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

[themongoose]

I haven't tried any gullwings, but I have had trouble with a few firespitter parts in the past that caused a "pulls to one side as soon as it is airborne" issue. Two things ended up making a difference for me...

1. I discovered that some parts caused my CoL to be off-center for unknown reasons. I narrowed this down to specific parts and in the end removed their lift characteristics.

2. Firespitters control surfaces and special lift cases were good potential problems from my perspective when using FAR, so in my install I removed those modules with ModuleManager.

While this might not be your problem at all (I wasn't quite following about your CoL being ahead of your CoM ... but you may have mean Trust vector), and I didn't do sufficient testing of my changes, I can say that my instant rolling condition was fixed when I made the above changes. Perhaps this will give you some clues or ideas to try.

-Talon

Thanks for your reply! I have done some additional tweaking and can now succesfully fly my design.

The problem was not the Firespitter parts as the plane flew fine with straight wings. What I found was that the design Yawed slightly on take-off, but the ASAS would massively over-react with opposite Yaw, flip the plane and crash. I have read already the incompatability with ASAS due to control delay.

The design can take off fine without using ASAS as long as using MechJeb Smart ASS Surface, guidance set to 5degree pitch, then it takes off under low speed by itself. Once airbourne, ASAS can be engaged and it does not seem to suffer over-reaction problem again.

Anyway heres some screenies to show it off.

It can fly up to 10,000m on Kerbin where the power starts to equalises (gain from solar matches exceeds draw from engines)

I had managed to fly the stock variant on Duna with stock physics, time to try this one with FAR!

[Tau137]

My mistake, it was 12.5.1. 12.5.2 Fixed that. Thank you, Ferram!

[DaMichel]

Here is something fun ...

While searching the interwebz for aircraft design tips i found the oblique wing concept and now i tried to replicate it in KSP.

In KSP

To my amazement it actually flies really well!

Result of my most epic (hard) landing yet

The wing can be rotated with Infernal Robotics btw.

[Surefoot]

Is the result like variable sweep wings ? As in reduced drag at high speeds ?

[SnappingTurtle]

Cool idea, I had a go myself and got the same roll coupling problems the wikipedia page mentioned but it was stable every other way; just needs the right trim.

http://imgur.com/a/JNgxu#0

Edited January 10, 2014 by SnappingTurtle

[DaMichel]

Is the result like variable sweep wings ? As in reduced drag at high speeds ?

I think so. It is supposed to be easier to manufacture and structurally stronger AFAIK.

Cool idea, I had a go myself and got the same roll coupling problems the wikipedia page mentioned but it was stable every other way; just needs the right trim.

Something broke my spaceplane version tough. In space (!) i got a mysterious torque on the craft which eventually ripped the wings off.

[ferram4]

The main issue with oblique wings is aeroelastic effects due to the differences in sweep.

The spaceplane torquing in space sounds weird. Did any of the parts have drag / lift values in the right-click menu? If not, then I'm going to assume I can simply giggle at the result without having to bugfix.

[DaMichel]

This needs further investigation. I doubt that it is actually a FAR issue because .. well it happens in space.

Edit: Will take a look at the Drag/Lift values later.

Edit2: Within the atmosphere it tries to roll but i suppose that is to be expected.

Now i have confirmed it

On a side note: The SABER engines are a little OP in FAR, aren't they? This vessel went over mach 6 at 50% thrust and when i regained control after the (very violent) switch to rocket mode i found myself with an apoapsis of 500 km

Edited January 10, 2014 by DaMichel

[ctbram]

Okay, apparently I suck as I cannot control getting into orbit with this mod at all and 90% of the time I cannot even get into orbit.

Is there a tutorial on using this mod. My assumptions are that I am either building the rocket with improper aerodynamics or I am mismanaging my ascent or both.

Aerodynamics:

I am using fins and I am keeping the center of lift aft of the CG. I tried on the CG but that was fail and as I pilot I was afraid to even consider putting it in fornt of the CG lol. With each launch the rocket wants to naturally start to fall off to the north no matter how hard I try to get it back to the east I cannot. Then it stalls and tumbles uncontrollably.

ASCENT profile:

PLEASE NOTE I AM NOT DOING THE WHAT VANILLA KSP CALLS A "GRAVITY TURN".

I believe I am trying to use the proper ascent profile by trying pitch the rocket gently over to the east while keeping the direction vector inside the pro-grade vector and let gravity and te aerodynamic forces on the tail fins to pitch the rocket over. But I can never get to this point because the rocket stalls and goes out of control and I cannot figure out what hell I am doing wrong?!?!?

I am trying to keep my ascent speed under control and I was trying to see when I hit max Q before throttling up to full. I am not sure what the proper max ascent speed(s) are up through the lower and upper atmosphere. From vanilla KSP they say keep V to under 200 m/s but everything in vanilla is dumbed down.

I do not want to switch back to the "EASY BUTTON" mode that is vanilla but I really could use some tips to get on the right track. It's frustrating to just keep randomly trying things.

I searched youtube and I could not find anything really usefull. People either know what the hell they are doing and LOVE it or cna't figure out what to do and get frustrated and uninstall it and go back the EASY-BUTTON mode. I am not that kind of person and I would rather figure it out then be a quitter or complainer. It would be great if there were a couple short youtube vids showing some of the common mistakes people make when trying to use the addon (like trying to do the wanky vanilla pitch over that everyone calls a "gravity turn"). But any tips to get me going would be appreciated.

TY

Edited January 10, 2014 by ctbram

[Z-Man]

I am using fins and I am keeping the center of lift aft of the CG. I tried on the CG but that was fail and as I pilot I was afraid to even consider putting it in fornt of the CG lol. With each launch the rocket wants to naturally start to fall off to the north no matter how hard I try to get it back to the east I cannot. Then it stalls and tumbles uncontrollably.

If it always, consistently falls to the same direction no matter what, it is probably slightly asymmetric. Start with a simple rocket to get a feel for the changes you need to make. Like nosecone, control unit, two orange tanks, fins and mainsail. Or something smaller if you prefer. Pretty much any sensible payload-less single stage rocket with an initial TWR between 1 and 2 can get into orbit with FAR.

Screenshots of your rocket on the pad and just as it starts spinning out (and before) would help.

As for a speed limit: That should be not on your list of things to worry about. If you go so fast that drag losses are a problem and the reason is not that you are going horizontal too soon, your rocket would also have had too much TWR to be optimal in a vacuum. Or your rocket is a pancake.

[ctbram]

Thanks I will give that a go. I am pretty consistent with making my rockets symmetrical and balanced, with the exception of maybe putting a thermometer on one side of the ship and not balancing it out on the other. I doubt that sort of thing is going to cause the kind of crazy behavior I am seeing. lol

I am playing in career mode. I had completed the tech tree in standard vanilla in career mode and had set up a space station, a geo stationary satellite network with remotetech, a moon base, and was just starting to go interplanetary and decided to add a bit more realism and started a new game with FAR, Remotech, tacLifeSupport, tacFuelbalancer, Mechjeb2, Engineer-Redux, Crewmanifest, ProceduralFairings, KW Rocketry, KerbalJointReinforcement, LazorDockingCam, and the Kethane addons.

But I quickly stalled at the 90 science level of the tech tree because I am struggling to get into orbit with any comfortable level of control and consistency.

Edited January 10, 2014 by ctbram

[AbeS]

Post pictures of your craft, with MechJeb showing it's stats preferably

[Traches]

I searched youtube and I could not find anything really usefull. People either know what the hell they are doing and LOVE it or cna't figure out what to do and get frustrated and uninstall it and go back the EASY-BUTTON mode.

TY

I've been planning on making a "rocket launching with FAR" tutorial for awhile; it's all planned and outlined, all I have to do is record it. I'll try and get it out in the next week or two.

[MR4Y]

This needs further investigation. I doubt that it is actually a FAR issue because .. well it happens in space.

Edit: Will take a look at the Drag/Lift values later.

Edit2: Within the atmosphere it tries to roll but i suppose that is to be expected.

Now i have confirmed it

http://i.imgur.com/df4FPCD.jpg

On a side note: The SABER engines are a little OP in FAR, aren't they? This vessel went over mach 6 at 50% thrust and when i regained control after the (very violent) switch to rocket mode i found myself with an apoapsis of 500 km

Have you even used SasquatchM's Pulse Detonation Engine?

[DaMichel]

If not, then I'm going to assume I can simply giggle at the result without having to bugfix.

You can giggle as much as you want. The error was between keyboard and chair, sort of. I tried to strut the wings to the IR joint and this caused the error.

Now how to fix the wobbeling ... ?!

Have you even used SasquatchM's Pulse Detonation Engine?

Nope. Sounds like something i should take a look at.

[Carthe]

delete this.

Edited January 11, 2014 by Carthe

[Carthe]

delete this.

Edited January 11, 2014 by Carthe
f

[localSol]

I did the same thing a few months ago based on the same plane and picture of it, DaMichel. It was fun and I was surprised at how well it flew even above mach, but no chance for this particular test getting to orbit because of (understandably accurate) whacky yawing I think because of the changing position of the control surfaces relative to the fuselage as the wing went to oblique mode, or my lack of ability to know how to deal with that. A month ago I tried a regularish swing-wing too with infernal robotics that was very stable and worked just the way I wanted it to in FAR, and as far as I know, realistically too. Most of the drawing-board caffeine-work for me was figuring out how to strut it to the hinge for better rigidity. At some angles the struts prevent the hinge from moving, which makes sense but I had to work on it and look extra closely.

Edited January 11, 2014 by localSol

[NWM]

Dear Ferram!

I think there is a little but ugly bug in the control system of your mod!

If the reference command pod is built in reverse(for examle docking lander) or the aircraft or rocket flies backward, the aerodynamic control elements start to work to the opposite direction. Using ASAS the wing tails instead of killing the rotatinon spin up the rocket! The gyroscopic stabilizators works properly in this situation, but the wing tails controlled by your mod overforce them!

The Squad "aero"(LOL) also work properly this situation.

I hope you can solve this problem soon!

Sincerelly, NWM!

[DaMichel]

I did the same thing a few months ago based on the same plane and picture of it, DaMichel.

... snip

Ah nice, have you pictures of it?

I couldn't make the strutting work unfortunately. My current solution is to strut the wings to a heat shield from the THSS pack.

http://i.imgur.com/ZLJVUWC.jpg

Edit: Well, this is slightly annoying. The THSS heatshield causes this

"[ERR 11:57:36.093] The hull has more than 255 polygons. This is invalid."

and this

"[ERR 11:57:36.324] Ignore collision failed. Both colliders need to be activated when calling this IgnoreCollision"

to show up in the log and the craft disintegrates on load. So no good either

For better control i use a joystick. It is really a totally different world than using the Kb, especially if you like to fly without stability augmentation systems.

Edited January 11, 2014 by DaMichel

[somnambulist]

Ferram - you might want to add a link to Scott's latest episode of Interstellar Quest. He builds a basic spaceplane and goes into some detail on FAR. It's a great tutorial.

http://youtu.be/fNSXAHLX0Uk

[ferram4]

@NVM: Know about it; I'm trying to find a way to fix it that doesn't involve updating the control surface "positions" every physics frame, which would add some performance hit that I'd prefer wasn't there.

@somnambulist: I added it. The minor error is that he says that negative Cms are necessary for the vehicle to be stable, but really it's a negative Cm slope that's necessary for that, but it's still better than nothing.

[illectro]

@somnambulist: I added it. The minor error is that he says that negative Cms are necessary for the vehicle to be stable, but really it's a negative Cm slope that's necessary for that, but it's still better than nothing.

See this is why you're writing this - you actually have a clue

Incidently I'm encountering an odd behaviour on OSX - where the game hangs when I try to launch something when I have FAR installed (only mod) and I'm on battery power. 0.22 + FAR works fine, and 0.23 without FAR works fine. This is on Mavericks too.

[ferram4]

That's really weird. Can you provide an output_log.txt?

I honestly don't have any idea what could be causing that one to be honest. The only guesses I can come up with are that battery power ends up preventing the game from handling an exception properly or that it leads to some type of deadlock somewhere... in which case I don't know what I can do about that, since FAR doesn't actually run multiple threads or anything like that.

See if there's some kind of "maximum performance, screw the battery" mode that you can throw it into and try launching something with FAR. Maybe FAR's heavy use of floating point math causes problems when the computer is trying to save power.

Anyway, I'm speculating about that. For now, upgrade to 0.12.5.2 before you try to aerobrake at Duna. I've seen some issues in that version where craft end up with stupidly high reference areas and end up slowing down to 10 m/s in the upper atmosphere and losing that thing would be funny, but still kind of bad. "Hullo! I'm Scott Manley, and my mission to Duna was just eaten by an aerodynamics glitch."

[ninjaweasel]

Do FAR and procedural fairings get along nicely? I can't even do a simple satellite launch right now without my rocket toppling over at just over Mach 1. I can build and fly spaceplanes / SSTOs no problem... but can no longer launch a simple 3 stage rocket. Very frustrating!