What causes swing to the left on take off?
03-18-2011, 03:28 AM
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What causes swing to the left on take off?
G'day I have been flying for some time and generally I have not had problems with taking off tail draggers or trikes but I have just built two very different models and both absolutely love to swing to the left on take off. Both need a small amount of right rudder to keep them pointed straight and then they are fine.
So ... What causes the left swing? Engine torque, gyro effect of the prop, gremlins? ? ?
One is a Kadet Mk 2 with an OS Surpass 52 in it with a 12 x 6 prop and the other is a 1/4 scale ARF Space Walker with a Laser 150 four stroke swinging a 14 x 8 prop.
Discussion welcomed.
Thanks
Mike in Oz
So ... What causes the left swing? Engine torque, gyro effect of the prop, gremlins? ? ?
One is a Kadet Mk 2 with an OS Surpass 52 in it with a 12 x 6 prop and the other is a 1/4 scale ARF Space Walker with a Laser 150 four stroke swinging a 14 x 8 prop.
Discussion welcomed.
Thanks
Mike in Oz
03-18-2011, 04:42 AM
#2
RE: What causes swing to the left on take off?
I will ask this, what happens when you correct with rudder and what happens when you correct with aileron? If rudder is what is needed then it is P-Factor, and maybe just a little spiral slip stream, if aileron is what is needed then it is torque. Gyroscopic effect is felt only when there is a change in either pitch or yaw and it is felt at 90 degrees to the force. Therefore you yaw right it try's to pitch down, you pitch up it try's to yaw left. Since torque and gyroscopic precession are a function of mass they have much less effect on model aircraft, P-Factor is strictly an aerodynamic phenomenon and therefore can happen regardless of model size.
03-18-2011, 04:55 AM
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RE: What causes swing to the left on take off?
ORIGINAL: mike109
G'day I have been flying for some time and generally I have not had problems with taking off tail draggers or trikes but I have just built two very different models and both absolutely love to swing to the left on take off. Both need a small amount of right rudder to keep them pointed straight and then they are fine.
So ... What causes the left swing? Engine torque, gyro effect of the prop, gremlins? ? ?
One is a Kadet Mk 2 with an OS Surpass 52 in it with a 12 x 6 prop and the other is a 1/4 scale ARF Space Walker with a Laser 150 four stroke swinging a 14 x 8 prop.
Discussion welcomed.
Thanks
Mike in Oz
G'day I have been flying for some time and generally I have not had problems with taking off tail draggers or trikes but I have just built two very different models and both absolutely love to swing to the left on take off. Both need a small amount of right rudder to keep them pointed straight and then they are fine.
So ... What causes the left swing? Engine torque, gyro effect of the prop, gremlins? ? ?
One is a Kadet Mk 2 with an OS Surpass 52 in it with a 12 x 6 prop and the other is a 1/4 scale ARF Space Walker with a Laser 150 four stroke swinging a 14 x 8 prop.
Discussion welcomed.
Thanks
Mike in Oz
If you think that's bad, fly a Fokker DR1 or scale warbird! That's normal for any aircraft (including full scale) unless you cheat and use a gyro. To me if I have to use one of them it's time to quit the hobby. JMHO
It's engine and prop torque without complicating a simple explanation. What I do is quickly move the throttle up and feel it with your rudder and she'll go where you want it. I sometimes slew my planes with the rudder to slow it down if I'm coming in to hot.
Many ARF, RTF and kit aircraft have the firewall angled to the right and slightly downward so the handling isn't so severe on the takeoff and regular flight. Some more so than others.
Because it's so close to St. Patty's day, I have to say right now Leprechaun's make your airplane want to go left. Or, what I like to say is, " Your Liberal plane wants to go left."
Pete
03-18-2011, 05:14 AM
#5
RE: What causes swing to the left on take off?
" Your Liberal plane wants to go left." Oberst.
Actually, Mike, you already know what to do. Let the theorists argue, torque, p-factor etc. etc. While it is good for pilots to understand the baloney, it is best that pilots can SAFELY drive the flying machine to where the pilot wants it to go.
In the case of prop planes during Take-offs and Go-Arounds, the use of rudder will fare thee much better than using the ailerons which can cause heartache in low airspeed and high angle-of-attack situations. To explain that takes a long look at theory, so just continue to do what you are doing.
03-18-2011, 09:01 AM
#7
RE: What causes swing to the left on take off?
Mike,
Four stroke engines develop more torque and swing bigger and heavier propellers that make the effects explained above more evident.
An additional thing to try: make the right wheel less free to roll than the left wheel.
The reason is that the torque put more pressure on the left wheel, which tends to develop more friction and drag behind the less loaded right wheel.
Best luck with that!
Four stroke engines develop more torque and swing bigger and heavier propellers that make the effects explained above more evident.
An additional thing to try: make the right wheel less free to roll than the left wheel.
The reason is that the torque put more pressure on the left wheel, which tends to develop more friction and drag behind the less loaded right wheel.
Best luck with that!
03-18-2011, 09:13 AM
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RE: What causes swing to the left on take off?
Being someone who cheats with a gyro I would still offer this.
Slowly advancing the throttle for a scale like takeoff will give the rudder a chance to gain authority & significantly cut down on the left turn tendency.
If you ever get to see some WWII carrier combat footage watch the F4U Corsairs going to full right rudder before they even begin to roll.
Slowly advancing the throttle for a scale like takeoff will give the rudder a chance to gain authority & significantly cut down on the left turn tendency.
If you ever get to see some WWII carrier combat footage watch the F4U Corsairs going to full right rudder before they even begin to roll.
03-18-2011, 09:39 AM
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RE: What causes swing to the left on take off?
ORIGINAL: cfircav8r
I will ask this, what happens when you correct with rudder and what happens when you correct with aileron? If rudder is what is needed then it is P-Factor, and maybe just a little spiral slip stream, if aileron is what is needed then it is torque. Gyroscopic effect is felt only when there is a change in either pitch or yaw and it is felt at 90 degrees to the force. Therefore you yaw right it try's to pitch down, you pitch up it try's to yaw left. Since torque and gyroscopic precession are a function of mass they have much less effect on model aircraft, P-Factor is strictly an aerodynamic phenomenon and therefore can happen regardless of model size.
I will ask this, what happens when you correct with rudder and what happens when you correct with aileron? If rudder is what is needed then it is P-Factor, and maybe just a little spiral slip stream, if aileron is what is needed then it is torque. Gyroscopic effect is felt only when there is a change in either pitch or yaw and it is felt at 90 degrees to the force. Therefore you yaw right it try's to pitch down, you pitch up it try's to yaw left. Since torque and gyroscopic precession are a function of mass they have much less effect on model aircraft, P-Factor is strictly an aerodynamic phenomenon and therefore can happen regardless of model size.
03-18-2011, 03:09 PM
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RE: What causes swing to the left on take off?
G'day
Thanks for the explanations. I have managed to tame both by doing two things - being gradual with my throttle up and using the rudder. The Space Walker now is quite under control but I am yet to fly the Kadet Mk 2 enough to fully understand it.
As you probably know, the Kadet Mk 2 should have been built as a trike but I used a different engine mount because this particular type is readily available here and it was easier to build the plane with it as a tail dragger. It certainly has given me some very good practice at doing scale like take offs. To add to the problem with the Kadet, the tail wheel is not steerable. It is just set up to free wheel. Despite this the plane is not difficult to steer on the ground as the rudder is large enough to do the job.
I was hoping to go flying today but it is really windy so it's off to the shed for some more playing. We are heading into winter as most on these forums are heading into spring. Despite this we will fly through winter.
Cheers
Mike in Oz
Thanks for the explanations. I have managed to tame both by doing two things - being gradual with my throttle up and using the rudder. The Space Walker now is quite under control but I am yet to fly the Kadet Mk 2 enough to fully understand it.
As you probably know, the Kadet Mk 2 should have been built as a trike but I used a different engine mount because this particular type is readily available here and it was easier to build the plane with it as a tail dragger. It certainly has given me some very good practice at doing scale like take offs. To add to the problem with the Kadet, the tail wheel is not steerable. It is just set up to free wheel. Despite this the plane is not difficult to steer on the ground as the rudder is large enough to do the job.
I was hoping to go flying today but it is really windy so it's off to the shed for some more playing. We are heading into winter as most on these forums are heading into spring. Despite this we will fly through winter.
Cheers
Mike in Oz
03-19-2011, 12:13 AM
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RE: What causes swing to the left on take off?
ORIGINAL: mike109
G'day
Thanks for the explanations. I have managed to tame both by doing two things - being gradual with my throttle up and using the rudder. The Space Walker now is quite under control but I am yet to fly the Kadet Mk 2 enough to fully understand it.
As you probably know, the Kadet Mk 2 should have been built as a trike but I used a different engine mount because this particular type is readily available here and it was easier to build the plane with it as a tail dragger. It certainly has given me some very good practice at doing scale like take offs. To add to the problem with the Kadet, the tail wheel is not steerable. It is just set up to free wheel. Despite this the plane is not difficult to steer on the ground as the rudder is large enough to do the job.
I was hoping to go flying today but it is really windy so it's off to the shed for some more playing. We are heading into winter as most on these forums are heading into spring. Despite this we will fly through winter.
Cheers
Mike in Oz
G'day
Thanks for the explanations. I have managed to tame both by doing two things - being gradual with my throttle up and using the rudder. The Space Walker now is quite under control but I am yet to fly the Kadet Mk 2 enough to fully understand it.
As you probably know, the Kadet Mk 2 should have been built as a trike but I used a different engine mount because this particular type is readily available here and it was easier to build the plane with it as a tail dragger. It certainly has given me some very good practice at doing scale like take offs. To add to the problem with the Kadet, the tail wheel is not steerable. It is just set up to free wheel. Despite this the plane is not difficult to steer on the ground as the rudder is large enough to do the job.
I was hoping to go flying today but it is really windy so it's off to the shed for some more playing. We are heading into winter as most on these forums are heading into spring. Despite this we will fly through winter.
Cheers
Mike in Oz
That's normal, sometimes I get cocky and slam the throttle forward and my plane winds up all over the place because I would over compensate with the rudder. I ease the right rudder with the throttle. I've flown R/C for so many years, when you asked the question I had to stop and think about it because it's all reaction without thought now when I fly.
Pete
03-19-2011, 12:32 AM
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RE: What causes swing to the left on take off?
Shamelessly copied from the Airplane Flying Handbook, 4 causes of the left turning tendency:
The torque of the engine causes a left rolling tendency. For each and every action, there is an equal and opposite reaction. As viewed from the cockpit, the crankshaft on an American-made engine rotates clockwise. The opposite reaction is for the airframe to roll to the left.
The propeller propels air currents around and about the airframe in a clockwise direction (as viewed from the rear). The airstream strikes the left side of the vertical stabilizer and rudder, yawing the nose of the airplane to the left.
Gyroscopic precession from the rotation of the crankshaft and propeller causes the airplane to yaw to the left.
In nose high attitudes, a left-turning tendency results from the fact that the descending propeller blade takes a bigger bite out of the air than does the ascending blade, which is on the left. This P-factor adds to the left-turning tendency when the airplane is in a nose-high attitude.
The torque of the engine causes a left rolling tendency. For each and every action, there is an equal and opposite reaction. As viewed from the cockpit, the crankshaft on an American-made engine rotates clockwise. The opposite reaction is for the airframe to roll to the left.
The propeller propels air currents around and about the airframe in a clockwise direction (as viewed from the rear). The airstream strikes the left side of the vertical stabilizer and rudder, yawing the nose of the airplane to the left.
Gyroscopic precession from the rotation of the crankshaft and propeller causes the airplane to yaw to the left.
In nose high attitudes, a left-turning tendency results from the fact that the descending propeller blade takes a bigger bite out of the air than does the ascending blade, which is on the left. This P-factor adds to the left-turning tendency when the airplane is in a nose-high attitude.
03-19-2011, 05:04 AM
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RE: What causes swing to the left on take off?
ORIGINAL: TheParrot
Shamelessly copied from the Airplane Flying Handbook, 4 causes of the left turning tendency:
The torque of the engine causes a left rolling tendency. For each and every action, there is an equal and opposite reaction. As viewed from the cockpit, the crankshaft on an American-made engine rotates clockwise. The opposite reaction is for the airframe to roll to the left.
The propeller propels air currents around and about the airframe in a clockwise direction (as viewed from the rear). The airstream strikes the left side of the vertical stabilizer and rudder, yawing the nose of the airplane to the left.
Gyroscopic precession from the rotation of the crankshaft and propeller causes the airplane to yaw to the left.
In nose high attitudes, a left-turning tendency results from the fact that the descending propeller blade takes a bigger bite out of the air than does the ascending blade, which is on the left. This P-factor adds to the left-turning tendency when the airplane is in a nose-high attitude.
Shamelessly copied from the Airplane Flying Handbook, 4 causes of the left turning tendency:
The torque of the engine causes a left rolling tendency. For each and every action, there is an equal and opposite reaction. As viewed from the cockpit, the crankshaft on an American-made engine rotates clockwise. The opposite reaction is for the airframe to roll to the left.
The propeller propels air currents around and about the airframe in a clockwise direction (as viewed from the rear). The airstream strikes the left side of the vertical stabilizer and rudder, yawing the nose of the airplane to the left.
Gyroscopic precession from the rotation of the crankshaft and propeller causes the airplane to yaw to the left.
In nose high attitudes, a left-turning tendency results from the fact that the descending propeller blade takes a bigger bite out of the air than does the ascending blade, which is on the left. This P-factor adds to the left-turning tendency when the airplane is in a nose-high attitude.
