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

[Van Disaster]

Honestly, it's the FPS more than the stability I'm concerned about! Game's already a bit slowed from all the other mods, just wondering if it's worth having FAR on top as well

Unless literally all you do in atmospheres is launch rockets, then FAR is one of the things to throw anything else out for. Certainly has been something I consider stock for years.

[tetryds]

Honestly, it's the FPS more than the stability I'm concerned about! Game's already a bit slowed from all the other mods, just wondering if it's worth having FAR on top as well

FAR uses the same amount of voxels regardless of the vessel size.

By logic it will handle big crafts better than stock.

And from my own tests I always got the same if not higher performance on normal rockets and airplanes.

So, performance is not a factor on that decision as long as you have more than one core.

[m4ti140]

The page I linked yesterday deals with Dutch Roll a good deal. Looking at the design history of the two RL planes specifically mentioned on that page that had notably bad Dutch Roll tendencies - the Boeing 707 and the KC-135 - would give you some clues as to how to fix the problem design-wise; the long and the short of it boils down to increasing yaw stability (the ß parameter) with MOAR FIN (the fin surface area I usually go for is 10% the area of the main wing, if you need a working guideline). And then that page I linked will tell you how an RL pilot would handle the Dutch Roll on your existing design (it's down at the bottom).

Thanks, this page you linked was especially helpful. +1 rep

[Northstar1989]

First update your FAR, some things regarding how it handles b9 pwings changed since then.

Also, don't expect to get support for an old release, it does not really make sense.

But there were some issues with b9 pwings back then, which got corrected, so yeah just update and your problem is likely to go away.

What on Earth are you talking about? Those *WERE* the latest releases of nuFAR and B9 Proc Wings at the time of my post (haven't checked for new versions in the past week since).

Also, the issue actually fixed itself spontaneously without my doing anything once I started taking screenshots (figures). The plane that had went tail-up the last 5 attempts took off perfectly without an issue or my doing anything differently the moment I loaded up KSP again and started taking screenshots. Which makes me think it may be some kind of asset-loading issues, as I suspect it was the restarting KSP, rather than the taking screenshots, which fixed it...

Not that it mattered- said plane still crashed due to Dutch Roll problems later in flight. But that was my fault- the stability derivatives were only *slightly* in the green for the roll derivatives at the subsonic airspeeds and altitude I was flying at- the design was optimized for supersonic rather than subsonic flight... (and didn't have enough dynamic pressure for the very large but low-deflection control surfaces to do their magic to a sufficient degree to prevent such problems...)

Regards,

Northstar

Edited October 10, 2015 by Northstar1989

[Svm420]

What on Earth are you talking about? Those *WERE* the latest releases of nuFAR and B9 Proc Wings at the time of my post (haven't checked for new versions in the past week since).

What on Kerbin are you talking about? That *WAS* *NOT* the latest release of nuFAR at the time of your post. The thread title alone proves you wrong. Euler is so old it's not even funny ITS FROM May, so check your facts and your attitude before "requesting" help

[baldamundo]

FAR uses the same amount of voxels regardless of the vessel size.

By logic it will handle big crafts better than stock.

And from my own tests I always got the same if not higher performance on normal rockets and airplanes.

So, performance is not a factor on that decision as long as you have more than one core.

Glad to hear! Definitely downloading then

BTW, does anyone know if the guides on the FAR Github wiki are up to date? And if not, do more up to date guides exist somewhere?

[Van Disaster]

Design didn't change much, just optimisations for wave drag which aren't *that* important - not doing anything will still let you fly - and I've noticed some differences with more esoteric configurations like forward sweep.

[baldamundo]

Calculating stability derivatives on one of my planes at 0km altitude, flaps at 2, a lot of the values suddenly jump sharply in value (and go from red to green) at a weirdly specific Mach number (between 0.39467705786 and 0.39467705787). Is this normal? Does that indicate the minimum speed required for flight or something?

The derivatives in question are Zw, Mw, Zu, Xu, and Mq.

If I actually try flying the plane, I can't even get it off the runway before it starts veering uncontrollably right-wards (and rolling left) at about Mach 0.3.

[cantab]

On the stability derivs screen there's an AoA value. If that shows 0, it actually means you can't fly level at any angle at that speed and altitude, ie you're too slow.

[baldamundo]

I do nothing but replace the small adjustable landing gear with large adjustable landing gear, and it suddenly goes from veering right at high speed, to veering left practically as soon as the engines start...I don't understand ;__;

And either way, if I ever do manage to somehow get it to the end of the runway in one piece, it just dives straight into the ocean, despite the FAR stability tools saying it needs an angle of attack of like negative 2 degrees for level flight...I'm at my wit's end here. And both these problems seem to be happening on /all/ of my old planes, regardless of size, style, design, stability derivatives, etc.

Guess I should try just making some new ones from scratch and see if the problems persist. Otherwise I'm about to give up. Do not remember FAR being this impossible in 0.90.

[softweir]

Have you tried any old designs to see how well they work?

[vrothenberg]

Anyone know why FAR makes rockets in orbit at 100km experience some weird forces mimicking aerodynamics? My relatively small 1.25m ship oscillates along the prograde vector in orbit above Kerbin. Trying to move to retrograde is nearly impossible and makes the game almost unplayable.

FAR shows no dynamic pressure and the atmosphere density indicator is at zero. Just uninstalled the mod to confirm it's causing the problem as well.

Edited October 12, 2015 by vrothenberg

[cantab]

vrothenberg, check you haven't left the pilot assistant tools on. That has caught me out several times.

[vrothenberg]

That was exactly it. Thanks cantab!

[capi3101]

Thanks, this page you linked was especially helpful. +1 rep

Glad I could be of help, and thanks for the rep.

[Van Disaster]

Could I get a checklist to look at as to why this panel is stalling? the surfaces attached are yaw brakes only, no pitch or aoa in them at present. I won't mention what I've looked at already so I don't pre-empt anything.

Cheers.

[tetryds]

@Van Disaster: did you clip two control surfaces inside of each other?

[Van Disaster]

No, it is just attached to the panel in front, it shouldn't have a leading edge of it's own. The outer edge isn't projecting outside the panel it's stuck on either.

Edit: the yaw spoilers shouldn't overlap either.

[baldamundo]

Derp! Finally figured out why my planes kept crashing - my procedural wings just weren't generating any lift because of how I fixed this bug before I installed FAR. Still not quite solved the veering on the runway though...

[ferram4]

I diagnose the wing panel issue as an obvious case of wing clipping. There's a lot of wing clipping in that plane, don't do that.

[Van Disaster]

I diagnose the wing panel issue as an obvious case of wing clipping. There's a lot of wing clipping in that plane, don't do that.

I'd go with that, except that's the one panel that isn't clipped into anything! if you're saying that's the end result of clipping panels elsewhere, then ok I'll work round it.

[cantab]

I diagnose the wing panel issue as an obvious case of wing clipping. There's a lot of wing clipping in that plane, don't do that.

It seems like there's no great way to handle wing shape in FAR then, if clipping is bad and procedural wings have proven buggy.

[Nansuchao]

I have a lot of planes and spaceplanes with B9 Procedural wings, never had any issue...

[Van Disaster]

I've personally never had an issue with B9 Pwings either - not built much since 1.0, but the things I have have worked fine even when they're somewhat extreme by aircraft standards.

You notice when something is off fast when you don't have much inherent stability...

Anyway: I rebuilt my wing making sure there were no overlaps, or at least I rebuilt it as close as I could - couldn't get quite the same shape. I feel like this is three years ago, but... when is a part considered to have a leading edge? Would the panel on the right here be considered to have a leading edge? I've attempted to minimize any overlap at the corners, but I've also attempted to make sure the leading edge of the right side panel is covered. Does FAR take another look at panels as the wing bends, at the moment? because I notice the leading triangular panel basically won't stall ( because of the drooping leading edge ).

I'm pretty sure my original wing's issues aren't just because of any clipping, something slightly odd about this shape.

The second is about as extreme as it gets ( and I realise we're looking at fairly extreme AoA here ) and this wing is more progressive, but it still starts at that back panel. Are the elevators causing something? I've tried to keep separation but it's a bit borderline, perhaps.

Any better ways of getting high-AoA roll control than feeding AoA into the ailerons, btw? not terribly effective.

[ferram4]

Oh. You're at 45 degrees AoA in that last one. And 32 degrees in the first one you showed.

Yeah, that's working as intended. An infinite, unswept wing stalls at ~15 degrees or so; finite wings with sweep will increase that a bit, but in the end, stalling still starts to show up above 20-25 degrees. No issues here, that's just trailing edge flow separation, perfectly expected for low AR, highly swept wings at high AoA.