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Re: C172 severe wing-over on take-off

Postby macnab » Fri Aug 26, 2011 5:29 pm

Hmm, so constant pressure is needed.
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Re: C172 severe wing-over on take-off

Postby Dragonmaster Lou » Fri Aug 26, 2011 6:14 pm

Yep, just like with the twist rudder or rudder pedals -- the only difference is that you're using fingers on your left hand instead of your feet or right wrist (using the HOTAS layout of throttle on the left, stick on the right).
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Re: C172 severe wing-over on take-off

Postby GregS » Tue Jul 09, 2019 9:19 am

I see this post is several years old, but I don't see a reason or resolution so I can hope somebody monitors this.
I have recently got the hardware to finally run FGFS (Linux version) after years of having it hang. I am using the default C172 out of HI to get a feel for the program and am experiencing this uncomanded torque roll exactly as described. This is categorically NOT normal with this class of aircraft in my 300+ hours on type; I'd expect something like this severity on something with a humungous radial, perhaps, but not for a 160/180 HP flat four.
I am using a Logitec joystick with twist control rudder (you cannot readily get anything much better here Downunder), applying sufficient rudder to stay on the centreline (as per real AC) results ina 45° torque roll andmyaw to the left immediately after rotation. It is conjecture that it may be due to an excessive setting for torque but I can see no way of viewing, much less adjusting this. Any ideas?
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Re: C172 severe wing-over on take-off

Postby Isaak » Tue Jul 09, 2019 11:36 am

Just to be certain: you don't have coordinated flying enabled, do you? This ties rudder and aileron control to each other, so a big rudder input would result in a steep roll movement too.

Otherwise there've been quite some discussions about the engine torque moment (p-factor), some people state that it 's overdone, others say that it's right. I don' t have any experience in the real aircraft, but it seems you have, so you could drop your opinion in :-)
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Re: C172 severe wing-over on take-off

Postby dilbert » Tue Jul 09, 2019 1:59 pm

Do other planes act the same? Try the PA 28 to see. If it doesn't, it's probably a 172 issue, If it does, it's a stick issue. Go to File>Joystick Configuration and select Reset Configuration, which will restore the stick defaults; then retry.
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Re: C172 severe wing-over on take-off

Postby GregS » Wed Jul 10, 2019 10:13 pm

Thanks Isaak & dilbert.
I have tried both autocoord and normal - same issue.
I am currently using a Logitech joystick with twist control for rudder - works fine on tracking centreline, massive yaw on rotate. Oddly, this seems to moderate greatly when levelled off in the circuit (all I have done to date) and power back to about 2000RPM (nearer 2350 in the real AC). Quite out of proportion to the relative power settings.
I have received some offline advice from polly wrt modifying the rudder settings in the joystiock .xml file (thanks) which doesn't seen to have made much difference, but I'm still experimenting.
I have only tried a light twin and heavy jet (obviously not affected) and the PA28 - which does not seem to have the same problem, so I suspect it is indeed in the C172 settings...somewhere.
I had the same problem before I upgraded to fedora 30 (which is also the FGFS spin I'm using, up to date as of yesterday - in fact the same problem has existed since Red Hat 9 when I first installed it!) and I ended up deleting the whole .fgfs config file after the upgrade and starting afresh as I had played around so much trying to get things working properly that nothing was.

By way of background, I have just returned to (real) flying after a 25-year break. I am regaining currency, updating in the Australian Airspace procedures, which are now more in line with ICAO/FAA, and completing a Night VFR rating. I wanted to try and maintain some currency while I was away from the cockpit, so initially tried Flight Simulator and later found Flightgear, but until recently did not have the graphics hardware to run it properly so am only now coming to grips.
My primary purpose is to use Flightgear to keep current with NDB and VOR; I can access a couple of 'professional' sims based on X-Plane at a cost of ~$200/hour or I spent $70 on a new joystick...
Eventually, I will download the local scenery pack but I am currently just trying to get a grip on the default software before I use up a humungous amount of download.
I still hope to sort this torque problem as the C172 instrumentation is a lot more like the aircraft (PA28) I am currently flying than the PA28 'Cadet' that I have downloaded.
One of our aero club members has a T10 Trojan with about the same torque performance as I'm getting - but that has a huge radial and a prop about as big as me - certainly nothing like what I'd expect from a light single.
Anyway, thanks for the advice. I'll keep plugging away at this.
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Re: C172 severe wing-over on take-off

Postby legoboyvdlp » Thu Jul 11, 2019 8:26 am

Hi,
I noticed you said the PA28 wasnt very good.
This one should be rather a lot better:
https://github.com/Octal450/IDG-PA28

;)
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Re: C172 severe wing-over on take-off

Postby wlbragg » Thu Jul 11, 2019 4:07 pm

Hi GregS, welcome to FlightGear.

It is conjecture that it may be due to an excessive setting for torque but I can see no way of viewing, much less adjusting this. Any ideas?


It can be adjusted in the FDM section.

First though I would recommend installing the most recent version of FlightGear as this aircraft has gone through many iteration in this area. The most recent has had adjustments made soften this effect.
It s hard to quantify what your experiencing especially against other setups. Myself and many others don't get this "exaggerated" torque roll. Is there some, yes, but easily controllable with ailerons alone in my case and that is with a mouse.
I am beginning to wonder if there isn't a couple of specific FG version and hardware combinations causing something more severe that what most of us experience. Thus why I recommend the most current FG/c172p possible.
Kansas(2-27-15)/Ohio/Midwest scenery development.
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Re: C172 severe wing-over on take-off

Postby sim » Fri Jul 12, 2019 8:59 am

Assuming normal weather and no crosswind or slight crosswind the C172 will not require any drastic rudder or aileron on the take off and climb out. Never found this a problem with C172 in Flightgear or with the real life C172 when I flew 'em. :wink:
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Re: C172 severe wing-over on take-off

Postby dilbert » Fri Jul 12, 2019 11:53 am

Agree with Sim. Also have had real 172 time, as well as an instrument rating. Flew the FlightGear version yesterday on both
my I3 with Invidia desktop and my old Celeron laptop. In both cases it took a very light touch on the twist grip to keep straight down the runway. I'm using FlightGear 2018.3.2, Windows10, and the Logitech 3D Pro stick. Agree on the advisability of using the latest FlightGear version, which includes latest 172 updates.

Have 4 Logitech 3D pro sticks, all of which work fine. However, I learned early on, that if I used the FlightGear
reprograming routine, things went haywire (specifically, in my case, the rudder slaved to the throttle). Fortunately, this
was easily remedied by resetting with File>Joystick Configuration>Rest Configuration. Since then, have always used these sticks in default mode (forgoing use of default mode unused buttons.).

Another problem encountered with 172 awhile back was that it had excessive elevator up trim when using AutoStart,
So if nose down trim wasn't applied prior to takeoff, the aircraft would try to climb while lacking adequate airspeed,
resulting in a stall and wing drop somewhat as you describe. However, I believe this problem to be corrected in the 2018.3.2
version, and didn't experience it yesterday.

Best Regards
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Re: C172 severe wing-over on take-off

Postby sim » Tue Jul 16, 2019 4:47 pm

Am sure Macnab resolved this 8 years ago and this topic has been resurrected. Along with Philosopher both have fantastic coding knowledge so nothing is a problem for long! :lol:
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Re: C172 severe wing-over on take-off

Postby GregS » Thu Jul 18, 2019 5:01 am

Thanks all (and polly, offline) for your suggestions.
I have managed to update my scenery to the local area and have tried both C182 and PA24 Seminole II in that environment, which appear to work reasonable well for the limited amount I was able to test them (a bit twitchy on the controls, but nothing like the C172).
It would appear that the C172 model (at least the one I have) is fatally flawed, although I believe there is a more recent model which is said to be fixed. I will have to look for more aircraft when i have time.
So, problem almost solved...at least I have models I can IF with for now, or so it seems.
legoboyvldp, WRT the PA28, I will have a look at the one you suggest when able; ideally I want to sim the aircraft I am currently flying, as near as practicable so that may well be the answer.
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Re: C172 severe wing-over on take-off

Postby wkitty42 » Thu Jul 18, 2019 7:38 pm

@greg: what c172 are you using? the c172p that comes with FG should be fairly well ok... if you are not talking about the "p" model, please include the letters of the version you are talking about in your writings... thanks!
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: C172 severe wing-over on take-off

Postby sim » Sat Jul 20, 2019 3:22 pm

Fly the souped up C150. We've stuck a C172 engine in so it really does rock 'n roll !
You can look for it and download the zip file from my Dropbox at
https://www.dropbox.com/l/scl/AABVqDBFr ... nlOkG9kLn8
It's the same old model but it does work well in FG 2018 too. :wink:
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Re: C172 severe wing-over on take-off

Postby GregS » Sun Jul 21, 2019 6:48 am

wkitty42 wrote in Thu Jul 18, 2019 7:38 pm:@greg: what c172 are you using? the c172p that comes with FG should be fairly well ok... if you are not talking about the "p" model, please include the letters of the version you are talking about in your writings... thanks!

It is the C172P (1982) that comes default with Flightgear. I am running the Fedora 30 version of 2018-3-2.
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