Search the Community
Showing results for tags 'burn'.
Found 4 results
-
I once made an ion craft in a sandbox game and spun it out to Duna but it was able to do it in a single burn. When I watch videos on youtube I often see people doing multiple burns at periapsis to take advantage of the oberth effect, which I get. What I don't know though is how do you calculate what burn you need to do the transfers? Obviously you can't set up a single node ( or maybe you do ) for a single burn and surely after say 5 burns the planet your orbiting will be a day or 6 ahead in it's orbit so how do you know if you're still on target? The only video I've seen that even briefly covered how to do it was one of Matt Lowne's but it was very brief, I didn't quite get it the first time around and now I can't find which video it was. Can someone explain it to me or direct me to a guide on the subject?
-
Hey all, so I've been trying to build a mars tranfer vehicle somewhat in the vein of Hermes (from The Martian). For me, it's an 80 ton, crewed, ion propelled spacecraft. Unfortunately, when I got it assembled and fueled in orbit, I discovered that my mod install had reduced the thrust of the engines from 2 kN to 0.25 N which is 8000 times less thrust, and KER told me a 10 m/s burn would take 4 hours and change (8 engines). I am obviously going to have to rethink my plan, but that's actually not my main point of interest. \ All this got me wondering, how would a real world ion rocket leave earth orbit for an interplanetary transfer? I am very experienced with using multiple perigee kicks to make low thrust escapes, but the thrust of real life ions is SO low that this isn't possible. Even if I halved the mass of my rocket to 40t and tripled the number of engines, it'd still be more than half an hour for 10 m/s. At that rate, it'd take more than 300 kicks to reach escape velocity. I know that all real world ion spacecraft to date have been lauched into heliocentric orbits using chemical rockets, so I'm not sure it's actually possible to use such a low thrust system for earth escape. There are however, several hypothetical vehicles, both fictional and real concept designs, that do appear to exclusively use ion propulsion once in orbit. Does anyone know what kind of trajectory would be used? The only one I can think of is a very long spiral up to very high orbit, and from there on to deep space. However, I imagine this would eat up an absurd amount of dV, so it doesn't seem like a good option for anything except maybe a solar sail vehicle. Ion drives in stock are time consuming, but you can basically treat them the same way you would small chemical rocket engines like the LV-1. With realistic ion drives though, I don't have the first clue how to use them. Thoughts? Ideas? -
I've built a big ship for a manned travel to Mars.It's powered by 3 nuclear engines with Liquid Hydrogen as fuel.The complessive burn time is around 2 hours and the fuel is just enough to the whole trip to Mars and return ( no errors or DeltaV waste possible).So , what's the best way to save as much DeltaV as possible in maneuvers by doing them efficently?Are there any rules that I have to know on how to save fuel? The ship plays a lot on throwing away empty tanks ( life support and fuel), squeezing DeltaV to make the vehicle lighter.Start mass : 600 tons. End mass (from Mars to Earth): 150-200 tons.
-
I have a couple of questions about the above. When circularising my orbit above Kerbin should I also be checking the inclination and if so what should it be at for the best transfer orbit to Mun? Often when I burn for the Mun I find the encounter is going to kick me up at around a 30-45 degree angle. Going for a capture burn at periapsis then puts me in a heavily inclined orbit around Mun. This is ok for tourists and small satellites when I have plenty of dV to spare but I'd like to do things more precisely. May I have some tips on getting a more equatorial orbit around Mun?
