Planes / Spaceplanes unflyable!

[fourfa]

This thread has been great! A couple more things -

that huge complicated Marcus House craft may never have been intended to fly by hand. There are tons of piloting mods, and generally they apply proportional control, not the keyboard bang-bang control. IIRC Marcus uses lots of mods. In other words that plane is not a good trainer.  

flying successfully with keys - it helps to study the control surface details and the aero model, and reduce deployment limits to below stall limits. Some of them instantly deploy to 35 degrees, or more if you crank the limits up. In this case it’s a drag surface not a control surface, which can make things extremely weird. Generally I make my nice stable well-handling planes with large surfaces with limits reduced to 40% or less - works a lot better with keys that way. With a stick it can be set up completely different. If I make something intended to SSTO by trimming up and never turning using MechJeb’s SmartA.S.S., it’s set up different again. 

Edited December 27, 2018 by fourfa

[Dunbaratu]

17 hours ago, Plusck said:

I'd even go further and say that you should ONLY use pitch trim (well, virtually all of the time anyway) and no SAS to fly planes in KSP.

I'd agree only if you never use physics warp.  Once you do use physics warp it (like on those long flights to waypoints halfway around the world), it's unfair to expect the human pilot to respond to things that are simulation artifacts and not real-world problems.  Physics warp introduces some phantom small jitters and nudges that tend to give the plane a bit of roll or yaw errors.  If you leave SAS off, and don't touch controls, then the exact same plane that would have flown level and straight for 50 kilometers in 1x time ends up banking way over and steering off if you fly those same 50 kilometers in 4x time.

Using SAS to fight the simulation artifacts of 4x physics warp that *aren't there at 1x speed* seems totally legit to me. 

When you want to change heading, drop out of 4x warp, perform the maneuver entirely without SAS, get it lined up and level again (without SAS) on the new desired heading, and then if you want to go back to 4x warp again, turn SAS on first.

I uses SAS only when flying under physics warp.  (but then you do get one more weird problem.  SAS views the world as 3D vector space, not as a sphere.  As you fly a long distance, an SAS hold will tend to start slowly pitching you up as you fly around the curve of the planet and it flys you straight instead of following that curve.  So even with SAS you still have to drop from warp every so often to correct this, then go back into warp again.  I really wish physics warp didn't introduce those kinds of errors because I'd much rather just fly without SAS all the time, but it is necessary for physics warp, it seems.

 

[Scarecrow]

Try downloading this one and see how you get on.  It's one of the most benign flying craft I've ever created.

https://kerbalx.com/Scarecrow88/Voodoo

With SAS on and flaps deployed, it will take off with no user input at around 90m/s.  Action group keys are detailed on the Kerbal X site, but there are only two.  1 toggles the engine mode and 2 toggles the flaps.  It has no real practical use other than just flying around, but I think it 's a good looking plane which has no real flying vices.

It does require SAS turned on to fly, but I believe that if it's available and helps, why not use it.

Edited December 3, 2017 by Scarecrow

[AeroGav]

Many of the problems with KSP are to do with SAS and the poorly calibrated joystick support, that makes analog control just about impossible.

I learned to work around it and make passively stable spaceplanes that have thrust in line with centre of mass, and zero cg shift as fuel burns off.     I fine adjust the angle of the tailplane/canards in the SPH so it is trimmed to hold the angle of attack it needs for the flight to orbit with no input from the pilot.   There's some trim flaps that deploy via action group for other flight conditions (something to force the nose down for airbreathing speed run),   and the control authority has been tweaked down so that you get just enough ability to make corrections with all-or-nothing keyboard control, and no more than that.       Of course, don't expect these airplanes to win any aerobatic contest.  They probably make an Airbus A380 look nimble.

https://kerbalx.com/AeroGav/Voodoo-Ray

No incidence or built in trim.  Designed to be flown with pitch trim.   No CG shifts in flight, thrust axis is in line with centre of mass.    Does suffer a bit with adverse yaw, could do with more stabilizer area...  but space planes don't turn, they just hold 90 deg due east.

https://kerbalx.com/AeroGav/Stretch-Ray

Improved version with built in wing incidence and trim flaps.    Fly with SAS set to prograde hold in surface mode.  Action group 1 trims the nose up a few degrees, action group 2 trims the nose neutral, action group 3 trims it down slightly.

@Scarecrow what's with all the Voodoo craft today ?!!

[Morgan927]

So, I think I am good now.  Not sure who all helped. quite a few so I thank you all.

I did the following:

+ stopped using SAS  (BIG ONE)

+ one control per surface (no controls on asymetrical surfaces)

+ used trim for most things

[Zeiss Ikon]

19 hours ago, Morgan927 said:

So, I think I am good now.  Not sure who all helped. quite a few so I thank you all.

I did the following:

+ stopped using SAS  (BIG ONE)

+ one control per surface (no controls on asymetrical surfaces)

+ used trim for most things

This trio of changes to the way I fly, combined with designs that match what I already knew from building model airplanes, have done wonders for my own spaceplane flying, too.  Now I just need to get more science, so I can research better engines (Panthers and Whiplash, if not R.A.P.I.E.R.).  I flew the Aeris A4 from the stock game's prebuilt library, and it was like it *wanted* to go into orbit.  Just climb gently until the Whiplashes start to lose thrust, then ignite the Dart aerospike, and after the Whiplashes flame out (around 20-25 km) fly it just like a vertical-launch rocket -- follow prograde to get apogee above atmosphere, shut down, and set up a circularizing maneuver.  Easy peasy!

[Corona688]

On 11/29/2017 at 6:04 PM, Morgan927 said:

@GoSlash27, I have tried setting control surfaces to only one function, but was trying to be more realistic.  How in the world do real aircraft fly if they are that sensitive?

For one thing, aircraft are generally flown by analog stick, not keyboard pushbutton.

For another, things which are difficult to measure in KSP - like drag and angle of attack - get designed into real aircraft from the bottom up, so they can give you flight data to tell you precisely how you should - and shouldn't - fly it under varying conditions of speed and payload.  Ignoring this data can have dire consequences.  (See 'stab trim')

Third, real aircraft come with optimized controls with all trimming set up for you and special warning features which yell at you whenever you're about to do anything especially dangerous.  That's what the "rumble" feature of modern joysticks originally was - an imitation of this aircraft control feature.  Which itself is in imitation of the natural rumble a small aircraft's wings make when its near aerodynamic stall.

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@Zeiss Ikon, I understand.  I have not hundreds, but dozens of hours flying RC

Drag solves a lot of aerodynamic problems at small scales.  Stall?  Oh well, just fall until your tail fins naturally point you in the right direction.  Others have been solved by modern electronics.  Try flying a quadcopter in cumulative-pitch mode, see how easy it is.

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, and I have 200 hours in a military F-16 simulator (worked for Singer-Link in the day) and about 10 hours in Cessnas, 2 in a C-130, 6 in T-37....etc   Never had so many problems.  I have literally thousands of hours flying various PC based sims.

Well, you leave me no choice.  Here's the dirty secret of KSP aircraft - most of them are really, really bad.  Even the ones people call good.  They're far too heavy for their wings and rely on angle-of-attack, engine power, vectored thrust and reaction wheels (i.e, magic) to keep them on course and upwards.  They are closer to rocket-powered bricks than traditional aircraft.

This is because we really have no clue what we're doing.  Someone like you, with real flight experience, rightly sees it as absurd.

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Also, not sure if the 15 pin adapter to USB for one, works with the others, 3 of them are 15 pin only.  Hate to buy another, my favorite was expensive, 15 years ago.

Old analog joysticks were kludges because of the way they had to work around the 15-pin port's limitations.  In 1985, you got four buttons and two axes and that never really changed.  Anything fancier had to be bit-banged through an ad-hoc digital interface made from unused button lines and various digital clutter attached to the port.  This is, to understate, an impolite way to write a device driver and very unlikely to work on anything but a real port.

Your analog sticks will probably never work again, not unless you gut them and put modern electronics in them.  I'm sorry.  I lost a few good ones too.

A proper USB joystick ought to work the same way anywhere since the driver is pretty direct and universal, if you keep away from weird features like rumble.

Edited December 11, 2017 by Corona688

[Zeiss Ikon]

1 hour ago, Corona688 said:

A proper USB joystick ought to work the same way anywhere since the driver is pretty direct and universal, if you keep away from weird features like rumble.

Oh, great.  Something else to shop for.  Please, at least tell me KSP has setup options to use a joystick for, say, pitch and roll.  I can handle throttle the way KSP does it, and to be honest I don't use rudder much except when taxiing (unless you're trying to keep from making the back seat passengers airsick, it's far simpler to bank more and pull elevator to keep the nose close to the horizon than to try to coordinate a turn when you don't have a turn-and-bank).

[Corona688]

2 hours ago, Zeiss Ikon said:

Oh, great.  Something else to shop for.

Sorry.  It's hard to blame KSP for this one, at least.

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Please, at least tell me KSP has setup options to use a joystick for, say, pitch and roll.

Every axis can be mapped to a joystick axis.  Every joystick axis can be adjusted, inverted, and dead-zoned.  Every key can be mapped to a joystick button or (I think) hat.  Throttle can be handled as an axis or incrementally.

Edited December 12, 2017 by Corona688

[EnderKid2]

I am getting a nice joystick setup for this (and war thunder) exact purpose.

[GoSlash27]

On 12/12/2017 at 12:47 AM, EnderKid2 said:

I am getting a nice joystick setup for this (and war thunder) exact purpose.

If you have the money, the Saitek X-55 comes highly recommended, especially when you include the rudder pedals. I also had the X-52 in the past. It's good if you only need a single throttle axis.

Best,
-Slashy

[EnderKid2]

On 12/13/2017 at 3:59 AM, GoSlash27 said:

If you have the money, the Saitek X-55 comes highly recommended, especially when you include the rudder pedals. I also had the X-52 in the past. It's good if you only need a single throttle axis.

Best,
-Slashy

i'm getting the X-56

[Corona688]

On 11/29/2017 at 11:58 PM, Steven Mading said:

To make a plane more flyable without SAS, avoid using the S and W keys directly to pitch.  They're just too jittery.  Instead control pitch with trim, using ALT-S and ALT-W.  Note that most people don't realize these keys work because they always have SAS on, and SAS suppresses the effect of these keys making them look like they didn't do anything.  (These keys affect where the controls get centered when you let go of them, and SAS takes over the controls when you let go of them so the trim setting has no effect under SAS).

I just managed my first proper bank turn in KSP with this.  But man, the controls are still so twitchy, even with trim.  I trim it up to rise, and trim it down to fall.

[Morgan927]

On 12/13/2017 at 4:59 AM, GoSlash27 said:

If you have the money, the Saitek X-55 comes highly recommended, especially when you include the rudder pedals. I also had the X-52 in the past. It's good if you only need a single throttle axis.

Best,
-Slashy

My favorite, which I was unable to get working, is a Saitek X-45 with separate throttle.  In total, there are 3 or 4 hat switches, multiple buttons, etc. It is a digital stick set.

[GoSlash27]

3 hours ago, Morgan927 said:

My favorite, which I was unable to get working, is a Saitek X-45 with separate throttle.  In total, there are 3 or 4 hat switches, multiple buttons, etc. It is a digital stick set.

Morgan927,

 I used to have the x-45 back in the day. The problem with it was it had potentiometers instead of Hall sensors. They'd pick up a lot of jitter as they aged, and you had to set the null windows really wide. They're all old now, so you probably won't find one in usable condition. 

Best,
-Slashy

[foamyesque]

I run with an X-52 myself, which I've always found perfectly adequate to KSP's needs.

I'd also like to register my disagreement with the no-rudder school -- I am personally a fan of both fairly substantial vertical stabilizers and moveable rudders on those v-stabs. This is partly because I like derping around with stunt flying, but I've also found them very useful during re-entry and final approach. On a spaceplane's flight up you can trust to thrust-vectoring to steer you but re-entries -- especially high-angle S-bank ones -- can load you with a lot of adverse yaw that it's wise to be able to counter.