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

[somnambulist]

Two things;

First, does anyone know where I could get a mod with half-size jet engines and fuel tanks? If I try to make an aircraft with the engines mounted underwing, in pods, using the huge stock one meter nacelles or fuel tanks looks really goofy. I don't want to download B9 (the massive number of extra parts annoys me), just want a simple half-size parts pack. Alternatively, if someone knows how to use the scaling factor to create the correct parts, that would be great.

Taverio's Pizza and Aerospace is *exactly* what you want. I'd also recommend downloading Taniwa's ModuleManager conversion so you you don't overwrite the stock Squad cfgs with Taverius' tweaks.

[ferram4]

@camlost: The current implementation already accounts for camber (that being what you build into the wings) and airfoil thickness is already assumed to be there; all the wings would stall at very low AoA and make very little lift if they were considered to be flat plates. The new implementation should account for it, but a little bit better.

The lifting body stuff that I've added will be easier to add in the new implementation, since it's easier to account for the entire body rather than try to divide the effects among many parts.

Leading edge flaps are already handled properly; they should help increase the stall AoA while causing a slight reduction in lift at all AoA, resulting in a higher maximum lift coefficient.

@theflyingfish: Look at Taverius' old TV Aerospace pack; I think you'll have to update it to work with the current part implementation, but it will give you what you want.

It should be possible to make the CoL and CoM appear in flight, though I'll admit I have no idea how to make that happen. I can look at the RCS build aid plugin that Torminator is using and see if that gives me any info about making that stuff appear in flight, but no promises about it coming soon.

[a.g.]

It should be possible to make the CoL and CoM appear in flight, though I'll admit I have no idea how to make that happen. I can look at the RCS build aid plugin that Torminator is using and see if that gives me any info about making that stuff appear in flight, but no promises about it coming soon.

I have that Show Acting Forces patch, which shows center of mass, thrust and aerodynamic forces (aka center of pressure) in flight. Since I don't know how to compute the center of lift, I can't show it.

The main problem with showing indicators in flight is it seems impossible to make them appear on top of the ship like in VAB/SPH, so they have to be ugly long lines sticking out of the ship. Interestingly, the same code does make them appear on top of the ship in SPH: http://imgur.com/a/wlMkg#2.

[NathanKell]

@ferram, ah, right, it's lift post-change-in-AoA. Must have just been some weird issue with that rocket, then, that made it tip madly like that.

Alas I have another issue to report--perhaps related to the drag issue? perhaps not--involving procedural fairings. For some reason my probe cores are not being shielded.

Speaking of drag--with those craft I posted, do you experience the same issue I do with it, or have you not had a chance to peek yet? (No worries if you haven't yet! Just checking. )

[Torminator]

Are you going to just tease us with that patch and then not release it? I would love that sort of in-flight info.

NathanKell, I regularly find that cargo bays, fairings, and the like are not shielding parts. It's nothing consistent. The B9 bays will work one flight and not work the next.

And Ferram, that re-write sounds intense. Glad to see you're putting all this effort into it, even if it will probably make things harder for my poorly-designed-but-good-looking planes.

While I'm here, a quick question for the aerodynamics brains: Having wingtips that curve up; I recall that on actual planes, this helps reduce/eliminate wing-tip vortices, and I think I recall you saying FAR handled this accurately, but I'm curious if there's a difference between having them angled up and having them angled down. I want to say that up felt more stable, but it's hard to tell with my planes...

[NathanKell]

What's weird is that Proc Fairings seem exempt from that problem--and everything else behind that fairing wall, including things that extend farther out, _do_ register as shielded!

As to winglets: if you have them straight up or straight down, I don't know if it makes a difference. But if they're any way off 90 degrees, then it's because the dihedral helps and anhedral hurts roll stability.

[Autochton]

First, does anyone know where I could get a mod with half-size jet engines and fuel tanks? If I try to make an aircraft with the engines mounted underwing, in pods, using the huge stock one meter nacelles or fuel tanks looks really goofy. I don't want to download B9 (the massive number of extra parts annoys me), just want a simple half-size parts pack. Alternatively, if someone knows how to use the scaling factor to create the correct parts, that would be great.

Go here, mate:

http://forum.kerbalspaceprogram.com/showthread.php/35872-Tweak-BlendedPasta-Stock-TV-and-FAR-Will-it-blend-Reqs-Modulemanager

This set of instructions and the modman config included will set you up with Taverio's parts mod, modified to work with module manager, and with tweaks added to make it silky smooth with FAR.

[luckyhendrix]

I'm quite content of my last SSTO space plane.But ,when I reach Mach 1.8-2.0 (around 16k alt and 8~10° AOA ) the plane starts to become very instable in roll, the wing leveler can't keep it straight event with high values of K. I think that it is because the AOA is too high that the plane becomes unstable in roll, but I have to keep high AOA otherwise I'll loose altitude and start decelerating.

So, how could I either reduce the AOA needed to maintain a certain rate of climb , or increase the roll stabilty of my plane at AOA =~10° ?

here are some pics of the plane :

http://imgur.com/a/AZWuV

[Boamere]

I'm quite content of my last SSTO space plane.But ,when I reach Mach 1.8-2.0 (around 16k alt and 8~10° AOA ) the plane starts to become very instable in roll, the wing leveler can't keep it straight event with high values of K. I think that it is because the AOA is too high that the plane becomes unstable in roll, but I have to keep high AOA otherwise I'll loose altitude and start decelerating.

So, how could I either reduce the AOA needed to maintain a certain rate of climb , or increase the roll stabilty of my plane at AOA =~10° ?

here are some pics of the plane :

http://imgur.com/a/AZWuV

Might be due do the fact that your center of lift is above your center of mass, try lowering it and see if that helps. Also use SAS

Also I'm considering on downloading FAR, does it help or hinder SSTO designs, and can you describe the pro's and cons?

Edited September 3, 2013 by Boamere

[Boamere]

Two things;

First, does anyone know where I could get a mod with half-size jet engines and fuel tanks? If I try to make an aircraft with the engines mounted underwing, in pods, using the huge stock one meter nacelles or fuel tanks looks really goofy. I don't want to download B9 (the massive number of extra parts annoys me), just want a simple half-size parts pack. Alternatively, if someone knows how to use the scaling factor to create the correct parts, that would be great.

Second, @ferram4, would it be possible to make CoL and CoM indicators appear in-flight? When I'm trying to re-enter my spaceplane, it's annoying to have to guess where my CoL is in relation to my CoM. If there was an indicator that helped me shift the CoM in preparation for re-entry, that would be incredible. it would make re-usable spaceplanes with heatshields much more viable. (and fun)

Well you could use the stretchy tanks mod, although i don't know if its compatible with FAR, and there is a fuel balancer mod that shows the COM in flight http://kerbalspaceprogram.com/pwb-fuel-balancer-for-rcs/ (although it might not be much help)

Edited September 3, 2013 by Boamere

[Torminator]

Might be due do the fact that your center of lift is above your center of mass, try lowering it and see if that helps. Also use SAS

Also i considering on downloading FAR, does it help or hinder SSTO designs, and can you describe the pro's and cons?

I find SSTO's are quite easy in FAR, but like everything, it's a tradeoff.

It's much easier to achieve orbit. While I couldn't even breach the atmosphere in Vanilla, I managed to get an SSTO from horizontal takeoff all the way to Mun orbit with FAR, but only after a substantial amount of reading this thread to learn how to properly design my planes. It's much more difficult to build a stable craft in FAR. Just like real life, the sorts of shapes that are good at going really, really ridiculously fast are not so great at going in a consistent direction.

[Boamere]

I find SSTO's are quite easy in FAR, but like everything, it's a tradeoff.

It's much easier to achieve orbit. While I couldn't even breach the atmosphere in Vanilla, I managed to get an SSTO from horizontal takeoff all the way to Mun orbit with FAR, but only after a substantial amount of reading this thread to learn how to properly design my planes. It's much more difficult to build a stable craft in FAR. Just like real life, the sorts of shapes that are good at going really, really ridiculously fast are not so great at going in a consistent direction.

hhhmmm Thanks, i might try it out, although does it require a lot of space? (I have a ton of mods and this might cause my ksp to go into the danger zone and crash consistently)

[Torminator]

hhhmmm Thanks, i might try it out, although does it require a lot of space? (I have a ton of mods and this might cause my ksp to go into the danger zone and crash consistently)

Usually what causes KSP to run out of memory is large textures and/or a lot of models. Since FAR is purely a plugin, it should have minimal impact on your memory usage.

[Torminator]

My sincerest apologies for the double post, but I feel this is worth a bump.

When calculating the drag for a part, is FAR looking at the visual mesh or the collision mesh? I ask because I made an engine, but putting it on my plane puts my Cd so high it barely fits on the graph. In-flight, it's about .9999999 as I crawl down the runway. That's 3200...thrusts there, and it goes a whole 90 m/s when it crashes into the sea. It IS also an intake, but that shouldn't cause problems, should it? The intake area is set as .1, like the stock intakes.

I also went in and changed the collider from a box collider to one that conforms to the trapehedral (It's my word and I'll use it if I want to!) shape. Any thoughts?

EDIT- commenting out the intake module did the trick, but I'm still a bit confused as to what was happening... is it that combined engines/intakes don't play well?

Edited September 3, 2013 by Torminator

[asmi]

Might be due do the fact that your center of lift is above your center of mass, try lowering it and see if that helps. Also use SAS

Also I'm considering on downloading FAR, does it help or hinder SSTO designs, and can you describe the pro's and cons?

There is a thread full of SSTOs made with FAR: http://forum.kerbalspaceprogram.com/showthread.php/47347-The-supplementary-SStO-thread-FAR

[ferram4]

@NathanKell: I haven't looked at the craft you posted yet, I've been focusing a bit more on planning for future FAR versions; apparently calculating the cross-sectional area / area enclosed by a group of meshes at any point is a little more difficult than I thought it would be.

I've never seen procedural fairings fail that badly; try seeing if using launch clamps on the rocket fixes it, since FAR updates the components in fairings and cargo bays when the ship adds or loses parts.

@luckyhendrix: You need a larger vertical tail; that thing is too tiny for your purposes here. What's actually happening is that your plane is sideslipping a little bit; this causes one wing to have a greater amount of sweep than the other. A wing with less sweep will make more lift and less drag at the same angle of attack, so the sideslip causes a rolling moment (which is what you're noticing) and a yawing moment that causes the problem. This isn't a lack of roll stability, it's a consequence of a lack of yaw stability.

@Torminator: That looks very similar to the problem that plagues the B9 intakes in the current implementation of FAR. Try it again when the revision comes out.

[Van Disaster]

Also I'm considering on downloading FAR, does it help or hinder SSTO designs, and can you describe the pro's and cons?

The pro and con is that you're flying through atmosphere and not magical syrup. Your planes fly like planes, but also have to be built like real planes ( somewhat - you can get away with things in FAR you couldn't IRL still ) and aircraft design for multiple flight regimes like an SSTO has to balance is not the most straightforward matter.

If you build a lot of aircraft it's worth it even just to be able to assign jobs to control surfaces.

[NathanKell]

@ferram, No problem--new version sounds great!

Re: fairings--nope.

Full bug report: With only Procedural Fairings and FAR installed (latest each), Command Modules (manned and unmanned) show two (related?) problems:

1. isShielded appears twice in the right-click menu

2. they remain unshielded (isShielded = false) despite being inside fairings.

I have tried with regular fairings (two-side) and the interstage adapter (four-side), and with regular and fuselage fairings.

Here is the output log: I note there are some null reference exceptions...

noshield_output_log.txt

[NathanKell]

Ok, it's definitely something in 0.9.6: I rolled back to 0.9.5.51 and the dual-mention disappeared and they started getting shielded again!

[ferram4]

Okay, the 0.9.6.1 revision is out, fixing some incompatibilities with B9 aerospace and Firespitter, improving the Flight GUI (slightly) with a.g.'s quick buttons, fixing another cargo bay / fairing issue and some moment of inertia issues. CoL issue continues to exist, unfortunately.

[asmi]

@NathanKell: I haven't looked at the craft you posted yet, I've been focusing a bit more on planning for future FAR versions; apparently calculating the cross-sectional area / area enclosed by a group of meshes at any point is a little more difficult than I thought it would be.

@ferram4:

Why don't you compute the mesh that represents outer "shell" of the whole vessel (the minimal mesh that would contain every single part of the vessel inside), and then calculate aerodynamics for that shell, instead of calculating aerodynamics for each individual part?

[ferram4]

@asmi: That is essentially what I'm planning for the code rewrite; the problem is that if the object has a concave cross-section things get kind of messy. The only reason that the current versions of FAR use part-based calculations is that it's much, much simpler to code than that type of method.

Basically I'm going to end up trying to group parts in "wing" sections and "body" sections, which will then be analyzed to get aerodynamic properties. Currently I'm trying to get the geometric properties of the "body" groups, the most important of which is cross-sectional area as a function of axial distance along the body; with that function the drag and lift properties can be fairly easily determined for all Mach numbers, but getting that distribution is difficult.

[NathanKell]

@ferram: I don't know whether that fixed things or not. I mean, on the one hand, _one_ of the IsShielded lines says true. On the other hand, the other says false. Seems like you're adding the Fairing module (or drag module?) twice to command pods?

Edited September 5, 2013 by NathanKell

[jrandom]

Seems to work great with Procedural Dynamics (wings). Funny thing I noticed, though, and I have no idea if this is an issue with F.A.R., Firespitter, or just KSP in general, but my trajectory line is perpendicular to what it should be.

Me flying sort of south-west:

Map shows me flying sort of south-east:

I went back and forth between the plane and map view to make sure I wasn't crazy.

[NathanKell]

jrandom, that's because of the difference between surface and orbital velocity. You may be flying south-west, but Kerbin's surface is traveling south-east fast enough to make up the difference. 180m/s is less than surface rotation, IIRC.

ferram, alas things are now worse. Command pods won't get _unshielded_ when fairings decouple.

The first isShielded line never changes, but once shielded...the second line never changes back from True, either, when fairings decouple.

So, a question for the entire thread--am I the only one experiencing the two isShielded lines for parts with command modules? Right-click and see what you get, if you would! Many thanks.

Edited September 5, 2013 by NathanKell