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

[Kniben]

The F-16C is still 8.5 tons completely empty. So you can figure his was still around 9.5-10 tons at that point, because he still had his ALQ-184 and his LANTIRN pod and any weapon stores still on the craft, odds are he still had two AIM-9 Sidewinders or AIM-120 AMRAAMs on the wings and the ammo for the M61 20mm.

You are a fighter pilot aren't you? =P

I did check up on the mass of the FAR Thunderbird, and it reads 12.5 tons with all the fuel. Maybe it has more wing area, but I would expect it not to glide like it does (or any of the other planes do).

Did try out the FAR Darkhammer aswell, which is very heavy. I was able to maintain a velocity of 168 at a glideslope of about 4%. Again, no thrust here.

Edited July 26, 2014 by Kniben

[Hodo]

You are a fighter pilot aren't you? =P

I did check up on the mass of the FAR Thunderbird, and it reads 12.5 tons with all the fuel. Maybe it has more wing area, but I would expect it not to glide like it does (or any of the other planes do).

Did try out the FAR Darkhammer aswell, which is very heavy. I was able to maintain a velocity of 168 at a glideslope of about 4%. Again, no thrust here.

Never was a fighter pilot, eyesight kept me from that job. Grew up around fighter pilots and B1B crew. I wanted to be a fighter pilot, F-15C to be exact, but that didn't happen so I joined the Army instead. Figured if I can't fly a multi-million dollar aircraft I will operate the heaviest meanest thing on land the M1A1 Abrams.

[somnambulist]

Ferram-

The latest version of RealChutes seems to have issues with the latest version of FAR. Logs and persistence file available HERE. Adding any real chute parachute causes FAR to throw the following error

NullReferenceException: Object reference not set to an instance of an object
  at ferram4.FARGeoUtil.IgnoreModelTransformList (.Part p) [0x00000] in <filename unknown>:0 

  at ferram4.FARGeoUtil.IgnoreModelTransformArray (.Part p) [0x00000] in <filename unknown>:0 

  at ferram4.FARGeoUtil.PartModelTransformList (.Part p) [0x00000] in <filename unknown>:0 

  at ferram4.FARGeoUtil.PartModelTransformArray (.Part p) [0x00000] in <filename unknown>:0 

  at ferram4.FARGeoUtil.CalcBodyGeometryFromMesh (.Part p) [0x00000] in <filename unknown>:0 

  at ferram4.FARAeroUtil.SetBasicDragModuleProperties (.Part p) [0x00000] in <filename unknown>:0 

  at ferram4.FARAeroUtil.AddBasicDragModule (.Part p) [0x00000] in <filename unknown>:0 

  at ferram4.FARGlobalControlEditorObject.FindPartsWithoutFARModel (System.Collections.Generic.List`1 editorShip) [0x00000] in <filename unknown>:0 

  at ferram4.FARGlobalControlEditorObject.LateUpdate () [0x00000] in <filename unknown>:0 

(Filename:  Line: -1)

Removing Incomplete FAR Drag Module

[ferram4]

@Kniben: Hopefully you can then point me towards some data and models to implement. I'm not very good at implementing feelings, I am good at implementing the USAF DATCOM. Then again, considering all these vehicles are coming down with no flaps or spoilers deployed, I'm not too surprised actually.

The odd thing is that FAR should be overestimating subsonic drag because of the assumptions is makes. It's optimized to handle supersonic drag, and that leads to subsonic drag being a bit higher than it should be.

@somnambulist: I could not reproduce the issue. In addition, FAR will not even attempt to do anything with RealChute modules; confirm that inside GameData/FerramAerospaceResearch that there is a file FARPartClassification.cfg with a block "ExemptModule" that has a line with the value "RealChuteModule". Then confirm that it also has that for CustomFARPartClassification.cfg.

[uraa]

A minor quible I know, but setting FAR to use blizzy's toolbar plugin results in:

"[Toolbar] [ERROR] button texture not found: FerramAerospaceResearch/Textures/icon_button" - suspect it should be loading 'icon_button_blizzy'

This only occurs in the hangar, flight scene is fine.

I am having same issue (VAB and SPH).

Dumb solution, make copy of "Textures/icon_button_blizzy.png" and rename it to "Textures/icon_button.png".

[Renegrade]

@Kniben: Hopefully you can then point me towards some data and models to implement. I'm not very good at implementing feelings, I am good at implementing the USAF DATCOM. Then again, considering all these vehicles are coming down with no flaps or spoilers deployed, I'm not too surprised actually.

Speaking of spoilers.. all the ones I'm familiar with live in the top of a wing... is it okay to attach control surfaces for that purpose? ie, will they be recognized in that way, and work as in real life?

I've gotten pretty good at unflapped/unspoilered landings in FAR, but it's still hit and miss sometimes, heh..

"Please don't give me a P-39,

with the engine mounted behind,

It will tumble and roll,

and dig a big hole...

Please don't give me a P-39".

[somnambulist]

@somnambulist: I could not reproduce the issue. In addition, FAR will not even attempt to do anything with RealChute modules; confirm that inside GameData/FerramAerospaceResearch that there is a file FARPartClassification.cfg with a block "ExemptModule" that has a line with the value "RealChuteModule". Then confirm that it also has that for CustomFARPartClassification.cfg.

Thanks Ferram -- I was somehow missing 'FARPartClassification.cfg' entirely.

[RoboRay]

And 58m/s isn't really slow, it is about 129-130mph, and that is faster then a Piper Cubs stall speed

It's way faster than a Piper Cub's top speed, really.

A Piper Cub's stall speed would be about 16 m/s.

[Renegrade]

It's way faster than a Piper Cub's top speed, really.

A Piper Cub's stall speed would be about 16 m/s.

I wish we had the parts to build Cubs. The J-3 is what, 200 kg? (I should try out firespitter again..)

My new improved science plane (now with four wings, I figured it was a kerbally thing to do) with flaps and kinda rudimentary spoilers (not sure I'm using them correctly, couldn't get top of the wing varieties to work) now has a landing/takeoff speed of ~50m/sec (97 knots / 180kph)!

I'd say 50m/sec is good enough for a landing on unprepared surfaces upto and including smoother highlands

[NathanKell]

Renegade: SXT adds a Bonanza cockpit, engine, and tail

[Renegrade]

Renegade: SXT adds a Bonanza cockpit, engine, and tail

Oh nice! Thanks Nathan, I didn't notice that. LLL and SXT both look pretty smooth, so they were already on my to try out list

I'mma movin' them up in the rankings! Maybe I'll make a "Flying" install with all the big airplane mods together... and then rearrange the tech tree with a MM config so you start with airplanes instead of spacecraft heh.

(I used to fly R/C planes when I was a kid, back when 27mhz was cool and people had big hair, PT-electric this and Two-by-Four glider that -- so I like slow/light/maneuverable prop craft)

[BudgetHedgehog]

I'mma movin' them up in the rankings! Maybe I'll make a "Flying" install with all the big airplane mods together... and then rearrange the tech tree with a MM config so you start with airplanes instead of spacecraft heh.

Check out The Wrong Brothers for inspiration but I don't know how well most of those creations will work with FAR

[guitarxe]

I know FAR is not intended to be used with rockets, but what's wrong with this rocket?

https://i.imgur.com/lgPUMN5.jpg

It flips shortly after takeoff. The long part between the payload and the engine is mostly an empty procedural structure, there only to increase the length of the rocket. The bottom part is the one with fuel for the engine.

[Traches]

I know FAR is not intended to be used with rockets,

Yes it is!

but what's wrong with this rocket?

https://i.imgur.com/lgPUMN5.jpg

It flips shortly after takeoff. The long part between the payload and the engine is mostly an empty procedural structure, there only to increase the length of the rocket. The bottom part is the one with fuel for the engine.

Why the large empty part? You want your center of mass forward of your center of lift; all that empty volume is moving your CoL forward without doing the same for your CoM. If nothing else, move your fuel tank to the top of the rocket rather than the bottom. Also, make sure you're flying a proper gravity turn (i.e. small turn not long after liftoff and then a long gradual turn as you climb up to altitude, not vertical to 10km and then pitch over 45 degrees.)

[guitarxe]

I pitch 5 degrees at the start and then keep slowly turning. About 5-8km into the air, the rocket flips on it's back.

Yes I know I need lift to be behind my COM, but how? My payload is not very much. Am I supposed to add dead weight to the top of my rocket just to make it top-heavy? Sounds like a waste of fuel.

And whenever I try to add winglets to the bottom of the rocket near the engine, it just gets very unstable and flips out before even reaching 1km.

[BudgetHedgehog]

My payload is not very much.

Then you don't need such a big rocket. That aside, I'd move the radial boosters up and slap some fins on the bottom. Also, I don't see any SAS units there, they'd help somewhat.

[guitarxe]

Yes, I don't need a big rocket, but first post suggests longer rockets good. So I tried that.

Here's the rocket without the dead weight added for making it longer:

https://i.imgur.com/VM8zMCU.jpg

It still flips once I drop my boosters.

Moving the boosters up only moves the COL further up away from the COM.

[BudgetHedgehog]

Longer rockets are good, yes, but only if they concentrate the CoM near the top (for reference, I just got this easily into orbit - a 3.75m Expanded payload on top of a 2.5m stack). Your CoM is fairly low down and near the CoT which will make it unstable. Quick question - what is inside the fairing? And how big is this main stack? I think that's a KWR 2.5m engine on the bottom which means the RCS ports (which add to the drag at the top) are the right size, but the radial decouplers are pretty big, bigger than stock.. the scale of things is confusing me. I think, and I could be wrong here, but your CoD is too high up as well.. as I said, put some fins on the bottom and if possible, shield those RCS ports.

Edited July 27, 2014 by ObsessedWithKSP

[Shad0wCatcher]

Regarding adding control surfaces at the bottom; keep their max deflection very low (0.5-2 degrees maximum; this isn't a jet flying horizontally; you're looking for a parabolic arc). This is especially true if you're using autopilot software.

[Hodo]

Ferram does FAR take into account variable geometry wings? Like the F-111, Mig-23, or Tornado?

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Because I made this in my normal sized KSP install and it works.... but having little experience with swing wing designs I am wondering if FAR accounts for that?

For those of you who doubt the FAR model, note the landing speed of less than 160mph.

It is amazing what you learn from old documentaries on the F-111, and Mig-23.

[NathanKell]

Yes it does. As long as the wing part itself moves via an IR hinge, it's not some animation of a part and the part stays still (like D12 swing wings).

[DaMichel]

Seeing that Kniben's plane glide so far sure looked strange at first. But then again, it was flying fast and at low angle of attack initially and it was full of fuel. I suspect that it was going at the ideal cruising speed drag wise. I.e. at the bottom of total drag curve

So the plane had a high energy state and a low rate of energy loss. I get the impression that later at high angle of attack it bleed off speed more quickly, which is expected due to higher induced drag. So i think the behavior is plausible.

In addition airliners have flaps and spoilers to help slow them down. If you use these you can do much more realistic landings. Since FAR models induced drag, you can literally do brake turns. Sideslips are also good for braking but not as good as pulling some G's. ... I'm very happy with FAR.

[Volt]

In addition airliners have flaps and spoilers to help slow them down. If you use these you can do much more realistic landings. Since FAR models induced drag, you can literally do brake turns. Sideslips are also good for braking but not as good as pulling some G's. ... I'm very happy with FAR.

Is it feasible to do a forward slip in KSP without a joystick? I've tried it, but having only the option for max deflection makes it damn near impossible for me.

[DaMichel]

I don't think so. Maybe with trim controls ... With joystick and keyboard it is doable. I normally don't but .. if the ruder is properly set up i can hold a/d for full rudder and control the pitch/bank angle with the stick.

[Renegrade]

Check out The Wrong Brothers for inspiration but I don't know how well most of those creations will work with FAR

Oh geez - no, I don't think the early creations would work very well with FAR at all - FAR hates the truss-like struts (they're very high drag, I tried using some as extensions to extend the landing gear away from the body of my plane laterally once, and it pretty much halved it's top speed)... That being said, I'm going to have to read that in detail later, that's hilarious!

And whenever I try to add winglets to the bottom of the rocket near the engine, it just gets very unstable and flips out before even reaching 1km.

Are they FAR-compatible winglets? (stock winglets are compatible, Ferram made configs for all stock wing-like parts in the basic install) Non-FAR winglets aren't advisable.

In addition airliners have flaps and spoilers to help slow them down. If you use these you can do much more realistic landings. Since FAR models induced drag, you can literally do brake turns. Sideslips are also good for braking but not as good as pulling some G's. ... I'm very happy with FAR.

Yeah, pulling some G's is a good way to slow down. Also, a tight 360-degree loop (horizontal or vertical) will not only kill speed, but also delay the approach. Or you can always add Moar Flaps!