Getting into orbit without killing your burn?

[Tortoise]

Why with IRL rocket launches

https://www.youtube.com/watch?v=So8SNjLg5kQ

They keep burning and never kill their burn, then wait til they get to their apoapsis and burn prograde like us KSPers do?

How do I do a launch like that?

I tried it, but my apoapsis ends up getting too high while my periapsis is still in the atmosphere.

I do use FAR.

Edited June 14, 2014 by Tortoise

[Maelstrom Vortex]

It's all about angling. If your apoapsis goes to high, then start turning earlier into a shallower angle. The apoapsis will come down, but the arc of your orbit will begin to extend.

[vetrox]

Practice.

I think the magic number is 2400 m/s to achieve a stable orbit. So when you get out of kerbins soupy part of atmosphere at 10km try shallower angles to get to orbit. Once you start to get proficient you will notice your circulization burns only gost 30m/s dv or so. You will get the hang of it eventually. ITs very satisfying when you do

EDIT: Just noticed you use FAR but still, dont go too shallow until you get above 10km or so

[Skorpychan]

That's because KSP rockets are overpowered, gravity is lower, and fuel is free. Plus, RL rockets don't just start and stop whenever like the ones in KSP.

[Fendleton]

From memory the reason IRL for not killing thrust is fuel flow: as soon as you go into microgravity it becomes a lot harder to get fuel out of the tanks when and where you want it (also how fast). To solve this, some craft use Ullage moters, tiny SRBs or other engines that don't have big tanks full of sloshy fuel that force the main tank fuel back to where the pumps can get it out.

In KSP, we don't really have to worry about this though.

[Kasuha]

You need to have weaker ship. Then your apoapsis will not rise so fast and you'll need to burn longer.

Also, FAR makes it easier to get into orbit as it produces less atmospheric drag.

[GoSlash27]

After your initial "gravity turn" kick at 7km, you bring your nose toward the horizon at a slow and steady rate so that you're pointing 22* off vertical at 15kM and 45* at 25km. Keep the pitch rate steady, and you will see your prograde marker switch from surface to orbit. At that point, switch to your orbit map view.

if you've kept your slow rate of pitch going, your apoapsis should be getting close to LKO altitude.

Now... the idea is to raise the periapsis without raising the apoapsis, so you steer it by what the apoapsis is doing. If you're pointed to the opposite side of the horizon far enough, your apoapsis won't change. If you're down even further, your apoapsis will decrease. Less, and your apoapsis will increase. No matter what, your periapsis will continue to increase.

The time to apoapsis will also be affected by what you're doing and vice- versa. the closer you get to apoapsis, the less effect your pitch angle will have on it's altitude, and the more effect it will have on it's time. You want to try to keep it 30 seconds ahead throughout the circularization.

So you juggle it simply by pitch to keep your apoapsis constant while raising your periapsis. Once it becomes impossible to keep your apoapsis marker steady at 30 seconds ahead, you're there, so cut the engine.

I've never used FAR, so I don't know how or if that will affect the process... but it shouldn't since the circularization happens outside the atmosphere.

Best,

-Slashy

[Kerba Fett]

Actual rockets are far more complex than KSP rockets. What happens if the engine wont restart AND there's a problem with the "Revert To Launch" button?

[Tortoise]

Thanks guys, i'll try.

[magnemoe]

You need to have weaker ship. Then your apoapsis will not rise so fast and you'll need to burn longer.

Also, FAR makes it easier to get into orbit as it produces less atmospheric drag.

Yes, then I launch ships where I use the LV-N as upper stage I tend to end up with the just a correction burn to circulate.

[pincushionman]

The "why" they do it was explained above, as well as the "how to do it in KSP". But the real secret to doing it in real life is...experience and engineering. Real launch companies and agencies have a lot of money invested in methods of tracking the past, current, and future states of the craft very precisely, and spend weeks or months working out the correct burn and turn schedule to get their particular craft where they want it, when they want it, with minimal fuss. With launches costing from hundreds of thousands, or millions, of USD per launch, this is not something to be taken lightly. A more efficient continuous burn that doesn't have the risks of losing fuel flow is well worth the cost and effort.

[Claw]

...snip...

Haha. Yes, I was going to post that each launch has an army of people behind it. All using sliderules and computers to ensure the launch is planned and simulated in great detail.

I am but one simpleton who is pretty happy when my rocket simply gets into orbit. Sometimes it's pretty, sometimes not.