Rocket with 6,500 delta v can't leave the atmosphere?

[UndyingWar]

Does anyone have any clue what could be causing this? The rocket is stable and flies straight, and there are multiple stages that detach. I'm at a loss. It can fly up to maybe 30k-40k. I might post a screenshot in the morning if that helps.

 

Is it possible my game could be bugged from a mod? I don't have anything that affects the atmosphere, aerodynamics or how rockets fly...

Edited February 27, 2018 by UndyingWar

[Ultimate Steve]

Yes, a screenshot would definitely help, at current there is not enough information to make more than a slightly educated guess.

[MaximumThrust]

Maybe you are looking at the vacuum dV instead of the atm one. Vacuum engines can give very high dV stats, but they are almost useless in ATM (In KSP, IRL they are completely useless).

Also Thrust To Weight Ratio also matters a lot. A rocket with 1.0 TWR will lose all it's fuel fighting gravity. 1.1 will rise very slowly, using only 10% of it's fuel to go up. A good amount is around 1.5. I personally like high values for TWR, like 1.5-2, reducing the throttle if needed after ~20 seconds, to reduce loses to drag (I usually let MJ handle this with the "LimitQ" feature).  

[James Kerman]

I would hazard a guess (assuming no bugs) that you may have too low thrust to weight on your upper stages?  Does your speed increase consistently or do you see it slow down or reverse during ascent?

If you are using an information mod in the VAB check atmospheric TWR.

Edited February 27, 2018 by James Kerman
Ninja'd

[Guest]

From your description, there are four possible causes I can think of. If there's more than one thing wrong, they compound each other:

1. You're using launch stage engines which don't work well in the atmosphere. Check ISP and dV at sea level and change to a different engine if necessary. 
2. You don't have enough thrust to weight ratio and are burning most of your fuel fighting gravity. Most important for the launch stage. Use bigger engines or add boosters.
3. You have too much drag and are burning most of your fuel fighting the atmosphere. Redesign to be more slippery, use fairings if you have them.
4. You're on an inefficient launch trajectory. Target 45 degrees at 10 km going 400 m/s or so.