[0.90] Stock Drag Fix - Mar 19, 2015 (BETA UPDATE)

[rynak]

Given that this plugin in the future will have to rebalance behavior of items, it would be nice if there'll be a configfile, where we can tweak global modifiers for the various effects. This way, people can adjust the strength of rebalancing to their taste. You know, kinda similiar to KerbalISPDifficultyScaler by ferram, which ironically is almost a mandatory complement to your plugin. You might actually want to link to it, so that people won't ask you to implement duplicate features (cause if it weren't for ferram's ISP and thrust tweaker, those features really should be added to to SDF .

[Starwaster]

There will definitely be some things that are exposed in the config file for scaling. It already has a couple of variables in it, one for global scaling of drag for SDF modules. When I do something about nose cones it will be necessary to scale global drag up a bit. (as I mentioned, drag for SDF parts is actually comparable to what it should be for nose coned stacks even if they have no nose cone)

As for KIDS, it's not even something I use myself as I usually play with RSS (Kerbin scaled up 10 times) and Real Fuels, both of which make KIDS redundant. I'd like to hear from other KIDS users as to their thoughts on the matter but the only features I'm really thinking about are those that are specifically drag related; that's the scope of this plugin really.

[rynak]

Soo, any news on when starwaster will strike back? It's not like NEAR is everyone's cup of tea.

[Starwaster]

I know I know

But I wanted to get some game playing time in with the new Career system too.

Plus Ioncross has some buggy resource problem that I have to look into. I'll get back to SDF real soon though

[Jahulath]

Love this mod, no more waiting to use up most of the fuel yay! For a long time I had wondered why they took so long to get up to speed lol IMHO fuel should be irrelevant to drag.

[vardicd]

so is this compatible with .24.2? or not? first page doesn't say, unless I'm blind.

[Starwaster]

so is this compatible with .24.2? or not? first page doesn't say, unless I'm blind.

Yes, it is. It's still the same build but nothing really changed to affect it. I'm using it with the latest KSP.

[Eleven]

Nice! Happy medium between NEAR and FAR!?!?!??!

[Kamuchi]

Going to test it tomorrow as my simple ssto`s that is ballanced near perfect but just keeps disintegrate even with a shallow re-entry at with PE at 38km to slow down over half the planet lol

Will be happy if it works out as a medium FAR and NEAR

[Taquarinha]

No MechJeb here, so I'll just fly a bunch of test flights and see what works best. I can report back findings when I have some for people who fly without MJ.

I've been getting good results starting to turn at 5km.

[Chase]

I look forward to your fairing/nose cone fix.

For the nosecones, what I would do, is I would increase all drag by a certain percent (like 10-20%) unless it has something above it in the stack, and remove it if the item is "aerodynamic" such as a wing, or a nose cone. Perhaps 10% for each side that it has nothing on in the stack. So a fuel tank would have a 20% increase by itself, a 10% increase with a nose cone on one end, or normal if it has a nose cone (or something else) on each side. Which means the items with the most `extra` drag would be items on the end of a stack.

The fairing issue is just the matter of finding everything within the fairing and removing drag for it (and somehow applying drag for the cross section of the fairing).

Edited August 15, 2014 by Chase

[Starwaster]

Thanks for your input Chase!

[Chase]

Actually I forked your code and did the nose cone thing yesterday. I even built a simple copy in releases. See my pull request for full details.

Edited August 16, 2014 by Chase

[Starwaster]

Actually I forked your code and did the nose cone thing yesterday. I even built a simple copy in releases. See my pull request for full details.

Thanks, I'll take a look later tonight. Have you tried comparing the results either against real life or either of the other two drag mods?

[Chase]

I ran a quick test against itself. A single solid booster gave more height with the nose cone then without across a sample size of 3 per (just aiming straight up). I haven't tested the altitudes reached against stock, but I can do that.

[Chase]

I ran a quick test against itself. A single solid booster gave more height with the nose cone then without across a sample size of 3 per (just aiming straight up), but that was against 5% rather then the 10% drag.

I haven't tested the altitudes reached against stock, but I can do that. I will retest everything now, and publish the results here (or in the pull request).

Edited August 16, 2014 by Chase

[Chase]

Welp, my latest tests show that a slight increase in drag on one or two parts does not make up for the added weight of the nose cones still. So ignore my pull request. But you may still want to look over my bug fixes and slight optimizations.

[Starwaster]

Welp, my latest tests show that a slight increase in drag on one or two parts does not make up for the added weight of the nose cones still. So ignore my pull request. But you may still want to look over my bug fixes and slight optimizations.

Assuming a typical and simple stack, the net result of your fix would be to add drag to the bottom piece (an engine) while leaving everything else alone. That's not necessarily wrong (well, it is actually but no more wrong than the stock system itself). But it's probably getting too much added.

It would probably help would be a substantial reduction for all the stack pieces in between (with shielded top and bottom nodes). The global drag multiplier might then need adjusting to make sure that net drag is balanced to something sane. That's the main reason it exists is that at some point I anticipated needing to do something about the fact that multiple pieces were all contributing an amount of drag that makes no sense given that they weren't actually facing against airflow. Actually, that wouldn't be realistic. I'm not terribly committed to full realism for SDF but it wouldn't make sense for the craft to have parts of its side oriented to the airflow and not have them subject to drag. There's a solution here but I'll not likely get around to it until the update I'm planning for Ioncross is released.

I'm not sure about some of the bugs you're referring to but I'll take that part of the to the pull request on Github

Edited August 16, 2014 by Starwaster

[aristurtle]

When I try to use this with MechJeb's landing guidance, it does a deorbit burn and then just says "Reentry simulation timed out". Any ideas on what's causing this?

[Starwaster]

When I try to use this with MechJeb's landing guidance, it does a deorbit burn and then just says "Reentry simulation timed out". Any ideas on what's causing this?

No, but I've seen MJ2 do that even before SDF came along. I doubt it's related.

If you want to send me a craft file for the craft this happened with I'll take a look and see if I can reproduce it. (if it needs staging, let me know how much staging to get it to the point where you had it)

[Galane]

So the Angular Drag numbers in the CFG files don't actually do anything? Drag for all parts is calculated the same no matter which way they're ripping through the atmo?

This looks like it's shaping up to be a very useful mod! Making nosecones beneficial instead of detrimental to performance and properly drag shielding parts inside fairings or stacked beneath other parts will be very nice.

On my heavy launchers I've taken to strapping on enough SRBs to where MechJeb will throttle back the liquid fueled engines to save fuel during terminal velocity ascent. But still it takes tons of strapped on asparagus to deliver even half a tank full (of pretty much any tank) of fuel to orbit with the stock drag model.

Edit: I'll have to try my failed Duna Kethane mining landers to see if this will make them efficient enough to be useful for bringing Kethane to orbit from there.

Edited August 29, 2014 by Galane

[Starwaster]

So the Angular Drag numbers in the CFG files don't actually do anything? Drag for all parts is calculated the same no matter which way they're ripping through the atmo?

This looks like it's shaping up to be a very useful mod! Making nosecones beneficial instead of detrimental to performance and properly drag shielding parts inside fairings or stacked beneath other parts will be very nice.

On my heavy launchers I've taken to strapping on enough SRBs to where MechJeb will throttle back the liquid fueled engines to save fuel during terminal velocity ascent. But still it takes tons of strapped on asparagus to deliver even half a tank full (of pretty much any tank) of fuel to orbit with the stock drag model.

Edit: I'll have to try my failed Duna Kethane mining landers to see if this will make them efficient enough to be useful for bringing Kethane to orbit from there.

Angular drag governs a parts resistance to being rotated. So far I have not seen a need to do anything with angular drag and I'm not even sure it has the same mass bug as the other drag fields. I'll reevaluate angular drag as needed.

I've got a good idea how I'm going to do nose cones and fairings. Just haven't got to it yet. Been working on an update for Ioncross and the reflection plugin claimed a few days of my time too.

[Guest]

Starwaster, I'm loving this mod! Well, besides having to go back and rethink my now ridiculously overpowered lifters, that is. A small price to pay for more realistic launch performance. Excellent work!

[Starwaster]

Starwaster, I'm loving this mod! Well, besides having to go back and rethink my now ridiculously overpowered lifters, that is. A small price to pay for more realistic launch performance. Excellent work!

Maybe you just need heavier payloads??

[Guest]

Maybe you just need heavier payloads??

Yeah, that would probably be simpler!

And I can try again to build the UR-700/LK-700 now that I know it stands a chance of flying.

Edited August 31, 2014 by Jack Wolfe