like pipes, engine, injector plate, etc.) before starting the ignition. At the time of launch the ...
Amar's user avatar
  • 2,246
3 votes
1 answer
1k views

How long does Augmented Spark Igniter fire?

The heroicrelics.org page J-2 Rocket Engine Augmented Spark Igniter mentions that The ASI operates continuously during entire engine firing Does this how all spark igniters function in rocket ...
karthikeyan's user avatar
  • 4,479
1 vote
1 answer
2k views

How is a spark plug igniter of rocket different from one used in IC engines?

US20120103302 shows a spark ignited prechamber combustion system typically used for IC engines. It basically consists of a chamber which has a input of premixed fuel-air mixture and a spark plug to ...
karthikeyan's user avatar
  • 4,479
6 votes
1 answer
720 views

Which is the preferred mode of liquid rocket engine cutoff - fuel lean cutoff or fuel rich cutoff?

When a bi-propellant liquid rocket engine receives a command to shut down, will the fuel gets cut off first and then the oxidiser - a fuel lean cutoff? Will the oxidiser gets cut off first and then ...
karthikeyan's user avatar
  • 4,479
3 votes
1 answer
615 views

When this F9 2nd stage engine suddenly moves upon shutdown, is it moving along the rocket's axis?

The GIFs are made from frames of the live broadcast of SpaceX JCSat-16 2nd stage around the time of the second engine cut-off (SECO-2). It looks like the engine moves outward axially as the thrust ...
uhoh's user avatar
  • 148k
0 votes
2 answers
597 views

Have reliable, restartable LH2/LOX engines ever existed? - ever used? [duplicate]

I just wrote the following paragraph as an edit to this answer: Using LH2 for regular burns to maintain ISS altitude would require a whole new set of engines that may not yet exist anywhere. While ...
uhoh's user avatar
  • 148k
11 votes
1 answer
982 views

What ever happened to SpinSat - did it work?

I can find several descriptions of what the SpinSat satellite was supposed to do. I can find some nice images of it being deployed from the ISS also. But I haven't been so successful in understanding ...
uhoh's user avatar
  • 148k
12 votes
1 answer
5k views

How does an Electric Solid Propellant rocket work?

I saw the section in Wikipedia about Electric Solid propellants but I can't figure out what it really is, and how it works. It sounds like a solid propellant rocket that you can start and stop ...
uhoh's user avatar
  • 148k
20 votes
2 answers
26k views

Why is TEA-TEB chemical ignition used instead of spark ignition?

Both the Saturn V and the Falcon 9 use TEA-TEB to ignite their kerosene-fueled engines. TEA-TEB is pyrophoric, igniting spontaneously on contact with air. This poses handling issues; it must be stored ...
Russell Borogove's user avatar
6 votes
1 answer
4k views

What causes the green flash during Falcon 9's ignition?

Right before Falcon 9's engines start, there's a green flash. I assume it's some kind of chemical ignition. What makes the flash the color green?
Thane Brimhall's user avatar
3 votes
1 answer
2k views

Why were there green ignition flashes after Falcon 9's landing?

Whenever Falcon 9's engines start, there's a green ignition flash. During the latest landing there were similar green flashes right after touchdown: 1st stage landing (3 camera angles): ...
Thane Brimhall's user avatar
4 votes
1 answer
409 views

How often can liquid hydrogen engines be restarted?

A proposal for lunar development, LunarCOTS, relies on a reusable shuttle running on LH2 and LOX to work. It lands, is refueled on the lunar surface, and then takes off again. Presumably it could sit ...
kim holder's user avatar
  • 21.4k
12 votes
2 answers
3k views

What limits the number of times that a liquid fueled rocket can restart?

I know the upper stage of the Falcon 9 can be restarted once, thus allowing an additional thrust for some circumstances that might require it. However, I don't really understand the mechanism that ...
PearsonArtPhoto's user avatar
  • 121k
9 votes
1 answer
2k views

Practical limits to a restarting a main rocket engine in orbit? [duplicate]

With current technologies, are there practical limits on the number of times a rocket engine can be restarted while still remaining in orbit? Given sufficient fuel, could an engine be designed today ...
Jerard Puckett's user avatar