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

[Raven Coldheart]

@Icecubecookie: I would try and stick fewer controlsurfaces on there. If the CoL goes forward enough, so that your CoM is behind it, the plane would become unstable. It's just a quick thought though.

And I have another question: Does FAR model ground effect? Because my planes always seem to glide better, when I'm low.

[ferram4]

@icecubecookie: Make sure that your wings aren't flexing in weird ways; that might cause some of the problems. Another possibility is that (based on where your landing gear is) you're getting some stalling to occur just as you take off, which shifts the CoL around; try moving the landing gear so that it doesn't have such a high angle of attack on the runway and get some more speed before taking off.

@Raven Coldheart: Nope, no ground effect; that's just the difference in atmospheric density.

@Nathan Kell & Taverius: Another problem with putting fuel in wings is that you'll get the fun of the wings drooping under the fuel weight since the surface attach joints are so flexible.

[iLOVEwindmills]

So when is squad gonna throw you a bag of cash to work on adding this to the game officially?

[EksCelle]

Alright, I think I have a small problem with FAR.

(pardon for dark pictures it was... dark out)

So I built this plane without wheels (career mode...)

To take this plane off, I have to start the engine and "heat it up" so that I can take it off easily. As you can see here, it all works perfectly fine...

So I take off, but immediately after the engine starts to die. After a while of flying it starts to become noticable. As you can see in this picture, the engine is still activated and throttled up.

I uninstalled FAR and tried this all over again in Vanilla KSP and it all worked fine.

Is this a FAR bug or does my plane just suck ass? I'm absolutely confused.

[ferram4]

That's correct. You're using the basic jet engine, which loses thrust quickly as velocity increases. It's intended for use on craft that aren't going to be flying much faster than Mach 0.7, 0.8; you should be able to get that up to a decent speed if you fly higher, where the atmosphere is less dense so that the thrust is better at moving it.

[Galacticruler]

That's correct. You're using the basic jet engine, which loses thrust quickly as velocity increases. It's intended for use on craft that aren't going to be flying much faster than Mach 0.7, 0.8; you should be able to get that up to a decent speed if you fly higher, where the atmosphere is less dense so that the thrust is better at moving it.

so...drones?

[icecubecookie]

@icecubecookie: Make sure that your wings aren't flexing in weird ways; that might cause some of the problems. Another possibility is that (based on where your landing gear is) you're getting some stalling to occur just as you take off, which shifts the CoL around; try moving the landing gear so that it doesn't have such a high angle of attack on the runway and get some more speed before taking off.

@Raven Coldheart: Nope, no ground effect; that's just the difference in atmospheric density.

@Nathan Kell & Taverius: Another problem with putting fuel in wings is that you'll get the fun of the wings drooping under the fuel weight since the surface attach joints are so flexible.

somehow the problem still persist at 200m/s at 1km altitude, ive checked the Cm is stable even at that speed, the wings are super solid(not even 1 degree flex) but somehow the aircraft behaves more tail heavy(completely unstable) than my other crafts that have near 0 Cm lines in older versions (still stable)

need much help for this

Edited October 20, 2013 by icecubecookie

[jpinard]

Success. Here are the pictures of my latest prototype flight test:

Changes from my previous design are:

* Added another small LFO tank section at the front following Ferram's recommendations (also had to give some extra deltaV, previous design was VERY tight for a Laythe target and had no margin of error). Results in more pitch stability, but seems to increase mach tuck effect at transonic speeds. Still can keep control so not a biggie.

* Added front canards to increase pitch stability (as per Ferram's suggestion, and to mitigate mach tuck effects)

* Added more length to the delta front section of the wings, to increase wing surface area (used a 3rd procedural wing clipped in between)

* negative dihedral on the whole wing area (one small rotation step in the SPH, not sure about the exact angle). The net result is very good stability in most flight situations.

* Move the tail fins a bit apart and gave them a slight tilt outwards, seems it's working (thanks again Ferram !)

* Increased the span of the rear part of the main wing, to account for the increased weight and length (added tank). Increased sweep a bit too.

It handles as beautifully as the looks suggest. Roll is very sensitive (like a jet fighter basically), new v0.22 SAS is totally lost there. Deactivate SAS and the plane flies very nicely. Landed without SAS at north pole, almost lost control just before landing (i use keyboard !!), AoA at low speed must be kept tight to avoid a stall (i guess due to the highly swept wings). It also wants to dutch roll like crazy so yaw inputs have to be very subtle and progressive.. I can now throw it into a stall while supersonic, by giving it too much pitch input, i guess it's a compromise i have to live with (like the real world counter parts, so it's not surprising). Good thing is in most cases it seems to come back to stable / prograde by itself and not go into a spin.

The 3 tank sections allow for more precise fuel balancing (wish i had fuel loaded wings..).

Flight data with unstable SAS roll (but stable normal flight):

Jeb approves this spaceplane and FAR !

Now we are still missing fully retractable ladders and gear bays. And maybe a MK2 docking port section (there is a 1.25m stock part already that does this) as the B9 shielded port is still protruding quite a bit.

Quick questions: do you think that reaction wheels make any difference in flight ? I got 2 of them (one in front just behind the cockpit, one in back just before the engine twin mount) for space, wondering what are their effects at subsonic and supersonic speeds in atmosphere. Also how do oblique surfaces affect flight, i am thinking not only dihedral wings but fuselage mounted winglets ?

Also do you think it's worth giving the same angle to my control surfaces (front and back) ?

@Raven Coldheart: i almost did a cobra with this design (which now that i think of it, is not unlike the SU-27 viewed from top), went to about 60° AoA and back. I guess the front canards helped there. It was not controlled though it was a stall.. (too sudden pitch) for control you would need proper thrust vectoring.

Surefoot - that het is beautiful! You seem happy with your current game setup. Would you mind posting all the mods you use so I can use them as well? Also, if you're using Deadly re-entry does the game lock up on you after you crash, then abort mission, then go to spaceport (so the Kerbal remains dead)? Mine keeps locking up, with just deadly re-entry mod running, but seeing as you like realism it seems like you might be using it too?

Thanks

[ferram4]

@icecubecookie: Try switching out firespitter parts one-by-one to see if that is an issue; there might be a bug with one of them.

[lipatden]

So I take off, but immediately after the engine starts to die

You're using the basic jet engine ... intended for use on craft that aren't going to be flying much faster than Mach 0.7, 0.8...

The screenshot shows the craft at 1km altitude doing 150m/s, way below the limits mentioned, surely the engine should still perform?

That said, I don't see the intakes and there aren't any readouts on air flow...

Edited October 21, 2013 by lipatden
Added original quote for context

[Surefoot]

Surefoot - that het is beautiful! You seem happy with your current game setup. Would you mind posting all the mods you use so I can use them as well? Also, if you're using Deadly re-entry does the game lock up on you after you crash, then abort mission, then go to spaceport (so the Kerbal remains dead)? Mine keeps locking up, with just deadly re-entry mod running, but seeing as you like realism it seems like you might be using it too?

Thanks

Hey mate Thanks for the compliments.

I use B9 and FAR (obviously), Novapunch (on this plane: using the "even heavier strut" for middle chassis), IonHybridElec pack (for the inline generators, could use RTG's actually.. i just like the blue glow from them ), procedural wings (obviously too ) and that's it.

To make the same plane you can replace NP struts with the quantum struts i guess (couldnt get them to show up in my SPH..), and normal RTG's tucked behind the landing gears instead of the IonElec generators, this reduces the mods to B9, PWings, QStruts and FAR. If you want i can post my latest craft file. On it there's a Mechjeb2 attached too (i can remove it if you want it mechjeb-free). Making it yourself can be time consuming (but FUN !) as some design details such as strut placement and wing angles are critical. Also you have to assign control surfaces to specific inputs in FAR - canards and stabilators for pitch, wing control surfaces for roll, and tail control surfaces for yaw.

I am not using DRE yet as i'm at the stability limit of KSP at the moment, although i'm quite sure this design can survive, apart from the cockpit side ladders maybe (unfortunately, no retractable / shielded parts are available for this) - but i'm considering it maybe later, at the moment FAR provides me with tens of hours of fun and engineering

Here are the results my latest aerodynamic improvements, after hours and hours of flight tests and fine tuning:

The HyperJet MK4

Thanks to B9 i now have more reasonably sized stabilators. Went for a more radical wing sweep. As a result of both i lost the stall recovery of the previous design: this one is very resistant to excessive input, but stupidity can still make it go into a spin (which is quite hard to recover). To avoid problems, as usual fuel balance is needed (the 3 tanks help here) - transfer from back to front before re-entry or aerocapture. The airbrakes help aerocapture performance, and of course landing.

I LOVE THE NEW B9 LANDING GEAR it's a lot more aerodynamic than the stock one. Blends perfectly with the underside of this jet...

Also it's capable of mach 5.4 around 27km max after which the SABRE's run out of air (truly i went a bit above and didnt get any flameout from either engine: FAR was reporting 97% air, weird).

Handling is improved at subsonic and supersonic speeds, although transonic is a bit crappy somehow ? (but who wants to stay there).

Mach 5+ flight, view of the belly with the nicely integrated landing gear

Hard turn at mach 4+ !

Top speed at top altitude, look at the wing configuration

I am now really pleased, it's a great fun to pilot it, landing is easy as low speed control is good (but keep AoA low, the SABRE's dont give much clearance), hypersonic flight is stable and i can point it the way i want, it's got enough fuel to go to Laythe and land there (which was my main goal for this design), atmospheric entry is stable and controlled (can even give a bit of AoA for that increased aerobraking effect). Handling without SAS has a tendency to dutch roll and otherwise wiggle around a bit especially at transonic speeds, but at mach 2+ if you just trim it, it flies straight, and for landings it's behaving nicely by itself. SAS tends to spaz with roll inputs sometimes (esp. at 0° AoA, perfect straight flight, weird stuff here), for no good reason, it goes into a "shake". Just give some pitch (up or down, doesnt matter) and it comes back to reason.. My previous design could do a "cobra" and still have control during the stall, i'll have to explore that a bit more with a lighter design (without SABRE's and all that fuel to go to Laythe).

Total weight is 33.8T fuelled up, 76 parts, so it's nice and light (for a Jool capable SSTO spaceplane..).

Total work on this is about 30 hours including flight tests ! I tried a LOT of aerodynamic setups. The new B9 stuff with the fixed trailing edges open some new possibilities (mhhh elevons..). Maybe the next step would be leading edge elevons/slabs: this is needed for tailless designs (cannot wait for procedural control surfaces for this !). Variable geometry would be fantastic too, i'll try to look at what i can do with the Magic Smoke pack, but that wont be a small jet-fighter-esque design like this one and more like a big cargo (due to size of mobile parts..). I'll also give another shot to the diamond-shape wings (a la F-22), not sure if FAR actually accounts for the effects of this kind of shape ?

Now going to work on my S2Wide cargo, another FAR challenge: delivering big stuff safely to the surface (with atmosphere, of course).

Edited October 21, 2013 by Surefoot

[Taverius]

I'm detracting points for using the stock canards up front

P.S. Post craft please.

[ferram4]

@liptaden: Well, yeah. It loses thrust, dropping to zero at around Mach 1. He's really close to the ground, so his top speed will be limited by the atmosphere (particularly since engine thrust doesn't drop off with a decrease in altitude).

[Surefoot]

I'm detracting points for using the stock canards up front

HA ! wait, there are B9 canards ? (didnt spot them somehow)

P.S. Post craft please.

I will tomorrow - now is time to get some sleep (did a lot of flying around with that plane, with a stick it really shines)

[Tiron]

I've encountered an odd sort of issue using FAR on Rockets. There seems to be some malfunction in the roll control scheme when fitted to a rocket.

Using 8-way symmetry really brings it to the fore, but it occurs in some variation or other no matter if the fins are placed individually, the location of the root part is changed, fins are exchanged for canards, or even if only four fins are used.

Basically, fins on one side of the rocket are reacting very incorrectly to roll commands. With 8-way, five of the fins correctly twist in the same direction. Three exhibit erroneous behavior, and it seems to be linked to the pitch axis: it's the three fins that are on the 'up' side of the pitch axis that respond incorrectly.

Two of them barely move at all; in fact unless you watch closely it looks like they haven't moved, it's such an infinitesimally small movement. Not only that, but the movement is along the pitch axis, in the same direction, instead of being a twist around the center.

The third fin, the 'top center' one, moves to full extension like the five that respond correctly, but in the opposite direction. That is, along the same direction on the yaw axis as the 'bottom center' fin.

Pitch and yaw seem to work fine, however.

It does seem to affect flight characteristics, because my attempts at spin stabilization on a ballistic rocket (just for fun) have all resulted in partially stabilized tumbling, worsening as the air thickens and easing as it thins.

HA ! wait, there are B9 canards ? (didnt spot them somehow)

They're called 'Stabilators' but are basically the same thing. Smaller versions were just added in R4.

Edited October 22, 2013 by Tiron

[ferram4]

Um... that's not supposed to happen. I'll look into it; the control surfaces probably have the wrong multiplier somewhere. Thanks for the pic with it; helps make things a lot clearer.

[NWM]

Dear Ferram!

A simple question can you make a active/passive switch in your plugin, wich makes able to test and save as unFAR an aircraft developed in FAR environment?

ps: great thanx for this mod!

[Surefoot]

Link to my Hyperjet craft file:

http://www./?u7co7rfj5ie4r7d

mods needed:

FAR - B9 - Novapunch - IonHybridElec - PWings - Mechjeb 2

Enjoy I have been flying stick and it was quite enjoyable. It needs trimming though, maybe i'll see if i can add some pre-camber on some control surfaces maybe...

[ferram4]

Okay, version 0.9.7 is out, fixing the roll control surface silliness, some non-wing drag issues, and fixing some issues where mod parts would not have their proper orientations determined (thanks to a.g. for that one).

@NWM: Any craft created in a save with FAR will be properly loaded in a stock save, using the proper stock behavior. Or do you mean a switch to turn FAR on and off at will in a save?

[Disfunctional_Rockets_INC]

Dear, Ferram4

I have been having an issue with preformance on aircraft with high part counts, my framerate seems fine but it gets very choppy in the space plane hanger. It varies with the parts I use but I usually start noticing it when the craft has around 125 to 200 parts and it happens if I have other mods and if I just have FAR. I do not get this issue once I launch the aircraft and I have tried turning the settings down. I also tried making one 1,300 part craft in a fresh install and it ran perfectly smoothly in the SPH but when I installed FAR the game became incredibly choppy while viewing it.

I put together this video to show you what I mean by choppy, the quality isn't great but it shows off the issue well enough. Do you have any idea what could be causing this?

The first two clips are of a completely fresh install where I made a large aircraft then moved the camera around with FAR installed then without. The second two clips show the same thing but with a lower part count craft made with lots of B9 parts, I also had DYJs GAU-19 and Infernal Robotics installed.

Do you have any idea what could be causing this? Do others get this issue or am I the only one?

Relevant system specs for reference:

CPU: 1090t hexacore clocked at 3.9ghz

RAM: 8gb of DDR3

GPU: 7870, was not overclocked for video

I have decent cooling for everything so I don't think anything is overheating, Coretemp says my CPU hasn't gone past 45c and my GPU rarely goes past 50c when not overclocked. I tried updating my video card drivers to the latest beta but it didn't change anything.

I'm not sure if they will do you any good but here are the .craft files of the ships in the video. One is stock (BTBS-1) and the other (FBMCH-2 CRD 1 A3) requires B9 aerospace and Infernal Robotics, neither of them actually fly yet.

Anyway, keep up the awesome work, I really love this mod!

Note: I guess you released a new version while I was writing this, I tried it and I still get the same issue though.

[ferram4]

It could be the debug log, which is somewhat resource intensive. It could also be all of the calculations necessary to figure out the aerodynamic properties of the vehicle. I can try things on my end and see if I can make things better.

[NathanKell]

Yeah, for the last, oh, bunch of versions, FAR dumps log quite frequently in the VAB/SPH, all the Part Loc: () Attach Loc: () lines.

[Suzie's Brother Max]

I'm probably gonna come off as completely n00b, but alas...

What exactly is the aerospace model right now? As in what of realistic effects is modeled? I'm not afraid of the DiffyQ's and calculus involved(I'm an engineering student so even if I haven't picked it up yet, I'm sure I can get a working knowledge of the equations) I just want to what main effects to plan for. I've read about 40 pages of this thread and various google/site searches and I can't find a changelog or such that shows what's been added over time. Did I miss something?

[NWM]

If saves remain compatibe it'll no question anymore. An I mean on/of switch affetcs the aerodinamic modell, avoiding the quit game/uninstall FAR/start again torture each occasion trying a craft as unFAR. (some craft doesn't like FAR, and some of them hates stock "aerodinamics")

[Taverius]

@ferram4: I noticed something last night while doing !!SCIENCE!! to kerbin with this bay:

Things inside it are shielded when its open, shielded when its closed, and not shielded when its animating between states.