How make my rocket more stable ?

[ineon]

[quote name='*Aqua*']Be gentle when maneuvering! This includes thrust control. [/QUOTE]

Great advice. When you are at 20-30km altitude you have plenty of time to get things right. If I was flying as you were in the last vid I would stage the lower half and then make sure that I am pointing in the right direction and not rotating before (gently!) increasing the throttle.

Another piece of advice (I don't think anyone mentioned it above) is that the Caps-Lock key changes the you to 'fine grain control mode'. If you can point the rocket in the general right direction, then using smaller changes get it to stop rotating and apply finer course corrections you should have a little more success.

[eddiew]

[quote name='Ulfstein']Put fins on the second stage as well will help with the fliping[/QUOTE]

That would add drag nearer the front of the rocket and make it [I]more[/I] likely to flip, surely?

[AeroGav]

[quote name='eddiew']That would add drag nearer the front of the rocket and make it [I]more[/I] likely to flip, surely?[/QUOTE]

Just a minor point -

Not drag, LIFT.

But yes, that's exactly the issue. Centre of lift must be behind the centre of gravity in any aerodynamic object. Be it a plane, a rocket lower stage, or an arrow shot from a bow (think of the fletchings).

Imagine that something disturbs your rocket and the tail sags for whatever reason. The lifting surfaces will now have greater angle of attack and will generate increased lift.

With an aft CoL, this additional force will act to lift the tail back up, and put it in line again. Self correcting.

If the CoL is ahead, the additional force will lift the nose instead, making the tail sag more, in a positive feedback loop that flips the vessel.

[BenCushwa]

Just adding my $0.02 after some other great posts explaining things: basically, you need to make sure that you have sufficient control authority. This can either be achieved in atmosphere by controllable fins and anywhere by vectored-thrust engines or sufficient reaction wheels (although I wouldn't rely too heavily on the latter while maneuvering under power).

Too-tall liquid fuel stages are also bad for stability: they drain from the top down making your rocket tail-heavy which makes it harder to control.

Good luck!

[Pawelk198604]

I made it, but forgot to add one part that was required :(
[video=youtube;J8NVzFZc8bM]https://www.youtube.com/watch?v=J8NVzFZc8bM[/video]
I forgot to read "Fine print" it was requested that probe need be equipped with "material bay" i think it's impossible to this, because "material bay" add weight and consume power i barely depleted battery, i would need to add more batteries, and my VAB allow my only 30 parts :(

I have also problems with ASScending nodes i want it to be 0.00

[GoSlash27]

pawelk,
It's not "impossible", merely "challenging" :D The [url=http://forum.kerbalspaceprogram.com/threads/127795-KSP-Caveman-Challenge!]cavemen[/url] do this sort of stuff for fun.
I would definitely wait for a battery at least and you're not far from having a reaction wheel.

Best,
-Slashy

[Pawelk198604]

[quote name='GoSlash27']pawelk,
It's not "impossible", merely "challenging" :D The [url=http://forum.kerbalspaceprogram.com/threads/127795-KSP-Caveman-Challenge!]cavemen[/url] do this sort of stuff for fun.
I would definitely wait for a battery at least and you're not far from having a reaction wheel.

Best,
-Slashy[/QUOTE]

I thinking about upgrading my VAB, so i can use more Parts, but i wonder how much i can add weight to not loss stability. and does i will need add more fuel to compensate weight.

[GoSlash27]

pawelk,
As you can see from that link, you can do an awful lot with just 18 tonnes and 30 parts. That's not really what's holding you back. In fact, building bigger ships with low tech parts will just make your problems worse.
What you need is [U]better parts[/U]. Better control modules, active fins, bigger tanks, reaction wheels,batteries, solar panels, and lighter engines for the upper stages.
Better parts come from filling out the tech tree and that comes from collecting science. I recommend focusing on science and not worrying about money so much unless you're really low on cash.
Best,
-Slashy Edited November 24, 2015 by GoSlash27

[*Aqua*]

[quote name='Pawelk198604']I have also problems with ASScending nodes i want it to be 0.00[/QUOTE]
The angle displayed at the ascending node is the angle between your orbital plane and the target orbital plane.

Look at this picture:
[IMG]https://upload.wikimedia.org/wikipedia/commons/2/24/Orbital_state_vectors.png[/IMG]

The plane of reference in this picture is the orbital plane of your rocket. The other one is the target orbit you want to get to.

If you've got a positive angle value at the asc. node, you need to burn in the normal direction (normal = upwards, pink triangle pointing up on your navball) or at the desc. node in the anti-normal direction (anti-normal = downwards, pink trangle pointing down). If you've got a negative angle value it's the other way around.
Also visit this link for images on how the orbit will change: [url]http://wiki.kerbalspaceprogram.com/wiki/Maneuver_node#Effects_on_orbit[/url]

The important point is to change the inclination right at the asc. or desc. node or your whole orbits changes in a way you don't want (it will rotate around the z axis in the picture in a difficult to predict way).


In your video your are randomly burning in the prograde or retrograde directions where the orbit lines cross. Don't do that.
When you want to change your AP, burn at the PE node.
When you want to change your PE, burn at the AP node.
When you want to change your inclination, burn at either the asc. or desc. node.

[fourfa]

It's not a problem to put fins on your second stage - you just need bigger ones on the first stage. And if you're using steerable fins - the steering in S2 will fight the steering in S1 if both are active. Use dumb fins and add more SAS wheels, RCS steering, more subtle gravity turns, or enable and disable fin steering as needed.

Make sure to compare your center of mass to center of lift, with tanks full AND tanks empty, on all configurations. S1+S2+S3/payload, S2+payload, just payload, etc. Usually the problem (for me) has been when stage 2 has emptied the forward tank but not the rear one - the CoM shifts behind the CoL, and the rocket flips. You can brute force it with fins, you can finesse it with manual fuel transfers, you can get complicated with fuel lines and crossfeed-blocking components, or there are fuel pump mods that can be set up with logical fuel flow and let you build elegant rockets with fewer fins and fuel lines.

[Pawelk198604]

I made the same mistake again the contract require power-generation i did not unlocked this :-(
And even i unlock it i would have to remove something to keep it under 30 parts.
[video=youtube;KvvOIGx2g-g]https://www.youtube.com/watch?v=KvvOIGx2g-g[/video]

[*Aqua*]

Then do other contracts first until you have solar panels, parts with SAS and a higher part number limit. SAS can automatically adjust you orientation to certain directions (the amount of options depends on the SAS level). Using that you only have to care about when to start and stop using your engines.

I saw you hover your cursor a lot over the nodes to see the numbers. You can click on the nodes and the numbers won't disappear until you click them again.
There's also a 'fine control' mode which is de-/activated by the capslock key. In this mode your steering input is lessened by 10 times (I believe). It helps when trying to keep a certain orientation.

Also you don't need to change to the tracking station. You can do time warping and quicksaves (F5 quicksave; Alt+F5 custom quicksave; F9 load last quicksave; Alt+F9 load custom quicksave) in the map mode too.

I don't know if it's because you get distracted but put more attention to the orientation of your rocket. And don't care about the asc. node until you got AP and PE right. Just concentrate to burn prograde. Only after that change the inclination. As I said before: Change only one axis at a time or it'll get confusing. Edited November 24, 2015 by *Aqua*

[Pawelk198604]

[quote name='*Aqua*']Then do other contracts first until you have solar panels, parts with SAS and a higher part number limit. SAS can automatically adjust you orientation to certain directions (the amount of options depends on the SAS level). Using that you only have to care about when to start and stop using your engines.

I saw you hover your cursor a lot over the nodes to see the numbers. You can click on the nodes and the numbers won't disappear until you click them again.
There's also a 'fine control' mode which is de-/activated by the capslock key. In this mode your steering input is lessened by 10 times (I believe). It helps when trying to keep a certain orientation.

Also you don't need to change to the tracking station. You can do time warping and quicksaves (F5 quicksave; Alt+F5 custom quicksave; F9 load last quicksave; Alt+F9 load custom quicksave) in the map mode too.

I don't know if it's because you get distracted but put more attention to the orientation of your rocket. And don't care about the asc. node until you got AP and PE right. Just concentrate to burn prograde. Only after that change the inclination. As I said before: Change only one axis at a time or it'll get confusing.[/QUOTE]

Thanks :)
[video=youtube;uLSM2rdMbxI]https://www.youtube.com/watch?v=uLSM2rdMbxI[/video]

i cannot complete the contract without panels, so i squeezed any science i can get from this mission :D

[Pawelk198604]

Easy science :D
[video=youtube;yVhJRiSkw1I]https://www.youtube.com/watch?v=yVhJRiSkw1I[/video]

I wonder does i should spend my 45 tech on "flight control" or try to get another 45 and spent 90 on electric components like "solar panels" ?

[Chaos_Klaus]

go with the solar panels. Nothing worse than running out of power.

Why are you useing all these FL-T200 tanks when you have the larger FL-T400 tanks unlocked? With the larger tanks you get less stability problems, because the larger tanks will drain as a whole and not shift around your center of mass so badly.

Part of your instability problem comes from the top tanks draining first, shifting your CoM backwards. At some point it moves behind the center of pressure/drag and your rocket wants to fly backwards.

Another big problem is really the probecore. It has no stability control and no reaction wheels. Unlocking flight controls would give you a reaction wheel, but without SAS to provide stability control that's basically worthless.

[Pawelk198604]

[quote name='Chaos_Klaus']go with the solar panels. Nothing worse than running out of power.

Why are you useing all these FL-T200 tanks when you have the larger FL-T400 tanks unlocked? With the larger tanks you get less stability problems, because the larger tanks will drain as a whole and not shift around your center of mass so badly.

Part of your instability problem comes from the top tanks draining first, shifting your CoM backwards. At some point it moves behind the center of pressure/drag and your rocket wants to fly backwards.

Another big problem is really the probecore. It has no stability control and no reaction wheels. Unlocking flight controls would give you a reaction wheel, but without SAS to provide stability control that's basically worthless.[/QUOTE]

I managed to get into proper orbit that was required in contract specification, but i did not have solar panels, it's very hard to control spacecraft without "reaction wheel" but i managed twice, it's just hard to this without "reaction wheel" and RCS :(

[Pawelk198604]

Now i finally have 90 tech i plan spend it on electric components because it's unlocking solar panels and better probe core
[video=youtube;SHgoQyDG5F0]https://www.youtube.com/watch?v=SHgoQyDG5F0[/video]

[Pawelk198604]

I made it, than you for you help :D
[video=youtube;whLlLgwd8lM]https://www.youtube.com/watch?v=whLlLgwd8lM[/video]

[Harry Rhodan]

Yay, good work. I have never tried doing it without manouver nodes. :D

[Pawelk198604]

[quote name='Harry Rhodan']Yay, good work. I have never tried doing it without manouver nodes. :D[/QUOTE]

Thanks :)
I see the maneuvers nodes in my head ;)
BTW i play the KSP long before the NavNodes was introduced.

[Pawelk198604]

I was bit surprised that i fulfilled the the contract, because the orbit was still little bit tilt and i was unable to compensate this

[*Aqua*]

Some deviations are always allowed because it's extremely unlikely to exactly match the target orbit. KSP tracks millimeters or even more finer values if circumstances allows for that number precision!

Maximum allowed deviations should be listed in the contract details.

[Pawelk198604]

[quote name='*Aqua*']

Maximum allowed deviations should be listed in the contract details.[/QUOTE]

That's True

[Pawelk198604]

I reached Mun :D i repurposed the probe i designed earlier for satellite contract.
[video=youtube;SdR9VXrn8wg]https://www.youtube.com/watch?v=SdR9VXrn8wg[/video]
The most amuses me the term "catastrophic failure" even when i destroyed probe on purpose! :)

[Harry Rhodan]

You could've also transmitted that temperature scan from space high above the Mun. The thermometer can be used multiple times.

And you can put KER in partless mode, if you click on the settings button in the VAB. Then you can use the HUD to show you your current AP and PE without having to switch to the map mode.