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Good Instructors know the little tricks - Directional control on the runway


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ACCIDENT INVESTIGATOR: Mr Student Pilot, can you tell me what happened to make your plane veer off the runway?

STUDENT PILOT: I was having my first lesson in taking off. I lined the plane up on the centreline and gently pushed in the throttle. My instructor told me to put in some right rudder to counteract propeller torque. So I did. I pushed the right rudder pedal all the way. The next thing was the plane turned sharply to the right and tilted over to the right and ran off the runway.

 

How many of you have been told to use the rudder to counteract propeller torque during take-off? How many have been told how to judge how much rudder to put in?

 

 I found this video which deals with a method to obtain the visual inputs a pilot needs when forward vision is lost simply due to the normal pitch up angle at rotation or during a climb. 

 

When they asked Lindbergh which window he wanted to get rid of in the Spirit of St Louis, he said, "The front one". He was used to flying with big bags of mail in front of him and didn't really need the front window anyway. In this video you will be shown where to look in an airplane anytime you lose your forward visual reference. Like Lindy, you will learn to fly the airplane using what might be dubbed "The Lindbergh Reference". This reference point is critical for takeoff, landing, climbs, and slow flight. Learning to use it will dramatically improve your takeoffs and landings.

 

The reference point is that part of the instrument cowl that curves down on the left side towards the edge of the window. The hardest part of learning to use this method is to train yourself to stop looking forward over the cowl when it blocks your view, and to turn your head to the side. 

 

 

 

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On 27/12/2020 at 6:06 PM, old man emu said:

My instructor told me to put in some right rudder to counteract propeller torque.

 

Torque really only comes into play with much higher HP engines, usually with CSUs, than we use in RAAus types.  Are you sure it isn't being confused with the 'slipstream effect' caused by the twisting wash of displaced air around the fuselage and particularly affecting the vertical fin and attached rudder?

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2 hours ago, poteroo said:

Are you sure it isn't being confused with the 'slipstream effect'

Okay! Okay! Slipstream. propeller torque, sudden willy willy, Act Of God. Doesn't matter. I was only writing an introduction to pull people in. Now I have edited the first part with a strike through.

 

So, watch the video and discuss that !

 

 

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I’d love to see this instructor try this in a taildragger - he spends an unreasonable amount of time looking at places other than where they’re going. Not really what you want a student to take away from this exercise. Same thing with looking for flaps and trim during the roll out, play with those things airborne.

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Edited by Roundsounds
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A lot of aircraft have the panel too high, probably to give them more space for all of the instruments. Now with glass you don't need so much panel real estate. The top of my panel is just the extension of the fuselage and my aircraft has a long nose. I never lose forward reference straight ahead except when on a steep climb out & it seems obvious to me to look out the side to make sure I am still straight especially if there is a good crosswind at takeoff.

Edited by kgwilson
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11 hours ago, Roundsounds said:

I’d love to see this instructor try this in a taildragger

OK. So you've got a Cub. Good luck to you. I repeat:

THIS TOPIC RELATES TO THE PILOTAGE OF AIRCRAFT WITH TRICYCLE UNDERCARRIAGE DESIGN.

 

If you notice, there are two pairs of eyes in that cockpit, with one pair being told to keep a look out ahead. The instructor, is the one who has his head inside the cabin and is operating the control column. I guess he has the experience to operate the control column while the student maintains direction with the rudder. Also, there is no intention to do anything more than a fast run along the ground, simulating and maintaining the attitude of the early part of a take-off run.

58 minutes ago, kgwilson said:

I never lose forward reference straight ahead except when on a steep climb out & it seems obvious to me to look out the side to make sure I am still straight especially if there is a good crosswind at takeoff.

You have obviously twigged to this method after your years of experience. I posted the video for the information of inexperienced pilots.

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2 hours ago, old man emu said:

OK. So you've got a Cub. Good luck to you. I repeat:

THIS TOPIC RELATES TO THE PILOTAGE OF AIRCRAFT WITH TRICYCLE UNDERCARRIAGE DESIGN.

 

If you notice, there are two pairs of eyes in that cockpit, with one pair being told to keep a look out ahead. The instructor, is the one who has his head inside the cabin and is operating the control column. I guess he has the experience to operate the control column while the student maintains direction with the rudder. Also, there is no intention to do anything more than a fast run along the ground, simulating and maintaining the attitude of the early part of a take-off run.

You have obviously twigged to this method after your years of experience. I posted the video for the information of inexperienced pilots.

When a tricycle undercarriage aircraft lifts its nose, torque pushes the nose to the *right* (so long as the propeller turns clockwise, viewed from the pilot's seat.)

 

THE SPIRIT OF ST LOUIS WAS A TAIL DRAGGER, SO I GUESS THIS TOPIC RELATES TO THE PILOTAGE OF AIRCRAFT WITH CONVENTIONAL UNDERCARRIAGE DESIGN.

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Torque forces are of a pretty low order unless you are "Driving"  a Griffon powered plane. Geared and big.. It's easy to overcomplicate things with smaller stuff. What engine torque figures are we actually working with?  120 ft lbs? Nev

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2 hours ago, facthunter said:

Torque forces are of a pretty low order unless you are "Driving"  a Griffon powered plane. Geared and big.. It's easy to overcomplicate things with smaller stuff. What engine torque figures are we actually working with?  120 ft lbs? Nev

The torque effect being referred to here is the precession effect. Lifting up the nose of the plane tilts the engine back (exerting a torque on it) and the precession effect means that the engine exerts a force (torque) turning to the aircraft to the right. It doesn't have anything to do with the torque produced by the engine. The torque produced by the engine is in a different plane. But, it is smaller stuff. I have checked for it and haven't managed to feel it. The torque produced by the engine will push the left wheel down harder and made the plane turn to the left, but I think that this is more a function of power than torque!

 

Applying more right rudder is important to me when the roll starts. At that time, in a tricycle grear aircraft, P factor will not come into play either. So, it seems the wind on the tail is the only effect that is important.

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With a tail dragger you have precession acting in two directions. You lift the tail first and then you lower the tail to start your climb, that means you have to use your feet in both directions, but You only use your feet to correct a swing. Using rudder before the swing you have no idea how much to use.

When I land and take off I hardly notice what I am doing with my feet, because it is second nature. I sometimes roll out on the landing and analyse what I am doing and it is just one constant jab this way and then that way without really thinking about it.

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OK Gyroscopic precession exists alright. While the pitch of the aircraft changes it happens at right angles. I wasn't sure if you were referring to "P" forces  or actual torque reaction. Any sort of x wind will often have more effect.  I'm sort of inclined to apply rudder to correct what ever is causing it as needed without trying to beat it first.. Things like Mustangs you preset rudder trim. Nev

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  • 2 weeks later...

Keep it tracking straight down the runway seems to work best, if it veers use rudder to get it back in the middle. Tailwheel, nosewheel works with either.

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Then you get the pilot that applies full power in a tricycle with the elevator all the way back... He quickly discovers that unlike the 172 an RAA aircraft is light enough and has enough control power to lift the nose wheel off the ground before the rudder has any authority... He then rapidly departs the runway, hits a fence post and calls his insurance company.....

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But that's a recommended technique with a Jabiru. Keep the weight off the nosewheel especially in soft ground. You can easily steer it on rudder. You just have to make sure you don't get airborne too slow. A bit less back stick once the elevator becomes more effective.  Nev

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Isn't that the standard wet field takeoff procedure for all tricycle u/c aircraft? Get the front wheel off the ground with thrust and elevator, then continue the ground roll a usual.

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Years ago, I once had an issue in a 172 training aircraft that developed a faulty nose wheel steering during takeoff. 

Believe me, you can certainly raise it's nosewheel off the bitumen before planned rotation speed if you need it to and use differential braking to steer (which was normal on some aircraft) so no running into fence posts.

Heavier aircraft or lighter aircraft. It doesn't matter. What matters is the inherent design of the main undercarriage positioning of a particular aircraft design in relation to the aircraft's centre of gravity balanced mass thereby having either a 'lighter' or 'heavier' feel because of the fulcrum effect on rotation. Some designs are just reluctant to lift their noses sooner because their mains are rearward of the CoG. And sometimes in those cases, the undercarriage mains are shorter than the nose leg giving a higher AoA whilst sitting stationary on the tarmac. 

Edited by Tigershark21
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1 hour ago, old man emu said:

Isn't that the standard wet field takeoff procedure for all tricycle u/c aircraft? Get the front wheel off the ground with thrust and elevator, then continue the ground roll a usual.

I guess it depends on your knowledge of the aircraft POH and its handling charestics.... Give it a go in a Tecnam Golf and see where you end up!!! 

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9 minutes ago, Jase T said:

I guess it depends on your knowledge of the aircraft POH and its handling charestics.... Give it a go in a Tecnam Golf and see where you end up!!! 

That's true too. I forgot to mention that some aircraft do have less little stabilty about the normal axis that is compounded with high aspect ratio wings on short fuselages that could do with more vertical stabiliser surface area.

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