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

[brusura]

@brusura: Barely large enough vertical tail there. I'd expect to get issues with that at high speeds to be honest.

ok thanks for the hint, I'll try another configuration

[wasmic]

Wow... I'd heard that it would be harder to fly with this installed, but I actually think that it's easier to both build and fly SSTOs with this installed!

Anyway, I've found a bug/incompatibility with the fairings from KW, CORE Anvil and the Service Module by Sumghai. Those fairings have a ton of free nodes, where you're supposed to use but one pair of them. As we all know, this mod applies a lot of drag to free nodes. My question is as follows: is there a way to make a free node not do any drag (by cfg edit)? If there is, how do I do it? If there isn't, can it be added?

[AbeS]

People will probably tell you to download pfairings (btw blackheart612 is working on pfairings that look just like KW). But I know Scott Manley uses KW fairings in his videos and he got them to work somehow

[a__gun]

Anyway, I've found a bug/incompatibility with the fairings from KW, CORE Anvil and the Service Module by Sumghai. Those fairings have a ton of free nodes, where you're supposed to use but one pair of them. As we all know, this mod applies a lot of drag to free nodes. My question is as follows: is there a way to make a free node not do any drag (by cfg edit)? If there is, how do I do it? If there isn't, can it be added?

I use FAR and KW and havn't noticed any unusual levels of drag with the fairings...

[DaMichel]

You'll need 2 pieces indeed, no choice here. One option with that many engines could be mounting engines on upper / lower nacelles, above and below the wing so you get 1 piece wings.. I have been toying with that a lot

I guess that would make it easier for me

Same here, when you reach optimal designs for supersonic you notice they are all quite arrow-shaped and at low speed they fly like bricks

I tried using some flaps now. Works quite well. Most noticeably they reduce Cm at low speeds, making the aircraft less unstable when returning from space with tanks drained ;D

@Ferram4: I made this plane with B9 Cargo Bay and i noticed that the CoL indicator moves with the location of the cargo inside the bay while the bay doors are closed. To my knowledge this is wrong. What is going on?

Edit: @wasmic: Was wondering about this issue as well, only with regard to some B9 parts which also have attachment points at the sides of the fuselage. Test flights showed nothing extraordinary in this regard. Drag was normal as far as i can tell. My bet is that FAR looks only at top and bottom nodes. Please, correct me if i am wrong.

Edited February 10, 2014 by DaMichel

[camlost]

@Ferram,

I've managed to make a plugin that incorporates NASA Enginesim to calculate thrust, isp and overheat. (See my signature below). I'm wondering how to accurately model inlets. I've disabled all "dynamic drag" caused by "moduleResourceIntake" but still don't feel right. Currently FAR just treats inlets like nosecones, correct? But the NASA program already counts for ram drag from inlet and compressor. What do you think should be done?

[ThorBeorn]

@Ferram

Hi, first of all, thanks for an amazing mod!

I'm writing because of an odd behaviour I noticed in one of my spaceplane SSTO's the other day. I got into an 80x80 orbit heading 270 deg around kerbin and when turning off SAS it behaved almost as it does at about 40k. The craft started to sideslip and pitch up etc (engines shut down of course) and the pitch up tendency increased with increasing AoA, as if it still was in the atmosphere. The orbit however wasn't affected and no parts seemed to register drag. For a while i thought the atmosphere had been extended since I had to struggle quite a bit to keep the craft pointing in the prograde direction. The forces could actually be noticed with SAS on too. When timewarping at x5, x10, x50 etc it dissapeared. I have never seen this before. Any ideas?

I'll create an imgur account and post pictures if that's of interest - if I can recreate the phenomenon.

Mods used in this craft: FAR, Stretchy tanks/SRB's, P-wings, Editor extensions, KER, KW Rocketry.

[ferram4]

@wasmic: Fairings have a special exception to deal with that. That's been there to deal with fairings since KW first started doing their interesting fairing design.

@DaMichel: A known issue with cargo bays. I have a fix from a.g., I'm just still testing stuff out.

@camlost: Probably the best way would be to look into defining a new FARBasicDragModel for those parts that produces no lift or drag and make sure to use ModuleManager to set all of the stock drag parameters for that part to zero.

@ThorBeorn: And you didn't have any trim set, nor did you have any of FAR's other control systems left on, correct? It just sounds like a control error, not a physics error to me.

[acc]

I want to use the flaps for a space shuttle body flap, but flaps only angle downwards.

So my suggestion is a tweakable for flaps, like "only negative", "only positive" and "both".

[DaMichel]

Oh my god Ferram4, now release you fixes already!

[ferram4]

@acc: There's a the option to set negative deflection angles that will be coming in the next version. That should do what you want.

@DaMichel: No, they need more testing. Besides that, I haven't been able to do much testing recently because I've been doing a job search, which is even worse because I'm trying to move out of NYC to Palo Alto / Sunnyvale to get into a bunch of the aerospace and satellite companies that are there (also personal reasons). So I've been somewhat distracted from KSP due to that. So I have no idea when things will be released.

[wasmic]

@wasmic: Fairings have a special exception to deal with that. That's been there to deal with fairings since KW first started doing their interesting fairing design.

Oh, alright. Then the problem must be something else in my design.

[NathanKell]

I've been doing a job search, which is even worse because I'm trying to move out of NYC to Palo Alto / Sunnyvale to get into a bunch of the aerospace and satellite companies that are there (also personal reasons). So I've been somewhat distracted from KSP due to that. So I have no idea when things will be released.

Yeah, saw your post on the SpaceX thread, didn't know if it was spur of the moment or more serious/general. Good luck to you!

[ThorBeorn]

@ThorBeorn: And you didn't have any trim set, nor did you have any of FAR's other control systems left on, correct? It just sounds like a control error, not a physics error to me.

-No trim set. I don't think I had any control systems left on either. I believe I checked for that, but it's a possibility - I was tired. I did two launches to 80x80 orbit with a 90 deg heading today and the spaceplane behaved just like it should, no oddities occured. I will try again with a 270 deg heading, but it couldn't possibly be that. I used a tiny bit of part clipping and a modified .cfg of a P-wing (only changes so it attaches a bit inside the fuselage - going for a MIG-25 look ). Maybe it's a stock game physics bug? It just felt very FAResque the way it handled.

Oh, and B9 was used for the intakes, shouldn't be that either. Anyway, I'll report again if I can recreate it. Thanks!

[acc]

@acc: There's a the option to set negative deflection angles that will be coming in the next version. That should do what you want.

Great, thank you... and good luck with your job search

[DaMichel]

Oh sounds cool Ferram4. I hope you manage to release at least a bugfix release before getting involved in a new job No, seriously, good luck.

[Piwa]

Ferram4, you can help me correctly configure fins for Saturn V?

[The Russian 1021]

Hello!, how come the bobcats buran doest work with far? ive tried flying it with far and dre, and the thing goes into a flat spin as soon as it goes transonic and into thicker atmosphere, also , it seems as though the wings arent producing alot of lift, as i can barely keep my descent below 150 m/s.

please help! i love the buran and i would love it more if it worked with far, another mod i love!

[camlost]

@ferram,

I used MM to do this for all intakes.

@PART[*]:HAS[@MODULE[ModuleResourceIntake]]

{

@MODULE[ModuleResourceIntake]

{

useDynamicDrag = false

}

@maximum_drag = 0.0

@minimum_drag = 0.0

MODULE

{

name = FARBasicDragModel

S = 1 //Surface Area

upVectorName = up //takes up, forward, right as arguments; used to set 0 for curves below; defaults to up

CdCurve //Drag coefficient at various angles

{

key = -1 0 .01 //backwards

key = 0 0.1 //sideways

key = 1.0 0.01 //forwards

}

ClCurve

{

key = -1 0 //Lift coefficient

key = -0.5 -0.03

key = 0 0

key = 0.5 0.03

key = 1 0

}

CmCurve //Moment coefficient

{

key = -1 0

key = -0.5 -0.01 //keeping angle and moment signs the same results in pitch instability; it will try to flip over

key = 0 0 //making them opposite signs results in pitch stability; it will try to angle fully forward

key = 0.5 0.01

key = 1 0

}

}

}

However intakes have this error

[Log]: FAR Error: Aerodynamic force = NaN

at B9.Aero.Intake.RBM

in FAR Flight Data, Cl=NaN and all other parameters based on Cl are NaN.

[ferram4]

@DaMichel: It'll probably get released before I get into a job, based on my experience with how unsuccessful job searching is.

@ThorBeon: Part clipping can cause a lot of weird things to happen. That's probably the cause.

@Piwa: Gimme the dimensions of the fin and I'll work out a config for you.

@The Russian 1021: That's because Buran isn't configured to work with FAR. Based on the work that Dragon01 was doing trying to get it to work, the entire thing will need to be redone to even have a hope of being compatible with it.

@camlost: Part of the error might be due to the CdCurve having three entries rather than two or four; that might cause an issue to occur.

But I think the actual error is due to a change in variables that I haven't properly documented (oops), where ClCurve was split into ClPotentialCurve and ClViscousCurve (potential curve drops off after Mach 1, viscous curve doesn't), so you need to change ClCurve to one of those and define a zero-at-both-ends curve for the other one. Then it should work.

[camlost]

What is the correct format of CdCurve? I thought the 3 entries are for forward, sideway and backward.

Can I just leave the ClCurve empty and let FAR calculate it?

[ferram4]

The first key you have for CdCurve is -1 0 .01; that will be read in as 3 numbers; either fix it so it's -1 0.01 or -1 0 .01 .01. That's the issue.

FAR can calculate all of the aerodynamic properties or you can override all the aerodynamic properties; there's no way to pick and choose. If you're not concerned about the lift parameters, just specify a 0 lift curve.

[camlost]

MODULE

{

name = FARBasicDragModel

S = 1 //Surface Area

upVectorName = up //takes up, forward, right as arguments; used to set 0 for curves below;

CdCurve //Drag coefficient at various angles

{

key = -1 0 //backwards

key = 0 0 //sideways

key = 1 0 //forwards

}

ClPotentialCurve

{

key = -1 0 //Lift coefficient

key = 1 0

}

ClViscousCurve

{

key = -1 0 //Lift coefficient

key = 1 0

}

CmCurve //Moment coefficient

{

key = -1 0

key = 1 0

}

}

Still has the same problem

[ferram4]

I don't know then. Does it occur with any other intakes, or just that particular one?

[camlost]

all intakes have the same problem.