BALANCE: Rescale Flight Testing

[jsolson]

Harder Solar System is not currently supported. It's not Sigma based.

Compatibility\Rescale\BlueSmurff.cfg is the file we're working with.

If you're familiar with SMURFF, this is based on that. We're reducing the dry mass of various parts to get the deltav we want. What gets reduced and by how much is determined by the rescale value from Sigma. Adding fuel is an option, but we want to exhaust the mass possibilities before throwing more fuel in.

Things we need to know to make adjustments:

How do the non-manned rockets fly with payloads. OP/Under-P/About right.

Do Mercury Atlas and Gemini Titan make orbit without too much excess dv. (No using the SM engine or mercury srbs.).

Saturn is a top down problem that should be done last, but we need to keep an eye on it. Enough dv for LEM ascent/descent, CM dv to circularize and return, S-IVB TLI burn, and then the S-II/S-IC stages. We want the S-II to burn out short of making orbit, but not so short the S-IVB can't do the TLI. We have ballast mass built in to Saturn that can be removed to tune the various stages.

Right now the settings look ballpark correct. We need to pretty much fly everything in every rescale and make sure.

[Daelkyr13]

I doubled the thrust in the J-2 and that did the trick. I've been able to get the Saturn 1B into an 80ish by 120ish km orbit from scales of x2, x3, and x4. The Saturn V also gets into orbit and burns for TLI without issue. However, at x4 scale the CSM doesn't have enough delta-v to to perform TEI. It ends up about 75 m/s short.

[jsolson]

We might need to use the 594/726 configuration for the SM tank then (that's what we use in 6.4x). Did you have the sense that there was enough surplus dv in the S-IVB and below to take the extra fuel? It's going from 1000 LFO to 1320.

[Daelkyr13]

I'll add the 320 extra LFO and see if it can handle the weight in x5. I have yet to actually test the LM. (It's next on my list of testing.) Going back to the S-IB stage of the Saturn 1B, what is the goal TWR your looking for? I still think we could pour just a little extra fuel into it.

[jsolson]

I checked in double the thrust and 33% mass increase on the J2 family. It really should be double mass, but I'm not sure the S-IVB can take it - it's got no ballast mass left on it I can take off to compensate.

I'll do some testing on the S-IB today. Last I checked it was fine. Keep in mind the entire Saturn family is underscale. While the S-V stack can absorb that below 6.4x, the S-I/S-IB/S-IE will underperform a bit. There's a full size Saturn rescale in extras.

[jsolson]

However, at x4 scale the CSM doesn't have enough delta-v to to perform TEI. It ends up about 75 m/s short.

I've got an extra 150 dv in 4x. With the unmodified CSM fuel at 1000 LFO plus a full load of 250 MP, and TAC life support supplies. I'm spending 22 dv on correction burns, 545 to circularize at 100 km, and 553 to return.

I took the S-IB for a ride in 4x as well. Seems fine. The uprated J-2s make it easy.

[jmrd98]

I think there is a problem at 6.4x in bluesmurff. Regarding apollo, i'm tracing my way back through it as all of my apollo parts have negative mass. This raised an eyebrow...

BDBRESCALECONFIG { systemScale = 6.4 tankFactor = 0.41 structFactor = 0.5 podFactor = 0.5 engineFactor = 0.41 srbIspAdd = 40 scaleFactor = 1 podSubtract = 0.5 apolloPodFactor = -0.1 tankSubtract = 0.59 structSubtract = 0.5 engineSubtract = 0.59 apolloPodSubtract = 0.6 ballastFactorS1C = 1 ballastFactorS2 = 0.5 ballastFactorS4B = 0.2 }

Talking through it... At systemScale >1, podSubtract starts at 0.5 and is multiplied by the scaleFactor ((6.4-1)/5.4 = 1) giving 0.5. podFactor (1) is subtracted by this 0.5 giving 0.5 again. apolloPodFactor is set to 0.5 at this point.

At systemScale >6, apolloPodSubtract is set to 0.6. This is multiplied by scaleFactor (1), and then subtracted from apolloPodFactor (0.5) giving -0.1. Aha! DINGDINGDING! It looks like this was last touched in f4da2408ed in november. Am I nuts here, or more likely blind and didn't notice this in testing before? The initial check in in 5ab970df8 would be even more out of whack, from my reading, apolloPodSubtract was at 0.7.

Clearly this doesn't seem right, so i'm wracking my brain trying to figure out how this got missed (if it's real). It would only manifest at rescale >6, so ... Yeah, I got nothing. I should have seen this prior.

Also... Rimworld is a hell of a drug >< Sorry to be absent for a bit!

E: There's no way I missed this... negative mass parts, well, levitate, after they rip themselves off the stack on the launchpad... But i'm vexed as to when this started. ... A problem for the morning, I think.

[jsolson]

I think there is a problem at 6.4x in bluesmurff.

Yup. The Saturn_rescale.cfg resets it back to match podFactor. Makes me wonder how much of those HAS[#systemScale[>6]] adjustments are even valid.

[jmrd98]

Yeah, that'd do it... I'll make the adjustment to match. I hadn't put it together, although obvious in retrospect: I'd just disabled the saturn rescale to test the 'stock' version at 6.4x. Didn't occur to me that it would catch the pods as well.

Nevermind, saw your commit just now. Checking presently.

[PaulMaynard]

Is scout supposed to make orbit?

[jsolson]

Is scout supposed to make orbit?

Yes. It has a very low payload capacity.

[PaulMaynard]

It doesn't have enough delta-v for 3x.

[CobaltWolf]

@IronCretin even empty? We're in the unfortunate position where, even with it oversized, the payload is still likely smaller than any of the probes in BDB.

[jsolson]

In 3x I was putting Sienno based sats in polar orbit this morning. There's also Amba (Pioneer 4). There used to be a microsat mod. Not sure if Coatle has any tiny probe cores available.

I gave it some thrust curves, and I've been lowering the thrust in the vab 10-20% to keep it from going hypersonic.

[CobaltWolf]

oh whoops lol