Running out of fuel on orbital burn.

[nitrous729]

Hi, new to the game and forums. I have been successful making a decent circular orbit with smaller craft. I am trying to make an attempt to get to the moon following this video http://www.youtube.com/watch?v=cJk9U-A1ps4. I feel like i am doing everything right but i always run out of fuel while trying to get the apoapsis to 100km. Any ideas?

[dlmarti]

If you are running out of fuel, that is the problem:

1. The craft you made, may not have the capability (not enough delta-v).

2. Your launch could be really inefficient.

Can you show a picture of your craft, and describe how you launched it, and when you did your gravity turn?

but tbh, you just need to keep trying really. Try using one of the stock designs (yeah I know they are not the best). If you ABSOLUTELY cannot make it, ask someone here for their easiest to launch design.

[cmoody]

Welcome to the community. If you build the craft like it is in the video, there shouldn't be any problems. Make sure you modulate your throttle so you keep a respectable speed. (~140m/s up to 12,000m, then work slowly up to 500 m/s until orbit)

[capi3101]

If you've got an exact replica of the craft in that video, chances are there's issues with your piloting. Here's what you do: make sure your navball's centered straight up (the little dot on the blue side of the navball) until you get to about 10,000m altitude. Next, aim for heading 090 at 45 degrees elevation - you should see 90 on the nav ball and a line halfway between the straight up dot and the line where the navball turns brown; the intersection of those two is where you need to aim. Hold that heading until you're at about 30,000 or so, then check the nav map for your time to apoapsis. If it's anywhere between 30-45 seconds, go ahead and change your elevation to 10-20 degrees and continue your burn watching the nav ball - shorter period stay at 45, longer go immediately horizontal. Cut your burn once your Ap is at about 105k; you should still be in the atmosphere at that point so you'll lose a little to your apoapsis while you're coasting upwards. At apopasis, burn as necessary to circularize.

Try that and see if it helps.

[jacob97]

if you have the mechjeb mod or flight engineer mod, it will display the Delta-V of a spacecraft. As a rough guide it will take 4000 m/s to reach a stable 100km orbit, plus a bit if u need to increase height at a later time. the delta-v will depend on how sttep in ascent u take is

[dave4002000]

if you have the mechjeb mod or flight engineer mod, it will display the Delta-V of a spacecraft. As a rough guide it will take 4000 m/s to reach a stable 100km orbit, plus a bit if u need to increase height at a later time. the delta-v will depend on how sttep in ascent u take is

For someone brand new to the game, i would recommend planning no less than 5000m/s dV for a launch to LKO. Once pilot skill increases, that number can be brought down to around 4400.

[TheDarkStar]

As has been said, you need practice. Also, learn about dV, which is the total change in velocity (not net change). The formula for it is dV = I_sp * G * ln(starting stage mass / ending stage mass). G is about 9.81 m/s², or Earth gravity. More efficient engines change your dV a lot, having a lot of fuel increases it with diminishing returns, and excess weight (like too many engines on an orbital transfer stage) lowers it.

[scooterjes]

As one of the previous posters suggested I will post some pics and the craft file(if you are interested) this rocket can easily lift 50-60 tons into a 100km orbit. As you can see I use Mechjeb(my piloting skill are mediocre at best) but that rocket is very stable and fairly easy to fly the only change you might want to make is depending on your payload is to add a RTG(electricity generator) or 2 and a battery.

https://docs.google.com/file/d/0B5QtXfJCkXZfLVVGcWZMeVBicWM/edit?usp=sharing

https://docs.google.com/file/d/0B5QtXfJCkXZfMm91Yy1xV0c3eFE/edit?usp=sharing

https://docs.google.com/file/d/0B5QtXfJCkXZfcndJdl9oMV8taUk/edit?usp=sharing here is where you can download the craft file while if you want to study it.

Edited August 3, 2013 by scooterjes