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

[Weatherman159]

Here's an interesting one: what is about the right landing speed? Most of my jets land at about 80-90 m/s, which seems rather fast to me. Is there a way to reduce this to, say, 30-40 m/s ? I've tried adding flaps, but they don't seem to help too much. Tips welcome

[WafflesToo]

Hey, how do IRL jets deal w external loads? The probe I'm trying to lift doesn't seem unreasonably heavy but i lose control out the aircraft at about 12k at mach 1.2. It just noses over and heads into the ground. Slinging it on top is even worse, it just flips end-over-end right at the sound barrier.

Honestly I'm flumoxxed and about to quit the mod just because it isn't fun anymore so if someone can steer me right again I'd appreciate it.

[a.g.]

Finally, it's possible that the mod parts are not set up correctly; FAR uses the size of the attachnodes to calculate drag caused by the base of an engine, uncovered fuel tanks, etc. 0.625m parts use size 0, 1.25m parts use size 1, 2.5m parts use 2, 3.75 use 3, etc.

Incidentally, do only forward-facing (relative to velocity) nodes create additional drag without nosecones, or do backward-facing ones need them too, e.g. in case of drop tanks and similar things?

[ferram4]

@Weatherman159: The Boeing 747 takes off at between 70 - 80 m/s; the F-104 Starfighter landed at ~90 m/s. It sounds like (for supersonic jets) you've got the right landing speed already.

If you're building something more U-2 styled then the solution is to take a longer landing approach. You need to give the air more time to slow down your plane before you try to put it on the ground. If you're coming down at a 20 degree angle you're not going to bleed off enough speed before you can land.

@a.g.:Backward facing nodes create additional drag, although their need for streamlining decreases as the Mach number goes to infinity. Long story short, the pressure on the rearward face becomes equal to the ambient air pressure at Mach = Infinity, which doesn't add any drag. However, at lower Mach numbers it can add quite a bit of drag.

[rhoark]

Not specifically about FAR, but I figured the people looking at this thread might be likely to know - why do real-world tailless designs like the f117a, b2, and x36 tend to have triangular notches cut out of the rear of what would otherwise be straight delta wings?

[Van Disaster]

40m/s is about 90mph, which seems awfully slow for huge jets I have had one that would land at about 45m/s but it had gigantic flaps & was built for STOL. Usually my spaceplanes land at around 85-90m/s ( around 200mph, 170ish knots ) which you might think is fast, but seems about right for a heavy aircraft I think. They don't bounce & take off again and nor do they run out of runway, so that's fine for me.

The delta notches might be stealth-related - the Eurofighter has straight trailing edges.

Edited June 24, 2013 by Van Disaster

[ferram4]

@rhoark: Partly, for stealth reasons; that angled trailing edge reduces radar cross-section. It also allows the flaps to be closed further forward, closer to the CoM; this makes deploying the flaps affect the necessary pitch trim less. It can also be done to change the area cross-section of the entire vehicle at that point, which can reduce drag at transonic and supersonic speeds.

[The Lone Wolfling]

Here's an interesting one: what is about the right landing speed? Most of my jets land at about 80-90 m/s, which seems rather fast to me. Is there a way to reduce this to, say, 30-40 m/s ? I've tried adding flaps, but they don't seem to help too much. Tips welcome

Most of my craft land at about 90m/s. That being said, I really need to learn to use flaps. Also, most of my craft are designed for high supersonic (mach 4 or so).

Could someone do a tutorial on proper flap placement and/or usage?

I, personally, wonder why the craft I build as jokes fly perfectly while more airplane-like designs fail miserably.

@a.g.:Backward facing nodes create additional drag, although their need for streamlining decreases as the Mach number goes to infinity. Long story short, the pressure on the rearward face becomes equal to the ambient air pressure at Mach = Infinity, which doesn't add any drag. However, at lower Mach numbers it can add quite a bit of drag.

Does this include attachment nodes below engines?

[Xechran]

Finally, it's possible that the mod parts are not set up correctly; FAR uses the size of the attachnodes to calculate drag caused by the base of an engine, uncovered fuel tanks, etc. 0.625m parts use size 0, 1.25m parts use size 1, 2.5m parts use 2, 3.75 use 3, etc.

So we should use a step function rather than rounding?

[ferram4]

@The Lone Wolfling: Flap placement is pretty simple: put it on the back of the wing were the wing is closest to the CoM. Design the pitch control surfaces to be able to adjust for the effects of the flaps. Would you mind posting examples of your joke and fail planes? The code might be malfunctioning.

The nodes at the bottom of engines also affect drag.

@Xechran: Yes. Attempting to use non-integer values will cause bad things to happen.

[Xechran]

@Xechran: Yes. Attempting to use non-integer values will cause bad things to happen.

Actually what I meant was the 3.75 meter part gets stepped down to size 3 rather than rounded up to size 4. A 3.9 meter part - should you find one lying on the roadside - is size 3. I'm kind caught off guard a bit because when I read the wiki the impression I got was the engine only supported node size arguments up to size 2 (still newb-ish dont flog me!) and Im trying to figure out what sizes I should edit into various parts, since their authors kindly left their sizes at default.

[ferram4]

No, that is actually the result of a scaling resize back in 0.16 (?). Basically, the sizes used to be 0.5m, 1m, 2m, etc. but back then a 3-man command had a 1m diameter. When problems with mini-Kerbals popped up, their height was pegged at 1m, the parts all got scaled up by 1.25, and the 3-man pod was stuck on the now-2.5m new parts. Basically, divide the number by 1.25, that will give you the proper size.

[SchroedingersHat]

@CaptainKorhonen: A TWR of 2.5 at launch is way too high. Try to lower the TWR to something like 1.2 - 1.4 at launch.

That low? I always thought you wanted it fairly high off the launchpad even if you throttle off your liquid engines and cruise on solid for a while after reaching mach 0.6-0.8. Is this strategy inefficient?

[asmi]

That low? I always thought you wanted it fairly high off the launchpad even if you throttle off your liquid engines and cruise on solid for a while after reaching mach 0.6-0.8. Is this strategy inefficient?

Hi TWR on low throttle means excess weight (higher-thrust engines are more heavy).

[zzz]

That low? I always thought you wanted it fairly high off

This depend on how your control things can counter air pressure wich trying to bend you rocket. Depends on angle of attack and position of center and value of drag (leverage of forces) counter stream to bend it more. Depending on your speed and air pressure counter stream is more powerfull. So in dence atmosphere in conjunction with high speed it can be very powerfull. If it's become more powerfull then you control things can to counter it - air will win and bend your rocket and your rocket will spin.

If you can move straight up with zero angle of attck(wich is barely possible becðuse of bend and sway of rocket), or if you control things always win - you can push with any speed if engine can handle drag.

This is how I imagine and understand this.

what is about the right landing speed? Most of my jets land at about 80-90 m/s, which seems rather fast to me. Is there a way to reduce this to, say, 30-40 m/s ? I've tried adding flaps, but they don't seem to help too much.

Right landing speed is when you not crash. 80-90 for jets, as all already said, is quite well, for me even 100-120 is well enough if plane still controllable and don't try to roll at the ground. Landing speed it's about amount of lift and control, as I understand.

This thing can land even at 40 but it's threshold for it, at 38-35 it's fly like a stone. Really like this bird - very agile at subsonic(above mach 2 need to be gentle), takes off almost immediately, survive almost any maneuvers, very controllable and fly in any position. Also because of engines close to each other and with some FAR yaw damper I sometimes even not notice engine flameout(sometimes it become bad as expected but nothing fatal ).

Yes, i'm bragging, and almost everyone did things much better, but you know this feel which KSP give, when you put pieces together and something actually work. It's also looks nice.

Edited June 25, 2013 by zzz

[willem_van_oranje]

I have a mac and i want to download this but it doesn't install properly and the instructions above don't work because you can only replace. Please help.

[Weatherman159]

Hmm...I'll try moving the flaps (I have them in about the middle of the wings, to be as close to the center of lift as possible) and adding more pitch authority. What I'm trying to do here is land on a an aircraft carrier, and that's a really small target to hit at 80 m/s.

[a.g.]

It seems I've found some very specific corner case bug: if I load the 'B9 BRV-4 Heinlein' craft in SPH, launch, end flight back to SPH, and then immediately launch again, all drag-related values in flight data go NaN, and the console is full of "FAR Error: Aerodynamic force = NaN at B9.Utility.InfoDrive". It seems to occur only with this craft, and reloading the craft from the file between launches prevents it; likewise, restart flight also fixes it. I wonder if this is even something generic, or limited to my specific setup too.

I could try adding some prints to try and debug this quirk, except that I don't understand much in the actual aerodynamics related code.

Edited June 25, 2013 by a.g.

[Dusty926]

This depend on how your control things can counter air pressure wich trying to bend you rocket. Depends on angle of attack and position of center and value of drag (leverage of forces) counter stream to bend it more. Depending on your speed and air pressure counter stream is more powerfull. So in dence atmosphere in conjunction with high speed it can be very powerfull. If it's become more powerfull then you control things can to counter it - air will win and bend your rocket and your rocket will spin.

If you can move straight up with zero angle of attck(wich is barely possible becðuse of bend and sway of rocket), or if you control things always win - you can push with any speed if engine can handle drag.

This is how I imagine and understand this.

Right landing speed is when you not crash. 80-90 for jets, as all already said, is quite well, for me even 100-120 is well enough if plane still controllable and don't try to roll at the ground. Landing speed it's about amount of lift and control, as I understand.

This thing can land even at 40 but it's threshold for it, at 38-35 it's fly like a stone. Really like this bird - very agile at subsonic(above mach 2 need to be gentle), takes off almost immediately, survive almost any maneuvers, very controllable and fly in any position. Also because of engines close to each other and with some FAR yaw damper I sometimes even not notice engine flameout(sometimes it become bad as expected but nothing fatal ).

*Snip*

Yes, i'm bragging, and almost everyone did things much better, but you know this feel which KSP give, when you put pieces together and something actually work. It's also looks nice.

Holy crap, I wish I knew how to make stuff like that.

[Van Disaster]

I like it! better than the one I threw together a while back:

It is stupidly manoeverable though ( check the G-meter, it can easily peg it to the top ) and tons of fun to throw around.

[Black-Talon]

[cross-posted in Firespitter Propeller Plane and Helicopter Parts Addon Thread]

I've been enjoying seeing all the great things made using Firespitter for quite some time. Unfortunately I had a rough time when I went to try it because I had the bright idea to install with into my game with Ferram Aerospace Research installed. My thinking was that of course I wanted to fly awesome planes using a much better flight model (thanks to Snjo or Ferram for great mods, and wonderful support!). I quickly realized there must be a problem with this and used Firespitter without FAR. But I still really wanted to do it... sadly I haven't seen anything obvious on how/if this can work. A couple comments seem to have the same issues I had when using with FAR...

Using the Firespitter's Stock K-17:

• Controls don't update graphically unless they are locked and then unlocked prior to flight
  
• Even once the control surfaces are updating graphically they don't seem to apply much control to the craft
  
• Take off results in a uncontrolled loop and unintentional rough 'landing' ;-)
  
• For someone familiar with FAR you would notice that the control surfaces aren't configurable in the VAB
  

After reading a few more tips about how to apply FAR onto wings, how Firespitter wings have the FAR values included on them by default, etc... I dug into seeing if something in particular was wrong...

DISCLAIMER - I really am new to both FAR and Firespitter. I did my best to find information on how to use both together... I don't claim to really know what I'm doing here. :-) And I would love to hear from others on the best way to get these two fantastic mods working well together.

Here are a list of things I found:

1. I firstly discovered that (sadly) the FSwingletRangeAdjustment Module seems to conflict with FAR.
   
2. The FAR configuration values are all configured as FARWingAerodynamicModel - it seems a FARControllableSurface is more accurate for the wings with control surfaces? Note that there is some concern noted in both the FAR and Firespitter threads that wings with integrated control surfaces are not yet supported in FAR...but I've found that without at least some tweaks, Firespitter wings are unusable in FAR, but work enjoyably once modified.
   
3. The default drag and lift configuration is zeroed out on stock parts...should the same should be true for Firespitter wing/control parts?
   
4. Some of the FAR configuration values used on Firespitter wings aren't documented in the FAR Readme.txt, perhaps they shouldn't be there? Others need to be there instead?
   

Results:

1. I created this ModuleManager config which allows me to use Firespitter and FAR together (suggested changes/improvements?): FirespitterFAR_MM_CFG.zip
   
2. With heavy trim, the Firespitter Stock K-17 is a joy to fly. :-)
   
3. I don't really have confidence that this was done correctly and it obviously loses the ability to adjust the control range in flight (something I'd love to have on all my planes while using FAR - hope a solution for them to be compatible is found/developed).
   
4. In FAR, when a AoA Sweep analysis is done, only CL is graphed... does the lack of CD and others indicate incorrectly configured parts?
   

Lastly - If either Snjo or Ferram object in anyway to the ModuleManager configuration I will happily take it down or adjust it to meet their needs. I only wanted to share what I've found to get things working. Oh, and I'd be happy to pass on videos and logs of the behavior I'm describing if that would be helpful to anyone.

-Talon

Edited June 26, 2013 by Black-Talon

[Asdefjak]

Hi,

shielding or at least the display of it doesn't work for me. The context menu of every part including those below nosecones or in the middle of the rocket displays "isShielded: false". This is the case with every craft and with no plugins except FAR enabled.

I'm running the current versions of both FAR and KSC on Linux. Here is my Player.log. Is there anything else I could check that might cause this error?

Edited June 26, 2013 by Asdefjak

[MR4Y]

This depend on how your control things can counter air pressure wich trying to bend you rocket. Depends on angle of attack and position of center and value of drag (leverage of forces) counter stream to bend it more. Depending on your speed and air pressure counter stream is more powerfull. So in dence atmosphere in conjunction with high speed it can be very powerfull. If it's become more powerfull then you control things can to counter it - air will win and bend your rocket and your rocket will spin.

If you can move straight up with zero angle of attck(wich is barely possible becðuse of bend and sway of rocket), or if you control things always win - you can push with any speed if engine can handle drag.

This is how I imagine and understand this.

Right landing speed is when you not crash. 80-90 for jets, as all already said, is quite well, for me even 100-120 is well enough if plane still controllable and don't try to roll at the ground. Landing speed it's about amount of lift and control, as I understand.

This thing can land even at 40 but it's threshold for it, at 38-35 it's fly like a stone. Really like this bird - very agile at subsonic(above mach 2 need to be gentle), takes off almost immediately, survive almost any maneuvers, very controllable and fly in any position. Also because of engines close to each other and with some FAR yaw damper I sometimes even not notice engine flameout(sometimes it become bad as expected but nothing fatal ).

Yes, i'm bragging, and almost everyone did things much better, but you know this feel which KSP give, when you put pieces together and something actually work. It's also looks nice.

I can never land my planes, but all of them take off at more than 100 m/s. Some even break the sound barrier before leaving the runway, like my SpaceShipOne + White Knight build.

For me all builds with the CoL behind the CoM work well. Even if the CoL is way behind the CoM.

[espm400]

I can never land my planes, but all of them take off at more than 100 m/s. Some even break the sound barrier before leaving the runway, like my SpaceShipOne + White Knight build.

For me all builds with the CoL behind the CoM work well. Even if the CoL is way behind the CoM.

With the exception of my atmospheric cargo plane (which will likely never leave Kerbin), virtually all of my jets land at roughly 120-140 m/s. A couple examples:

I guess what I'm saying with the pics is that I generally keep my CoL behind, but quite close to my CoM as it makes for a much more maneuverable aircraft.

BTW, @zzz That's a nice jet you've got there. The third pic looks a lot like an F-14 (assuming that's what you were going for), which makes me want sweepable wings all that much more.

EDIT: Am I alone in finding it hilarious that Romfarer's Lasor missiles are located in the 'science' tab?

Edited June 26, 2013 by espm400

[Van Disaster]

I did movable wings ( well, wingtips ) with Damned Robotics a while back and it did work as it was meant to, to shift the CoL a little, so I suspect we just need a better hinge part. Wings attached to DR hinges are not terribly stable.

For supersonic craft especially you really want the CoL ball inside the CoM ball in the SPH, and preferably at the balance point of the tanks, although all you really need is enough tankage either side so you can pump fuel around a little to trim for various parts of a mission ( mainly referring to spaceplanes at this point ). Don't forget once you go supersonic the CoL is going to move backwards.

I like this:

And for spaceplanes I don't think I've ever got better than this:

--

With vectored thrust a lot of crazy things are possible.

Edited June 26, 2013 by Van Disaster