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-   -   Cessna 152 Take off Procedure (https://www.pprune.org/private-flying/592961-cessna-152-take-off-procedure.html)

mkqq 31st Mar 2017 11:50

Cessna 152 Take off Procedure
 
Hi all,

I'm suddenly confused by something that I thought I knew all these years. I'm asking now as tomorrow I will be doing my first introductory flight in a Cessna 152.

When rotating to take off, I've always thought that you would pull the yoke back until the plane reaches a certain angle of attach (say 15º), and then slowly release the yoke back to its center position, and the plane will climb at the 15ºC angle.

I thought that if I continue to hold the yoke back, the plane's nose would keep on rising and either stall, or flip over on itself backwards.

The same applies to turning, i.e. I thought you would turn the yoke until a certain bank angle is reached, release the yoke back into the centre position, and the plane would keep on turning at that angle. If you continue to hold the yoke at that angle, the plane would completely roll over.

But I just realise I may be wrong from watching Youtube videos? It seems during take off, one will need to continue to hold the yoke back for the plane to climb, unless pitch trim is used.

I am totally confused now and nervous about my flight tomorrow.

Could someone please clarify?

Many thanks

tobster911 31st Mar 2017 13:20

Hi mkqq,

If it's an introductory flight, I wouldn't worry as your instructor will do this for you.

However, this is not the case, you can often relax a little bit, but you'll still need to keep the yoke in the position, otherwise, the aircraft's nose will start to drop. Similarly, in a turn, if you go back to centre, the aircraft will roll level, as by it's nature, it wants to stay straight and level.

Also, on take off, you will generally want to achieve either best rate of climb (Vy), or best angle (Vx). Vx will allow you to climb to an altitude in the shortest horizontal distance, but is a slow way of doing it. Vy will allow you to climb to an altitude in the shortest space of time, but a longer horizontal distance. We usually use Vx where I fly to avoid obstruction, but as you are at a steeper angle, it is more dangerous as you fly closer to the stall threshold.

chevvron 31st Mar 2017 13:28

Your instructor on your introductory flight will brief you on this.
Different aircraft require different lift off techniques; personally with a 152 doing a normal (flapless) takeoff I prefer ( and it is my personal preference) to pull the yoke back just slightly aft of neutral as I begin to roll and the aircraft will then lift off when it is ready.
With a Shadow you MUST pull the sidestick right back as you begin to roll and when the nosewheel lifts, you push it slightly forward to keep it off the ground and once again, it flies off when it is ready.

tobster911 31st Mar 2017 13:39

Most importantly, in something like a 152 on takeoff, it would be near impossible for it to flip over back on itself. They have very docile handling, and if it was near a stall, your instructor a) shouldn't really be conducting introductory flights and b) would correct it. The stall doesn't *just* happen, there's plenty of warning from the aircraft and its systems.

Above all, don't be nervous. Relax and enjoy it. Are you thinking of doing your license?

Heston 31st Mar 2017 13:51


Originally Posted by mkqq (Post 9725247)

I thought that if I continue to hold the yoke back, the plane's nose would keep on rising and either stall, or flip over on itself backwards.

The same applies to turning, i.e. I thought you would turn the yoke until a certain bank angle is reached, release the yoke back into the centre position, and the plane would keep on turning at that angle. If you continue to hold the yoke at that angle, the plane would completely roll over.

This is confusing and top marks for noticing. The pitch control and the roll control actually do work slightly differently.
If you turn the yoke and hold it turned then the bank will continue to increase, as you say.
But the fore and aft movement of the yoke works differently in the way it controls pitch attitude. You have to keep it where you've moved it to in order to maintain the new angle of attack. If you release the pressure on the yoke it will return to its first place and the pitch attitude will return to its original attitude. Do the same in roll however and the bank angle is maintained.

It sounds odd and I've simplified it a bit but in practice it's easy once you get the feel for it.

Ask the instructor to show you. You'll enjoy seeing what i mean.

Incidentally aeroplanes are more stable in the air than you think. Mostly they fly themselves.

Momoe 31st Mar 2017 14:17

Agree with Chevvron, always seemed good practice to pull a little and unload the nosewheel and let it fly off when it reaches the right airspeed.

Nose gear failures are relatively common on most training types compared to main gear, anything that reduces nose gear loading won't do any harm.

Don't worry about how the controls affect the handling, once the instructor hands over to you, you will be making small movements and getting the feel of the plane. Nothing happens in a hurry and you'll find that it's a lot easier than you think.

Above all, enjoy!

bingofuel 31st Mar 2017 15:21

Initially do not over analyse it, just use whatever control input you need to achieve the attitude you want the aircraft to be in.

Just remember "power + attitude = performance"

460 31st Mar 2017 16:53

Fascinating question mkqq; thanks.
There are buckets of expertise here, but not many offering your fresh viewpoint.
Please, could you let us know how you got on?
You have a world of airborne adventure ahead of you.

n5296s 31st Mar 2017 20:34

Interesting, I'd never thought about this before. For sure a small elevator deflection just changes the angle of attack, while a large (but not enough to stall) deflection results in a loop, or at least the beginning of one. Wonder why? Nothing obvious comes to mind.

Gertrude the Wombat 31st Mar 2017 21:28


Originally Posted by Heston (Post 9725366)
This is confusing and ...

... if you're taking off from 2km of tarmac you might actually relax the back pressure just after take-off and accelerate in ground effect to a decent speed before climbing away, ignoring all this Vx and Vy stuff. Less likely to fall out of the sky due to slow reactions if the engine stops.

9 lives 31st Mar 2017 22:25


Different aircraft require different lift off techniques; personally with a 152 doing a normal (flapless) takeoff I prefer ( and it is my personal preference) to pull the yoke back just slightly aft of neutral as I begin to roll and the aircraft will then lift off when it is ready.
This.


For sure a small elevator deflection just changes the angle of attack, while a large (but not enough to stall) deflection results in a loop, or at least the beginning of one. Wonder why?
Not really. The elevator deflection required for a loop entry would likely be less than that applied to raise the nose for takeoff. It's the "entry speed" which differs. If you applied the elevator you would use during takeoff at the entry speed for a loop, you would damage the aircraft.

For my 150, and most tricycle aircraft I fly, I will apply and hold full elevator up, and if a crosswind, full into wind aileron, and hold those inputs until the control affect begins (speed increases control effectiveness) and then I will relax the controls toward neutral to maintain the desired aircraft attitude.

A le Ron 31st Mar 2017 22:43

15° seems a little aggressive to me.

Heston 1st Apr 2017 07:09


Originally Posted by A le Ron (Post 9725844)
15° seems a little aggressive to me.

And in most aircraft exceeds the critical angle of attack for stalling, so it ain't gonna take off like that...

mkqq 1st Apr 2017 08:04

Ok I've just done my trial flight. It was really awesome. I was quite nervous in the beginning especially with moderately bumpy conditions due to heat effects and wind, but felt quite comfortable fairly quickly.

To answer my own question... every aircraft is different so there's no definitive answer, which partially explains the range of responses above. In the case of the 152 I felt there was no "definitive" neutral position with the pitch.

On the ground the elevators are actually in a fully down position. When you pull the yoke back to take off, you'll actually have to find the centre position with a combination of the pitch control and trim.

The controls also became a lot easier and smoother as we picked up altitude and speed.

As for turning it did work somewhat like I expected. I would turn the yoke and the plane reaches a certain angle of bank, and I can return the yoke to the center position and the plane would keep turning at that angle. To level out of the turn I need to push the yoke in the other direction.

We did a little aerobatics which I was really nervous about. The instructor did a couple of barrel rolls for me which wasn't as scary as I thought they would be. During the actual roll I didn't feel any g force but I did feel quite a bit when pulling out of the roll.

I was not brave enough to do loops, which I'm now kicking myself for.

Lastly I did really overthink a lot of things. Before we took I asked the instructor about how I handle the yoke when taking off, how I would correct for the slipstream using the rudder etc.... She said I didn't need to worry about any of that. Basically I could have gone in with absolutely zero knowledge of planes and it would still have been perfectly ok.

fujii 1st Apr 2017 08:14

There you go mkqq, welcome to Pprune. Thirteen answers already. All you need to do now to impress the instructor is start your conversation with "I was reading on the internet...."

foxmoth 1st Apr 2017 20:27


Basically I could have gone in with absolutely zero knowledge of planes and it would still have been perfectly ok.
Something instructors are frequently faced with!

scifi 2nd Apr 2017 07:25

Hi MKQQ, one thing that has not been mentioned yet, is the effect of the Max Throttle used for Take-Off.


Previously.. In the cruise, you have trimmed the aircraft for level flight at about 80% power. So you could fly 'hands free' if you wanted. The aircraft is balanced at that speed, power setting, and trim setting.


So if you land and maintain that cruise setting of the Trimmer, when you want to take-off, you apply Full Power and the plane will naturally want to climb. All you have to do is give it one little pull on the column to get the friction of the wheels off the ground (when the speed is right.) It should then climb all on its own.
When you reach your cruise altitude, just reduce the throttle to 80% and the plane will continue straight and level.


It is a bit counter-intuitive that the throttle can control the rate of climb or descent.
The control column will alter the speed... Just remember... It's forward to go faster, backward to go slower, and fully back will get you to the stall speed. (so avoid fully back..!)
.

cotterpot 2nd Apr 2017 07:36


(so avoid fully back..!)
..except when taxiing, when it is definitely required to protect the prop from damage by stones etc.
Well it is on our airfield.

Enjoy.

9 lives 2nd Apr 2017 13:04


and fully back will get you to the stall speed. (so avoid fully back..!)
Well..... not absolutely...

It is certainly possible to stall an aircraft accidentally, or deliberately, with the controls not all the way back. The application of pitch control, and resulting effect on what the aircraft does are dependent upon many factors, which all inter relate.


(so avoid fully back..!)

..except when taxiing, when it is definitely required to protect the prop from damage by stones etc.
Well it is on our airfield.
Very much so! Controls fully back while taxiing, and at application of power for takeoff (then relax as speed builds). In a high wing tricycle Cessna, the proper use of full nose up elevator while taxiing is greatly enhanced by taxiing with 15 degrees of flaps extended. That improves the effectiveness of the tail in raising the nose, by changing the downwash off the wing onto the tail.

Cessna oleo struts and propellers are expensive to repair and replace, so minimize wear and tear on them at all opportunities!

magyarflyer 2nd Apr 2017 14:29

152 take off
 
simple way
full power keep direction of flight straight pull yoke back just enough to take the weight of the nose keep that attitude plane will climb when gains speed raise the nose when you feel lift raise gently there you go


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