[0.23.5] StretchySRB: A StretchyTanks Continuation v9 Final Pre-PP edition 3/21/14

[Guest]

Actually, you can model fragility. Disable surface attachments (no way you could simply bolt anything to a balloon!) and decrease it's crash/G tolerance.

EDIT: OK, I think I should release this:

CONFIG        {
            name = HybridLOX
            maxThrust = 62
            heatProduction = 157
            throttleLocked = False
            useEngineResponseTime = False
            allowShutdown = True
            PROPELLANT
            {
                name = SolidFuel
                ratio = 2.0
                DrawGauge = True
            }
            PROPELLANT
            {
                name = LiquidOxygen
                ratio = 1.0
                DrawGauge = False
            }
            IspSL = 1.2
            IspV = 1.2
        }

It's an alternate config for a Solid/LOX hybrid engine. Just add it to ModuleEngineConfigs for the Stretch SRB. It might not be very balanced, but it's a proof of concept, mostly.

Edited November 22, 2013 by Guest

[praise the suuun]

i posted my query to the original ST thread but was told that this is the continuation so ill just copy and paste it to here.

ive run into a problem with stretchy tanks. first i stretched a KI-9000 to a certain size and cycled through the fuel types till i had simply LF. the problem is i have roughly half the amount of L in comparison to LFO. the size of the tank had not changed. why is the automatic converter limited my total fuel amount like this?

all these values were examined with the nifty highlight for details contraption.

[NathanKell]

Are you using Modular Fuels or not?

[praise the suuun]

no modular fuels. heres my mod folder

[Ambulatory Cortex]

What would it take to get a spherical stretchytank ingame?

[NathanKell]

Dragon01: Crap, yes, you mentioned that before, I was going to do it, and I forgot.

For hybrid LOX, I'll need to set StretchySRB to use a modular fueltank, I think.

praise the suuun: I will try without MFS on my end and see if I can replicate.

Ambulatory Cortex: What would it take? Finding me more hours in a day?

It's planned, and Talisar already said I could use the Spherical Tanks pack's models. I just need time.

[Ambulatory Cortex]

Ambulatory Cortex: What would it take? Finding me more hours in a day?

It's planned, and Talisar already said I could use the Spherical Tanks pack's models. I just need time.

Wonderful! I shall wait patiently.

[Kiapha]

On a somewhat related note: how about other resources, and lack thereof? I often need parts of various sizes just to make things fit, which would make a structural tank useful, and some of us actually use ion engines, giving a use for xenon. Also, kethane, ore, and rocketparts are useful for anyone trying to create a base to launch from. Asked in stretchytanks threads, but this one seems more active.

[NathanKell]

Kiapha: Use modular fuels. StretchyTanks use tank type default, so if MFS tank type default doesn't support your resource, just add it to the tank definition via MM patch (or bug me to add in on the main MFS).

[MAKC]

Dragon01: Crap, yes, you mentioned that before, I was going to do it, and I forgot.

For hybrid LOX, I'll need to set StretchySRB to use a modular fueltank, I think.

praise the suuun: I will try without MFS on my end and see if I can replicate.

Ambulatory Cortex: What would it take? Finding me more hours in a day?

It's planned, and Talisar already said I could use the Spherical Tanks pack's models. I just need time.

Don't burn yourself out.

[AngelLestat]

In any place where NathanKell adds code, it becomes a great improvement.

I think that I like it so much becouse I also share that taste for realism.

But I have so questions to see if anyone can guide me.

What it does the Key "g" in the tanks? It said to change the tank type. But it does not do nothing I guess.

Also I notice that different SRB sizes do not burn fuel in the same time ratio that I set.

For example I have a short and large srb, but i want that both last the same amount of time.. But I cant get it.

All these problems can be due to the fact that I delete all stock tanks and NP tanks?

Versions that I current use: stretchy srb v6 and mudular fuel 3.3

[AbeS]

fuel toggling with 'g' only works without MFSc as far as I know

[Surefoot]

Seems like with modular fuels you can only change the fuel type with the action groups, the "g" key becomes inactive indeed.

[NathanKell]

AngelLestat, thanks!

Yep, G for regular fuel tanks is disabled with MFS because you have much finer control now.

Regarding the SRBs: You set burntime by holding G and mousing over the tank. Are you saying that despite the tanks saying "Burn time x" and "Burn time y" when you mouse over them, where x and y are as desired, when you launch they in fact burn for different amounts of time?

[AngelLestat]

Are you saying that despite the tanks saying "Burn time x" and "Burn time y" when you mouse over them, where x and y are as desired, when you launch they in fact burn for different amounts of time?

Yeah, that's what I meant to said with my creepy english.

In my example I have the srb1 with large "x" and burn time "a" then srb2 with large "y" and burn time "a", but when I launch; the shorted srb burn its fuel faster depending on its large and not in the amount that I set.

Also I realize that the thrust in each srb is the same and correspond to the shorted..

So yeah, it seem that I had a big mess. I just delete all stock tanks and the large stock SRB (at begining also delete the short stock srb until I notice that the stretchy srb use the short stock srb model, so I put it back)

Edited November 26, 2013 by AngelLestat

[Camacha]

Don't burn yourself out.

This. I have seen too many good mod makers quit because they did too much too quickly.

[Firov]

Nathan, you're probably already overextended, so this is mostly just curiosity. Anyway, I was looking at the 1:1 replica SRB thread and I noticed that it's got variable thrust (as determined by the shape of the fuel grain), like the actual space shuttle SRB.

Is that something that might eventually be able to be implemented in stretchy SRB's? For standard rockets it wouldn't necessarily be that useful, but it could come in handy for offset payloads (AKA space shuttles).

[NathanKell]

I was just about to PM HoneyFox about that, so that it can be MFS compatible. So yes.

[ChronicSilence]

Nathan, you're probably already overextended, so this is mostly just curiosity. Anyway, I was looking at the 1:1 replica SRB thread and I noticed that it's got variable thrust (as determined by the shape of the fuel grain), like the actual space shuttle SRB.

Is that something that might eventually be able to be implemented in stretchy SRB's? For standard rockets it wouldn't necessarily be that useful, but it could come in handy for offset payloads (AKA space shuttles).

I think you already can do this, by holding 'g' and moving the mouse over the stretchy SRB. It trades thrust for burn time. Yes, I just tried this and it works.

[NathanKell]

ChronicSilence: Firov is talking about variable thrust _over time_, i.e. the SRB provides 1100kN thrust at start, then 1500 by 30s, then 800 by the end of the burn. This can be done IRL (as it is for the Shuttle RSRM) by varying the grain, as Firov says.

[ANWRocketMan]

*snip*

This is an unfortunate result coming from several factors in the way burn time is calculated.

F           
----    = Mr
Isp.Go

F = thrust(N); Isp = efficiency(s); Go = Gravitational acceleration at Earth's surface(m/s^2); Mr = Mass flow rate(kg/s)

Disregarding the slight difference in Isp, here's what is happening:

#1: Stretchy Tanks calculates your burn time with the VAB thrust value and Vacuum Isp. This gives you nice equal burn times.

#2: Once the game loads, both engines suddenly have their thrust set to a default value:

As you can see in this next image, it gives ALL the SRB's the thrust of the SRB in the craft with the lowest thrust:

#3: Assuming a constant Isp and gravitational acceleration and using the above formula, one can calculate that as both engines' thrust is now equal, their Mass Flow rate will now change against what they were in the VAB. Instead of having 60s burn times for both engines, you're suddenly left with 112(e.g.) seconds for the one engine and a mere 65(e.g.) seconds for the other.

I'm not sure whether this is a problem with Stretchy Tanks or MFS.

EDIT:

The problem is with Modular Fuel Systems. This is the result after removing it from the install:

Edited November 27, 2013 by ANWRocketMan

[AngelLestat]

wow thanks to clarify where is the issue. I thought that was just me.

But is weird, MFS in principle ignores the solid fuels. mmm, maybe a variable is reset from the VAH to Launch.

I will keep an eye to the MFS source.

[ChronicSilence]

ChronicSilence: Firov is talking about variable thrust _over time_, i.e. the SRB provides 1100kN thrust at start, then 1500 by 30s, then 800 by the end of the burn. This can be done IRL (as it is for the Shuttle RSRM) by varying the grain, as Firov says.

That makes more sense. I had thought, though, that thrust on the SRBs was varied primarily by shaping the fuel inside to give more or less surface area to burn.

[Goozeman]

This is an unfortunate result coming from several factors in the way burn time is calculated.

F           
----    = Mr
Isp.Go

F = thrust(N); Isp = efficiency(s); Go = Gravitational acceleration at Earth's surface(m/s^2); Mr = Mass flow rate(kg/s)

Disregarding the slight difference in Isp, here's what is happening:

#1: Stretchy Tanks calculates your burn time with the VAB thrust value and Vacuum Isp. This gives you nice equal burn times.

#2: Once the game loads, both engines suddenly have their thrust set to a default value:

As you can see in this next image, it gives ALL the SRB's the thrust of the SRB in the craft with the lowest thrust:

#3: Assuming a constant Isp and gravitational acceleration and using the above formula, one can calculate that as both engines' thrust is now equal, their Mass Flow rate will now change against what they were in the VAB. Instead of having 60s burn times for both engines, you're suddenly left with 112(e.g.) seconds for the one engine and a mere 65(e.g.) seconds for the other.

I'm not sure whether this is a problem with Stretchy Tanks or MFS.

EDIT:

The problem is with Modular Fuel Systems. This is the result after removing it from the install:

Having the same problem, though it seems that it gives all three stages the thrust of the first stage. This is a little bit of a pain when I want the first stage to have high thrust and the next two to be low thrust.

[123nick]

how do the ballon type stretchy tanks work? i dont see a difference from them and the standard super stretchys