Using the target button for launch

[SteveP]

 I have a question about the target button while I was doing one of the tutorials that are built in to the game I was told that I can hit the target button and the pilot would actually take off and follow  The trajectory to where I need to be how do I create that so that I can have the  pilot do the beginning trajectory to get me to a good orbit every time I do it I screw it up. 

Thank you

[Pecan]

Can you point me to where it said that?  The SAS target prograde/retrograde will point your ship in the relevant direction but that's usually a lot different to the direction you'd need to burn in order to reach the target.  Even with the correct manoeuvre node calculated and set - which stock KSP won't do for you - there is no 'autopilot' feature in KSP that will actually do the burn at the right time.

The MechJeb mod has exactly such an autopilot function but even so launch-to-orbit through an atmosphere is the least predictable of flight stages, because of drag, etc.

[SteveP]

What I will do is record the portion of the tutorial where that part happens und upload it to YouTube with a link. This should better explain what I am talking about. 

[SteveP]

Here is What I was talking about. I hope it explains it better.

 

 

 

 

[Pecan]

Right ... seems to have been a forum error but let's hope this reply gets through.

OK, nicely explained.  This is the "Go For Orbit" training mission and ... there is no similar 'target marker' for normal launches :-(

As mention, the MechJeb mod does have a "Show ascent navball guidance" button in its Ascent Guidance module.  You can use this even if you don't want to use the autopilot itself (in which case, just don't click the "Engage autopilot" button).  Note that there is no one 'perfect' ascent path - it depends on each vehicle's design and aerodynamic performance.  As a general rule - whether you're using MJ or not - I find I generally want to be at around 45-degrees from the horizon at around 10km altitude.  Start the turn early (by 1km altitude) and don't turn too quickly - keep the 'heading' indicator within the prograde marker if in doubt - or drag will probably cause your vehicle to flip.

[SteveP]

1 hour ago, Pecan said:

Right ... seems to have been a forum error but let's hope this reply gets through.

OK, nicely explained.  This is the "Go For Orbit" training mission and ... there is no similar 'target marker' for normal launches :-(

As mention, the MechJeb mod does have a "Show ascent navball guidance" button in its Ascent Guidance module.  You can use this even if you don't want to use the autopilot itself (in which case, just don't click the "Engage autopilot" button).  Note that there is no one 'perfect' ascent path - it depends on each vehicle's design and aerodynamic performance.  As a general rule - whether you're using MJ or not - I find I generally want to be at around 45-degrees from the horizon at around 10km altitude.  Start the turn early (by 1km altitude) and don't turn too quickly - keep the 'heading' indicator within the prograde marker if in doubt - or drag will probably cause your vehicle to flip.

Thank you for your reply the one thing that I noticed about flying with the keyboard especially making  Thank you for your reply the one thing that I noticed about flying with the keyboard especially making movements because you have to constantly tap on the keys which in turn makes jerky movements. When I watch videos of takeoff I never see these jerky movements. Am I doing something wrong.  I want to try that ascent guidance modul, are there any good videos to watch to learn how to use it??

[kBob]

Try using the caps lock key; then hit the movement keys they will have a much finer control.  Do note that this mode gets reset when you do other things so don't pay any attention the LED caps lock indicator, if you are getting big fast movements with the keys than fine control if off and you need to hit caps lock again to turn it on.  Also sometimes having SAS on (especially pro/retrograde hold) can cause jerky motions though I mostly notice that on re-entry.

[SteveP]

14 hours ago, Pecan said:

Right ... seems to have been a forum error but let's hope this reply gets through.

OK, nicely explained.  This is the "Go For Orbit" training mission and ... there is no similar 'target marker' for normal launches :-(

As mention, the MechJeb mod does have a "Show ascent navball guidance" button in its Ascent Guidance module.  You can use this even if you don't want to use the autopilot itself (in which case, just don't click the "Engage autopilot" button).  Note that there is no one 'perfect' ascent path - it depends on each vehicle's design and aerodynamic performance.  As a general rule - whether you're using MJ or not - I find I generally want to be at around 45-degrees from the horizon at around 10km altitude.  Start the turn early (by 1km altitude) and don't turn too quickly - keep the 'heading' indicator within the prograde marker if in doubt - or drag will probably cause your vehicle to flip.

Hey Pecan, is there anyway to make the mod work without having to go through the hole science tree?? I just want to use the mod so I can get a good orbit but with the mod in career mode you have to be fairly into the game in order to get the research that you need to unlock that specific section of the mod. 

[Pecan]

2 hours ago, SteveP said:

Hey Pecan, is there anyway to make the mod work without having to go through the hole science tree?? I just want to use the mod so I can get a good orbit but with the mod in career mode you have to be fairly into the game in order to get the research that you need to unlock that specific section of the mod. 

No simple way as far as I know (all sorts of config-file editing is needed).  While you're learning it's best to just practice in sandbox mode if you can cope with all the similar parts.  That way you can follow anyone's instructions/tutorials,  kBob mentioned using SAS prograde lock once you've made your initial (5-10 degree) turn and the prograde marker shows you aren't going straight up any more. After that prograde will always tend to be a little lower to the horizon than your heading - because not all your thrust is countering gravity.  With a bit of practice on the initial turn and when to engage SAS (I tend to put it on a few seconds after prograde has passed heading) then as SAS follows prograde and prograde continues to drop you 'should' be able to get a reasonably smooth and continuous turn.  Switch to map mode and engine-off when Ap reaches the desired altitude (eg;  75km to ensure you're clear of the atmosphere) then create the orbit injection manoeuvre node and turn to the manoeuvre marker once in space at 70km,  Finally circularise by doing the burn starting half the time before you get to the node (so if the burn will be 10s start 5s before you get there).  A 'proper' gravity turn is exactly the same but doesn't use control-input or SAS at all after the initial turn - it merely requires you to design a rocket that will fly the curve all on its own (simple right ^^).

Note there is a lot of 'about' and 'around' in what I'm saying - a lot does depend on specific vehicle design, drag characteristics, TWR at different altitudes/stages, etc. etc.

Edited July 26, 2016 by Pecan

[SteveP]

Awesome thank you for all the information I appreciate it. 

[SteveP]

On 7/26/2016 at 11:36 AM, Pecan said:

No simple way as far as I know (all sorts of config-file editing is needed).  While you're learning it's best to just practice in sandbox mode if you can cope with all the similar parts.  That way you can follow anyone's instructions/tutorials,  kBob mentioned using SAS prograde lock once you've made your initial (5-10 degree) turn and the prograde marker shows you aren't going straight up any more. After that prograde will always tend to be a little lower to the horizon than your heading - because not all your thrust is countering gravity.  With a bit of practice on the initial turn and when to engage SAS (I tend to put it on a few seconds after prograde has passed heading) then as SAS follows prograde and prograde continues to drop you 'should' be able to get a reasonably smooth and continuous turn.  Switch to map mode and engine-off when Ap reaches the desired altitude (eg;  75km to ensure you're clear of the atmosphere) then create the orbit injection manoeuvre node and turn to the manoeuvre marker once in space at 70km,  Finally circularise by doing the burn starting half the time before you get to the node (so if the burn will be 10s start 5s before you get there).  A 'proper' gravity turn is exactly the same but doesn't use control-input or SAS at all after the initial turn - it merely requires you to design a rocket that will fly the curve all on its own (simple right ^^).

Note there is a lot of 'about' and 'around' in what I'm saying - a lot does depend on specific vehicle design, drag characteristics, TWR at different altitudes/stages, etc. etc.

Ok Pecan or anyone here is another video showing where I am stuck, If anyone can help me I would greatly appreciate it

 

[Pecan]

(Written on return from pub.  Will edit when more capable!)

Forgive me, the start of this is going to sound bad but the whole is that I love your frustration because it shows what we've all been through so well.  The videos of what you are doing and your explanation of what you're trying to do are great (not too long and no "repurposed bovine waste" <- phrase substituted by mind-control censor software)  You're explaining things brilliantly and once you start making tutorial vids you'll be a natural.

Dude - you asked MJ to take you to the moon; so it has set you on a course to hit that rock dead-centre.  "Landing" straight-down from several thousand km is not a good choice.  I know you're new and I know you're trying but - excuse me - that's why I love that it doesn't work!  I hope you understand that I'm laughing with you.  We've all been through the crying with you stage and you'll soon be laughing too.

So; you have an 'encounter' with Mun; it's the biggest thing in your sky.  There are 3 possibilities:

1) Impact = Fly fast enough towards a rock, or slow enough while a rock comes up behind you, and it's all going to end badly suddenly (I wouldn't want to prejudice any collision-related mission objectives you may have ^^).  That's what's happening at the moment.
2) Fly-by = not matching orbits closely enough to it that you stay in its Sphere Of Influence (SOI), you'll just sail straight past it.
3) Orbit.  Like getting to space - orbital altitude is not enough on its own.  Without an orbit injection burn you'll just fly past your target or smash into it.  You will have seen your orbit-line expand towards Mun's altitude as you did your (Kerbin) ejection burn.  THAT orbit still holds true.  After the burn your ship drifted until it entered Mun's SOI.  It's orbit is still around Kerbin (and the sun) as well.  If you don't adjust your orbit then you'll either smack straight into Mun (as now) or fall back towards your Kerbin Pe.

Remember getting to orbit in the first place?  
You burn until your Ap is where you want it, drift (engine off) until you get there then burn again to bring your Pe up to the same altitude.
  To orbit Mun (or anywhere else) you have to follow a similar regime - Burn to get there, wait until you're there, burn to circularise your orbit.  
Changes of SOI can be confusing.  It's possible to see your orbit as a Mun->Kerbin->sun oriented thing but not easy.  Best to just think about Mun in your situation (at least at first!).

Right now you are in such an orbit that before you fall back to Kerbin Pe you will smack straight into Mun.  Time to think about a fly-by as probably better than Impact!

Impact = Pe at/below ground level.  We sometimes call that "lithobraking" (aero-braking = braking using the air, 'litho' = rocks, work the rest out yourself).  It works if you're going slow enough relative to the rocks but ... you're not.
Fly-by = Let's try missing that sucker!  If you're heading straight for it then probably any other direction is a good bet.  In this case you want to increase your Pe so it is not quite so ... terminal.  Ideally you increase Pe at Ap but since you aren't going to get back to (Mun) Ap until you've literally bitten the dust NOW!! would be a good time.  Although it's well worth learning to do this stuff yourself I'm not one to reject a teacher so, in MJ, activate the Maneuvre Planner (sic).  This is THE most useful module in MJ!  Towards the top of the pop-up window is a button with the name of the required manoeuvre - Change Periapsis would be a good choce for you!  10km would be great, 9km 'brave' and 8km liable-to-hit-mountains.  The choice is yours.  I think I mentioned that NOW!! would be good = schedule 'after a fixed time', 0s (or 10s to give your vehicle a chance to turn), create and execute.

Phew!  Now you aren't going to die in the immediate future.  Just fall all the way back down to(wards) Kerbin.  Unless you orbit or land on Mun while you're passing.  It's not strictly necessary to enter orbit around a body before landing but it does make it a lot easier.  Specifically - because I get the feeling you're not going to be doing this manually - MJ will work much better if you orbit first, then land.

Orbit = Staying in the SOI (but above the litho- and, preferably, the aero-sphere) of a body.  Your (Mun) Ap is many, many Km away, the other side of Kerbin.  MJ might just have an option for changing Ap, similar to changing Pe.  Now you have a non-fatal Pe that's the best place to change Ap.  Circular orbits are good, so 10km (or whatever you chose above) is a good option.  No, I'm not telling you every button you should click.  I'm also not telling you there is a simple 'circularize' option (damn, I gave it away!).

*cough* Make sure Pe isn't inside some rock then circularise your orbit at that altitude once you get there, OK?

LANDING!
Alt-F5 lets you save a named version of your game.  Alt-F9 lets you reload it.
Go On!  Do it yourself.  You know you want to!
 

Edited July 28, 2016 by Pecan

[SteveP]

wow I must say that was the best reply I have ever read. It reads just like a book. I have been practicing different things and I did eventually land on the moon, Even found that huge structure for Neil Armstrong. I'm going to keep practicing until i know I can get It right then I would like to know how to send satellites to orbit lol.

 

[Pecan]

*grin* My KSP books Exploring The System and Induction To Construction are a bit out of date.  Hope you were amused by this answer.  Good job on the practice and landings.  Incidentally, in Exploring The System, I recommend the SCANsat mod for mapping planets and moons to find Easter Eggs like the Armostrong monument.

[SteveP]