Bouncy Planes - How To Fix Them?

[TARPSBird]

Forgive me for posting this if there is a pertinent tutorial thread somewhere.
I've been flying Tim Conrad's A-1 Skyraider for a while now since setting up my FSX in March. It's a beautiful model of one of my favorite USN planes, and I'm finally able to land it on CV's without any fatalities (usually, lol), but it seems to bounce awfully high in the air on landing. In FS9 I have the Razbam Spads and I don't have the bounce problem with them. I am totally confused as to how the numbers in the [contact points] section of the aircraft.cfg file can change the behavior of the aircraft on landing. Specifically: Static Compression, Ratio of Maximum Compression to Static Compression, and Damping Ratio. I wish the SDK would explain this stuff in a bit more detail. Bottom line, what numbers do I change and in which direction - up or down - to reduce excessive bouncing on landing???

[michael davies]

Hi, try here from the grand master Mr Schupe.

http://www.sim-outhouse.com/sohforums/showthread.php?944-Perfecting-Suspension-Setup-(Repost)&daysprune=-1

It helped me refine my proceedures, for some helo's I wanted really soft long stroke main gear animation, for others (tail wheel) I needed short stiff parameters, read through these, you will be limited as you cannot control the source deflection, but you should be able to refine the compression and stiffness in the cfg file.

Hope that helps

Michael

[TARPSBird]

Thanks Michael! :salute:

[napamule]

Tarpsbird,
You wasted your time if you re-did the A-1 cnt pts. They are perfect. So the 'fix' should be looked for elsewhere. Not my OPINION but FACT. Lands at 85 to 90 kts, on it's tail, as it's a carrier type and you DON'T want to land on a carrier with tail up in the air like the regular taildraggers do. Right? Right.

Tim did a bang up job on this model. Sweetest flying and landing ac I have (of ANY type) in FSX (Acceleration). In fact I don't have many 'Warbirds' right now. And I am glad I got this one (I installed it today to check how the cnt pts were-just for you). But by now you probably already found out that the cnt pts WERE perfect. I hope so. Put them back to how he had them and use +5.0 of pitch trim, reduce speed with spoiler just before touchdown, land at 90 kts or so. It don't bounce. Unless you 'plunk' it down (ie: stall it) from 20 ft up at 110 kts. So there you go. Sorry about the 'criticism', but I want to chime in and say Tim really got the FDEs right. No. Make that PERFECT! (Did he get 'expert' help?-maybe?-then good on him-he should use him/her again). Or, he learned how to do 'good' FDEs. (About time-hehe).
Chuck B
Napamule

[stansdds]

I agree, the flight dynamics in Tim's Skyraider seem pretty realistic to me.

[Piglet]

Thank Jerry Beckwith, and his Airwrench program thingy. I just plug in the numbers....:wavey:

[TARPSBird]

My original post was not meant to be a criticism of Tim's work or suggest there was anything wrong with the contact points as he originally set them up. I certainly will admit to the possibility that I simply suck at landing the Spad. :redf: I no sooner touch down and I'm back up 20 ft or so in the air, even when I think I greased the landing. But if it works fine for the rest of you, I am glad.

[stansdds]

Sounds like your descent is too rapid, tail draggers tend to need a good bit of flare and a soft, preferable three point, landing.

[TARPSBird]

I've made quite a few carrier approaches where I come in at a stately 85-90 kts per napamule's post, tail down, cross the ramp and settle into the arresting gear, at which point I sometimes land safely but more often find myself either back up in the air or cartwheeling tail over nose down the deck if I catch a wire. I'll keep practicing - it's not like I'm gonna run out of Spads. :icon_lol:

[napamule]

That's funny! If you are coming in at 85 kts and do a 3-pt landing, you should stop rather quickly with just brakes. Why you need a tailhook? (hehe).

The truth is that tailhook postitioning and cable force is not an exact science. You need to adjust them. I did notice the tail hook looked rather long and saw how it 'digs' into the surface. Below is my 'best-guess' of how it might work better (will try out later as I'm tied up with xyz right now).

[tailhook]
tailhook_length= 0.6000
tailhook_position=-24.000, 0.000, -0.600
cable_force_adjust= 2.200 //This setting will cure 'whiplash' (c:b).
Chuck B
Napamule

[Rich]

napamule, I think your hook settings will be a failure as the virtual hook catch point is way to short to catch a wire.

2 screenshots to illustrate one in Royal Navy garb is what I posted and works and is how it should look,the US paint is your fix, the red cross is the location of the virtual tail hook the bit that does the stopping, that is with hook extended, a bit short I think. I have a very useful little prog that shows the hook end.

What I used

[tailhook]
tailhook_length = 6.0
tailhook_position = -25.000, 0.000, -0.500
cable_force_adjust = 6.0

[napamule]

Rich,
Well, you are 'using' a lot more 'science' than I ever used or tried to use. And that is just fine (if that's your bag). Me? I just use a bigger hammer. I made a 'demo' video.
Link: http://www.youtube.com/watch?v=w3WSfaGjDhs .
And now I'll wait for your video. Perhaps? Or should I just 'Go On' and just fly (hehe).
Chuck B
Napamule

[Rich]

Do'nt do videos but if you watch your tail hook on touch down it actually goes through the deck a good way and your catch occurs on tailwheel compression and the tail is very close to the deck.

I have been hoping someone would take on this tailhook thing so I can get my planes landing properly.

[napamule]

Rich,
I make videos at the drop of a hat. 2 Gig a day is nothing. Sometime I do 10 Gigs.

I was hoping you would have noticed that IF YOUR MAIN WHEELS DON'T LAND ON (OR BEFORE) THE WIRES that the hook will 'miss'. So, perhaps the hook is tied in with the 'squat switch' in that the hook will not 'catch' until there is total compression of main wheels? Your call. I don't even need to know. But it's an interesting question/topic. Worth mulling over, perhaps. And this is just with this tail dragger. How about the F-18 tail hook (AND contact points). They are not perfect, either. Have you ever worked on them? I see a lot of videos of the F-18 nose wheel digging into deck after catch and it doing pitch and jerk movements that are not as 'real'. I fixed mine. No more digging of nose wheel or 'whiplash'. Smooooth as silk. Cheers.
Chuck B
Napamule

[TARPSBird]

Chuck,
I watched your video. If you're making those landings with no modifications to Tim's original contact points, then I guess I just need to admit I don't have the skills and walk away from the airplane. When I touch down before reaching the wires - even gently - I am back up in the air like Wile E. Coyote wearing coil spring shoes and I never even catch a wire. Or if I do I nose over and crash.

[Rich]

Tarps, this is what he says he is using

[tailhook]
tailhook_length= 0.6000 // = 7.2 inches / or 18.288 cm
tailhook_position=-24.000, 0.000, -0.600
cable_force_adjust= 2.200 //This setting will cure 'whiplash' (c:b).
Chuck B
Napamule

The tailhook length of 0.6000 equates to = 7.2 inches / or 18.288 cm that measured -0.600 under the cog line so the hook would not touch the deck even sitting on the deck.

My thoughts are that RCBO gauges are being used not FSX accel .

Just had 5 attempts at catching and all failed, as you know I have a gau that tells me which wire was caught, airspeed and rate of descent nothing registered = tailhook miles too short.

Time to leave tail hooks alone I think

[Rich]

Last screen shot, on the ground hook fully extended, not sure if the old saying a picture is worth a 1000 words is true.

[napamule]

Rich,
One thing that is part and partial of posting information on ANY forum is that it is the TRUTH. You (I?) will soon find that out by the processing of the info by the 'knowledgeable' sim members. Guessing is not the way to go. Prove it. Show me.

I resent your implication that I am somehow misleading the Sim Community by posting mis-information (ie: am really using RCB gauges and not just 'stock' FSX Acelleration). That is wrong on your part. Calling me a liar is not proper or polite. I try to be both.

So, the reason for the video was to demonstrate that my settings work (IF you follow directions). I even stalled it in to prove the hook works and the plane don't bounce. Thinking about it a little leaves little doubt that the amount of ELEVATOR you use (as opposed to pitch trim) AND amount of throttle influence the end result-trap or no trap. Like I said, the main wheels APPARENTLY must be 'down' for hook to 'catch'. Or that is what it seems to be, going by what the model does. You can 'duck' out of this thread, if you wish, and you got nothing to 'add'. But, nothing says that you set the standard for tail hooks by putting up a drawing with lines. I've been tweaking planes for 10 years and it (pictures) don't tell me anything. You ASSUME the entire tail hook must be seen above ground. It is MODEL related and THAT (what you see) can not be adjusted from the cfg settings.

At least my video shows that landing can be done. Best at 70 kts. Best with +7.0 pitch trim and 45% power (which you shut off just before touchdown). No input (ie: elevator) is requred as the tail will 'sit' AFTER the main wheels touch & compress. And you DO NOT brake hard as that will cause a nose over. And any use of elevator will cause model to 'soar/zoom' and you'll 'miss' the trap. Just plain ole flying technique (and 'practice') to match the requrements of the Sim. NOT rocket science. Or RCB gauges (sorry Rob).

Tarpsbird,
You said: '... I never even catch a wire. Or if I do I nose over and crash.'. Did you try my setting for (tailhook)? And do you use +7 pitch trim? (A lot of simmers disagree (and refuse to use) pitch trim as it's not 'real' and contend 'it should not be necessary', then FAIL at carrier landings. Cheesh.). Full flaps? 45% throttle on aproach (to maintain 'control')? Do you let plane 'float' onto deck (and leave the elevator alone)? By the way, do you use twist grip joystick or yoke? There MUST be a reason you can't catch wire. And do have 90% fuel (you NEED that for weight distribution). This tells me that the FDEs COULD use some tweaking specific for carrier ops. But not otherwise. And hey: IT IS NOT AN AEROBATIC type airplane. It is just for flying from Point A to Point B, then drop bombs, and return to Point A. It's not a Extra (hehe).
Chuck B
Napamule

[roger-wilco-66]

[...]
I resent your implication that I am somehow misleading the Sim Community by posting mis-information (ie: am really using RCB gauges and not just 'stock' FSX Acelleration). That is wrong on your part. Calling me a liar is not proper or polite. I try to be both.
[...]


Dear Chuck,

I followed this discussion which much interest and see that both of you have valid points (in my eyes) and more knowledge about this than me, at least, but I didn't see Rich calling you a liar or anyone accusing you of misleading the community. You guys have just two different opinions, thats all, and to me there's nothing serious about that. Happens all the time.

Maybe we can continue to dig into that to come to a positive conclusion...


Peace,
Mark

[napamule]

Mark,
What do you call this? Chopped liver? Rich (quote): 'My thoughts are that RCBO gauges are being used not FSX accel .' There was no one else involved so it must be directed at me. So, how do you account for that statement? It's an (unfounded) accusation, at the very least, and is therefore calling me a liar. A gray mule has gray hairs so that's why they call it a gray mule.

I understand his fraustration. (Quote: '..so I can get my planes landing properly.'). Too bad so sad. It's all flying technique and skill attained by practice. Not cfg edits.

Rich,
I tried your tail hook settings and they are producing undesired effects (nose pitches over so tail is in the air (not right) after trap. Sorry.

Tarpsbird,
Went and did some more flying and landing. I made some changes to cfg. You will find that they will improve the dynamics significantly. (Won't do anything for your 'skill' though (hehe)). The other thing that I wonder is, do you land from (LOCKED) spot view, or from the panel (2D or VC)? If you land using panel view, you should adjust the view so that you can see the deck without pitching nose down. OK? OK!
Here are mods. The most important one is the 'c of g' entry. This value change will prevent nose over 'crash'. Helps keep it level after trap, too. Copy/paste to cfg. Save a copy first, please. Happy Landings. (Don't give up yet.

Set up this routine for 'easy' repeat landings: use slew to raise to 1100 ft, then back away to about 1/2 mile. Push stick forward (all the way!), let go slew, cut throttle, add spoiler to slow to 100 (then remove), full flaps, wheels down, hook down, and pitch trim +7.0. Then just use throttle (30% or so) to maintain 80-90 kts on approach, (with SLIGHT use of elevator, and 'ok' to use aerlions for banking due to cross wind, etc), align with deck heading, and throttle as needed and land 75 kts or LESS (landing at 65 kts IS very possible)). Good luck.

A-1 Skyraider CHANGES / MODS: 11July28, 11:40 am, by c:b (Napamule).
-------------------------------------------------------------------------
(1). empty_weight_CG_position= -0.060, 0.000, 0.000
//prevents nose over on (locked) brakes + 100% throttle
(2). station_load.1=" 2200.000, 2.000, 0.000, 0.000, Ordnance"
(3). point.1=1, 2.000, -7.420, -8.100, 2001, 1, 1.313, //wheel radius: was 2.313
point.2=1, 2.000, 7.420, -8.100, 2001, 2, 1.313, //wheel radius: was 2.313
(4). toe_brakes_scale= 1.000 //o=0.78000
differential_braking_scale= 0.850 //o=1.00000
(5). Center1= -0.500, 0.000, 0.000, 380.000, 0.000
(6). oswald_efficiency_factor= 0.680 //0.79300
htail_pos_vert= 2.500 //0.00000
htail_incidence= -0.234 //0.00000 //for cruise pitch at '0.0' (@ 60% Pwr)
(7). (flaps.2):
drag_scalar= 1.3 //o=1.00

Chuck B
Napamule

[Piglet]

Maybe we can continue to dig into that to come to a positive conclusion...


Or I'll take my planes and go home!:running:

[Rich]

Tim, sorry about the miss use of your plane, as far as I am concerned this thread is ended, a very nice model that worked well for me except the original tailhook settings caused nose over on catching a wire.

[napamule]

Rich,
I am sure Tim does not mind you making changes, if it would help with a problem. Why do you not add this line 'empty_weight_CG_position= -0.060, 0.000, 0.000' and then use my tail hook settings and see what happens. The '-0.060' is just enough of a change (with this model) to cancel out the pitch (nose over) even if you hold the brakes (now 1.0) and give it full throttle. Try it as original ('0.0') and see what happens. Not sure if Tim will try to use any of this, as he might not 'do' carrier landings of war birds (and a tail dragger to boot). Or jam it full throttle with brakes on, either. But there it is, in black and white. Use it or loose it. What can I say.

I love to fly models and expect them to fly 'right'. If they don't I investigate and make the necessary changes where needed, somtimes determined by trial & error, and sometimes by pure 'logic' (ie: by thinking outside of the 'Airwrench' box). Then I offer my findings here and hope someone can come away with a smile after having some success after using my mods. And that is ALL I want/expect. Your smile.
Chuck B
Napamule

[N2056]

I've been following this thread, and I have noted that at times the exchanges have been a bit more "adversarial" than we tend to desire. Offer suggestions, and then let it go. When it starts looking like an argument I start looking for my locks.

[Rich]

N2056, I would be quite happy to have the locks applied thank you.

[N2056]

Rich, I have noted your opinion. Please understand that we really prefer to only lock a thread by request when it comes from the individual that started the thread, or we decide that it needs to be done.

[Rich]

N2056, not a problem but I feel it a waste of time carrying on with this thread as it is going nowhere.

[TARPSBird]

N2056,
This thread has taken a turn that I certainly didn't intend for it to take when I started it. Thanks everybody for the comments and suggestions and my apologies to Piglet for any inference that the Spad's specs were erroneous. If other people can land OK then it's operator error on my part. I'd prefer the tailhook placement debate be carried on elsewhere, so pls lock it up.

[N2056]

Okay. It's done. TARPSBird, I'm sorry it went south. Hopefully something is learned from this in terms of what not to say.