Yaw question

aeromed202

aeromed202

SOH-CM-2014
Anybody know why a twin engine prop would develop severe yaw on full power takeoff? Once in the air it regains stability and direction at any power setting. Its as if one engine loses power until the wheels leave the ground. It has only happened with one plane so far. Weather is set for light head winds.
 
I have tried some one engine out flying on a couple FS twins and when I would bring that bad engine back up it's throttle would not go back in snc with my Wingman joystick throttle.

After landing and then attempting a takeoff it would do just as you described due to only one engine would throttle up for take off. The fix for that is to reboot the flight. Don't know what made it not snc back up with the stick on engine restart though.
 
Well, it's a freeware Mosquito, both engines good on start up, brakes off. Thought it might be torque and was wondering if that can be toned down in the CFG somewhere. Haven't tried realism settings yet as other twins work fine. This model did have an in-flight turn bias that was fixed with a wing twist adjustment. I can increase rudder effectiveness but then the input gets too severe in flight.
 
Check the air pressure in your tires...a tire that is low on air will have more drag than a properly inflated tire...thus producing the "yaw".

Maybe you have a wheel bearing going out...or a brake pad hanging up.

As I have found out, if you are taking your mother-in-law for a flight, having nearly 500 pounds of ugly on one side of your plane will really play havoc with flight dynamics. Turned my plane into a winged cattle trailer. I felt like a dyslexic NASCAR driver, as all I could do was right hand turns.

OBIO
 
aeromed202 said:
Well, it's a freeware Mosquito, both engines good on start up, brakes off. Thought it might be torque and was wondering if that can be toned down in the CFG somewhere. Haven't tried realism settings yet as other twins work fine. This model did have an in-flight turn bias that was fixed with a wing twist adjustment. I can increase rudder effectiveness but then the input gets too severe in flight.
Click to expand...

In the aircraft.cfg Flight Tuning section, try this:

p_factor_on_yaw = 0.3
 
Another thing is to ease the throttles forward slowly and apply rudder ( sometimes lots of it ) to keep straight.

In a tailwheel aircraft ( in a 3 point attitude ) two things are happening .... Torque & P Factor.

P Factor is when the down going blade is at a higher angle of attack and therefore producing more thrust than the up going blade. This off sets the thrust line and causes a turning moment.

Torque , or rotating moment, causes the aircraft to rotate putting more pressure on one tire, therefore more drag.

Both of these effects are at work whether it's a single or twin engine tailwheeled aircraft.

Another thing that happens is when the tail is raised , there's a gyroscopic effect on the prop disc. The top of the disc rotates forward but the resulting force acts at 90* to it also causing the aircraft to turn.

A good demonstration of that is when you are using a skill saw , turn the saw when the blade is rotating and the whole saw will twist in your hands.

Pete.
 
It also happens to some powerfull single engine fighters like the Corsair or Bearcat. It is the engine torque. That is why some multi engined planes have counter rotating props to eleminate the effect.

Differential braking is not enough to compensate for the torque pushing you to the side of the runway at full power. You have to apply just enough power to get the tailwheel up, then you can go full power because you can use the tailrudder to compensate.
 
Being a Mossie maybe its the 100 imperial gallons of whiskey rations. They had to stash it in the port wheel well. I did find a low tire though; pumped it up in the points section but nada.
 
Lock the tail wheel, apply the thrust slowly, use rudder trim and differential brakes as necessary. Milton's suggestion for the cfg file is a good one. Also if the plane does not have a differential brake scalar in the .cfg file you can add one. This will link the braking to the wheel toward which the rudder is deflcted. Also if there is a throttle popup panel you can lead with one engine till things straighten out.

Cheers: T.
 
Tried all the above:blind: Another freeware one works fine so I grafted its model over and still no change. The fuel locations were a bit off so I centered them and will cross fingers. Too bad, I really like this plane.
 
Well don't keep me in suspense what's the fix? And don't tell me to fly with my eyes open or something like that hardy har har:isadizzy: I can't quite remember whos it is but the name is Mosquito FBVI and it may have come over from CFS. Other identifiers are: DH98 and from the description: description=Mosquito FBVI Always present, always deadly, mosquitoes were the\nLuftwaffe's worst nightmare\n1% Solution AssemblyLine Version 2.79.45\n714VFTS & William Tell© \nMosquito FBVI. Lost a bunch of zips a while back and was probably amongst them.
 
aeromed202 said:
Well don't keep me in suspense what's the fix? And don't tell me to fly with my eyes open or something like that hardy har har:isadizzy: I can't quite remember whos it is but the name is Mosquito FBVI and it may have come over from CFS. Other identifiers are: DH98 and from the description: description=Mosquito FBVI Always present, always deadly, mosquitoes were the\nLuftwaffe's worst nightmare\n1% Solution AssemblyLine Version 2.79.45\n714VFTS & William Tell© \nMosquito FBVI. Lost a bunch of zips a while back and was probably amongst them.
Click to expand...
Thats one of PH Burnage's
no its not something like keep eyes open
thats an old cfs2 airfile and cfg
i know i have an update as i have every mossie out there
let me have a look at what i have
he did a few
i will check and get back
it needed a major overhaul for fs9
H
 
That's an old AVhistory Mossie, not sure who's model it was based on, possibly Phillipe Burnage, he did a whole range of variants for the olé sim, not sure if or how well they work in 9 though.

look here and here if you want a peak. The 1% FM's are realistic but demanding, especially with torque, etc.

EDIT: beaten to the punch!!
 
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