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PearsonArtPhoto
PearsonArtPhoto
02:34
Guys... are you ready!? #FalconHeavy LAUNCH DATE! February 6th, with a backup on the 7th. Launch time is 13:30-16:30 EST (18:30-21:30 UTC) #ItsHappening
Tweeted by ChrisG_NSF on January 26, 2018 at 7:00 PM
Mazura
Mazura
03:22
Would it ever be more efficient to continue burning once/as you exit the atmosphere, than it would to exit and then wait to burn at your apoapsis?
... in KSP ;)
It doesn't really matter? There's this thing called 'q' that I shouldn't be exceeding... so it's : yes, exactly halfway between the two? I.e, a gravity turn?
According to the preset on MechJEb, I would guess I should try to get as close to 2000 pa as possible, but never exceed it?... The balance between fighting gravity and fighting the atmosphere?
 
9 hours later…
PearsonArtPhoto
PearsonArtPhoto
12:21
@Mazura The ideal burn is to do it all as quickly as possible, but it's challenging.
The faster you are going, the more of an affect you have from the Oberth effect, and the less gravity drag you have.
The best trajectories, as I recall, is to be at about a 45 degree angle at 10 km, and almost pure horizontal at 30 km.
Keep going until you are about 75 km, and then wait to burn until you hit that point.
 
4 hours later…
Mazura
Mazura
16:19
@PearsonArtPhoto burn as quick as pos - does that hold true in the real world? Everyone says not to go too fast at first or you're wasting fuel on aerodynamic drag. Do we not have real rockets with enough TWR to even bother considering that effect? Or is there a name/equation for that too?
And finally, what about that trajectory changes if I'm using an SSTO with giant wings on it? ;) Does that change everything and I should get what I can out of my lifting surfaces first, while I can still use my 7k ISP air breathing engine?
PearsonArtPhoto
PearsonArtPhoto
16:43
It is true that too fast in the atmosphere is bad. The newer aerodynamic model is more realistic then the previous, but year, going fast and low will burn fuel quickly.
SSTO changes things considerably. It depends on the engine type, but basically go fast until you are at the peak speed for your engine, go up slowly until you reach about 15-20k, and then level off to build up speed. When you reach the max speed, go up at a steep angle. There is far more depending on the engine you are using.

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