Unsure about rocketry and gaining altitude

[Arctodus]

Hey all, first things first, I've been using this guy's guide, and its been ACE so far (found in Tutorials: http://forum.kerbalspaceprogram.com/threads/62814-Tutorial-Beginner-Science), and I asked my question in that thread too a few days back.

I'm having a problem with the posted mission 4 setup: I have everything recommended, but my rocket will just not gain altitude beyond 54km. Even before the second rocket has run out of fuel, I have started to descend, and this is while it's still boosting. As an experiment, I de-coupled my capsule from the second stage whilst it was firing, and it plummeted beneath my capsule like a stone.

Didn't have the problem with the mission 2 and 3 setup though, that was almost perfect to what it was said it'd be, it was great. The mission 3 setup runs out when it says it does, and I continue via momentum up to 110km, textbook.

If anyone has any ideas that'd be ace? I didn't want to just start strapping more rockets on before I knew what it could be

Thanks in advance!

EDIT: Answered!

Edited March 19, 2014 by Arctodus

[lockpicker]

I have no idea why that should happen to you.. Just tried it myself in a vanilla ksp, had the results the guide said.. The only things i can think of are:

1- Are you running any mods? If you are they may be interfering some way.

2- Have you set the correct thurst limiters?

3- Are you burning upwards only? (Trivial question, i know, but i can't think of any other reason..)

Hope this helps!

[Pecan]

Nope, just tested it and even without setting the thrust limiter so the boosters last longer it still got an apoapsis over 230km. Are you actually putting throttle to full when you launch? The solid rocket boosters (SRBs) don't need throttle - and in fact ignore it - but the T30 and T909 certainly do!

[Arctodus]

Thanks everyone for the quick answers!

I'm not running any mods, just vanilla KSP - I'm astoundingly new

Aye, I've set the main engine and SRBs to 60 and 38 respectively, and the second stage T909 is at 100. I'm definitely throttling up on lift off - do I have to re-throttle up when firing stage 2?

I'm burning straight up with SAS on, but theres an interesting line "If you went slightly to the west you will already be above the highlands, if you went slightly to the east you will be above the mountains." but doesn't say I should be pointing anywhere but straight up? Should I in fact be adjusting course at some point?

EDIT: Just tried a second time, and uncoupled my pod as soon as the second stage fired, and my capsule continued up whereas my second stage did not. Perhaps I've made it wrong? :-/

Edited March 19, 2014 by Arctodus
retest

[Skorpychan]

For launching to orbit, you generally want to incline west (45 degrees on the navball) to use gravity to assist you, after you're past 10km up, where the atmosphere thins right out.

[lockpicker]

Well, that is indeed strange.. No if you have throttled to full, you don't require to re-throttle. Also, i recreated the results burning straight up all the time, so adjusting your course is not necessary.. Maybe there is a heavy kerbal as a pilot? I have no clue. :S

Also if you are new to ksp, i'd suggest you try the sandbox mode first, so that you can get to know all of the parts and a bit of orbital mechanics, assuming you don't already know them .

[lockpicker]

For launching to orbit, you generally want to incline west (45 degrees on the navball) to use gravity to assist you, after you're past 10km up, where the atmosphere thins right out.

I think you mean east

[Pecan]

No, you shouldn't have to adjust course - he's just pointing out what happens if you do. Neither is there any need to re-throttle. It's just 'T' for SAS, left-shift for throttle, spacebar to stage and launch. Straight up until the first stage burns-out, then spacebar to stage again. (With the thrust limiters - I just tried it again - I get an apoapsis above 370km).

If it's not mods, throttle or direction the only thing I can think of is your staging. CHECK that stage 3 (confusingly enough the first one that fires) just contains the T30 and the three boosters, stage 2 contains the decoupler above them, the 909 and booster parachutes (make sure it isn't firing the top one, lol), stage 1 is just the pod-decoupler and 0 the top parachute

[Arctodus]

Well, that is indeed strange.. No if you have throttled to full, you don't require to re-throttle. Also, i recreated the results burning straight up all the time, so adjusting your course is not necessary.. Maybe there is a heavy kerbal as a pilot? I have no clue. :S

Also if you are new to ksp, i'd suggest you try the sandbox mode first, so that you can get to know all of the parts and a bit of orbital mechanics, assuming you don't already know them .

Cheers for the advice - I figured a dipping a toe might be better than the deep end, but I'll give it a crack I had a wee go at the tutorials that come with the game, and seemed to not blow up, lol

I think I might have an idea - could staging be a problem? Its listed as a three stage rocket, but mine seems to have inexplicably gained a fourth. My LV909 engine firing is a seperate stage, I have to do it manually rather than it kick in automatically at stage 2 when I decouple. Could that be it?

[Arctodus]

No, you shouldn't have to adjust course - he's just pointing out what happens if you do. Neither is there any need to re-throttle. It's just 'T' for SAS, left-shift for throttle, spacebar to stage and launch. Straight up until the first stage burns-out, then spacebar to stage again. (With the thrust limiters - I just tried it again - I get an apoapsis above 370km).

If it's not mods, throttle or direction the only thing I can think of is your staging. CHECK that stage 3 (confusingly enough the first one that fires) just contains the T30 and the three boosters, stage 2 contains the decoupler above them, the 909 and booster parachutes (make sure it isn't firing the top one, lol), stage 1 is just the pod-decoupler and 0 the top parachute

I noticed my staging was off just before I read this - I reckon thats probably my problem then Thanks man, I'll get back to you!

[Pecan]

My LV909 engine firing is a seperate stage, I have to do it manually rather than it kick in automatically at stage 2 when I decouple. Could that be it?

Well, possibly. Since you're spotting it and manually staging to it there shouldn't be too much problem but in general it is best to be very careful about staging and very easy to get it wrong.

EDIT: Incidentally (information for later in your KSP experience), some designs call for the engine to be in a different stage to the decoupler below it - the way you've got it in other words. The reason is that sometimes the lower stage(s) throw the upper so quickly you can afford to just drift upwards for a few seconds between dropping the spent stage and firing the upper one. Doesn't usually make that much difference but 'cruise and burn' is a genuine and useful technique.

Edited March 19, 2014 by Pecan

[Arctodus]

Ok, I fixed the staging, and managed to get to 55,369. A new record for this vessel...

[lockpicker]

Cheers for the advice - I figured a dipping a toe might be better than the deep end, but I'll give it a crack I had a wee go at the tutorials that come with the game, and seemed to not blow up, lol

I think I might have an idea - could staging be a problem? Its listed as a three stage rocket, but mine seems to have inexplicably gained a fourth. My LV909 engine firing is a seperate stage, I have to do it manually rather than it kick in automatically at stage 2 when I decouple. Could that be it?

Unlikely to be your problem, but give it a try nonetheless. You never know what your problem could be . Also about that blowing up thingy you mentioned.. Yeah, you're gonna get a lot of that if you go on on bigger constructions (I know from experience )

[Arctodus]

I'm half tempted to just whack one of the bigger thrusting engines on instead, see how that goes, lol

[cantab]

Check you don't have the LV-909 thrust-limited. It's a low-thrust engine to start with, you want 100% out of it.

[Arctodus]

Check you don't have the LV-909 thrust-limited. It's a low-thrust engine to start with, you want 100% out of it.

Its at 100% :-/

I had the Science to go for the mission 5 setup, and that works perfectly too - it just seems to be the setup for 4 that's not working out for me, lol.

Thanks everybody for the help, I'll keep at it!

[Pecan]

Well I thought I was off to the pub but my lift left without me (it's a long walk from here!) so I've been trying a few more things but even without the T30 I'm getting to 80km+. All I have left is - make sure the fuel tanks are full! All tanks and the 909 should be 100%, the T30 at 60% and the boosters 38% thrust/full fuel (but as I've said before, even with everything at 100% I was getting 250km+).

It helps if you can post a screenshot of your ship in the VAB so we can see exactly what you've got where. Apart from that can you give us a commentary on your flight - speed every 100m up to 1km and every 500m after that? That's probably a bit much, but at least what height you reach when you stage, what speed the navball shows when you do, similar for when the upper stage burns out and when you start falling again.

[Arctodus]

Well I thought I was off to the pub but my lift left without me (it's a long walk from here!) so I've been trying a few more things but even without the T30 I'm getting to 80km+. All I have left is - make sure the fuel tanks are full! All tanks and the 909 should be 100%, the T30 at 60% and the boosters 38% thrust/full fuel (but as I've said before, even with everything at 100% I was getting 250km+).

It helps if you can post a screenshot of your ship in the VAB so we can see exactly what you've got where. Apart from that can you give us a commentary on your flight - speed every 100m up to 1km and every 500m after that? That's probably a bit much, but at least what height you reach when you stage, what speed the navball shows when you do, similar for when the upper stage burns out and when you start falling again.

I will see what I can do

[Arctodus]

Well I thought I was off to the pub but my lift left without me (it's a long walk from here!) so I've been trying a few more things but even without the T30 I'm getting to 80km+. All I have left is - make sure the fuel tanks are full! All tanks and the 909 should be 100%, the T30 at 60% and the boosters 38% thrust/full fuel (but as I've said before, even with everything at 100% I was getting 250km+).

It helps if you can post a screenshot of your ship in the VAB so we can see exactly what you've got where. Apart from that can you give us a commentary on your flight - speed every 100m up to 1km and every 500m after that? That's probably a bit much, but at least what height you reach when you stage, what speed the navball shows when you do, similar for when the upper stage burns out and when you start falling again.

Right, here's my setup - I have checked and triple checked my first stage, the T30 is at 60, all three boosters at 38, all tanks full, thrust for the 909 at 100.

[Taki117]

Found your issue! Your LV-909 appears to be attached to the bottom node of the decoupler, and the tank attached to the top, this will cause the decoupler to not function properly and actually end up blocking the thrust of the LV-909. Pull off the tank, re-install your decoupler (Ensuring the nodes are properly attached) then attach the tank to the bottom of the decoupler. Happy flying.

[Pecan]

ninja'd :-)

(actually I was still thinking "that 909 looks very thin" and trying it in the VAB). FWIW my first stage burns-out at about 23km and 817m/s then the 909 takes it out past 370km. Have fun.

Edited March 19, 2014 by Pecan

[Arctodus]

Here'sa quick, ten shot log of my average outing with this

On the pad

Liftoff!

KM or so up

10km up

Boosters quit around 20km

T30 quits soon after, so I stage and light the 909

50km and slowing drastically

909 craps out and decouples

only for me to peak at 54km and start my descent

Chute deploys at 7/8km, just after I pass by my spent 909, but it quickly passes again as i slow

I land, uneventfully.

Sorry for the night-flight!

[Arctodus]

Found your issue! Your LV-909 appears to be attached to the bottom node of the decoupler, and the tank attached to the top, this will cause the decoupler to not function properly and actually end up blocking the thrust of the LV-909. Pull off the tank, re-install your decoupler (Ensuring the nodes are properly attached) then attach the tank to the bottom of the decoupler. Happy flying.

ninja'd :-)

(actually I was still thinking "that 909 looks very thin" and trying it in the VAB). FWIW my first stage burns-out at about 23km and 817m/s then the 909 takes it out past 370km. Have fun.

Saw this after I posted my epic saga, lol - I will have a look in the VAB, thanks for the heads up!

[Taki117]

Saw this after I posted my epic saga, lol - I will have a look in the VAB, thanks for the heads up!

You are most welcome, this can happen with thin parts, you need to be careful when attaching these kinds of parts.

[wolfedg]

I would move the three SRB's into the 1st stage by themselves and only activate the t-30 after they burn out. Also I'm not sure bout it looks like the decoupler on the 909 is upside down causing it to stay on the rocket (and probably blocking the thrust as far as the game engine is concerned.".