[1.3.1] Ferram Aerospace Research: v0.15.9.1 "Liepmann" 4/2/18

[NathanKell]

Presumably by split control surfaces, for drag-induced yaw? That gave me an idea...

[JackCY]

Is it possible that after a back flip a plane will be in large scale stall even when the AoA is zeroed for a reasonable time (few seconds, 5-10s no problem)? It flies I can climb and control ok but it feels like there is stall drag applied to it and it never gets out of large scale stall unless I do some other hard maneuvering/flips etc. through some more stalls, side slips and large AoAs, and it only ends up in some other kind of stall or slide slip or again in large scale stall, while the plane is easily controllable and flies where intended but seems to have stall drag applied.

Made such a test plane.

The flight status in the screens is missing because it was blinking large scale stall in yellow text.

If you want to look at it, let me know I'll upload the craft file somewhere.

No tweaks were done to wings or control surfaces they are default, it has no flaps, no spoilers.

Even if I point it at prograde for a while which means it starts dropping and going down, it never recovers and the AoA is very close to zero, don't need SAS to keep it stable and on prograde.

Now minor stalling with only one wing, again unrecoverable, this time the drag is on one wing so it's not actually very flyable.

I know the plane sucks, it's a test plane but still, shouldn't it go to Nominal when AoA is very close to zero?

It's like the status gets stuck.

Edited October 16, 2014 by JackCY

[velusip]

@velusip: Reproduction steps and a log, please? Just saying, "X thing that shouldn't happen happens" doesn't help me find out what is wrong.

I'm just chatting with the locals and hoping to find some common ground before submitting anything. If you really want this hopeless bug report, sure, but I have nothing more yet. Steps:

$ unzip ksp-linux-0-25-0.zip
$ unzip Ferram_Aerospace_Research-v0.14.3.zip
$ mv GameData/* KSP_LINUX/GameData/
$ LC_ALL=C ./KSP_LINUX/KSP.x86_64 -force-gfx-st
$ cat ./KSP_LINUX/KSP.log | sprunge

Without changing any options in-game I merely started a new career, created a very simple craft (pod, some tanks, engine, some solid boosters), and upon launch only the pod remains, hurdling into space at billions of meters per second. Same happens when playing with other mods, but here's the log from a bare install with just FAR:

http://sprunge.us/BEDF

Edited October 16, 2014 by velusip
typo

[ferram4]

@JackY: That shouldn't be happening. I have confirmed it, I'll see what I can do. And it's not the status, it's the wing interactions + stall that's messed up.

@velusip: Launching it through Steam? Try without. That worked for someone else. Dunno what launching through Steam changes, but it changed something.

[velusip]

@velusip: Launching it through Steam? Try without. That worked for someone else. Dunno what launching through Steam changes, but it changed something.

No Steam. I downloaded the game directly from kerbalspaceprogram.com account management. I'll see if I can find the environment variables that KSP uses from Steam and tinker with that.

[ferram4]

Please try. It seems to be something related to Linux 64 somehow, but only a very few people can cause it. I have no idea where it's coming from, and the effects don't make much logical sense.

Oh, JackY; fixed the issue, I was being a little stupid. The dev build has the fix, and I'm just polishing up some efficiency changes before I push a patch.

[Wanderfound]

I usually use the FAR flight assistants in atmospheric flight and SAS on and off but trim sounds like it would be useful. Thanks

regex's PID Controller is good for this as well. Halve the default value of pitch clamp and it'll stick much more solidly. You may need to toggle SAS to manoeuvre if you overdo it, though. Season to taste.

[Wanderfound]

I appreciate that Ferram has been working hard, so please consider this a vote rather than a demand, but:

Please fix the wing strength tweakable UI. It's unpleasant to use at the moment; picking the exact spot on the slider for 0.4 instead of 0.39 or 0.41 is a nightmare.

If possible just adding a set of +/- increment buttons would do it; you could click near the value you want, then fine tune by increment.

A "set default wing strength" would be even better, though.

[nickexists]

I haven't played ksp since 0.22 and now coming back it seems like FAR has changed a lot. In particular it seems more difficult to make a plane that is stable but still has a decent turn radius across a large speed range. It also seems like it's more difficult to make a plane that doesn't oscillate when turning. Does anyone have any design advice for me?

[Wanderfound]

I haven't played ksp since 0.22 and now coming back it seems like FAR has changed a lot. In particular it seems more difficult to make a plane that is stable but still has a decent turn radius across a large speed range. It also seems like it's more difficult to make a plane that doesn't oscillate when turning. Does anyone have any design advice for me?

If you want to turn fast, you need a broadwing design. Either chunky rear deltas and nose canards or mid-mount swept/structural plus a tailplane. I'm liking the look of the new swept wings with a pair of the also new needle-skinny swept wings along their leading edge.

Wind down your maximum control authority a bit, and consider having a play with regex's PID Tuner.

[endl]

hey ferram i dont know if i should bring this to your attention or not but the space plane plus docking port does not shield parts from your mod, the reason this is an issue for me is because i like to put lights inside for better visibility when docking. should i report this to squad/sp+ dev or is this something you can handle since its a stock part now.

[ferram4]

@Wanderfound: Like PP does for its parts? I can try implementing that.

@endl: The docking port is not a cargo bay. That's not surprising, and I'm not going to consider making it one, because then I risk getting a lot of false positives.

[endl]

@Wanderfound: Like PP does for its parts? I can try implementing that.

@endl: The docking port is not a cargo bay. That's not surprising, and I'm not going to consider making it one, because then I risk getting a lot of false positives.

fair enough except now i need some kind of lights that i can mount externally that are far friendly any suggestions?

[ferram4]

@Wanderfound: Scratch that, not happening. That requires a dependency on KSPAPIExtensions, and my experience with that is that adding that dependency is a bug no-no. It's pretty bloated and takes a long time to update when KSP updates. I'm not willing to deal with that.

@endl: Umm... any of them should be fine. B9 lights especially.

[Wanderfound]

fair enough except now i need some kind of lights that i can mount externally that are far friendly any suggestions?

I'd been using that trick as well...

There's a mod called aviation lights that is nice. Their lights are prone to burning up or breaking off if you really push it, but I don't mind: the lights are small and expendable and they make good coalmine canaries during a hot reentry.

[jrandom]

Minor feature request, if you ever happen to have the time: I'd love to be able to toggle the various FAR flight assistance buttons via custom actions.

[endl]

I'd been using that trick as well...

There's a mod called aviation lights that is nice. Their lights are prone to burning up or breaking off if you really push it, but I don't mind: the lights are small and expendable and they make good coalmine canaries during a hot reentry.

wanderfound is there some kind of special cereal that you eat in order to poop wisdom like that?

[Climberfx]

Thank you Ferram4 and Nathankell, this last update put FAR in the place it deserve.

Is amazingly balanced. All my Builds working again.

And that supersonic jet that came together make me learn more stuff on how to use flaps.

Thank's a lot!

[Hyomoto]

There is a first time for everything, and today I accomplished something that has long evaded me: landing safely on the runway. The landing was a bit on the rough side, but I'll take what successes I can get!

[blowfish]

fair enough except now i need some kind of lights that i can mount externally that are far friendly any suggestions?

B9's omni lights work well.

[Matrix Aran]

Presumably by split control surfaces, for drag-induced yaw? That gave me an idea...

That would be it exactly. I've just not had much experience trying to build split control surfaces with FAR, so I'm curious if anyone else has had any previous experience.

Oh and I'm curious, what idea have you just had?

[Lexx Thai]

Ferram, may I make you a feature request? Can you add tint for aerostress forces to detect some design issues: my ICBM's (some roleplay style "space program") are explodes in the air during descension.

[JackCY]

@JackY: That shouldn't be happening. I have confirmed it, I'll see what I can do. And it's not the status, it's the wing interactions + stall that's messed up.

Oh, JackY; fixed the issue, I was being a little stupid. The dev build has the fix, and I'm just polishing up some efficiency changes before I push a patch.

Cool thanks.

I appreciate that Ferram has been working hard, so please consider this a vote rather than a demand, but:

Please fix the wing strength tweakable UI. It's unpleasant to use at the moment; picking the exact spot on the slider for 0.4 instead of 0.39 or 0.41 is a nightmare.

If possible just adding a set of +/- increment buttons would do it; you could click near the value you want, then fine tune by increment.

A "set default wing strength" would be even better, though.

I find setting it lower than 1 results in ripping the wings apart, I fly hard

Plus setting it all the time for every wing added and the balance CoM it changes and all, ugh such pain.

I don't have an issue to select any value, it sure is sensitive but it's just about mouse control and sensitivity. And it doesn't really matter if it's 0.39 or 0.41 the difference is tiny. It's only OCD to have it all on 0.4 spot on

[GabeTeuton]

Post screenshots for each ship with the FAR stability derivatives analysis showing, and we'll see if we can figure out exactly what the problem was.

Do one set with temperature zero, density 0.5 and speed Mach 1.5 (this is the low altitude ascent one), another with temperature -20, density 0.04 and speed Mach 5 (just before the rockets go on) and a third set with temperature -20, density 0.01 and speed Mach 6 (just after the rockets go on).

So as you requested I've done the tests and here are the results, in spite of the analysis you guys may do on boths designs in this particular case, i would like to ask for a place to reference to the meaning, (and more importantly the PRACTICAL meaning) of these values... I read the FAR wiki at github many times trying to memorize it or understand it, but it's still under construction (unless i'm searching the wrong place) and i tried looking for stability derivatives in google but i can't find a practical not that much mathematical reference to them...

I'm no engneer, so in other words what i'm requesting, if anyone is interested is a very short summary of what does every value mean and what's the practical application=

For instance "Under Longitudinal Derivatives; Down Vel Derivatives; Zw Value means blah, and it should be green (as it already more or less says in the editor GUI, but adding >>>>), and if it's red you should move your main horizontal wings back, or up, or pitch them, in order to increase or decrease this value"

This request is not because I don't like what you say, but i would like to be independient of the forum in order to avoid bothering people every time i have a failed airplane/ssto, and who knows maybe help someone instead, i do know the basics as i love airplanes, my father was a pilot, both helicopter and planes, and i've been playing Flight Simulator and most simulator kind flying games, specially helis one, I love helicopters... So what i'm trying to say is I would like a short guide with every value in the Editor GUI analysis of stability derivatives in a practical way, so i don't need to became an Aerodynamics engineer or something close to it and still know what to do when it comes to some of those red values... For instance in the third analysis of the SSTO X-149 the lateral derivatives analysis, YAW rate derivatives, Yr is red, and it says it should be positive, aswell as "Change in Y-direction acceleration with respect to yaw right rate, etc", okay kind of get what it means, but have no clue whatsoever on how to apply a solution to it, and have no will to waste time on making a very long trial and error process.

Without further ado=

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(didn't use the spoiler code as it doesn't work properly due to imgur issues as i read in other thread, how should i work around the fact that the album is not tall enough???)

Thank you to all those interested in this, and everyone who responded...

***I would like to add, just in case, that in the CT-50 design, the inline cockpit I edited it to have a Crew Capacity of 4 in order to fulfill my mission once and for all, not sure if that will make any difference as it's the only value I edited...***

***Also just in case, it start to get the unrecoverable stall when I hit around 25km (talking about SSTO X-149), and never got to mach 6, just around mach 5.5 by that time and that happens in EVERY design in which i use this cockpit/parts***

[madadam]

Hi Ferram (and others),

Is it possible to figure out whether my craft has enough pitch authority to maintain level flight under certain conditions (speed + atmospheric density, etc...), just from the data provided by the analysis windows?

Sometimes I build a craft which seems aerodynamically sound (all the stability derivatives green, etc...) but then during low speeds (as when landing for example) it cannot keep itself level and it noses down until it crashes. Another situation where this problem sometimes occurs is a spaceplane in very hight altitudes when the plane cannot pitch up enough to keep climbing higher.

So, is there a way to predict these problems while still in the SPH? Or do I have to actually flight it to find out?