Question Multistage2 SRB questions

[Interceptor]

Hello,I recently have been messing with a rocket I created using Multistage2,but I noticed when the SRBs seperate from the craft they burn up in the atmosphere,how do I prevent them from burning up,so they will land in the ocean near my launchpad?also is there a way to add a parachute in multistage2?

 

[garyw]

I'll have to dig out the changes I made to do this but yes it's possible. There is an option in multistage to spawn a proper vessel rather than a time limited vehicle owned by the stage class.

I recall having a lot of issues with the parachutes as the braking force setting didn't seem to work.

 

[Interceptor]

Thanks,garyw, when ever you have the time,even if I could get the SRBs to not burn up in the atmosphere,and land in the ocean I'll be a happy man.:thumbup:
BTW,Where did you get that nice looking parachute?

 

[PhantomCruiser]

I'm looking to do a trick along similar lines... I want the boosters for the Energia-M to have flyback capability. The mesh looks rough for now... Maybe a summer project?

In the .ini file for the rocket in question under the booster section, there is an unmandatory parameter for MODULE. The documentation says that it defaults to stage (as in stage.dll) when jettisoned. Add the parameter to the .ini to force it to be something else.

 

[garyw]

BTW,Where did you get that nice looking parachute?

That's borrowed from the shuttle fleet and edited slightly to give it three chutes like a real SRB. The SRB itself is from the Neptune and if I recall right when the SRB seperates it creates an SC3 vehicle that has the parachute in there somewhere.

I'll dig out the files for it either tonight or tomorrow night. Time is a little short at the moment.

 

[garyw]

In the .ini file for the rocket in question under the booster section, there is an unmandatory parameter for MODULE. The documentation says that it defaults to stage (as in stage.dll) when jettisoned. Add the parameter to the .ini to force it to be something else.

Correct and that's part of the trick. If you use multistage to jettison something it will have a class of 'STAGE' which sometimes isn't useful - I think it even deletes the stages after 300 seconds or something.

For my neptune one mission the STAGE1 section looks like this:

[STAGE_1]
Height=40
Diameter=10
EmptyMass=55420
FuelMass=477745
Thrust=8896250
BurnTime=145
off=(0.,0.,19.628)
eng_1=(0,0,-19.628)
eng_diameter=2.2
ENG_TEX=Nep-1\exhaust
ENG_PSTREAM1=con2
ENG_PSTREAM2=con3
MeshName="Nep-1\Ns1"
SPEED=(0,0,-3)
ROT_SPEED=0
module=srb

note the module=srb section, when the stage is jettisoned it picks up the class 'srb'.

the srb.cfg looks like this:

Meshname = ns1
Mass = 55420
Size = 1

Very simple, same mass as an empty NS1 stage and same mesh but no longer governed by the stage class so I can do other things with it.

EDIT: I've checked and I can't recall exactly how it was done, I know that Loru assisted and I think the parachute was attached via UCD.

 

[Interceptor]

So,could you actually using this trick to spawn the shuttle fleets SRB's with the parachute,with your own rocket?

 

[garyw]

So,could you actually using this trick to spawn the shuttle fleets SRB's with the parachute,with your own rocket?

Not the shuttle fleets as that does everything in a DLL. This trick would only work for things using multistage as essentially when the stage jettisons the module line is hijacking the detached component.

 

[Interceptor]

I wonder if there are any addons,on OH that use this trick?

 

[garyw]

The only addon I'm aware of that 'bolts' on a parachute is this one -> [ame="http://orbithangar.com/searchid.php?ID=3842"]Universal Parachute[/ame]

But it is insanely unpredictable and caused more grief than it saved.

I wouldn't have thought that it would be too hard, display mesh and apply a deceleration force opposite the direction of gravity....

 

[Interceptor]

So, if I just use the dummy mesh of an SRB to spawn after SRB's jettison it should work?

 

[garyw]

do you mean to spawn a shuttle fleet SRB in place of whatever multistage jettisons? If so, yes, that would work fine but you'd have to code a vessel cfg file as I did for the NS1 first stage as that's what provides it some very basic parameters such as mass.

 

[Interceptor]

OK,I got it, thanks again

---------- Post added at 05:27 PM ---------- Previous post was at 05:20 PM ----------

Hey garyw,where do place the new SRB config after making it?

 

[garyw]

vessels/config.

 

[Interceptor]

I'm looking to do a trick along similar lines... I want the boosters for the Energia-M to have flyback capability. The mesh looks rough for now... Maybe a summer project?

In the .ini file for the rocket in question under the booster section, there is an unmandatory parameter for MODULE. The documentation says that it defaults to stage (as in stage.dll) when jettisoned. Add the parameter to the .ini to force it to be something else.

I like your idea for the Energia M,PhantomCruiser.:thumbup:

---------- Post added at 06:21 PM ---------- Previous post was at 06:16 PM ----------

OK,one last question garyw,do I need a seperate dummy mesh config for each SRB that jettisons?

 

[garyw]

OK,one last question garyw,do I need a seperate dummy mesh config for each SRB that jettisons?

I'm not sure what you mean.

Inside the multistage ini file are a bunch of sections headed [STAGE] as per the above example of the NS1 above you just add in the module line and a pointer to a mesh be that the original mesh or an entirely new one. No dummy mesh as such is needed.

The only changes I made to the NS1's multistage ini file were these two lines:

MeshName="Nep-1\Ns1"
module=srb

the Meshname being the post jettison mesh and the module name being the module that'll own it. After jettison this gets added to the .scn file:

Nep-1\Ns1:srb
  [parameters]
End

 

[Interceptor]

OK,that clears things up.Thanks

---------- Post added at 07:34 PM ---------- Previous post was at 07:02 PM ----------

Correct and that's part of the trick. If you use multistage to jettison something it will have a class of 'STAGE' which sometimes isn't useful - I think it even deletes the stages after 300 seconds or something.

For my neptune one mission the STAGE1 section looks like this:

[STAGE_1]
Height=40
Diameter=10
EmptyMass=55420
FuelMass=477745
Thrust=8896250
BurnTime=145
off=(0.,0.,19.628)
eng_1=(0,0,-19.628)
eng_diameter=2.2
ENG_TEX=Nep-1\exhaust
ENG_PSTREAM1=con2
ENG_PSTREAM2=con3
MeshName="Nep-1\Ns1"
SPEED=(0,0,-3)
ROT_SPEED=0
module=srb

note the module=srb section, when the stage is jettisoned it picks up the class 'srb'.

the srb.cfg looks like this:

Meshname = ns1
Mass = 55420
Size = 1

Very simple, same mass as an empty NS1 stage and same mesh but no longer governed by the stage class so I can do other things with it.

EDIT: I've checked and I can't recall exactly how it was done, I know that Loru assisted and I think the parachute was attached via UCD.

Would the SRB.CFG need to be a spacecraft3 config also,or would the SRB.CFG in vessels folder alone work?

 

[Donamy]

Pretty sure they both work.

 

[Interceptor]

OK,I have them working great now, the only problem I noticed is that when the SRBs seperate from the rocket they seem like they disapear from view faster,is there a way to see the SRBs for longer,would the size in the config have something to do with it?Thanks

 

[garyw]

What do you mean by 'disappear from view'? Are you talking about the speed at which it moves away from the parent vessel or does the srb actually vanish?

Pretty sure they both work.

Yup, Anything will work that works in orbiter. :lol:

All the module line does is to provide a class for that vessel to use. It's quite handy for spawning SC3 or actual DLL vessels from multistage.