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Stick back pressure on take off - how much?


Jnowak

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Not sure how much is enough - I apply back pressure during rollout on take off only gently - I did that one time too much and the plane took off before I think it should have. I have low time on CTLS and not sure what to look for. Any thoughts?

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The plane wants to start lift off around 40-42 knots. I think most of us wait until 45-50. This is slightly a personal choice. I prefer 50, some may like 45. I prefer the little extra in case of an issue. I prefer to climb in 15 flaps at 60 knots. Some may like zero flaps if solo, some may like 70 knot climb. Try a few different ways and see what you like.

 

There is no one exact number for this. There is a range.

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The plane wants to start lift off around 40-42 knots. I think most of us wait until 45-50. This is slightly a personal choice. I prefer 50, some may like 45. I prefer the little extra in case of an issue. I prefer to climb in 15 flaps at 60 knots. Some may like zero flaps if solo, some may like 70 knot climb. Try a few different ways and see what you like.

 

There is no one exact number for this. There is a range.

Note: Rogers lift off around 40-42 kts is at 15 flaps for the takeoff. If at zero flaps closer to 55 kts when heavy.
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I normally use flaps 15 for take off and start the stick back gently for a lift off when it is ready. I don't look at the ASI, don't care what it reads until airborne then look for 60K until 500'. When I say I start the stick back, I don't mean to lift the nose wheel immediately like you would in a soft field take off. Just steady back pressure until the nose lifts about half way through the take off roll. I believe in a smooth application of pitch but also don't believe in leaving it on the ground any longer than I have to.

 

If gusty winds are a factor, or if really heavy and high DA, I might leave the nose wheel on the ground until about 40KIAS.

 

There are as many opinions about this as there are people on this forum. You will eventually settle on what is comfortable for you.

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A lot will depend on how you have takeoff trim set.  If you set it dead in the middle per the manual, you need some back pressure when you hit takeoff speed.  I usually put mine set a little farther back than that and it takes just a slight pressure at about 45kt solo or 50kt dual to break ground. 

 

That is for my airplane, all of this also depends on how the anti-servo tab is rigged.  I had to adjust mine after I bought the airplane to get a better (slower) power off speed with it trimmed full aft.  That's my approach trim setting; it used to trim out at about 65kt and I adjusted the trim tab rod ends to get it to about 55-57kt. 

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Not sure how much is enough - I apply back pressure during rollout on take off only gently - I did that one time too much and the plane took off before I think it should have. I have low time on CTLS and not sure what to look for. Any thoughts?

Pop a "Wheele" at 45-50 Knots, and the aircraft will take off on it's own.

 

Cheers

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[back from self imposed exile]

 

Easy question, here are the considerations:

  • The result of any amount of back pressure is dependant on the trim setting (and even flap setting) which can have an imprecise read out. You can begin with a lot of back pressure and begin releasing some of it after a couple of seconds. The nosewheel is not heavy duty so keeping weight light on the nose wheel is being kind to it.
  • Once you have the nosewheel light/elevated you can maintain that and allow the CT to takeoff at the correct speed for the current weight/conditions.  The exception to this is CROSSWINDS.
  • Crosswind takeoffs can result in an inability to maintain the centerline as your CT skips sideways towards the runway edge.  In this case forget the extra back pressure and stay in firm contact until you have flying speed plus 5 knots. Rotate abruptly but don't hold the extra backpressure long to avoid a high pitch attitude in your initial climb.
  • Too much back pressure for too long can result in an excessively high pitch attitude, keep the nose low enough to climb at a safe speed.
  • High wind shear takeoffs - consider accelerating to 78kts before climbing (runway lenght and obstacles permitting)
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Thanks a lot everyone that is quite helpful. The question remains - how much is enough? Is there a way to find out what is the right level of back pressure to lift the nosewheel? I am not realy sure it is up until I feel that the plane wants to fly. I did most of flying on DA 40 where lifting the nosewheel is not part of the procedure (though most recently met a CFI who puts the back pressure on the stick and waits till the plane lifts off). If I pressure too much before taking off can I stall the plane...?

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Thanks a lot everyone that is quite helpful. The question remains - how much is enough? 

 

Enough to lift off, not enough to bang the tail.    :laughter-3293:

 

Just start pulling back slowly at the speeds mentioned, it's pretty easy to get the feel for it after a few takeoffs.  It doesn't take very much.

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Andy's right it's really easy to get the hang of.  

 

To avoid stalling simply use enough back stick to get the nose a bit high and let it take off from that attitude. Once flying (in steady state air) don't pull back any farther and you won't stall, instead adjust pitch to desired climb speed.

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Thanks a lot everyone that is quite helpful. The question remains - how much is enough? Is there a way to find out what is the right level of back pressure to lift the nosewheel? I am not realy sure it is up until I feel that the plane wants to fly. I did most of flying on DA 40 where lifting the nosewheel is not part of the procedure (though most recently met a CFI who puts the back pressure on the stick and waits till the plane lifts off). If I pressure too much before taking off can I stall the plane...?

After , you lift the nose wheel, wheele if you will, it will climb on its own. Watch the airspeed. Use the stick to control your airspeed, pull back slightly to slow down and climb, push forward to climb slower or not climb and speed up. What works for me is; with flaps 15 , climb at about 65 knots airspeed, with 0 flaps climb at at 70 knots. Remember , your speed control is not the throttle, its going to be your stick, forward faster, pull back to slow down. You will get the hang of it quickly I'm sure. Anyhow that is what works for me.

 

Cheers

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In the CTLS I normally rotate at 45kts, then if you put the base of the windshield at the center on the horizon it should put you close to best rate of climb regardless of flap settings.

For a soft field take off I hold the stick all the way back and slowly add power, and then rotate to and hold the same pitch attitude as climb. If you add power to quickly you will bang the tail on the ground.

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In the CTLS I normally rotate at 45kts, then if you put the base of the windshield at the center on the horizon it should put you close to best rate of climb regardless of flap settings.

...

 

Problem with this approach is it doesn't adjust for density altitude.  You need much lower pitch attitude for Vy at 9,000' DA.

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  • 3 weeks later...

Indicated speed varies with DA. Groundspeed at 9000ft is much higher than at sea level. So isn't that a self correcting situation? It's the same reason you can land a CT at 50kt indicated at MSL and at 12,000ft...but at 12k you are going much faster over the ground to generate the same pitot pressure (and thus lift).

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Indicated speed varies with DA. Groundspeed at 9000ft is much higher than at sea level. So isn't that a self correcting situation? It's the same reason you can land a CT at 50kt indicated at MSL and at 12,000ft...but at 12k you are going much faster over the ground to generate the same pitot pressure (and thus lift).

 

 Indicated airspeed does not vary with altitude. The pitot tube is measuring the same size molecules of air that is flowing over the wing. The ratio of air flowing over the wing and into the pitot stays the same regardless of DA. It takes X number of molecules to register rotation or landing speed on the airspeed indicator. When that number is reached then there are enough molecules flowing across the wing to provide the needed lift. 

 

You are correct that groundspeed will be higher.

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In the CTLS I normally rotate at 45kts, then if you put the base of the windshield at the center on the horizon it should put you close to best rate of climb regardless of flap settings.

For a soft field take off I hold the stick all the way back and slowly add power, and then rotate to and hold the same pitch attitude as climb. If you add power to quickly you will bang the tail on the ground.

"Rotate at 45 kts" Must be at 15 flaps?
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Indicated airspeed does not vary with altitude. The pitot tube is measuring the same size molecules of air that is flowing over the wing. The ratio of air flowing over the wing and into the pitot stays the same regardless of DA. It takes X number of molecules to register rotation or landing speed on the airspeed indicator. When that number is reached then there are enough molecules flowing across the wing to provide the needed lift.

 

You are correct that groundspeed will be higher.

I misspoke, I meant to say your actual speed varies with altitude. 45kt indicated at 10,000ft is faster (over the ground, more potential enery, however you want to define it) than 45kt indicated at MSL. You will be using a greater percentage of available engine power at higher altitude to reach the same indicated speed.
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I misspoke, I meant to say your actual speed varies with altitude. 45kt indicated at 10,000ft is faster (over the ground, more potential enery, however you want to define it) than 45kt indicated at MSL. You will be using a greater percentage of available engine power at higher altitude to reach the same indicated speed.

That is confusing. Ground speed has nothing to do with potential energy, and the amount of engine power available decreases at higher altitudes because of air density. That is why turbocharged engines are better in higher altitudes.
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If you crash a CT at 45kt IAS at MSL and at 10,000ft, the one at 10,000ft will sustain more damage, as it has more potential energy that converts to kinetic in the impact.

 

You'd rather crash at 45kt IAS at Death Valley than Denver, because the same IAS carries more energy at the higher density altitude. After all, that is the only reason the IAS is reading the same.

 

What else do you think ground speed is?

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You have zero potential energy on the ground no matter what your altitude! If you are sitting on the ground at 10,000 ft you have no potential energy to trade for kinetic.

IAS has nothing to do with kinetic energy.

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You have zero potential energy on the ground? Even if you are going 500mph? If you hit a tree on the ground at 500mph I guarantee you are going to see a whole lot of potential energy show its face as it turns kenetic. Potential energy relates to velocity or altitude.

 

Potential energy is relative between two objects. In the case we are discussing, the two objects are the Earth (and anything fixed to the Earth - trees, buildings, etc) and an airplane. As that airplane moves faster over the Earth, the relative difference in energy between them grows. Surely you accept that a higher groundspeed brings more energy into a crash, right? If you crash on landing at 45kt IAS with a 30kt headwind, your GS is 15kt. You will walk away. The same crash with a 30kt tailwind now has a 75kt GS, and you have a decent likelihood of dying (statistically, airplane crashes at 80kt or more end in fatalities in very high percentages).

 

That's because higher groundspeed equates to more relative energy between the Earth and the airplane. When the impact occurs, we call that energy "kenetic". Before it occurs, we call it "potential".

 

I'd love for the other Andy to weigh in here, since he's an aerodynamic engineer and knows all this stuff in and out.

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