Wobbly rockets - Now 1.09 - 2 metre parts, verniers, payload fairings, MUCH more

[DrLucky]

I played with that, too. It's a neato idea and it does work somewhat if you stack the retro and then the decoupler in the same stage (or it used to when the part was first included during KSP 0.8). You still lose velocity, but it kinda works. If anyone knows how to make it work flawlessly, please spill.

I just built a test-bed to try out various configurations.

The test-bed rocket is pretty simple - I put a lateral tricoupler near the top of a powerful 1m central stage. Then I'd hook whatever test rig to the top or bottom of the lateral.

The best results I obtained were the following:

- decoupler

- retro

- rest of stage

With the retro staging before the decouple, and staging by pressing space twice. This yields a small velocity decrease, but the retro works fine.

Putting the retro in the stage with the decoupler and staging them together appears to do nothing; that is, the retro is a dud and the decoupler works fine.

Trying to stage the retro later than the decoupler does not appear to work.

Bear in mind that the retro is effectively a small solid motor with a 3.33 second fuel supply and the thrust vectored up. Despite the four-flame appearance, it's really just one thrust, straight up, due to the way KSP works. At any rate, it behaves like any other solid rocket, just backwards.

To see the operation of another small solid, try installing a lateral tricoupler under the command module, and put the following stack (bottom to top) on top of each limb of the tricoupler:

- light decoupler

- small solid motor

- 1m parachute adapter

- parachute

Set the staging so the the solids fire a stage before the decoupler. Put the parachutes in a stage following the decouplers.

Like so:

Go to the launch pad, and zoom out a ways.

When you light the first stage, the solids will turn on, but be captive. Once you commit the second stage, the decouplers will let the lit solids go, which will fly away. Let the solids burn out, then activate the chutes. They should hit the pad either side of you if you don't punch the chutes too early:

Now try it again, but move the solids and decouplers into the same stage. Note that the solids never light. You can try it with the solids in a later stage, too, but they don't work there, either.

Retros do the same thing as these small solids -- if you don't light them explicitly prior to separation, they don't function. Parachutes are the only parts which seem to work (ie: are triggerable) after separation.

The good news is that the retros are only 60 thrust for 3.33s, so if you're using them on a beefy rocket, they won't do much to your velocity.

I also played with making a burnable decoupler - I moved the heat tolerance of a few decouplers down to 1 and 100, so that the retro would burn through them when activated. The results were not great; at a tolerance of 1, the decoupler is prone to break spontaneously during lower stage operation. At 100, it takes about as much time to burn through as staging manually would, plus there's an off-putting explosion (although it works). Perhaps there's a happy medium, but I didn't experiment long enough to find it.

edit:

Okay; courtesy of someone's thread about making launchable missiles, I discovered how to make the retros work:

Add the line

ActivatesEvenIfDisconnected = True

to the part.cfg for the retro.

Now you can put it in the stage with the decoupler, and works fine.

[rdfox]

I don't see why putting the retro in the same stage as the decoupler wouldn't work. If you put ullage engines in the same stage as the decoupler, they fire along with it. Maybe it's something to do with it being on a 'discarded' segment of the rocket?

And what happens if you rearrange the stage itself to have the two solids above the decoupler in the list? Does that make a difference to the order in which the game activates things? It might be that each stage reads from either the top down or the bottom up, sending activation commands to each item in sequence, one or two clock ticks apart, rather than sending simultaneous signals. If that's the case, then if you put the retrofire pack in the stage sequencer *before* the decoupler, it would get an activation command before the stage is decoupled, and therefore would work.

I'm certain that at least once, I did get a stage with a retropack to fire its retropack, the decoupler to activate, and ullage engines on the next stage to fire all in one swell foop...

[DrLucky]

I don't see why putting the retro in the same stage as the decoupler wouldn't work. If you put ullage engines in the same stage as the decoupler, they fire along with it. Maybe it's something to do with it being on a 'discarded' segment of the rocket?

And what happens if you rearrange the stage itself to have the two solids above the decoupler in the list? Does that make a difference to the order in which the game activates things? It might be that each stage reads from either the top down or the bottom up, sending activation commands to each item in sequence, one or two clock ticks apart, rather than sending simultaneous signals. If that's the case, then if you put the retrofire pack in the stage sequencer *before* the decoupler, it would get an activation command before the stage is decoupled, and therefore would work.

I'm certain that at least once, I did get a stage with a retropack to fire its retropack, the decoupler to activate, and ullage engines on the next stage to fire all in one swell foop...

For the record, I did try reordering the parts within the stage, and got the same result each time. I didn't try it with additional parts in the stage, and who knows, that might matter. It's pretty clear when the retros fire; they're not subtle and it lasts for 3+ seconds, and I wasn't able to get them to fire when co-staged with the decoupler.

edit:

Just wondering what you might have been using as ullage engines, if I'm going to try and reproduce? I mean, since ullage doesn't really matter (yet) in KSP, were you using an SRB? Or are you talking about a particular small engine from another parts kit? It might matter...

re-edit:

I built another test-bed, and I'm unable to reproduce the retros igniting unless explicitly lit before separation.

I had noticed that at times I wasn't sure about whether or not the retros had lit, since the decoupler emits some particles as part of its operation. The stack of 6 retros eliminates all doubt It gets... bright... when they go off.

Anyway, I've tried staging the retros with the decouplers and solids which remain attached; still no joy. If anyone can reproduce a retro firing with the decoupler, please let us know what you did!

[rdfox]

I've not reproduced it yet. The ullage engines are from Captain Slug's Radial Booster pack; they come with spin-stabilization engines and liquid- and solid-fuel vernier booster engines that can be very useful at times on designs with marginal performance...

[Rocket Surgeon]

I just want to say that I've noticed that a lot of your parts, Sunday, wobble like jelly, the same as the chute nosecone adaptors mentioned earlier. I think it's most noticable in the short load-bearing size adaptors.

[BadManiac]

And the wiggliness is almost certainly caused by the mass of that part being too low, I'll try and fix that for the next release.

I'm eagerly awaiting this! Even tho the 'wiggliness' has caused some catastrophically hilarious launch attempts I'd really like it gone.

Thanks for all your hard work Sunday Punch.

[Sunday Punch]

I'm eagerly awaiting this! Even tho the 'wiggliness' has caused some catastrophically hilarious launch attempts I'd really like it gone.

Thanks for all your hard work Sunday Punch.

Yes part making is an iterative process, with every release I hope to get closer to perfection. I'm pretty busy with coursework at the moment so the next update might be next week or something. Who knows!

And you're welcome

[Andras]

Sunday- can you make some 3m nose cones, one with a detachable function, and one with the attachment point up inside the cone so cargo can stick up out of the decoupler below and still be hidden?

Something that looks like the top of the Ariane 5 or STS external tank.

[Frostiken]

Unfortunately having some problems on the lower stages... everything keeps breaking apart, particularly at the 2m - 3m shroud junction... hmmm.

[Warringer]

Ohhhh... Thats a nice upper stage...

[rdfox]

Struts, dude, struts! 8)

Seriously, I use struts at coupler junctions, which end up looking more like either clamps or ribs on the fairings, and they help a great deal in keeping the rocket from falling apart in flight.

[Frostiken]

Struts, dude, struts! 8)

Seriously, I use struts at coupler junctions, which end up looking more like either clamps or ribs on the fairings, and they help a great deal in keeping the rocket from falling apart in flight.

I'll give it a try. I thought the struts were just going to hold the whole thing together...

[Frostiken]

Ohhhh... Thats a nice upper stage...

Thanks More pictures are here. It doesn't do much, but I was looking more for something attractive-looking than capable of interstellar travel.

[rdfox]

I'll give it a try. I thought the struts were just going to hold the whole thing together...

That was my initial worry, but they separate when a decoupler is fired. Evidently, they have their own linear shaped charges to cut them, too!

[Andras]

Heh, whoops. I just fired a space probe right though the 2m cargo shell nosecone and they let it slip right out and then closed up behind it like nothing happened. Got the staging a little off but it was an interesting (and non-disasterous) result

[McLuv]

I find the 2m to 2x1m adaptor very problematic. It loves to wobble uncontrollably when connecting two 1m engines to the 2m tanks

[rdfox]

Known issue. Until it's fixed, the best workaround is three struts to hold the adapter firmly to the tank, and then two struts to link the engines to the tank. Makes 'em rock-steady.

[NoXion]

Apologies if this has already been addressed, but I would really like to know why I can't seem to find a particular part in this pack:

I'm talking about the white SRBs with red text that can be seen in this image with pointy 1m nosecones. I like the look of them and fancy using them in my designs.

[Andras]

You forgot the image

[millsw]

Ahh! Those SRB's are in Sunday Punches pack, and you have to put a nosecone on BY YOURSELF.

[NoXion]

You forgot the image

Loads fine for me.

Ahh! Those SRB's are in Sunday Punches pack, and you have to put a nosecone on BY YOURSELF.

I know you have to add the nosecones during design/construction, but none of the boosters in the Sunday Punch pack I downloaded look the ones in the image from my previous post. Let me show you again:

The SRB on the left is the closest-looking one I could actually find in my collection. The one on the right is the one I'm interested in. Notice the differences, such as the flanges (?) and if you look carefully at the bottom of the right-hand image you will notice that the SRB has two red stripes while the one on the left has only one.

Either a booster has undergone significant mesh and skin changes (which is a shame since I think they could both be present as different boosters), or I'm missing a part somehow.

[Itchono]

Loads fine for me.

I know you have to add the nosecones during design/construction, but none of the boosters in the Sunday Punch pack I downloaded look the ones in the image from my previous post. Let me show you again:

The SRB on the left is the closest-looking one I could actually find in my collection. The one on the right is the one I'm interested in. Notice the differences, such as the flanges (?) and if you look carefully at the bottom of the right-hand image you will notice that the SRB has two red stripes while the one on the left has only one.

Either a booster has undergone significant mesh and skin changes (which is a shame since I think they could both be present as different boosters), or I'm missing a part somehow.

CORRECT!

Sunday Punch re-textured the solid booster in V1.05

but if you look in the kerbal space repository,you'll find V1.04

Or look for the posts on the front page

EDIT: I just checked and sunday punch reskinned the solids in V1.03

So you'll have to check the front page of this topic

[NoXion]

OK, now that is a shame. I think the skins and meshes are sufficiently different for potentially both to count as different booster types. Perhaps if the old booster mesh could still be used was resized so it was midway between the KSP-30 and the KMX Industries Minibooster/RT-10 Solid Fuel Booster? Or maybe it could be taken in the other direction, and become the first 1.75/2m booster?

The new booster mesh/skin is certainly good and it's a part I like to use, but the old version has a junky charm about it.

[Itchono]

Or maybe it could be taken in the other direction, and become the first 1.75/2m booster?

The new booster mesh/skin is certainly good and it's a part I like to use, but the old version has a junky charm about it.

I'd love to see a 1.75 m booster for Nova's 1.75m radial clamp

[Andras]

I'd love to see a 1.75 m booster for Nova's 1.75m radial clamp

I posted a cfg edit for a 1.75m solid booster in Nova's SIDR thread on pg 13 and a new Titan based texture a couple posts later.