Kerbal Space Program

[RizzoTheRat]

That's why I don't usually use Labs, but on my current game progress is rather slow due to doing everything with KOS so I stuck one in Mun orbit to earn some more science. Bloody hell they're slow! it's managing nearly 10 science per day having loaded it up with all the data from a couple of landings.
Then I went off to set up a Komms relay round Minmus and failed to spot the "Home" parameter of USI-LS, came back to find none of them working despite still having supplies and habitation

Currently trying to figure out how to get my KOS docking script to cope with offset docking ports, trickier than I thought as it seems to use all vectors from the centre of mass not the controlling port, and then you have rotation caused by RCS translation...

[BrettMRC]

I've done nothing yet other than experiment with space planes.

I have one that actually flies now.

Doesn't get to space, obviously!

[Flibble]

My game is going slowly, still largely firing sounding rockets. The three stage sounding rocket made it almost to Canada.

My kos launch program can handle hot staging and separation motors for ullage now, and I have a single stage version of NASA's powered explicit guidance working.

I also knocked together an offline launch stimulator to test optimal pitch over settings (and validate the guidance). It can simulate 512 launches in about 3 seconds. Rather pleased with it.

[RizzoTheRat]

Flibble said:

I also knocked together an offline launch stimulator to test optimal pitch over settings (and validate the guidance). It can simulate 512 launches in about 3 seconds. Rather pleased with it.

Interesting, what's the maths behind it? My launch script defines an altitude and pitch setting for the initial turn, and then follows prograde with a bearing correction the rest of the way to its target altitude. I'd fiddled around trying to derive the pitch angle from TWR and drag measurements based on experimental data, but it doesn't really work as different craft will stage at different times, and presumably it should take in to account the centre of mass and centre of pressure? What I generally do is try a "test" launch, and then revert to launch with updated values in the script.

So far in KOS I can do most of what I want to do terms of exploring the Mun and Minmus. The next big challenge will be to see if I can combine my precision landing and docking scripts to allow a skyscrane to assemble base components on Minmus.

Then I want to move from just aerobraking for capture and splashdown, to re-entering Kerbin orbit, docking with a VTOL SSTO, and then landing at the KSC under power (once I have enough science to resurrect my previous games SSTOs). Then I should be ready to try it all on Duna...
It's never ending

However at the moment I'm trying to tidy up my existing code and have broken quite a few of my code segments as I go through hacking reoccurring bits out and replacing them with functions to simplify the code a bit.

[Flibble]

RizzoTheRat said:

Interesting, what's the maths behind it? My launch script defines an altitude and pitch setting for the initial turn, and then follows prograde with a bearing correction the rest of the way to its target altitude. I'd fiddled around trying to derive the pitch angle from TWR and drag measurements based on experimental data, but it doesn't really work as different craft will stage at different times, and presumably it should take in to account the centre of mass and centre of pressure? What I generally do is try a "test" launch, and then revert to launch with updated values in the script.

It runs a basic physics simulation of rocket flight, with some assumptions.
Gravity is based on an assumed spherical planet (which I think KSP uses anyway).
Drag is based on having a drag lookup table for the craft. I use FAR to generate me the table using it's Mach Sweep feature (I have a modded version which saves it to CSV). AoA is fixed at 0 degrees (it's assumed that the rocket is flying at zero AoA where it counts).

It's configured to run a simulation with varying pitch angle and pitch over speed. I then get a nice bunch of graphs and can poke through the data and pick a suitable pitch profile for the mission.

I'll generally try a test run using KRASH before launching as well.

Here's a screenshot, with my current orbital test vehicle (still needs a bit of tweaking):


Lots of data, the heatmaps at the side are usually the most interesting, along with the pitch profile in the main graphs.
The graph background also shows staging and flight phases.

RizzoTheRat said:

So far in KOS I can do most of what I want to do terms of exploring the Mun and Minmus. The next big challenge will be to see if I can combine my precision landing and docking scripts to allow a skyscrane to assemble base components on Minmus.

Then I want to move from just aerobraking for capture and splashdown, to re-entering Kerbin orbit, docking with a VTOL SSTO, and then landing at the KSC under power (once I have enough science to resurrect my previous games SSTOs). Then I should be ready to try it all on Duna...
It's never ending

However at the moment I'm trying to tidy up my existing code and have broken quite a few of my code segments as I go through hacking reoccurring bits out and replacing them with functions to simplify the code a bit.

There's loads to do. I've mainly been refining the staging and guidance loop. Staging is pretty reliable now, I can also cut engines short automatically and it somewhat handles engine failure mid flight. Guidance can somewhat recover from a partial engine failure, depending on remaining fuel.

[RizzoTheRat]

Ah, I'm using stock aerodynamics so don't get that data, I've done on the fly drag calculations to try and predict impact point in atmosphere, which I then use to control the airbrakes when trying to land close to KSC, but never tried taking it quite that far.

I've never tried Realism Overhaul, so with a stock-ish game staging is simple (with the exception of drop tanks which I use on my current Mun lander, but I just have the quantity of fuel in the final stage as an input parameter) and I don't have to worry about engine failures. If I ever get all the orbital mechanics bits sorted out I guess that should be my next challenge.

[Flibble]

The main issue for getting to orbit in RO is that you can't throttle your engines (for the most part) so you pretty much have to fly a correct ascent profile (or waste a tonne of fuel).

In the screenshot sim the rocket actually ends up flying down a little (horizontal pitch is middle of the graph) to get the orbit corrected. That said the orbit is hit to within 50 metres accuracy, so it seems to work!

I went with RO as I found stock was just a bit too straightforward in terms of flight dynamics - you just point in the right direction and it'll more or less work it out.

[MartG]

[BrettMRC]

...and heres me just about able to make the parts line up in the assembly building....

[RizzoTheRat]

BrettMRC said:

...and heres me just about able to make the parts line up in the assembly building....

Everyones first few craft result in large explosions. In fact most us of continue have occasional... well ok, regular.... explosions years later

[Flibble]

RizzoTheRat said:

Everyones first few craft result in large explosions. In fact most us of continue have occasional... well ok, regular.... explosions years later

While getting used to procedural fairings I managed to design a craft where the second stage literally fell off on the launchpad. Not my finest hour.

[BrettMRC]

Had fun not taking enough oxidizer.

That crew is still up there somewhere....

[RizzoTheRat]

Flibble said:

While getting used to procedural fairings I managed to design a craft where the second stage literally fell off on the launchpad. Not my finest hour.

I've had so many where I haven't got the staging order correct and blown up when engines start in the wrong order...
Or not enough struts (auto or otherwise) that it's fallen apart on the launch pad...
Or bad drag/mass layout that flip and explode before max Q...


So many ways to kill Kerbals...

[Flibble]

There was a bug in 1.6 (maybe still in) where if you warped on the launch pad it would reset your throttle to zero but not update the ui. I lost a few rockets and launchpads to that one when the rocket fell off the launch clamps.

[Scottish Wyldcat]

Loved messing around in the Kerbal demo (0.18.1 I think it was). and I intend to buy this along with a PC upgrade next week, however, I have read the latest releases are buggy as hell.

Is the latest release worth buying or is there a very less bug ridden earlier version available to me? (I don't want the kraken getting me after all).

Edited by Scottish Wyldcat on Sunday 28th April 12:15

[Donbot]

I haven't noticed KSP being particularly buggy since the big 64 bit update a couple years ago(?).

I still do all the things I used to do to keep the Kraken at bay though. And physical time acceleration can still cause problems.

[Flibble]

You can get hold of earlier versions, how depends on how you're buying the game.

[RizzoTheRat]

I'm on 1.6 still (current version is 1.7, I tend to wait a while before upgrading to let the modders catch up), and not really noticing any show stopping bugs. There's minor stuff like targets being offset in timewarp, and occasional issues when physics loads if you've any parts clipping inside other parts, but it's generally pretty good.

Just a point as you mention upgrading the PC, KSP isn't well optimised for multiple cores, and will run faster on a processor with a low number of cores and a higher clock speed than on something with more cores but slower clock, eg an i5 can often be better than an i7 for it.

[Flibble]

Still slow going on my game, I hit some issues with kOS and complex RO engines. So I have started modifying kOS to make my stuff work.
Hoping to get a successful launch to orbit test today.

EDIT: Successfully launched to orbit.

Edited by Flibble on Monday 29th April 14:02

[superlightr]

Scottish Wyldcat said:

Loved messing around in the Kerbal demo (0.18.1 I think it was). and I intend to buy this along with a PC upgrade next week, however, I have read the latest releases are buggy as hell.

Is the latest release worth buying or is there a very less bug ridden earlier version available to me? (I don't want the kraken getting me after all).

Edited by Scottish Wyldcat on Sunday 28th April 12:15

I play it lots - not buggy as far as I can tell.

I think if you are a normal player having fun with it there wont be any bugs you notice - some other posters have talked about x y when they do cj+k-^ x7.00 = a small bug which gives a blue light instead of a red one.
That's not going to affect a new player in the slightest

Buy it - its so much fun and a real brain teaser. I whooped with joy after successfully docking with a ship last night which is really really tricky when you are learning ! ( sadly although the wife feigned interest in my explanation of how and looked impressed she was not open to try any close encounters or docking manoeuvres).

buy it.

Edited by superlightr on Monday 29th April 14:07