A question about propeller torque during takeoffs
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Our 160HP Rallye requires some right brake on take off. It has a castering nose wheel and a distinct left turning tendancy, which is why I line up with the nose pointing to the right of the centreline. Until there is enough airflow over the rudder it tries to turn left.....
Touché
Not wishing to be unconventional, I'd go for some brake on the downwind wheel...until the rudder comes alive......(I'd hope thats what you really meant !)
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Gyroscopic effect
I could not resist adding to this thread....The difference between flying light tail aircraft such as the Auster, chippy and flying a high power advanced piston trainer or a fighter is like night and day....The effects of P factor, torque, slipstream effect and gyroscopic effect are barely noticeable on light tail aircraft however quirky they me be...
Modern nose dragger trainers such as the Cessna 150, Cherokee and Cessna 172 are all too easy to fly and they do not penalize the pilot who does not fly them well. This is mostly due to the “anyone can fly” message that the manufacturer wants to send. The characteristics that make them easy to fly include nosewheel gear, limitation of adverse yaw, offset tails and tilted motor mounts to minimize P-factor and heavier, stable control feel.
Guppy has expertly given the answers however for me I would just like to add a little about the effects of "weather cocking"..This is in pure Lay mans speak!
When I transitioned to the T6 Harvard/Texan from the Auster, Chippy etc I could not believe the power of the effects of P Factor and Gyroscopic precess...Before the T6, I thought I was ready to jump right in to a Spitfire with my light tail time! "How hard could it really be?" I had read everything I could find on P Factor and torque effects and I was ready...Hmmmmm Wrong!
Having just mastered the T6 on the grass runway, I transitioned to the tarmac for some take off and landing practice, this threw another dimension in, especially with a cross wind coming from my left...The tarmac with its low friction on the rubber increased the sensitivity of the beast and didnt allow the rubber to slip and give a little as the grass had done...
As I raised the tail on the tarmac runway the machine immediately slewed to the left and was captured "luckily" by my instructor who skilfully kept the machine straight...I thought I had nailed the T6... This really took me by surprise... I could not believe how this happened so easily? I was using rudder?...Trimmers were correct?..... However not enough aileron...!
I had just had my first lesson in the use of aileron! Yes this is basics I hear you say but the majority of pilots keep talking about rudder... The rudder will keep you pointing straight however it's the aileron that will keep you out of the weeds and scaring the hedge hogs!
The rudder keeps you pointing straight and the aileron will stop the drift...As the power is applied the stick is fully back on the T6 to use the advantage of the tail wheel steering and then at around 30 - 40 MPH its time to move the stick forward... As the stick goes forward and the tail lifts you need to have that stick moving across in to the wind... Not to much though or you will bury the wing tip in to the ground, however just enough to stop the drift...
If you dont do this the wind will get under the wing and start to weather cock the aircraft in to the wind... Along with P Factor, torque, Slipstream effect, Gyroscopic effect of the 8 foot prop all wanting to drive the aeroplane to the left, a LEFT cross wind will seal the deal if this isn't corrected and accounted for with aileron, If the drift is not corrected for then stand by for the ride of your life!!!
Modern nose dragger trainers such as the Cessna 150, Cherokee and Cessna 172 are all too easy to fly and they do not penalize the pilot who does not fly them well. This is mostly due to the “anyone can fly” message that the manufacturer wants to send. The characteristics that make them easy to fly include nosewheel gear, limitation of adverse yaw, offset tails and tilted motor mounts to minimize P-factor and heavier, stable control feel.
Guppy has expertly given the answers however for me I would just like to add a little about the effects of "weather cocking"..This is in pure Lay mans speak!
When I transitioned to the T6 Harvard/Texan from the Auster, Chippy etc I could not believe the power of the effects of P Factor and Gyroscopic precess...Before the T6, I thought I was ready to jump right in to a Spitfire with my light tail time! "How hard could it really be?" I had read everything I could find on P Factor and torque effects and I was ready...Hmmmmm Wrong!
Having just mastered the T6 on the grass runway, I transitioned to the tarmac for some take off and landing practice, this threw another dimension in, especially with a cross wind coming from my left...The tarmac with its low friction on the rubber increased the sensitivity of the beast and didnt allow the rubber to slip and give a little as the grass had done...
As I raised the tail on the tarmac runway the machine immediately slewed to the left and was captured "luckily" by my instructor who skilfully kept the machine straight...I thought I had nailed the T6... This really took me by surprise... I could not believe how this happened so easily? I was using rudder?...Trimmers were correct?..... However not enough aileron...!
I had just had my first lesson in the use of aileron! Yes this is basics I hear you say but the majority of pilots keep talking about rudder... The rudder will keep you pointing straight however it's the aileron that will keep you out of the weeds and scaring the hedge hogs!
The rudder keeps you pointing straight and the aileron will stop the drift...As the power is applied the stick is fully back on the T6 to use the advantage of the tail wheel steering and then at around 30 - 40 MPH its time to move the stick forward... As the stick goes forward and the tail lifts you need to have that stick moving across in to the wind... Not to much though or you will bury the wing tip in to the ground, however just enough to stop the drift...
If you dont do this the wind will get under the wing and start to weather cock the aircraft in to the wind... Along with P Factor, torque, Slipstream effect, Gyroscopic effect of the 8 foot prop all wanting to drive the aeroplane to the left, a LEFT cross wind will seal the deal if this isn't corrected and accounted for with aileron, If the drift is not corrected for then stand by for the ride of your life!!!
Last edited by T6Texan; 29th Apr 2014 at 04:57. Reason: Grammar gramar
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I just found this old thread, and couldn't resist bringing a question specially for those of you with experience in powerful taildraggers...
In a model ( flight dynamic mathematical model ) I am using, for a P51d, an effect that was completely unknown to me was made evident when taking off at extreme x-wind situations.
With a true x-win component of, say, 15+ knots from your left, summing to the typical prop effects for a CW rotating prop, it appears that it can be expected that the aircraft veers to the right ( downwind ) at least during the initial takeoff run, specially if flaps are being used !
The effect has it's explanation, supposedly, on the deflected propwash that hits the downwind surfaces of the aircraft ( right wing and right tail sections in this case ), creating additional lift and associated induced drag, and making the nose want to drift downwind, requiring the application of left ( into de wind!!! ) rudder and even right aileron to prevent the right wing from lifting.
This effect that can overcome weathervane during the initial stage of the takeoff run, is something totally unexpected to me, and I reported it as a "bug", but apparently, it may well be the case, although it is not common to such an aircraft to be operated under such extreme x-wind conditions....
In a model ( flight dynamic mathematical model ) I am using, for a P51d, an effect that was completely unknown to me was made evident when taking off at extreme x-wind situations.
With a true x-win component of, say, 15+ knots from your left, summing to the typical prop effects for a CW rotating prop, it appears that it can be expected that the aircraft veers to the right ( downwind ) at least during the initial takeoff run, specially if flaps are being used !
The effect has it's explanation, supposedly, on the deflected propwash that hits the downwind surfaces of the aircraft ( right wing and right tail sections in this case ), creating additional lift and associated induced drag, and making the nose want to drift downwind, requiring the application of left ( into de wind!!! ) rudder and even right aileron to prevent the right wing from lifting.
This effect that can overcome weathervane during the initial stage of the takeoff run, is something totally unexpected to me, and I reported it as a "bug", but apparently, it may well be the case, although it is not common to such an aircraft to be operated under such extreme x-wind conditions....
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You should NEVER use brake on take off, unless you've 'lost it' and are aborting the take off. You simply refrain from usuing full power until the rudder has sufficient authority to keep the aeroplane straight. Crosswinds will have an effect here, as well.
In the Chippy (145hp tailwheel), left foot goes forward with left hand at the start of the t/o roll. As speed increases less left rudder is needed.
In the Yak 52 (360hp nosewheel) you use full left rudder but you don't use full power until the rudder has enough authority to keep the aeroplane straight (doesn't take long in that hot ship! T/O gives a real shove in the back!).
The Yak has some unusual steering characteristics on muddy winter airfields. It has narrow mainwheel tyres so differential braking (the usual method of steering on the ground) is usually ineffective as the wheels simply lock and slide rather than restraining one side of the aeroplane. You can use course power changes to steer, however, as the torque from the engine will 'dig in' the right wheel on power application, and the left wheel on sudden power reduction.
This picture shows a little bit of left rudder still held on after take off as the aeroplane is at full power, in level flight, and accelerating:
In the Chippy (145hp tailwheel), left foot goes forward with left hand at the start of the t/o roll. As speed increases less left rudder is needed.
In the Yak 52 (360hp nosewheel) you use full left rudder but you don't use full power until the rudder has enough authority to keep the aeroplane straight (doesn't take long in that hot ship! T/O gives a real shove in the back!).
The Yak has some unusual steering characteristics on muddy winter airfields. It has narrow mainwheel tyres so differential braking (the usual method of steering on the ground) is usually ineffective as the wheels simply lock and slide rather than restraining one side of the aeroplane. You can use course power changes to steer, however, as the torque from the engine will 'dig in' the right wheel on power application, and the left wheel on sudden power reduction.
This picture shows a little bit of left rudder still held on after take off as the aeroplane is at full power, in level flight, and accelerating:
