Are there any rockets that leave extra fuel as a backup? For this purpose I mean fuel that is not intended to be used at any point during the mission. I’d imagine this could be useful in case of a non critical failure that increases the amount of propellant needed to reach orbit. Do any rockets do this?
$\begingroup$
$\endgroup$
3
-
10$\begingroup$ the industry term is "margin" $\endgroup$– Erin AnneCommented Aug 25 at 18:42
-
10$\begingroup$ They would be crazy not to. Shuttle launch propellant margin is described in this answer space.stackexchange.com/a/42011/6944 $\endgroup$– Organic MarbleCommented Aug 25 at 19:04
-
$\begingroup$ When you shut down because you ran out of fuel, you end up with a slightly random final orbit. Shutting down the engine before fuel is fully gone means you get to be exact about where you end up. There are ways to fix it if your launch vehicle doesn't get you exactly where you wanted to be, but it usually means your satellite has to burn off some portion of the fuel that would otherwise keep it on-station over time, which means it's spending some of its useful lifespan to get where it needed to be in the first place. A precise launch means your satellite lasts longer. $\endgroup$– Darth PseudonymCommented Aug 26 at 13:13
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
4
All of them have it. Because either the engine is turned off when there's still fuel left, or the engine is turned off because there's no fuel left. The former is under control ,the latter is not.
There is extra fuel that you can use to get more payload into orbit but if you use it, the uncertainty increases.
-
1$\begingroup$ Is "command shutdown probabiity" the chance that you don't run out of propellant? $\endgroup$ Commented Aug 26 at 0:50
-
-
3$\begingroup$ @OrganicMarble Yes, the probability that fuel doesn't run out before shut down command. $\endgroup$ Commented Aug 26 at 3:22
-
1$\begingroup$ One of rare exceptions was Intelsat 35e launch on Falcon-9. Previously it was planned to launch on Falcon Heavy, but because of delays and upgrade of Falcon 9 to Full Trust version the launcher was changed. The launcher upper stage had no cutoff, it worked "until flameout" to compensate the underperformance as much as it could. The launch was succesful. $\endgroup$– HeoppsCommented Aug 26 at 8:22