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

[ferram4]

That's part of the fairing issue I'm looking at right now. In flight it shouldn't be quite as bad though, the editor just doesn't handle fairings quite as well as it should.

[enki]

I've noticed some pull with the fairing bases but I'm not sure if it's something wrong with the part or just my terrible flying skills.

The fairings also seem to affect the CoL disproportionately. Yes I know, different shapes, but different enough to cause this?

http://imgur.com/a/BWIE3

Had the same issue a page or two back, open the FAR gui and smack the sweep AoA/Mach button. It seems to fix things.

[ferram4]

Alright, version 0.12.5 is out, with another attempt at fixing the supersonic roll-twitch issue, a fix for some payload fairing drag problems, CoL corrections and fixes to how the flap code works. And your control system settings will be saved now.

Edited January 5, 2014 by ferram4
Edit: I can not type proper version numbers before going to bed.

[SkyHook]

Alright, version 0.12.4 is out, with another attempt at fixing the supersonic roll-twitch issue, a fix for some payload fairing drag problems, CoL corrections and fixes to how the flap code works. And your control system settings will be saved now.

Every update is christmas and a new challenge for my shuttle!

[Surefoot]

Alright, version 0.12.4 is out,

You mean version 0.12.5

Testing the roll twitch now.

(edit) yay no more twitch Supersonic and hypersonic are now smooth as silk. Went up to mach 7.3 with the turboramjets, everything was fine.

Edited January 5, 2014 by Surefoot

[DresCroffgrin]

I'm having a problem with 0.12.5. Whenever I reenter Kerbin's atmosphere, my craft spontaneously explodes, with a message about the crew dying due to G-forces. Normally I would say this is something up with Deadly Reentry (which I have installed), but reverting to 0.12.4 removes the problem. My guess is whatever is happening is happening when FAR loads. The craft was built and launched under FAR 0.12.4, but I doubt that has anything to do with the issue.

EDIT:

Launching the same craft in 0.12.5, it seems to behave fine when reentering. Still not sure what was causing the initial problem, as it occurred 3 times in a highly repeatable fashion.

Edited January 5, 2014 by DresCroffgrin

[Surefoot]

That could have been explained in 0.12.4 due to the twitch glitch, but since it's gone from 0.12.5 this is very weird. I just tested hypersonic flight (similar to re-entry) with 0.12.5 and had no weird g-force, no "bump" ot twitch, everything was smooth. I suppose you keep a small AoA and low profile for re-entry ? Maybe one part is creating too much drag ?

[Selgald]

Hi ferram,

with 0.12.5 I have some strange things going on in the Kerbin atmosphere.

My Ver/Hor velocity almost dropped to zero on re-entry.

Short video what happened:

[Surefoot]

Wow, that must be what happened to DresCroffgrin just above.

[DresCroffgrin]

Wow, that must be what happened to DresCroffgrin just above.

It probably is. However, it does not occur 100% of the time, as I got a successful reentry a little later with a different vessel (but the same .craft). However, it does seemed to be pre-determined by something; all of my ships keep their exploding or safe-return behavior across saving/loading. It might be worth noting the one that exploded was coming from a Munar return trajectory, and the one that was safe was just a suborbital hop for testing if things were working again. Both had a periapsis of 20km.

[steakbbq]

It seems with rockets, if you have the water vapor going around your craft you have a LOT less margin for angle of attack before losing control. Is that correct? Less drag at the tip of the rocket?

[ferram4]

@steakbbq: You'd have little margin either way, but the stock mach effects are a decent indicator of dynamic pressure, and higher dynamic pressures mean higher aerodynamic forces.

@DresCoffgrin & Selgald: I'll investigate. Based on the video, it looks like the area calculation is off; it said that you had a reference area of ~100,000 m². Can either of you provide a craft file that is confirmed to cause this?

Edit: Found it. Caused by reloading a craft in orbit... I think I know what might be causing it. Look for a hotfix soon.

Edit2: v0.12.5.1 hotfix is up. If you downloaded v0.12.5, you better download this or you're going to have problems.

Edited January 5, 2014 by ferram4

[jrandom]

I'm seeing minor roll twitches now at AoA of 10 degrees at mach 1 with this latest version.

[ferram4]

At Mach 1 and at high angles of attack you're going to have lots of detached shocks all over the place, so roll twitches there should make sense. Faster and I don't think it should happen.

[jrandom]

At Mach 1 and at high angles of attack you're going to have lots of detached shocks all over the place, so roll twitches there should make sense. Faster and I don't think it should happen.

Oh! Well then, if that's realistic behavior then carry on! (I was testing a failed experimental plane and had to pitch up quite a bit during the test flights.)

[DresCroffgrin]

@steakbbq: You'd have little margin either way, but the stock mach effects are a decent indicator of dynamic pressure, and higher dynamic pressures mean higher aerodynamic forces.

@DresCoffgrin & Selgald: I'll investigate. Based on the video, it looks like the area calculation is off; it said that you had a reference area of ~100,000 m². Can either of you provide a craft file that is confirmed to cause this?

Edit: Found it. Caused by reloading a craft in orbit... I think I know what might be causing it. Look for a hotfix soon.

Edit2: v0.12.5.1 hotfix is up. If you downloaded v0.12.5, you better download this or you're going to have problems.

ferram, your ability to identify, debug, and release solutions to problems faster than the blink of an eye never ceases to amaze me.

[Black-Talon]

Ferram, I've wondered for a long time if there is a way to draw the lift vector and center of gravity while in flight. Knew you'd know, do you do anything like that for debugging? Or is this one of those things mentioned too many times?

[illectro]

I

Also I am encountering a quite annoying bug.

I think I'm running into the same bug, it forces me to restart the game, which takes a long time with all those mods.

[Volt]

ferram, your ability to identify, debug, and release solutions to problems faster than the blink of an eye never ceases to amaze me.

No kidding. Ferram is on par with SQUAD devs in terms of skill IMO, and that's no mean feat. Hint hint nudge nudge wink.

[camlost]

No kidding. Ferram is on par with SQUAD devs in terms of skill IMO, and that's no mean feat. Hint hint nudge nudge wink.

Does anyone in the dev team has proper knowledge of aerodynamics?

[ferram4]

@Black-Talon: Send a PM to a.g.; he's implemented some code of his own into a private version of FAR that does that. He hasn't been able to get it to get it to render on top of the parts, but it does accomplish that.

@illectro: That is a bug in FAR v0.12.4 and earlier; update to v0.12.5.1 and it should be gone. I just hope you didn't update to v0.12.5; that one was quite nasty.

[SnappingTurtle]

Did something happen to the amount of lift generated in the last patch? I have this craft that seemed to fly a lot better before than now. Could just be me.

[ferram4]

Depends on the flight regime and what parts you're using. Fixing the supersonic roll twitch would have changed the lift of supersonic wings a bit. I also made the CoL shift in the transonic regime a little less crazy to help compensate for the changes to body lift, since it made taking pretty much anything supersonic a nightmare. So yeah, planes should be a little more stable.

Oh, has anyone noticed that the SR-71 included with FAR acts a lot like the real one? It's stable at relatively low angles of attack but gets really unstable at high angles of attack.

[lilzkiller]

I'm still getting a pull from a lot of different parts now (that i have discovered)

I have only FAR and KW Rocketry installed during these pictures

http://imgur.com/a/dysMX#14

[ferram4]

That's intentional. What do you think happens if you pitch one of those parts upwards? It creates lift upwards. The CoL shows were that lift force will be centered.

After seeing this question a bunch I'm tempted to try and get rid of the vector part of the CoL so that it's just a point without the vector to confuse people. And see if I can change the tooltip so that it says "Aerodynamic Center" rather than "Center of Lift."