Gravity turn oops indicator.

[Bryce Ring]

I have been putting the few Brain cells I have to work regarding gravity turns, and came to the conclusion that while in the atmosphere and wanting to maintain zero lift you can increase the Trun shape % by reducing TWR and you can decrease the turn shape percentage by increasing the TWR, but I am thinking that if you are limited to a TWR, and you accidently increase your Trun shape % too much, then when you try to increase it from that point with the max TWR you currently have, then you will not be able to stop the vector passing below horizontal before you want it to without correcting by pitching/yawing above the Velocity vector and thus presenting a huge side portion of you rocket to aerodynamic forces that may cause IRL un wanted damage. OOPS

is there a mod or way to tell when you are getting close to you TWR's capability to keep your velocity vector above horizontal without needing to correct with the unwanted introduction of slip side drag destruction.

Bryce Ring.

[pincushionman]

Yes. Any mod that will display your time to apoapsis (KER, MechJeb) will help, because your velocity vector is horizontal at that point. You can even use the map screen to do this, it displays such time. If this value is decreasing while under power, you are losing the fight with gravity.

Although if you're trying one of those burn-once-until-circular stunts, that might not be the case at the end.

Edited January 21, 2015 by pincushionman

[Bryce Ring]

anything that can predict and indicate how close you are to the "YGD" point while coasting at reduced TWR to get a more shallow turn shape (Ya Gana Die)

[Laie]

is there a mod or way to tell when you are getting close to you TWR's capability to keep your velocity vector above horizontal without needing to correct with the unwanted introduction of slip side drag destruction.

I'm not sure whether I understand the last four words. Are you playing with some aerodynamics mod that will tear apart your rocket if you point too far away from prograde?

Like pincushionman, the best indicator I can think of is the time-to-apoapsis, modified by some experience. TTA can be seen in map view, and eccentricity too, so you're all set. You may want to start flying by TTA: during your next ascent, as soon as time-to-apoapsis reaches one minute, you start pitching downward to keep it at one minute. Once you're pointed at orbital prograde, you leave it there (skilled pilots can do that for you, or Smart A.S.S.) and reduce throttle to keep it at one minute.

A little more advanced: in the end, your orbital velocity should be ~2200m/s. Take the difference between that and your current velocity, then divide by your acceleration (a simple calculation that can be done while flying). If TTA is so far in the future that your vessel can reach orbital speeds until then, you're safe. Actually, TTA may be less because as long as you're under power, you're constantly moving it forward. How much less, I can't tell. I guess it should be possible to calculate this (that would be the precise number you're asking for), but as for myself, it's a gutsy-feely thing.

[flashcactus]

Well, as was said before, a good guideline would be to monitor your time to apoapsis (with or without mods, doesn't really matter). The general idea being that if it decreases at some rate, then compare the burn time you have left and the time until it reaches zero. Note that this is a very rough guess, as it will start going up as you increase your orbital velocity and/or TWR (both of which will happen).

There probably is no mod that would actually integrate this for you, showing where you'll end up if you continue with the current setting and/or if you throttle up to full right now. It should actually be pretty easy to write a script for a mod like Kerbulator or kOS that does it if one knows how to calculate this. Unfortunately, I don't know anyone who does :-/

So, to sum it up, your best bet would be either eyeballing it or figuring the correct profile out by trial-and-error (which is pretty much what I tend to do).

[Alshain]

The general idea is to hold your Time to Apoapsis at a decided value. This all would be in the later part of the ascent (after you leave the soup-o-sphere) so it wouldn't differ too much between Stock and FAR... in theory, but I only use FAR so I have no pratical test of this. Works beautifully in FAR though.

I usually aim for 1 minute to Ap. If you start getting closer to the Ap your going to fall back once you reach it and if your Ap isn't as high as you need it, that is bad. Likewise, if you get too far away, you burning too much fuel and you will end up with a sharper arc and a longer circularization burn. So you adjust your throttle to maintain 1 min to Ap while burning just ever so slightly above the artificial horizon. By the time you reach 80km Ap, you should have at least a positive Pe if you timed it right, unfortunately there is no exact science to this*, you just have to practice it.

Your circularization burn should only be around 5 seconds. In a nutshell, you use the same fuel to raise both your Ap and Pe, rather than using fuel to raise your Ap then more fuel to raise your Pe.

*EDIT: In KSP, I'm sure NASA has some exact science for this.

Edited January 22, 2015 by Alshain