Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throttle

Post any technical issues here. This forum gets priority from our staff.
Buzz313th
Technical Sergeant
Posts: 680
Joined: 08 Feb 2009, 17:03

Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throttle

Post by Buzz313th »

Gotta question...

Been spending a bit of time enjoying the 51. With Brakes nice and fresh, no crosswinds and zero throttle, I notice after landing or even durring a highspeed taxi that the aircraft yaws left which is countered by right pedal. Now I can understand this Adverse Yaw with power, but can someone explain why I am experiencing this with no power? I also noticed that as I slow on the rollout as airspeed drops, so does the intensity of the left yawing tendency.

FYI, I am no longer using any right rudder trim for takeoff and landing as I have enough pedal in my hardware rudders to avoid having to dial in rudder trim.

Edit... I am also noticing the need for quite a bit of right rudder to stay coordinated durring short final @ around 100-150 indicated with power chopped.

Thanks in advance

JB
Buzz313th
FASA Founder and dedicated Staff Member
TeamSpeak 3 @ "ts3.digitalthemepark.com"
Facebook @ http://www.facebook.com/FsxAirSportsAssociation
Website @ http://www.fsxairsports.com

Image

User avatar
CAPFlyer
A2A Aviation Consultant
Posts: 2241
Joined: 03 Mar 2008, 12:06
Location: Wichita Falls, Texas, USA

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by CAPFlyer »

Well, I can think of 2 things -

1) Your rudder pedals aren't properly centered.
2) You have left rudder trim dialed in even though you may not think so.

Additionally, whether or not you have enough rudder available, you MUST use the prescribed rudder trim because it's to ensure you have enough EXTRA rudder if something happens and you're able to quickly deal with it. Because of the reverse boost tab, in the real plane especially, you'd be physically unable to deal with any adverse yaw that hit because you'd already be using too much rudder.
Image

Buzz313th
Technical Sergeant
Posts: 680
Joined: 08 Feb 2009, 17:03

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by Buzz313th »

CAPFlyer wrote:Well, I can think of 2 things -

1) Your rudder pedals aren't properly centered.
2) You have left rudder trim dialed in even though you may not think so.

Additionally, whether or not you have enough rudder available, you MUST use the prescribed rudder trim because it's to ensure you have enough EXTRA rudder if something happens and you're able to quickly deal with it. Because of the reverse boost tab, in the real plane especially, you'd be physically unable to deal with any adverse yaw that hit because you'd already be using too much rudder.

Cap, thanks for the reply..

I double checked the pedals and they are centered.. Confirmed by flying other aircraft including other A2A planes. No other addons show a yaw tendency to the left in the same situation..

I checked the trim and visually in the VC it indicates neutral rudder trim. Confirmed by using the FSX hotket to center rudder trim.. Still getting the adverse yaw.

Two other online Simmers flying the A2A P-51 are noting the same behavior.

I understand that trimming out the rudder in the real P-51 would reduce control pressure, but unfortunately we are in FSX and trim does not effect control pressure, it actually changes control position as it would be impossible to simulate trimming in a simulator without having the sim designed around force feedback.

Cap, thanks for the ideas... They are definately good ones... Please if you have any other hunches please send em my way..

JB
Buzz313th
FASA Founder and dedicated Staff Member
TeamSpeak 3 @ "ts3.digitalthemepark.com"
Facebook @ http://www.facebook.com/FsxAirSportsAssociation
Website @ http://www.fsxairsports.com

Image

zebra288
Airman First Class
Posts: 63
Joined: 28 May 2012, 03:44

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by zebra288 »

Any fuel in the fuselage tank?

the weight in the back will want to make it swap ends as you are slowing down
Image

Buzz313th
Technical Sergeant
Posts: 680
Joined: 08 Feb 2009, 17:03

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by Buzz313th »

zebra288 wrote:Any fuel in the fuselage tank?

the weight in the back will want to make it swap ends as you are slowing down
Does it in all configs unfortunately.
Buzz313th
FASA Founder and dedicated Staff Member
TeamSpeak 3 @ "ts3.digitalthemepark.com"
Facebook @ http://www.facebook.com/FsxAirSportsAssociation
Website @ http://www.fsxairsports.com

Image

User avatar
CAPFlyer
A2A Aviation Consultant
Posts: 2241
Joined: 03 Mar 2008, 12:06
Location: Wichita Falls, Texas, USA

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by CAPFlyer »

One more thing, how are you clearing the weather?
Image

Buzz313th
Technical Sergeant
Posts: 680
Joined: 08 Feb 2009, 17:03

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by Buzz313th »

CAPFlyer wrote:One more thing, how are you clearing the weather?

With FSUIPC.. It clears all the weather and sets everything to ISA.

I don't think this is isolated to my system as others I have been simming online with have noted the same thing.

I think the only reason others arent noticing this is because they are probably setting 6 degrees right trim on approach as you guys advised... Lets just say that the model has a left yaw tendency coded into it based on airspeed and not power, then 6 degrees right rudder trim in FSX will counter this yaw tendency and won't be noticed in game on low power, since trim isn't changing control pressure, but actually changing control position. Now in the real plane, if you dialed in 6 degrees right rudder trim on approach and low power, you the pilot, would need to push left rudder pressure against the trim tab to get coordinated flight, since the right trim you dialed in would cause the plane to slip right with low power.

Maybe this was a workaround to get the realistic levels of Adverse Yaw in FSX to represent the levels found in the real 51.

I dunno.. To be honest, it's really not a game changer for me.. I still love the AccuSimmed P-51. I'll just kick right pedal on low power for coordinated flight.
Buzz313th
FASA Founder and dedicated Staff Member
TeamSpeak 3 @ "ts3.digitalthemepark.com"
Facebook @ http://www.facebook.com/FsxAirSportsAssociation
Website @ http://www.fsxairsports.com

Image

Hobart Escin

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by Hobart Escin »

Buzz,

I see weird yaw on landing roll outs and, like you, I only notice this with A2A aircraft. I swear the problem seems to exacerbate sometimes, and it's like there is some gremlin lurking in the physics modeling that defies aerodynamic logic. I'm really wondering if it has something to do with saved .flt files and the way the Accusim core interfaces with such.

For instance, if I start a 'virgin' flight with the Mustang with fixed ISA weather conditions and calm winds set, all is hunky-dory and my landings are really something to behold. I can't make a bad landing if I try. Now, later I start up FSX again and do the same flight from a saved file with the same weather conditions and fuel/payload settings, and the Mustang will yaw off on landing roll out no matter how hard I dance on the rudders. The aircraft will starting skidding and it's like the tailwheel has fallen off or something. I can't make it go straight no matter what I try. If I start another 'virgin' flight situation the problem disappears. Again, same weather conditions and payload.

I have also noticed this behavior on the Accusim P-47 - in fact it got so prevalent with that plane that I quit flying it altogether out of frustration. I've always figured it was some funk with my particular installation and never followed in finding a solution.

Conversely, I have NEVER seen this phenomenon with either the Accusim P-40 or B-17 under any circumstance - both of these aircraft seem immune to the weird landing rollout yaw gremlin.

This problem has made me want to go out into my backyard, have a few beers, and then start annoying my neighbor's cats with the garden hose like I always do on Fridays after work. I will admit that I would probably do this irregardless of my landing yaw problem, but still.

VulcanB2
Master Sergeant
Posts: 1146
Joined: 14 Nov 2009, 01:25

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by VulcanB2 »

It's strange... the only way I can describe it is like a hard crosswind from the right. It actually requires that I point the nose across the runway (to the right) to track the center line during roll-out (no brakes), otherwise the aircraft mysteriously blows off the side. :?

Best regards,
Robin.
A2A/AccuSim. 'nuff said!

Hobart Escin

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by Hobart Escin »

VulcanB2 wrote:It's strange... the only way I can describe it is like a hard crosswind from the right. It actually requires that I point the nose across the runway (to the right) to track the center line during roll-out (no brakes), otherwise the aircraft mysteriously blows off the side. :?

Best regards,
Robin.
EXACTLY, EXACTLY, EXACTLY. You've actually hit the nail on the head with this description. For me it happens at random times during landings, irregardless of crosswind component, loadout, technique, etc, but the scenario is precisely the way you mention. I cannot keep the aircraft on the runway without extensive use of differential braking - the rudder alone just does not have enough authority. I've also had the same experiences with the Accusim P-47 behaving the same way as I mentioned earlier. It's very weird.

I will say that I have not experienced the weird random landing yaw since Core Update 1.4; in fact, I had my best landing ever last night. This could be placebo effect, however, lol. I'll be doing some pattern work after work this evening, so I'll see if I can make the gremlin resurface.

Have you updated to Core 1.4 yet, and if so, have you experienced the yaw problem again with 1.4 installed?

-Hobart

Buzz313th
Technical Sergeant
Posts: 680
Joined: 08 Feb 2009, 17:03

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by Buzz313th »

Hobart Escin wrote:
VulcanB2 wrote:It's strange... the only way I can describe it is like a hard crosswind from the right. It actually requires that I point the nose across the runway (to the right) to track the center line during roll-out (no brakes), otherwise the aircraft mysteriously blows off the side. :?

Best regards,
Robin.
EXACTLY, EXACTLY, EXACTLY. You've actually hit the nail on the head with this description. For me it happens at random times during landings, irregardless of crosswind component, loadout, technique, etc, but the scenario is precisely the way you mention. I cannot keep the aircraft on the runway without extensive use of differential braking - the rudder alone just does not have enough authority. I've also had the same experiences with the Accusim P-47 behaving the same way as I mentioned earlier. It's very weird.

I will say that I have not experienced the weird random landing yaw since Core Update 1.4; in fact, I had my best landing ever last night. This could be placebo effect, however, lol. I'll be doing some pattern work after work this evening, so I'll see if I can make the gremlin resurface.

Have you updated to Core 1.4 yet, and if so, have you experienced the yaw problem again with 1.4 installed?


Well I do wanna mention that the Real Mustang is known for very unstable rollout and that you have to keep your "Feet Alive" when on the ground. So maybe A2A implemented this Yaw tendency to simulate that. I am not interested in A2A dumbing this flight model down at all. Personally I would like then to maintain as real of a flight model they can get within the confines of FSX.

JB
-Hobart
Buzz313th
FASA Founder and dedicated Staff Member
TeamSpeak 3 @ "ts3.digitalthemepark.com"
Facebook @ http://www.facebook.com/FsxAirSportsAssociation
Website @ http://www.fsxairsports.com

Image

Nico081
Staff Sergeant
Posts: 413
Joined: 21 Jan 2011, 06:19
Location: Europe

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by Nico081 »

Good description of that "right nose" approaches (in flare, just befor touchdown) and also on ground getting blowed away to the left. You need also heavy nose right and sliding nose right not to get off the runway to the left. That effect stops at lower speeds. I have same experience still before the core updates. It also has nothing to do with A2A addons only.

Is it maybe an buggy FSX propeller moment effect at full realism settings inside FSX? That issue need to be solved, but how? :roll:
P3D v3.2
Addons: FSG2010, REX4 Direct+Soft Clouds, Hifi ASN, PMDG, Dodosim, A2A accusim all, Katana4X, Majestic, ORBX, Fly Tampa, DRZEWIECKI DESIGN, FSDreamteam, Flight Beam,..,..

User avatar
DHenriques_
A2A Chief Pilot
Posts: 5711
Joined: 27 Mar 2009, 08:31
Location: East Coast United States

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by DHenriques_ »

Buzz313th wrote:
Hobart Escin wrote:
VulcanB2 wrote:It's strange... the only way I can describe it is like a hard crosswind from the right. It actually requires that I point the nose across the runway (to the right) to track the center line during roll-out (no brakes), otherwise the aircraft mysteriously blows off the side. :?

Best regards,
Robin.
EXACTLY, EXACTLY, EXACTLY. You've actually hit the nail on the head with this description. For me it happens at random times during landings, irregardless of crosswind component, loadout, technique, etc, but the scenario is precisely the way you mention. I cannot keep the aircraft on the runway without extensive use of differential braking - the rudder alone just does not have enough authority. I've also had the same experiences with the Accusim P-47 behaving the same way as I mentioned earlier. It's very weird.

I will say that I have not experienced the weird random landing yaw since Core Update 1.4; in fact, I had my best landing ever last night. This could be placebo effect, however, lol. I'll be doing some pattern work after work this evening, so I'll see if I can make the gremlin resurface.

Have you updated to Core 1.4 yet, and if so, have you experienced the yaw problem again with 1.4 installed?


Well I do wanna mention that the Real Mustang is known for very unstable rollout and that you have to keep your "Feet Alive" when on the ground. So maybe A2A implemented this Yaw tendency to simulate that. I am not interested in A2A dumbing this flight model down at all. Personally I would like then to maintain as real of a flight model they can get within the confines of FSX.

JB
-Hobart
I'm a bit confused as to who has said what here....BUT...........:-)

Quite to the contrary concerning the roll out in the 51; the Mustang most certainly is NOT known for it's "very unstable rollout". The 51 has ALWAYS been known for her STABLE rollout.

I will say this in added comment. I'm not experiencing what is being described here on landings with the A2A Mustang. I am of course flying it in the sim exactly expecting the same behavior I would be seeing in the actual aircraft.
I don't doubt that the poster here is having some kind of issue and that others are reporting it as well. but my best guess is that it is NOT something inherent in the FSX code or in the A2A flight model. If it was, I'd be having the same thing happen here.
This being said, all tail wheel airplanes share some common habits concerning rollout. First of all, the engine should be powered back so any left turning forces should be negligable if any at all. The main thing about tail wheel rollout is that as speed decreases, so does dynamic pressure on the rudder. Tail wheel steering helps a great deal but doesn't solve the rollout equation entirely.
The platform is a triangle and it's NOT equilateral. It's length is greater than it's width so the main gear and tail wheel form a naturally unstable condition where any disturbance on an arm that long wants to become divergent. The name of the game is keeping any and all departures from a straight track to an absolute minimum.
This means that as speed dissipates and dynamic pressure available to the rudder decreases with that speed, you need MORE rudder to accomplish what was accomplished with LESS rudder at a higher speed.
The last sentence sums it all up concerning rollouts in tail wheel aircraft and the Mustang is no exception.
It's quite stable as far as comparison with other airplanes with shorter coupled main gear and fuselage length, but the Mustang still requires the same care on the roll out as do other aircraft.
As speed decreases, remember, you will be needing MORE rudder for directional control so be prepared to use it. Don't expect the rudder to respond as quickly at 50mph or with as much response as it did early in the landing with higher speed in the equation.
Best rule for landing a Mustang is the same for any tail wheel airplane. Be ready and be on time with the rudder. If you need a touch of differential braking below 50mph use it but VERY carefully and with as little as possible.

I can't address what has been said concerning "tracking sideways" on the rollout as I am not getting that behavior at all here.
Check those controllers carefully and make sure if any crosswind that you are carrying aileron into the wind during your rollout. Keep the stick well back to pin the tail wheel and engage the lock.
Good luck
Dudley Henriques

Nico081
Staff Sergeant
Posts: 413
Joined: 21 Jan 2011, 06:19
Location: Europe

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by Nico081 »

Hi Dudley,

thanks for reply. As i wrote in my opinion that generally "crosswind from the right"- effect must have something to do with a general settings somewhere in FSX or is generated at specific situations. Also had that this effect landing the B377. It has nothing to do with the P51/Spit etc.
It feels definitely wrong and nearly uncontrolable using full rudder and a massive slide on ground until speed is slow enough. For me it is not equivalent to real world situations, it is an simulation thing..
P3D v3.2
Addons: FSG2010, REX4 Direct+Soft Clouds, Hifi ASN, PMDG, Dodosim, A2A accusim all, Katana4X, Majestic, ORBX, Fly Tampa, DRZEWIECKI DESIGN, FSDreamteam, Flight Beam,..,..

Buzz313th
Technical Sergeant
Posts: 680
Joined: 08 Feb 2009, 17:03

Re: Adverse Yaw Durring Rollout/Highspeed Taxi W/ Zero Throt

Post by Buzz313th »

Thanks for replying Dudley, it's great that A2A has you as an adviser.

I'm the one who mentioned the instability of the Mustangs Rollout. I have no time in a P51 (wish I did) so I can't comment from experience. I got my info from a video another user posted of a current owner of the P51 named "Lady Alice".

If you view the video starting at 17:21 he starts talking about the rollout stability of the P51 that he owns. Maybe it's just specific to his mustang, dunno.


Here's the kink to the video. http://www.youtube.com/watch?v=WBIIhP_eOvE
Buzz313th
FASA Founder and dedicated Staff Member
TeamSpeak 3 @ "ts3.digitalthemepark.com"
Facebook @ http://www.facebook.com/FsxAirSportsAssociation
Website @ http://www.fsxairsports.com

Image

new reply

Return to “P-51 Tech Support”

Who is online

Users browsing this forum: No registered users and 8 guests