I am attempting to reach LKO in a air/spacecraft and always stall

[Sad+Lonely]

I am attempting to reach LKO in a air/spacecraft and always stall i use a rocket like engine but am always ending up falling even though i have enough fuel. Why?

[bewing]

Not enough thrust? Not enough wing area to give you lift? Too much drag? Posting a screenshot of your craft in flight might help to diagnose your problem.

[Sad+Lonely]

3 minutes ago, bewing said:

Not enough thrust? Not enough wing area to give you lift? Too much drag? Posting a screenshot of your craft in flight might help to diagnose your problem.

(BTW I am modded and am also using infinite fuel so i now fuel isn't my issue)
For some reason i am unable to post a screen shot (PrtSc refuses to work)

[bewing]

Usually F1 will get you a screenshot, and store it in your Screenshots folder (below your game folder). Then you will need to use an image hosting service such as imgur to post the image here.

[DeadJohn]

Since you are using infinite fuel, have you tried emptying your tank before takeoff so your craft is lighter? You might have to leave a little fuel to get the engine to ignite.

You said "modded"? Any mods like FAR that change the stock atmosphere's behavior, or mods like RSS that resize Kerbin?

When you stall, what's your velocity, altitude, and pitch?

What engine are you using? If it has poor vacuum performance you might be losing thrust at altitude.

What's your TWR (thrust to weight ratio) when you stall? TWR increases as you burn fuel because your plane becomes lighter. With infinite fuel you'll have a lower TWR. Kerbal Engineer Redux can display current TWR; I think the stock staging display can do it, too, but I rarely look there.

Are you taking off horizontally from the runway? A typical ascent profile is to climb to 20km (depending on engine and plane design), level off to a very slow climb, accelerate to 1300m/s, then nose up to 20 degrees. Higher TWR is easier to get to orbit; find a climb angle at takeoff that lets you continually accelerate yet avoid catastrophic overheating, and then you can just keep going without temporarily leveling off at 20km you can just keep climbing.

[Fierce Wolf]

What engine do you use? Most jet engines will drown in the vacum of high atmosphere.

[Vanamonde]

You're flying a rocket with wings? I suspect you're trying to achieve orbital velocity while too low in the atmosphere. Since your craft is not an air-breather, you won't lose anything by flying it more like a wingless rocket. Try going up first and then transition to horizontal flight.