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theskyisthelimit

XP11 beta, full throttle down runway in GA single prop immediate left hard turning? Realistic?

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I know people had commented on weathervaning issues with xp11 beta.. i'm not sure this is the same thing, but for some reason with any single prop aircraft i load up, weather carenado or the default cessna.. if i sit on the runway (any runway) and apply full throttle... the plane immediately starts a left turn.. within 2 seconds.. i had limited time with lessons and not with a cessna but i dont recall this ever being the case.. i know some rudder was needed but not the degree things seem to be here..

 

I've done the data output to see that the rudder is centered and no control surfaces are moving and also disconnected all joysticks to rule them out (ch yoke and pedals)..

 

Is this still a bug..?

 

Thanks in advance

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I've noticed that too it's like the ground friction and wind aren't meshing properly.It's like the weight on wheels isn't being figured properly so the aircraft blows around like a kite.

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I've noticed that too it's like the ground friction and wind aren't meshing properly.It's like the weight on wheels isn't being figured properly so the aircraft blows around like a kite.

Ah that makes sense.. i wonder if there is a hack to correct it for now.. someone posted up a modified vertical stabilizer airfoil file before (for the default cessna anyway) meant to fix light winds and weathervaning.. but it has no effect on this situation.

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I know people had commented on weathervaning issues with xp11 beta.. i'm not sure this is the same thing, but for some reason with any single prop aircraft i load up, weather carenado or the default cessna.. if i sit on the runway (any runway) and apply full throttle... the plane immediately starts a left turn.. within 2 seconds.. i had limited time with lessons and not with a cessna but i dont recall this ever being the case.. i know some rudder was needed but not the degree things seem to be here..

 

 

I actually have no memory of this ever not being the case. Whenever I start up a vehicle in Xplane I expect it to pull sharply to the left.

 

I was one of the first people to grab Xplane10, and I remember it through all those years, so I thought nothing about it when it occurred in Xplane11 as well.

 

I'm not even sure Xplane considers this a bug?

 

Betcha The UninstallerTM could answer this.  :smile:

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I actually have no memory of this ever not being the case. Whenever I start up a vehicle in Xplane I expect it to pull sharply to the left.

 

I was one of the first people to grab Xplane10, and I remember it through all those years, so I thought nothing about it when it occurred in Xplane11 as well.

 

I'm not even sure Xplane considers this a bug?

 

Betcha The UninstallerTM could answer this.  :smile:

Well that's unfortunate and I don't think p3d behaves like this. You would think there would be a fix by now then. It certainly isn't realistic (?)

 

This isn't enough to make me abandon xp11 though :)

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Well that's unfortunate and I don't think p3d behaves like this. You would think there would be a fix by now then. It certainly isn't realistic (?)

 

This isn't enough to make me abandon xp11 though :)

 

I think Jcomm, also known as The Uninstallertm  when he's wearing his cape, has been chasing that torque issue for years.

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Someone called me :-)

 

Yes, me, Larry Adamson, and Murmur and many others, but it was thanks to Murmur that finally the culprit was found in a double calculation of prop torque, and fixed somewhere along the XP10 track...

 

But probably due to the adjustments Austin is doing to his calculations of interaction of propwash with aircraft surfaces, maybe something has changed again ? 

 

I really can't tell because I don't have XP11 installed :-/ 

 

Anyway, as a passenger, I've flown in some GAs, from Cessnas to Pipers, going through Mooneys, Beechcraft, Extra, Pitts, Auster,... and the left turning tendency is always there, specially as you start the takeoff run, and specially if you firewall the throttle more abruptly. A DR-400 pilot used to start the takoff run with full right pedal to counter the left turning tendencies, even with starboard winds!

 

I think it is right, although I don't know if it's magnitude might have increased in the latest XP11 betas ?

 

ELITE ( all versions up to v9 I am beta testing ) was probably one of the serious flight simulators I used, and it models this tendency very markedly. But it's the same in well designed prop aircraft with non-counter-rotating props, specially small / medium GA in MSFS, AEFS, DCS, IL2, FG, ...

 

There is a very interesting training video for the TBM 750 in youtube you can watch showing the effect on a Pt-6 - powered single turboprop.

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Posts like this make me laugh and frown at the same time. No scientific evidence, just claims. And the best: It´s not like this in P3D, so it must be wrong!! What?? ROFLMAO. FSX can not even model a sustained sideslip (unless the flightmodel is hacked by talented designers, I hear) - so it´s hardly the authority here.

 

I tested with no wind and the default Cessna. Output flight control deflections to screen. At full throttle and very low speed I need ca. 0.2 out of a total of 1.0 rudder deflection. In other words, for the mathematically challenged: I only apply one fifth or 20% out of the total available deflection. This is in XP11pb8.

 

My conclusion: This feels right, if not even a bit weak, but my 220h of SEL are in F33 Bonanzas, and they have a stronger engine.

 

My advice: Calibrate your devices properly. Check that you don´t have ANY wind (many users set a strong wind at 30.000 feet or so - and forget that it will propagate unabated all the way to the surface).

 

Jan

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. And the best: It´s not like this in P3D, so it must be wrong!! What?? ROFLMAO.

 

Jan

:LMAO: :LMAO:

 

Some right rudder is required is what i have noticed in XP10 / 11, and if there is a X-wind component hitting the stab on the left and then the right rudder needs to more input.  Also comes down to the modeling of the aircraft , tire friction modeling may also be playing up here you know what happens when you have bald tires

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Perhaps we should start a P3D Anonymous class, to help bring those folks up to speed.  For people to claim that the reactions and effects in XP on aircraft are incorrect because they didn't act that way in P3D, doesn't make it so.  If anyone has noticed, Austin has put a lot of work into the physics of the aircraft, and some may argue that it's a little too much, but overall, it's more accurate than FSX and P3D.  I switched from P3D to XP because of the realism, both in environment and in flight models.  I suppose if you set up P3D's aircraft to a hard level, you would get some of what LR did for XP, but with XP, out of the box, the aircraft handle realistically, so it's a challenge.  I expect the aircraft to act erratic every time I fly now and am prepared because I have started to learn the behaviors of all forces acting on the aircraft, and while it is more challenging, I still have fun and learn something along the way.

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Forget XP or P3D, see real life discussions...

 

I think a lot of us here understand the physics involved.  The question is, does X-Plane 11 get it right?  Will a Cessna 172 really shoot off the left side of the runway during the take-off roll without a sufficient amount of right rudder?

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I think a lot of us here understand the physics involved.  The question is, does X-Plane 11 get it right?  Will a Cessna 172 really shoot off the left side of the runway during the take-off roll without a sufficient amount of right rudder?

 

That was basically what i was after.. some real world parallels from pilots (hopefully).. I wasnt trying to battle the merits of P3D vs XP :)  And for the record, I always set realism to the max in P3D and i'm aware of the pfactor and the standard left turning tendency.. i was just trying to gauge if maybe there was a bug here that made it worse than it should be.

 

In fact, digging around i see there may have been a "double" pfactor bug back in XP10, which i thought maybe followed through somehow (I think it was corrected back then though).

 

I recognize the need for right rudder on take off etc.. no questions there.. just the "force" of the left turn if you throttle to full and go right away (instant left turn here).. obviously the better approach is the slow ramp up, 25% then 50% then full while applying the right rudder (but again how much right rudder).

 

My ch yoke/pedals are calibrated and i've tried it without them connected, same issue, so its not the controllers.   

It probably is as it should be, I was just seeking verification.. and those youtube links are good references in general.

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Using 0% control response for yaw might improve things. It's in "Joystick"->"Control Sensitivity"

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Posts like this make me laugh and frown at the same time. No scientific evidence, just claims. And the best: It´s not like this in P3D, so it must be wrong!! What?? ROFLMAO. FSX can not even model a sustained sideslip (unless the flightmodel is hacked by talented designers, I hear) - so it´s hardly the authority here.

 

As an authority here, bearing in mind, I'm not a commercial aircraft pilot like Janov,........ I do have the time in lot's of small single engine aircraft, ranging from the Cessna's, Pipers, to the Pitts, Marchetti SF260, Super Stearmans, many high powered experimental class, and backseat in a P-51D mustang.

 

In reality, thanks to third party intervention over the years, FSX (and I'll assume P3D, as I don't own it), became very capable of producing the effects of left drift, & side slip. Every time I tried a new model for MSFS, even before FSX, these forces are the first thing I tried. I'm the same way with X-Plane. For many years, I complained about X-Plane over doing some of these forces. It's well known, about my feelings on this subject.

 

Problem here, is that many non-pilots do not know, what their trying to reference. They have no real idea about the forces and reactions of real aircraft. And, FSX will add auto-rudder, if the box isn't unchecked, if you don't have rudder pedals, or a twist grip. IMO, twist grips never provide the right sensation of feel, anyway. Point is, numerous FSX models do provide the correct feel ( or close to it), and response. I say close to it, because I still see FSX & X-Plane models that tend to wander too much during the roll down the runway. The force is actually there, and we push the pedal against it. The force doesn't get all wishy-washy & cause wandering that needs constant right/left pedal to correct. It's more like riding the side of a gutter, or wake while water skiing. Just push against it.

 

P.S. ---- Lot's of X-Planes (especially some of the 3rd party addons) do fine, these days with left drift. IMO, it had better be there! But there has to be pedals or something to offset it. Otherwise, you'll end up in the weeds. Some models may do too much, or not enough. Same with products for MSFS,

I recognize the need for right rudder on take off etc.. no questions there.. just the "force" of the left turn if you throttle to full and go right away (instant left turn here).. obviously the better approach is the slow ramp up, 25% then 50% then full while applying the right rudder (but again how much right rudder).

I once sat in the back seat of a Piper Archer, for my daughters first flight lesson. On the way to the airport, I told her about left drift. Told her she'd end up running over the left side runway lights, if she didn't push right pedal. Of course, in reality, an instructor would be hitting right pedal, if she didn't. Planes certainly do vary. Much to do with engine size versus aircraft weight, size of the vertical stab/rudder, whether the engine & possibly the vertical stab is canted or not, etc. Expect it on the first part of the roll, especially if powered up quickly, and to stay there throughout the roll & initial takeoff. You'll still need rudder to maintain runway centerline. As airspeed picks up, the push needed on the rudder will diminish. Shouldn't be needing right aileron (see note). If so, the model or real thing, needs some re-rigging.................unless the pilot is just terrible with fuel, passenger, and cargo management.

 

note: a little bit of subconscious aileron may be needed for imbalance, in aircraft which don't have a form of aileron trim. Unfortunately, a desktop joystick/yoke centering spring is usually more than the real life force. Being an inflight perfectionist with my kitbuilt Van's RV, I did add aileron trim. Very nice!

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