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

[Tirak]

Trying to make a Saturn V but I can't get the 3-1x5 adapter to work. The engines explode the moment I hit space.

[Sunday Punch]

Oh my god, that's a Saturn IB. I fucking love you man.

I wondered if anyone would notice that

Tirak you may be giving it too much throttle, which snaps the connections between modules. I boosted the breaking strength of all the particularly fragile modules to absurdly high values (I think I set it to 160 000) but this still happens. It's quite annoying.

[feanor]

There is one part missing from all 2 meter packs - a simple, non shroud, decoupler.

Also, your rockets wobble REALLY hard, especially when they are nearly empty. LoM hard.

[Sunday Punch]

There is one part missing from all 2 meter packs - a simple, non shroud, decoupler.

Also, your rockets wobble REALLY hard, especially when they are nearly empty. LoM hard.

The 2 metre decoupler shrouds have top attach nodes that let you use them as normal decouplers if you want. Just use the topmost node. Although this does make for a pretty long decoupler! I do plan to make a small, dedicated 2 metre decoupler, it's just that this update was way overdue so I decided to release it with what I have at the moment.

[NovaSilisko]

I do hope you start giving your parts realistic costs soon, though! That's what I've been doing.

[Sunday Punch]

Well since the cost has no effect on anything I haven't been bothering with it. I mean how do you even decide what price to set for a certain part? When it's actually implemented in the game I certainly will be giving some thought to prices.

[NovaSilisko]

I'm just thinking ahead of time. Your 3m parts could be considered the high end, 1m the low end and 1.75/2m the middle ground. After determining what at least two are, you can price the third accordingly.

[Tirak]

Tirak you may be giving it too much throttle, which snaps the connections between modules. I boosted the breaking strength of all the particularly fragile modules to absurdly high values (I think I set it to 160 000) but this still happens. It's quite annoying.

Nope, just tested it, put the throttle to 0, hit space and the engines on the bottom disappeared immediatly.

[feanor]

Nope, just tested it, put the throttle to 0, hit space and the engines on the bottom disappeared immediatly.

I can't replicate that. post your .craft file please? are you sure you have the correct 1 meter size engines on the points, and that the adapter is well placed straight below the fuel tank above?

The 2 metre decoupler shrouds have top attach nodes that let you use them as normal decouplers if you want. Just use the topmost node. Although this does make for a pretty long decoupler! I do plan to make a small, dedicated 2 metre decoupler, it's just that this update was way overdue so I decided to release it with what I have at the moment.

I know, but what I am looking for is not only functionality but also aestethics - when I make a payload fairing on top of a 2nd stage I like the rocket to not get overly tall and slanky.

So a small 2 meter decoupler would be very much appreciated. Thanks in advance!

Also, something that will make my life much easier, and is also something aesthetic:

In the attached picture, you can see your RCS module, and an ideal last stage for orbital changes and reentry burn.

Wouldnt it be a good idea to bring out a chopped up version of your awesome -looking RCS module?

IE chopped in:

a decoupler ( small ejection strength, low weight? ) on top

a SAS module (With your very nice RCS boosters on it) in the middle, perhaps with slightly higher weight then a normal SAS, but also a bit stronger? ) in the middle

and a small fuel tank on the bottom

Then your small liquid engine fits on it and it would make a truely marvelous upper stage composite!

When all these stages are skinned in the same ( apollo- greyish? ) colour as the RCS module is right now it'd not only be more realistic but also way cooler and nicer to use!

[Animal Mother]

I've only started exploring the new version, and I have to say I am impressed, especially with the new verniers. It allows you to redirect your craft whilst engaged, but does it so that it doesn't cause the rocket to crash either

[Andras]

I don't think that aero decoupler has enough ejection force, it wrecked my rocket twice. I used the new large 3m tank with 4 aero decouplers and 4 large SRBs. On decoupling the aero crashed into the tank and blew up the rocket.

ETA- I tried dialing up the ejection to 25, but it still blew up the new large 3m tank. The original 3m tank doesn't blow up when the decouplers blow.

[Animal Mother]

Just a note, the Aero Decoupler always destroys my ship, and tried to find out why. The ejection force is down as being 5, whereas the the default Radial Decoupler has an ejection value of 15, presumably this is to ensure the decoupler and its payload is ejected far/fast enough from the rest of the ship.

It might of just been a typo when putting in the values

[edit]Beat me to it :'(

[Andras]

It blows up the new 2m tank also.

Animal Mother- ;P

[DrLucky]

Sunday Punch

First off, thanks so much for your parts packs. I'm always eagerly awaiting the next. I'm a big fan of your work, keep it up, please!

Ok, I've been trying to debug the parts in 1.09. The aero decoupler, from close, zoomed-in analysis, is ejecting *into* the rocket body.

Comparing your part.cfg to the radial decoupler's, your 'UpX' vector is negative. Any chance that the line

node_attach = -0.55, 0.0, 0.0, -1.0, 0.0, 0.0

is what decides the *direction* of the decouple charge? ie: the stronger the more you're imploding?

I tried setting the eject force to 0 and it works fine, though no clearance, obviously.

edit:

changed the ejection force to

ejectionForce = -5

and it works splendidly. So if anyone's having issues with the aero decouper, just change the sign on the ejectionForce to patch it.

[Sunday Punch]

Yeah it looks like setting the ejection force to a negative value works. I didn't notice this problem before release because I was using the decouplers exclusively with fuel tanks and liquid engines, which didn't seem to have an issue with inward ejection for whatever reason. So just stick a negative sign in front of the parameter 'ejectionForce' in the aero decoupler's part.cfg file and you should be good to go. I'll update all the download links with a fixed version, but there's no need to redownload for such a simple fix.

[aimmlegate]

Aero decoupler is great, finally I make my Proton.

But I dont understand fuel flows through them or not?

[Sunday Punch]

Fuel does indeed flow through them, if you wanted to you could stick engines directly on the decouplers so long as they're connected to a fuel tank.

And that's a pretty righteous Proton!

[Rocket Surgeon]

Re: 1.09

Wow. You and Novo are really battling to be the forum's favourite modder. This looks so amazing. I appreciate how you seem to be making parts that work somewhat with each others' packs.

[DrLucky]

Yes, fuel flows through them, which leads to interesting possibilities -- as far as I can tell, the game draws fuel from one symmetric set of tanks at a time. If you can arrange the tanks so that the booster tanks get emptied first, and have a configuration with liquid fuel engines in both the core and boosters firing at once, you can throttle back and drop the boosters after they're exhausted leaving the core engines with full tankage.

EDIT: This isn't what's happening, as others have pointed out, just my puny core engines are not consuming much of the central tank before I stage, and mine's *not* cross-tanking for whatever reason. Sorry for the confusion /EDIT

I believe this is how Spacex intends to get extra payload out of the Falcon 9 Heavy when they get that going - having two Falcon 9s as boosters for a core Falcon 9, and cross-tanking to keep the centre one full until the boosters stage.

I used this principle and got an 18 minute burn for my core engines (7xSPS-10). The result was a pretty rocket which lofted a (Command + 2 x FLS-100 + K2-X) final stage to 4900 m/s. That final stage is good for about 9000+ m/s dV, so it was a satisfying launch. EDIT: well, that's what the rocket does; just not why

I've also spent a while trying to figure out what's wrong with the 3m to 5x1m and 3m to 7x 1m adapters. There seem to be two problems involved. The first is that when the rocket is placed on the pad, I'd swear it gets dropped there. The forces involved with just standing there is often sufficient to break off one or more liquid engines, and results vary with the position of the spacecraft in the VAB. So when you launch, Bad Things happen. However, if you attach, say, some SRBs that extend lower so that the core engines don't take the weight, they're usually fine.

Secondly, and more dangerously, the combination of high thrust and an adjacent heavy mass gives very large vibrations of the adapter relative to the tank it is attached to. e.g if you put on 5 or 7 M-50s (the largest single liquid engine) for thrust in the 2000 or 2800kN range, you get .5m+ oscillations. This usually breaks off an engine or three eventually, and certainly yields stability issues. I'm wondering if there's a programmed-in vibration to these engines that's identical (ie: using the same RNG seed) and results in a compounded vibration when using multiple engines. Certainly it doesn't help that these monsters are directly stuck to the heaviest part of the rocket, so there's a tremendous amount of inertia to work against. It's not clear that there's any way to fix this through the part.cfg Since running heavy, inefficient engines at part-throttle makes no sense, I've tended toward using 7xSPS-10 on a couple of the new 5000 fuel 3m tanks. While not enough thrust to lift the stack at 10m/s/s from the pad, with prudent use of boosters to get them to higher altitudes and lower gravity, they are stable, work well and burn forever. (At full thrust, almost 12 minutes!)

Also, for those who haven't adjusted their part.cfg for the Aero Decouplers, do so! The decoupling of a bunch of symmetric boosters using these softer charges is really pretty.

[Sunday Punch]

In regards to the vibration on the 5X and 7X adapters, someone mentioned to me that increasing the mass of the part helps keep it under control. I don't have time to test this myself at the moment, but you could try messing with that and see what happens.

[Capt'n Skunky]

Yes, fuel flows through them, which leads to interesting possibilities -- as far as I can tell, the game draws fuel from one symmetric set of tanks at a time.

It's a parent-child relationship. Fuel is only drawn from parent pieces and that is determined at the time of attachment. The oldest set of parents in a stage are used first, then the next oldest and so on.

Arrr!

Capt'n Skunky

[sirmonkey]

sorry for bugging you sunday punch, i know people keep requesting a lot of stuff.. but one last request that i think could have a pretty big effect..

is there any chance you could make a single piece coupler thats the same thickness as the double and triple lateral couplers? sometimes when building stuff i have a left over space and the only thing that is the exact same thickness as those couplers are the small fuel tanks. down side to those is they explode and they don't have the ability to hold a ton of weight like the couplers do.

[molo]

@DrLucky, what order do you need to add the boosters to create the Falcon Heavy scenario? I haven't been able to get it working properly, as the core gets emptied and then I'm carrying dead weight. Pretty weird.

[Pete-Dakota]

I really need some advice on stopping my designs from tipping over off the pad. Seems that if I build something using 2 and/or 3 meter parts the whole thing slowly starts tilting after launch and cannot be brought under control. No matter how much SAS I use, or where I put it, I can't stop these larger rockets from falling over.

Wobbly Rockets and the new version of Kerbal are amazing fun, but it's a bit annoying that my most grand designs aren't viable as they just fall over all the time.

Regards,

Pete.

[Andras]

@DrLucky, what order do you need to add the boosters to create the Falcon Heavy scenario? I haven't been able to get it working properly, as the core gets emptied and then I'm carrying dead weight. Pretty weird.

You can't. Fuel always flows from the center out.