Keep passing Apoapsis.

[Solis]

So I finally got into orbit a few hours ago by watching Scott Manley's tutorial but one weird thing that happened is that I passed my apoapsis but still got into a very stable orbit. (and even re-landed)

However now whatever I do I pass the apoapsis and theres nothing at all that I can do about it even though im using the same ship and doing the same maneuvers.

Note: I am in career mode and on PS4.

[bewing]

Welcome to the forums.

If you pass your Ap by too much while you are burning prograde, it can get inefficient. That is, you end up raising your Ap really high while you are raising your Pe. In some cases, you can even fall back into the atmosphere if you take too long to get your Pe above 70km. On the other hand, passing your Ap by a little while you are burning doesn't cause any problems at all.

In order to avoid passing your Ap, you need to have a fairly powerful engine, and you have to control your trajactory fairly carefully. If you go a little too "straight up" then you may not even be able to make orbit. There's a tricky thing called a gravity turn that gets you to orbit efficiently. It takes practice.

 

[Spricigo]

Achieving orbit after passing apoapsis is not a problem per se. However it may be a signal that  a bit more TWR would increase the efficiency of the ascent. (As bewing pointed) 

Something that may help its to keep a bit of pitch up while circularising. It's less efficient than a pure prograde burn,  but a much better alternative than falling back into atmosphere. 

Finally,  as any question that is craft dependent,  a image of the vessel can help to diagnosis a particular problem and give more tailored advice. 

 

[Solis]

16 hours ago, Spricigo said:

Achieving orbit after passing apoapsis is not a problem per se. However it may be a signal that  a bit more TWR would increase the efficiency of the ascent. (As bewing pointed) 

Something that may help its to keep a bit of pitch up while circularising. It's less efficient than a pure prograde burn,  but a much better alternative than falling back into atmosphere. 

Finally,  as any question that is craft dependent,  a image of the vessel can help to diagnosis a particular problem and give more tailored advice. 

 

Im not sure how to post a pic here from my PS4 so ill try describing it instead.

My rocket is incredibly simple with 4 FL-T400 fuel tanks. First stage has 3 tanks with a "reliant" engine and the second has 1 tank with a "terrier" engine and a MK1 Command Pod. Has 3 basic fins at the very bottom, a Mk16 patachute, a Communatron 16, and 2 Goo Canisters on the command pod. The first design of the rocket had 3 "hammer" engines on the side but I removed them because I couldn't make my gravity turn soon enough.

So does all of that look right?

My process is this: As I launch I slightly point east and once im at 10k meters point 45°. Once my apoapsis is at 100k I cut engines until im almost right at it and burn prograde full throttle until my PE is at 100k as well. 

Last time I went into orbit my AP was about 120k and my PE about 100k.

Edited June 3, 2017 by Solis
Grammar

[bewing]

Then you have to start burning prograde just a few seconds sooner.

And you should be able to get screenshots on your PS4 by clicking the "Share" button once. Then exit the game. The screenshot should be in your Caputres folder -- and you can put it on a USB drive if you need to, in order to move it to a PC. Read the FAQ in the forum about how to post an image on a thread -- you need to use an image hosting service.

 

Edited June 3, 2017 by bewing

[Solis]

5 hours ago, bewing said:

Then you have to start burning prograde just a few seconds sooner.

And you should be able to get screenshots on your PS4 by clicking the "Share" button once. Then exit the game. The screenshot should be in your Caputres folder -- and you can put it on a USB drive if you need to, in order to move it to a PC. Read the FAQ in the forum about how to post an image on a thread -- you need to use an image hosting service.

 

Alright, ill have to look into that next time.

I think I have figured out my problem but im not too sure. I launched just now and tilted a little further east than usual and when I looked at the map I noticed that the trajectory line was widening by a ton. Im pretty confused as to if this is a good thing or even exactly hoe it happened so some clarification would be useful haha.

Thanks for all of your help btw. I would figure that people would get tired of helping new players all the time! (Especially if said player doesn't even know exactly what hes doing and how it works half of the time!)

Edited June 4, 2017 by Solis

[bewing]

Yes, widening your trajectory line is a very good thing. That's the basis of getting the most efficient possible gravity turn.

[Spricigo]

As you noticed a degree can make a huge difference.  You will also notice that reaching orbit is a matter of achieve enough horizontal velocity.  The only reasons to not go horizontal rigth from the launchpad are the atmosphere and the terrain. 

 

Unlocking the Launch Stability Enhancer,  under the General Construction technology node,  will allow to have your rocket tilted at the launchpad.  That in turn make powerful rockets with low control authority more viable. 

 

[Human Person]

In reality, many spacecraft do burn past Apogee to circularize, including the Saturn 5. They do this to reduce dry mass by using fewer/smaller engines thereby reducing TWR.

It's a trade off, they now have to deviate from prograde to perfectly circularize.

Rockets with a higher TWR later in the Ascent phase (e.g. Falcon 9 or the Space-Shuttle) don't necessarily need to do this.

Edited June 5, 2017 by Physics Student

[Zhetaan]

@Solis:

If your flight path has you pointing a few degrees east and then forcibly turning your rocket to forty-five degrees at ten kilometres altitude, then you can get some more efficiency out of it by taking a smoother ascent.  If possible, you can help yourself a lot by letting the rocket turn slightly but constantly so that you start a few degrees east (as you do) and then sweep through the angle so that you happen to be pointing at forty-five degrees at about ten kilometres altitude.  By the time you reach thirty kilometres, you should be pointing almost horizontally.  Those points are just rough thumb rules, though, so don't feel the need to go crazy over them, and a lot will depend on the rocket itself.  If you design it correctly, the rocket can actually fly itself to orbit with nothing more than a little nudge at the beginning (to point it the first few degrees east) and a bit of throttle control (to keep your apoapsis the right distance ahead of you).  That's a true gravity turn, and there are a few example craft scattered about the spacecraft exchange and tutorials to show you how to make a rocket that can do this--though you're honestly fairly close with what you have.

One of the Scott Manley videos also mentions switching to map view occasionally and keeping your apoapsis roughly a minute ahead of you until you're almost circularised.  This advice is still good and can help you see what you want the trajectory to do.  Having it widen is a good thing because it means that you're raising your periapsis and making an orbit rather than a dive-bomb.  One of the things to remember about orbits is that the key is horizontal velocity, not vertical velocity.  The thing that keeps you in the sky is not going up but rather, in the words of XKCD, 'going sideways really fast'.  When you start off you need to go up a little because you have to get off the ground, get out of the atmosphere, and fight gravity for long enough that you can build up enough horizontal velocity that you don't need to fight gravity any more, but in order to save fuel and effort, you also need to start tapering off the vertical component in favour of the horizontal one right away--which is what you do when you nudge it a few degrees east and sweep through the turn.  When you get to landing on and returning from Mun and Minmus you'll find that you can take off and then turn nearly horizontally almost as soon as you leave the ground, so you're actually learning the more difficult ascent first, on Kerbin.

Congratulations on making orbit--now you're halfway to anywhere.  Have fun.

[Solis]

@Zhetaan

Thanks!

And, actually, since the time of posting I have made an orbit around the Mun and are attempting to make a return trip. All I need is to do is add a heat shield and im golden!

 

[Kryxal]

Returning from the Mun without a heat shield tends to not be that big a deal, but you can't afford to be low on your reentry.  It might help to keep your engine attached and use it as a heat shield.

Also, one key reason for the gravity turn is that you don't want to try to point much off surface-prograde until you're quite high up, bad things tend to happen, so you want to make gravity altering your trajectory work FOR you.

[Rocket In My Pocket]

Keep an eye on your "time to AP" you want to be somewhere between 5-20 seconds from it while circularizing your orbit (You can check time to Ap in stock by mousing over the Ap node in map view.). Raise your nose to increase time till Ap, lower it to decrease. Imagine your craft is "pushing" it along on it's nose.