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

[wminsing]

So does this work with Procedural Wings?

-Will

[NathanKell]

Yes. It does.

[wminsing]

Thanks for the fast answer, I've been re-training myself to fly using FAR and for my future spaceplanes I'm considering Procedural Wings.

-Will

[Surefoot]

See a few posts before, i clearly mentioned i tried the elevon design (and even played around with fuel transfers) - and i am still missing something. When i look closely these planes all have some degree of wing camber, clever tricks such as lifting body for the blackbird, and so on. The combination of all these tricks is what makes them fly, and i am missing at least one, since so far my tests are mostly lawn darts.

[camlost]

Concorde didn't have flaps, only elevons - elevator/aileron dual-function control surfaces. In order to deal with Mach tuck, fuel was pumped from forward tanks to rearward tanks.

Trim by transferring fuel would be a neat feature for a KSP mod...

Also the Concorde's engines are mounted below the wings, providing a pitching-up moment. Some negative camber can help with trim too.

And most tailless designs have very big swept angle, ~60 degrees. So the elevons can be far away from CoM. Sometimes I find myself putting together a 45 degrees delta wing and trimming can be a problem.

[Surefoot]

Checked the Concorde configuration, it's a delta wing with slight ogival shape, anhedral (drooping from the middle of the wing approximately), no leading edge slats, no flaps, no airbrakes, no canards ! Just elevons (3 pairs). Doing this with pwings and still attaching the engine pods straight on will be an interesting challenge.

(edit) useful link: http://www.concordesst.com/wing.html

Edited January 24, 2014 by Surefoot

[MaverickSawyer]

Quick question: Does FAR allow dihedral to increase the stability of an airplane?

[Hyomoto]

I have an inquiry concerning FAR. I'm a big fan of RasterPropMonitor. I love how it lets you play the game from IVA. Where my interest lies is a prop module that allows us to toggle the state of your flight assistants, or being able to get the current flap level, etc... RPM can handle the various requirements for display and such, but it can't interact with FAR specifically. Is there any chance you might be interested in providing things like this? I'd like to also ask Mihara about it, but I suspect there's little that can be done if one party or the other isn't interested.

[Surefoot]

Quick question: Does FAR allow dihedral to increase the stability of an airplane?

Worked for me, so i would say yes.

[MaverickSawyer]

Cool. Now I won't have that slight roll-off that I've been getting with the stock aerodynamics.

[camlost]

Quick question: Does FAR allow dihedral to increase the stability of an airplane?

Even stock KSP allow dihedral. It's something rather basic

[MaverickSawyer]

I've got a plane aloft right now with 5* dihedral (more than enough under most circumstances), and it's actually less stable than if the wings were straight out. IDK why...

[ferram4]

@Hyomoto: I can look into possibly adding some RPM support, but I have no experience with it at all. I actually haven't gotten around to playing with it since I'm very selective in the mods that I install. I hope that Mihara's code allows for easy implementation of 3rd-party stuff.

@MaverickSawyer: Well, dihedral produces a rolling tendency when the plane sideslips, which tends to help make a plane stable in roll because when the plane is rolled to one side gravity induces some amount of sideslip. Dihedral can make things less stable if it's highly pronounced compared to the amount of yaw stability a plane has, which is a common occurrence in KSP since people tend to put half-hearted vertical tails on their planes in this game. It's generally better to go with polyhedral wings for most designs, which allows you to have more control over the magnitude of dihedral effects.

There's a very sweet spot of roll stability relative to yaw stability. Too much of roll stability and you get dutch rolling motions that take a long time to damp out or end up being unstable, causing lots of yawing and occasionally rolling issues. Too much yaw stability and the plane ends up having an unstable spiral mode, which basically means that the plane starts to roll one way or the other and keeps rolling that way; it causes lots of crashes for pilots unfamiliar with using instruments to fly in bad conditions, because they don't realize that they're banked 70 degrees until they crash. Generally you err on the side of making the spiral mode slightly unstable and focus on a well-behaved dutch roll mode since it's easier for the pilot to correct for a non-oscillatory motion than an oscillatory motion.

[MaverickSawyer]

I have an issue where I'm flying straight, and it rolls to one side or the other, depending on what my bank is. The steeper the bank gets, the harder it begins to roll. It goes from 0.1* to 1.9* inside of 30 seconds.

[Rokker]

I have an issue where I'm flying straight, and it rolls to one side or the other, depending on what my bank is. The steeper the bank gets, the harder it begins to roll. It goes from 0.1* to 1.9* inside of 30 seconds.

That sounds more like an anhedral wing.

[Goozeman]

I have an issue where I'm flying straight, and it rolls to one side or the other, depending on what my bank is. The steeper the bank gets, the harder it begins to roll. It goes from 0.1* to 1.9* inside of 30 seconds.

That's the spiral mode that Farram was talking about. Try a touch more dihedral or a slightly smaller vertical tail.

[ferram4]

There's also a possibility that he has very swept wings. The slight change in sweep angle caused by sideslip could cause enough difference in lift between the wings if the sweep angles are high enough.

[MaverickSawyer]

Nope, straight, 2-piece wings from the bomber in Firespitter, and an AV-R8 as the vertical fin. It is a little close coupled, though.

Keep in mind, this is still stock aero...

[ferram4]

You have virtually no yaw stability with that. The AV-R8 isn't enough vertical tail for those wings unless you've got it on a tail boom that's as long as the rest of the plane.

[MaverickSawyer]

One sec...

here's a pic of the plane in question:

[ferram4]

You have even less yaw stability than I thought. You need a vertical tail almost 3 times as large to deal with the effects of wings that big.

[MaverickSawyer]

Huh... She flies fine, other than that slight roll issue. Really well balanced, quite responsive, and climbs like a U-2 at full power. However, I'll swap that for the larger Delta Deluxe and see how she handles.

EDIT: Good call, Ferram. That does slow down the roll-off rate. I'm still tinkering with the trim settings to counteract the engine torque, but she's cruising smoothly as I type this.

Edited January 25, 2014 by MaverickSawyer

[darcgekco]

So I built a shuttle using procedural wings as structural pieces - is there any way to make them act like they aren't wings?

[MR4Y]

I always wondered why FAR doesn't use the game's stock ASAS and relies on it's own. Wouldn't be better to make it rework or replace the ASAS code to make the mode better integrated with stock? I think one of the reasons people steer away from the mod is that as soon as they turn ASAS on and see their plane oscillating erratically...You know the drill.

[ferram4]

@darcgekco: No. That would require completely rewriting the procedural wing code on DYJ's side, since that's where it's applying the wing properties.

@MR4Y: SAS is closed off to me and pretty much every other modder, so there's nothing I can do. The thing I can do is set all the default deflection limits to very low numbers (~3-4 degrees) so that when people build a plane with a stock-standard number of control surfaces for what it is they'll end up with something controllable. There's really nothing I can do for bad design though.