Landing gear can't wait for 1.2, needs bandaid.

[klesh]

You told me you doubt my suggestion would work, you're saying you know his wont work, yet you dont have 1.1.3 installed to test and you wont give us the craft file so we can tinker to maybe solve it.  Sure the wheels are broken, but there are ways to make them work.  I guess you feel you shouldn't have to tweak your ship due to a bug, but its alot more fun to do that and continue enjoying this great game than to let frustration get the better of you.  I get that we're late to the party and you're done trying to find a solution, but really we're just trying to help you.  

Edited July 17, 2016 by klesh
Spelling

[Alshain]

17 minutes ago, klesh said:

You told me you doubt my suggestion would work, you're saying you know his wont work, yet you dont have 1.1.3 installed to test and you wont give us the craft file so we can tinker to maybe solve it.  Sure the wheels are broken, but there are ways to make them work.  I guess you feel you shouldn't have to tweak your ship due to a bug, but its alot more fun to do that and continue enjoying this great game than to let frustration get the better of you.  I get that we're late to the party and you're done trying to find a solution, but really we're just trying to help you.  

I know his won't work because I did it before I abandoned 1.1, so I'm positive that simply changing the angle of the wings does nothing to help.  Your suggestion, I did try it in 1.1.2 with the LY landing gear (I actually thought the front gear was supposed to be in a backward position to what it is for those but then someone showed me a cesna picture) but not 1.1.3 with the gear I was using on that particular plane.  I just really doubt it will change anything, but that is an educated guess.  I only gave him the screenshots because he was asking for screenshots of a plane that didn't work.  I wasn't asking for help, I was trying to help him with what he wanted to see.

I didn't need anyone to fix it, I'm no longer playing 1.1.  I certainly didn't need someone to change it to a delta wing profile and eliminate independent authority control on roll and pitch and make it hard to fly .

[gilflo]

First of all

-Tweak your gears so that they can support the weight of your craft

-Place your main gears not far from COG.

-You can have more than 2 main gears if your craft is very heavy, especially for heavy body, and you can have 2 front gears if necessary

-Use this mod to perfectly align you gears in 3 dimensions:

-Always disable steering on rear gears, you can even disable steering on front gear, just before take off, rudder should be enough for take off run.

-Set more friction on rear and main gears than on front gears (1.5 and 1.0)

-Set more brakes on rear gears and main gears than on front gears.

-You can land with no steering

- My damper settings are <1.0

 

 

[klesh]

1 minute ago, Alshain said:

*snip*

Right on.  

 

Because I have nothing better to do on this lonely Sunday morning, I am going to try recreating it for poops and giggles.  If you'd like, I'd love to take your original for a spin if you care to provide it (pretty please?).  If not, thats cool too.

 

[Alshain]

Just now, klesh said:

Right on.  

 

Because I have nothing better to do on this lonely Sunday morning, I am going to try recreating it for poops and giggles.  If you'd like, I'd love to take your original for a spin if you care to provide it (pretty please?).  If not, thats cool too.

 

Oh sure, I can upload the craft file.  I don't know if the authority limiter settings will persist since they didn't exist in 1.0.5.  1.1 had very sensitive roll if I remember right.

https://dl.dropboxusercontent.com/u/9097777/Shrike MK2.craft

 

[klesh]

13 minutes ago, Alshain said:

Oh sure, I can upload the craft file.  I don't know if the authority limiter settings will persist since they didn't exist in 1.0.5.  1.1 had very sensitive roll if I remember right.

https://dl.dropboxusercontent.com/u/9097777/Shrike MK2.craft

 

 

 

Good timing, I just got the main body sorted and was about to add wheels.  Not too bad going purely from the one screenie in your sig.  Thanks for the .craft, I will check it out now.

 

 

I'll check to see if authority settings carried over, etc.

[Wraith977]

20 minutes ago, Alshain said:

Oh sure, I can upload the craft file.  I don't know if the authority limiter settings will persist since they didn't exist in 1.0.5.  1.1 had very sensitive roll if I remember right.

https://dl.dropboxusercontent.com/u/9097777/Shrike MK2.craft

 

Uh, heh, I just took off in the exact craft you posted with no problems whatsoever... no fishtailing, nothing.

Only thing I could complain about is that the nose dips down too much due to the far back COL...

[Deddly]

Correct me if I'm wrong but I do believe there were some minor aero changes between 1.1 and the various patches that could explain why this and other planes can be made to work in later versions with some tweaks. 

[klesh]

Okay, I just had a go.

By just throttling up and touching no controls Ashlain's original will veer to the left, for me, by a total of 1m or so until you reach 100m/sec and then it violently goes to the right which at that speed induces fishtailing.  Its enough to throw you off the runway.   You can however take off before all that happens. Reversing the front gear had no effect, and it did the same thing.

My replica craft, although not exactly the same, is able to reach 175m/sec by the end of the runway and is dead on down the middle, straight as an arrow.

I'm starting to wonder if there is something funky saved in the build of the original craft, a relic of being updated from 1.0.5 to 1.1.x that might be causing the weird behaviour. Something else that changed between the two versions.

[Alshain]

37 minutes ago, Wraith977 said:

Uh, heh, I just took off in the exact craft you posted with no problems whatsoever... no fishtailing, nothing.

Only thing I could complain about is that the nose dips down too much due to the far back COL...

See, that's been the experience.  Either everything is fine for you or nothing is.  It seems to be half the users have the problem and half do not (roughly).

4 minutes ago, klesh said:

I'm starting to wonder if there is something funky saved in the build of the original craft, a relic of being updated from 1.0.5 to 1.1.x that might be causing the weird behaviour. Something else that changed between the two versions.

Except I've seen reports of it in the console forums.  Nobody on consoles had 1.0.5 and therefore have no craft from 1.0.5.

[Boris-Barboris]

1 hour ago, Alshain said:

I'm positive that simply changing the angle of the wings does nothing to help

Does it?

[klesh]

28 minutes ago, Alshain said:

Except I've seen reports of it in the console forums.  Nobody on consoles had 1.0.5 and therefore have no craft from 1.0.5.

 

Do we know what version the console's are running?  Honestly, I would take most console people's reports with a grain of salt.  They might all be taking about those terrible tier 0 landing gears for all we know. Its quite odd when some experience this phenomenon and other's dont.  I know mine is a Steam install that was upgraded automatically.  I'll have steam validate the cache right now.

 

If anyone cares to have a try with my replica of Ashlain's Shrike, feel free to download it here:

https://dl.dropboxusercontent.com/u/141568437/Shrike Replica.craft

Compare how it performs on your machine to how Ashlain's original.

 

 

 

[Wraith977]

Took off in original craft at 100m/s with no issue after pulling up at around 70m/s, further testing shows craft loses control on the runway after 100m/s if it hasn't taken off yet - craft veers violently to either side causing crashes

Took off in replica at around 110m/s with the same method, further testing shows the replica remains stable at up to 195m/s on the runway, could possibly go faster but the runway is only so long...

SAS was on for all tests

Long story short the "replica" has better control on the ground, would tune down the controls though it's far too sensitive in the air. Also technically not a replica, you straightened the rear wings and moved the COL closer to the COM, one of the fixes that was mentioned.

@Alshain, don't take this the wrong way but your design is part of the problem and tweaking it as @klesh has seems to mostly, if not entirely fix the problem. Also check your method of taking off, don't let the craft go over 100m/s while it's on the runway, that's when the problems start...

Also, you said straightening the wings doesn't help... took your craft file (the original Shrike Mk2), straightened the wings and retracted your deployed flap and it works as well as if not better than the "replica", no issues on the ground or in the air...

Edited July 17, 2016 by Wraith977

[klesh]

I just tilted the wings a little like I remembered them looking, That wasn't entirely on purpose.

I never mess with the control authority setting on flaps and ailerons, I suppose I should.

[Alshain]

Well I'm glad it works for you guys.  But it never did for me.  I have other planes that don't have titled wing with the same issues.  Frankly I just got sick of trying to troubleshoot it.

Edited July 17, 2016 by Alshain

[foamyesque]

9 hours ago, Alshain said:

Well I'm glad it works for you guys.  But it never did for me.  I have other planes that don't have titled wing with the same issues.  Frankly I just got sick of trying to troubleshoot it.

Looking through the planes in that Imgur gallery, you have a persistent issue with over-tailing them. Balanced correctly you can drive a three-hundred-tonne aircraft on a pair of standard canards used as either a tail or as canards, including through reentry.

 

I pulled out your original to test and discovered a bunch of clipped stuff, which I disapprove of on principle but which also meant that expecting anyone to duplicate your ship from the screenshots alone was kind of silly. Anyway, I tried it out. Here's my thoughts:

It has a lot of handling problems and they mostly stem from you giving it a very strong desire to pitch down. Takeoff is unnecessarily difficult -- the pitch down means you need a strong pitch command to pull the nose up. Level flight requires a constant pitch-up command, which means you've got additional drag from the elevons. It also means that if you let up on that, the plane'll lawndart on you; this is particularly noticeable when attempting to land and especially if the flaps get deployed to try and slow down. Your flap arrangement makes the nose-down worse if you deploy them, which is unhelpful at best. It's murder on the reentry profile, too; I tried maxing the control authority of the canards and tail, as well as engaging the RCS and transferring all the fuel to the back, and I still couldn't generate enough angle of attack for a clean reentry. I lost the battery to heating, and the cockpit hit 2350K, so I very nearly lost the whole craft. That's a tighter margin than I'm comfortable with.

The nose-down pitch is also what is causing your handling issues on the runway.

The engines contribute to this, as well; they're above your CoM, and so impose a downward pitch when they're running. It isn't huge, but it's noticeable in vacuum; if you have KER I'd experiment with fiddling with the vertical placement of your wings to null out the torque reading.

Another problem you've got is that with the clipped FL-T400 tank in the back, you get a major CoM shift between fully-fuelled and bingo; it moves forward as you burn fuel. That's contributing to the reentry problems.

The Clamp-A-Tron Jr at the back has a bunch of drag. A shielded docking port would be a much better alternative.

You've got too many RCS ports, which also load on more drag. The torque provided by the command pod is more than adequate for orbital attitude control on something this small, and translation for docking manouvers can be accomplished with four ports (four quads, or two quads and two linear, can provide full translation).

 

But it's easy to criticize, yeah? So I fixed it for you.

 

1. I broke the FL-T400 into two FL-T200 tanks and added them to the front of the nacelles. Aside from reducing the hyperdimensionality of the plane, it reduces the CoM shift.

2. Moved the 40 liquid fuel from the precoolers (now dry) to the Mk 1 fuselages (for 120 total). Reduces the CoM shift. Improves the streamlining, too; things clipped inside other things still have drag.

3. Slid the nacelles as far back as they can go without the engines obstructing the docking hatch. Reduces the CoM shift.

4. Levelled the wings. Eliminates pitch down.

5. Moved the canards right to the nose, and maxed their control authority. Dramatically improves responsiveness.

6. Deleted now-unnecessary tail elevators. Saves mass and lowers drag.

7. Swapped the adapter/Clamp-O-Tron Jr for a shielded docking port. Masses a hair more, but cuts drag. The additional mass also helps reduce the CoM shift just a bit.

8. Slid the tail backwards. Better yaw stability and control, and reduces the CoM shift.

9. Slid the wings backwards until CoL is square on CoM. Compensates for the levelling, canard shift, and tail removal. By mounting them further back overall the CoM shift is reduced as well.

10. Canted the wings very slightly to pull the CoL forward just a hair without moving the CoM lengthwise. Moves the CoM up to compensate for the tail deletion. Also improves roll stability.

11. Moved all the landing gear further forward.

12. Pulled the rear gear outwards and upwards. Improves stability through a wider stance, imparts a natural nose-up attitude for takeoff, and moves the CoM upwards to place it exactly in the CoT.

13. Slid the solar panels backwards to keep them clear of the wings.

14. Completely redid the RCS. Cut it down from twelve ports to six: a dorsal/ventral RCS quad on the CoM, and a dorsal/ventral pair of linear ports at the nose and tail. Provides translation in all axis and strong pitch control for re-entry. Yaw and roll attitude control can be handled trivially by the pod.

 

End result: Better flight in all regimes. Takes off smoothly, hypersonics smoothly, reenters much more smoothly, lands effortlessly.  How's a Mach 2.6 landing approach grab you?

 

 

 

Drag comparison (as close as I could manage, since your design can't actually go that fast on the ground and retain control; I did ground-skimming flight instead):

Yours:

My revision:

 

EDIT: Top speeds ASL, running with infinite propellant and no heat:

Yours:

(this required a lot of horsing around to get to since SAS can't hold the thing level, and manually controlling it meant I kept bleeding speed; the absolute maximum in level flight could be higher, but it'll never be reached)

 

My revision:

(I mostly let the SAS fly this one. All I needed to do was soft-correct to keep from climbing out of my testing bounds. )

 

 

Craft file:

https://www.dropbox.com/s/ldl6f0jsv0hfmly/Shrike MK2 - Corrected.craft?dl=0

 

Apparently you've got me on ignore, so this was probably a waste of time, but hey, maybe others will find it useful.

Edited July 18, 2016 by foamyesque

[KerikBalm]

So, in the end, he designed his plane to be stable in the air, but not on wheels... its easy to see (to me at least) why he's having gear issues. I don't see any bug, I just see wheels that are less forgiving.

He keeps saying its a well documented bug, but has never provided any documentation.

Are the wheels perfect? nope. Could various stats be adjusted? yes. Have I seen any bugs related to the issue at hand? nope. Do they need some of their stress, suspension, friction, etc values tweaked? Yes.

When CoL is too far behind the CoM its going to produce a nose down torque. Thats going to put a lot of force on the nose gear which is in front of the CoM, which is *unstable*.

So, an unstable design is... unstable. THAT IS NOT A BUG!

 

Yes, normally, CoL should be a bit behind the CoM for aerodynamic stability... but you should be able to pitch up, which means CoL should be able to move in front of CoM with appropriate control input. Do that.... lift the nose wheel off the ground, have the wheels that are bearing the planes weight be behind the CoM, and everything is fine.

What is happening here is due to principles that are the same reason I always disabled the brakes on my nose gear even pre 1.1

No evidence of a wheel bug has been provided.

[Deddly]

@KerikBalm to be sure wheels are bugged, let's not go overboard with the criticism here. But apparently there are also design issues that replicate the effects of a bug.

[foamyesque]

5 hours ago, KerikBalm said:

So, in the end, he designed his plane to be stable in the air, but not on wheels...

<snip>

When CoL is too far behind the CoM its going to produce a nose down torque. Thats going to put a lot of force on the nose gear which is in front of the CoM, which is *unstable*.
 

It isn't even stable in the air -- the tilted wings try to force you into a nose-down loop. Frankly it flies better inverted, which actually would probably solve the reentry problem. :v

A CoL well behind the CoM will not necessarily produce a nose-down torque; if everything is lined up, it will simply keep you locked on your prograde vector and gravity will gradually pull the trajectory down. Same principle as a rocket executing a gravity turn. But with planes there's so many opportunities for aerodynamic loading (and the very smallest gear, the fixed ones, have so little traverse and suspension strength that not overloading them is difficult) that you need to be conscious of your gear positions and flight characteristics and not just stick 'em on wherever and trust to TVC to let you pull up.

[KerikBalm]

Well.. if there is zero AoA, it produces no torque, true.

But if its lifting up the back end, thats a nose down torque, even if its not directly pushing down on the nose.

The loading should come off the nose first, not the rear wheels, and that design does the opposite without pitch input... which apparently works for people flying it... so... the problem is he wants to keep that thing on the runway past 360 km/h while lifting up the back with the fixed incidence and leaving the front without anything to counteract the force of gravity - front gear stays loaded, load comes off the back, plane becomes unstable... lots of complaining, but this is physics and not a bug.

Yes i have seen some wheel bugs where a craft will jitter just standing still. But thats a different discussion