[Part] Advanced SRB [WIP v0.7] by Kerbal Science Foundation

[Mekan1k]

So... Will there be small, med, large, and F**K WHAT!! sizes of these? I just like the idea of making a small rocket, then a MASSIVE SRB that boosts it nearly into orbit (In the first stage, naturally).

Just saying... THIS MOD IS COOL!

Keep up the awesomeness.

EDIT:

Oh, also- will there be variable thrust versions? Like.... Different propellants? I was just watching fireworks, and I remembered that fireworks have at least 2 different types of propellant- one that is visible, and one that isn't, for the ascension burn, so that manufacturers can customize the ratios in their burns, and I got to thinking, as I posted this that if we could control the fuel 'layering' in the SRB's we could set up a custom thrust pattern.

So, for the 'get some speed' stage, high-thrust-low-efficency fuel, to get as much 'punch' as possible, and then a longer, lower-thrust, more efficent burn that slowly slopes to nothing, that keeps your speed constant on ascension.

Just a thought.

[White Owl]

I'm happy to confirm the hotfix does indeed fix the compatibility problem, and this mod plays nice with FAR.

Your example shuttle vehicle can't be loaded, though. It wants a mechjeb part.

I very much like the notion of the separation gimbal! Radially attached boosters colliding with my shuttle wings has always been a problem, and this looks like a good solution. However... it's kinda startling to jettison the spent booster and see it instantly accelerate away in front of the rocket/shuttle, like firing a missile. Any way the thrust for that brief separation burn could be turned way down?

Once I figure out how to get Mission Controller to charge a sane fuel cost for this custom SRB fuel, this mod will be ready to go.

[Absolute Human]

Shouldn`t more segments result in a longer burn time not higher thrust?

All things equal, no.

When rocket fuel burns you can think of the mass of the fuel burned as creating a certain level of thrust in a certain time. So for a certain amount of propellant, the faster you burn fuel, the higher the thrust generated at the expense of burn time.

A simple way to think of how fast something burns is based on its surface area being burned. Liquid engines you can think of as having a fixed surface area for combustion, so no matter how much fuel you have, the rate of burning is the same, and therefore thrust doesn't change. Solid rockets burn fuel all the way to the top of the stage through a hollow channel in the segments. This means that adding another segment and making a booster taller increases the surface area being burned, creating a higher thrust level, but because the segment you've added also contains more fuel, the burn time is unaffected.

Nope. SRBs are hollow in the middle, so they burn from the center outward. Longer = more surface area burning = more thrust. Wider = more fuel = longer burn time. Extremely simplified explanation, but that's pretty much how they work.

Wait, wait, wait. I can't really agree with you, if you just make a SRB longer it wouldn't affect only thrust, it would increase the Isp, and, as a disadvantage, its internal pressure (ie chance to explode). If not that simple, then maybe:

Like this:

1_____2_____3_____4

/ _ \_/ _ \_ / __ \ _/ __ \

|| || || || || _ || | | | |

|| || || || || _ || | | | |

|| || || || || _ || | | | |

|| || || || || _ || | | | |

|| || || || || _ || | | | |

|| || || || || _ || | | | |

|| || || || || _ || | | | |

|| || || || || _ || | | | |

|| || || || || _ || | | | |

|| || || || || _ || | | | |

|| || /___\/ ___ \ / ___ \

|| ||

|| ||

|| ||

/___\

1 has higher thrust, exhaust velocity (ie Isp) and internal pressure than 2, burn time is the same.

3 has higher thrust than 2, but internal pressure and burn time are the same.

4 has longer burn time than the others, and its thrust gradually grows from thrust of 2 to thrust of 3, as the burn surface expands.

Am I wrong? Maybe it is a bit too complex for the game, but in reality I suppose it to work like that.

The whole thing- 'longer - more thrust' is acceptable, but not very precise.

Oh, if the addon could add this kind of functionality, it would be just freaking awesome! So big possibilities to customise...

Edited July 5, 2013 by Absolute Human
damn space cutters, I hope it looks, like I wanted

[kujuman]

Wait, wait, wait. I can't really agree with you, if you just make a SRB longer it wouldn't affect only thrust, it would increase the Isp, and, as a disadvantage, its internal pressure (ie chance to explode).

It doesn't increase the Isp directly, that would be a result of a higher pressure.

Even so, I figure Kerbal engineers are smart enough to make modifications to a nozzle design to prevent such accidents from occurring. (Otherwise, there would have to be several nozzle types and would make building rockets just that much harder.)

I guess it would be pretty simple programically to implement, but the gameplay would be pretty unchanged (aside from chance of explosion or under performing nozzle...neither of which I'd like in a game) and building rockets would be more complex.

I'm happy to confirm the hotfix does indeed fix the compatibility problem, and this mod plays nice with FAR.

Your example shuttle vehicle can't be loaded, though. It wants a mechjeb part.

I very much like the notion of the separation gimbal! Radially attached boosters colliding with my shuttle wings has always been a problem, and this looks like a good solution. However... it's kinda startling to jettison the spent booster and see it instantly accelerate away in front of the rocket/shuttle, like firing a missile. Any way the thrust for that brief separation burn could be turned way down?

Once I figure out how to get Mission Controller to charge a sane fuel cost for this custom SRB fuel, this mod will be ready to go.

Ok, I'll remove MJ in the next major release (this is why I should not post hotfixes after enjoying adult beverages...I forget things)

Well, at this point, I don't even know if the separation gimbal works correctly yet. It sometimes did in testing, but yeahhhhhhh... I'm going to be rewriting it for the next release for sure, maybe make it a standalone PartModule. And I am aware the booster tend to go super fast...rebalancing this is as easy as reducing the massFlow keys in the .cfg of the nose, but it's a lowish priority balance.

I'll check out Mission Controller to see what's up with fuel pricing...I do want to change the way fuel is handled, and so maybe next major version I will.

[CaptRobau]

If after 45 days there are no updates to this mod, then the license shall revert to a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. The 45 day period will reset with each update. For these purposes, updates will be noted by version number increases, i.e., v.1 to v.2 This is to give me exclusive right to updating the software while still allowing the community to take over if I let it languish.

Just want to commend you on this. We've lost a lot of great mods because of the creator leaving and this addition is a great way to prevent that. Great job!

[Absolute Human]

It doesn't increase the Isp directly, that would be a result of a higher pressure.

Yes, that is exactly what I meant, I just wrote it in other words.

I understand: Longer -> More gas (with the same out vent) -> Higher pressure -> Faster exhaust speed (and more exhausted mass)-> Higher Isp and Thrust.

Just to point out this feature. I guess, Kerbals have inflatable rockets, that widen to reduce pressure, and get this additional thrust with the same exhaust speed

[Kerbal01]

Is this plugin powered?

[kujuman]

Is this plugin powered?

Yes. It's the only way to make the SRBs have variable thrust based on the booster segments attached to them.

[Cepheus]

Any more news on this? I've got something I want to use it on, but I need to know if it'll be supported in the later versions of KSP.

[kujuman]

Any more news on this? I've got something I want to use it on, but I need to know if it'll be supported in the later versions of KSP.

I'll do my best to keep it updated. I've got a v0.4 patch pretty much ready to go (need to double check everything), but i'm waiting right now for .21 to see if there are any changes I need to make for it. Though if .21 doesn't come out by tomorrow I might have a version ready to go and I'll just release it.

But if you're going to wait to put it on a ship, then yes, wait until v0.4, as there's a small chance it will break craft files.

[kujuman]

Version v.4 released, get it now!

Confirmed to work* with

MechJeb (mechjeb does not compute delta-v or thrust of the boosters however)

FAR

Procedural Fairings

Programmable Computer

Fuel Balancer

Component Space Shuttle

ISS & Buran Arms

*basically having these installed should not cause AdvSRBs to malfunction. I am unable to know if AdvSRBs cause any issues in these plugins, however

[dave4002000]

Do you happen to know if Kerbal Engineer calculates the dV with these correctly? Or is it a limitation with how these are coded that prevents any mod from making the calculation? I played around with these and they are awesome. But, unfortunately, not having the correct dV in the mechjeb readout in the VAB stopped me from using them.

[The Lone Wolfling]

Do you happen to know if Kerbal Engineer calculates the dV with these correctly? Or is it a limitation with how these are coded that prevents any mod from making the calculation? I played around with these and they are awesome. But, unfortunately, not having the correct dV in the mechjeb readout in the VAB stopped me from using them.

Hmm...

It should be possible to add a fake moduleengines to the nozzle and remove it on flight start.

[kujuman]

I've not tested Kerbal Engineer, but I doubt it would work at this point in time.

I do want the final version to work with KE and MJ, and I have 3 ways I have figured out which might work.

1. Possibly simplest but most messy-create a fake "ModuleEngines" and figure out how to trick the fuel flow logic in KE and MJ

2. Create own in-editor analytic tool to work along-side KE and MJ

3. If permissions work out-either integration into the actual MJ and KE code (officially supported) or if permissions work, create a "hack" version of MJ and KE which will override certain parts of the code (or just add figures to variables)

So it is something I want to do, but I want to make sure I have everything working great before I start thinking about that sort of thing.

[dave4002000]

Fair enough. I'm happy to hear that you have a plan to get a correct dV readout one way or another. I will keep my eye on this mod, for sure!

[tryrar]

One nitpick/issue I've run into with these: Autostaging using Mechjeb with these is a bad idea if you have different flow rates in each section, due to mechjeb autostaging as soon as one section empties, regardless of how much fuel is actually remaining in the entire stack(leading to unintentional hilarity when they fly off like missiles).

Also, can you do something like quantum struts between sections? Whenever I make a tall booster, I have to usually basically staple them together in order to not get bending and twisting, which usually ends in catastrophic random disassembly with explosive results

[Lurven]

Does this work on .21?

[sidfu]

ive had not problems iwth it

[Lurven]

Good to hear Using the v4?

[Avalon304]

Im trying to use this on the lastest KSP and for whatever reason, when ever I try to ignite the SRBs they just putter out on the pad and nothing happens.

[Kerbal01]

do you have the nozzles facing the right way?

[Avalon304]

do you have the nozzles facing the right way?

Yes... they are facing the right way.

[kujuman]

Yes... they are facing the right way.

Pic of craft? (or .craft if it's otherwise stock)

The booster tanks also have to be facing the right way. One black bar on the bottom, two on top.

If you have mods installed, which ones are they?

[Avalon304]

Pic of craft? (or .craft if it's otherwise stock)

The booster tanks also have to be facing the right way. One black bar on the bottom, two on top.

If you have mods installed, which ones are they?

Craft was simple, as a test to see how the SRBs worked, was just a couple of fuel segments, with a nozzle at the bottom and a remote guidance unit at the top with a nose cone above that and some canards to keep it steady. Its possible that the fuel segments were upside down, but I dont believe so, as all I did was click on them from the parts menu and then set them under the remote guidance unit.

I have many mods installed;

Kethane

MechJeb

Lazor Docking Cam

Spherical Fuel tanks

KSPX

Procedural Fairings and Wings

Large Strucural Components for space stations

and probably a couple more that I am missing.

[Hyratel]

these are - or would be great, if they had better documentation - IE some kind of mass flow calculations available in VAB, and you CAN generate resource gages in the staging tree. also, if there was a better indication for how long they'd continue burning after primary burnout

also they're wiggly as snot, and ill-suited to being used as a "core booster"