@AirCrashInvestigationFLR I don't have a discord, how about this: i'll tag you on an unlisted post and you give me the link there.

@Korzalerke The problem is, the speed keep decreasing until the pitch angle is -20. It should increase if the pitch angle is -5.

@Korzalerke What is your discord? I never like sharing unfinished builds to public.

@Korzalerke Okay.

@AirCrashInvestigationFLR Can you post it as unlisted and give me the link? Maybe i can figure out what's wrong.

@Korzalerke Well, it does work. But only for a limited amount of time. The main problem is drag.

@AirCrashInvestigationFLR Maybe try moving the wings closer to the center of mass? That should work.

@Korzalerke Okay, just tried it out. What is does is decrease the stall speed.

@Korzalerke Oh, liftScale. I never knew that existed! Thanks, gotta try it.

@AirCrashInvestigationFLR You're right about the acceleration and deceleration, for the lift problem there are two things you can try, one is increasing the wing size (may mess with the design) or, you can open the wings in overload, select the category 'Wing', add a item named 'liftScale' (written exactly like that) and set the number to something higher than 1 like 2.5.

@AirCrashInvestigationFLR
da.

@ZeroWithSlashedO
Okay, here is my solution:

For the acceleration, in the XML you find: powerMultiplier and you lower the value.
For the deceleration, it is all about drag, you find: dragScale and scale the value down. But im not going to spend 2 days since there is hundreds of parts.
For the glide, maybe because of the drag.

Is it correct?

Acceleration, you quite simply tune down the engine's power, but I dunno about the decelration. The gliding thing doesn't work probably because it doesn't have enough lift