Phantom force on vertical launch

[DeMatt]

Build a satellite of about 0.5 tons. Put it on top of an S1 SRB-KD25k (the biggest stock SRB), using a TR-2V decoupler. Tweak the SRB's thrust down to 60%, then launch straight up (hit T, hit Space, hands off the controls). The resultant flight will have the SRB burn to about 46 kilometres altitude, with an apoapsis just above 450 kilometres.

So where's the phantom force, you ask? Well, if you let it stay in normal 1x time, while clear of the atmosphere, the apoapsis of our unpropelled satellite (and its discarded booster) will tick down by about 1 metre every four to five seconds. Switching to 5x time acceleration freezes the apoapsis, but reverting to 1x time causes it to resume shrinking.

This behaviour was seen on v0.90.0.705 Beta, via Steam. Yes, this doesn't sound like much, but when you use the satellite's own engine to further increase altitude (e.g. to the Mun), it interferes with the high precision needed by such a bare-bones launch.

[vexx32]

The issue here is that you shouldn't be able​ to use 5x warp before you're at 70km altitude. Are you using any mods?

[DeMatt]

The issue here is that you shouldn't be able​ to use 5x warp before you're at 70km altitude. Are you using any mods?

No mods. The phantom force (and thus the time acceleration) is all AFTER passing 70km.

[vexx32]

Ah, I see. I misread. I'm not 100% certain, but if that's the case, it's likely that the phantom force is the result of floating-point errors...

Hard to say if there's anything that can be done about it.