How to gain altitude fast flaps full or not ?

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Styggron
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How to gain altitude fast flaps full or not ?

Post by Styggron »

Hello everyone,

Been watching vids and saw one of a person flying a C172 and they manage to get decent altitude, 1000 feet sooooo fast. When I try it takes forever.

What should my flaps setting me for fast climb ? I thought full gives you the most lift, sure it slows you down but the climb still seems pretty slow. I always seem to have trouble climbing fast.

Ideas ?
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Piper_EEWL
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Re: How to gain altitude fast flaps full or not ?

Post by Piper_EEWL »

Full flaps are not going to improve your climb rate. They add drag to slow you down. And that same drag will decrease your climb performance.

For short field takeoff you should use flaps 10 - 20 degrees because they reduce your stall speed and get you off the ground faster.

The manual will state the best climb configuration and climb speed. I can't check right now but for the 172 I think it's something like 70kts and no flaps.

What speed are you climbing at? How is the plane loaded? What is the density altitude your climbing at? What climb rate are you achieving?
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Styggron
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Re: How to gain altitude fast flaps full or not ?

Post by Styggron »

Piper_EEWL wrote:Full flaps are not going to improve your climb rate. They add drag to slow you down. And that same drag will decrease your climb performance.

For short field takeoff you should use flaps 10 - 20 degrees because they reduce your stall speed and get you off the ground faster.

The manual will state the best climb configuration and climb speed. I can't check right now but for the 172 I think it's something like 70kts and no flaps.

What speed are you climbing at? How is the plane loaded? What is the density altitude your climbing at? What climb rate are you achieving?
Hello Piper,
Well, when I watch videos such as this one, https://www.youtube.com/watch?v=ok0zCuhjI30 they seem to be able to climb to 1000 feet SO fast and I struggle. As for my plane loading, it is all default I don't change anything. I have unlimited fuel set to on though. Density altitude ? (homer simpson blink blink). Rate of climb I try to match that on the video but can't quite do it.

I am using the same airport in the video (EGPE). I am flying the default C172 (but I have the same problem with the A2A C172 with climbing quickly). I prefer to use the default C172 at present though.

[EDIT: Tested again with the C172 and there is no climbing problem, I can match the video, the issue is only with the default C172 and my poor use of flaps]

I thought it might have something to do with how I use the flaps. In the vid he is already at 500 feet when he does his first turn, my goodness and before you know it, he is at 1000 at the second turn.

I just can't seem to get the same height in the same time allotted. I am clearly doing something wrong.
[EDIT: I am doing something wrong alright, the default C172 flight model is waaaay out for climbing. If I try the A2A, spot on]

Thank you :)
Last edited by Styggron on 27 Jun 2016, 16:15, edited 1 time in total.
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Piper_EEWL
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Re: How to gain altitude fast flaps full or not ?

Post by Piper_EEWL »

Well did you take the actual times? Are you climbing slower? What's the climbrate you're getting in the A2A Cessna?

His fuel levels are at 40%. So here's your first major difference. I don't know what unlimited fuel gives you but I guess at least 100%. Why don't you try to fly without unlimited fuel? It's not like you fly long hauls that will be restricted by the fuel? At least that's what I take from your other posts about the 377.

Also it looks like he has quite a headwind. That's gonna make it feel like he climbs faster because his ground speed is slower.

Believe me. The flaps will only make your climb shallower. They are additional drag that you don't want on a climb. You only want them on takeoff and landing!
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Styggron
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Re: How to gain altitude fast flaps full or not ?

Post by Styggron »

Piper_EEWL wrote:Well did you take the actual times? Are you climbing slower? What's the climbrate you're getting in the A2A Cessna?

His fuel levels are at 40%. So here's your first major difference. I don't know what unlimited fuel gives you but I guess at least 100%. Why don't you try to fly without unlimited fuel? It's not like you fly long hauls that will be restricted by the fuel? At least that's what I take from your other posts about the 377.

Also it looks like he has quite a headwind. That's gonna make it feel like he climbs faster because his ground speed is slower.

Believe me. The flaps will only make your climb shallower. They are additional drag that you don't want on a climb. You only want them on takeoff and landing!
Thanks everyone. Problem solved. Climbs are now just like on the video but ONLY if I use A2A C172 which of course is what is used in the video. If you use the default and try to match the video you will only get to 200 feet by the first turn and 500 feet if you are lucky by the second turn so you are out by 100% essentially. My goodness. The default C172 is waaaaay off in climb rates no wonder it was not possible. The only way to get those climb rates in the default C172 is slew :o

I seriously underestimated how less accurate the default C172 is. I learned when I first try to take off in the A2A C172 I was all of a sudden heading left on the run way and thought what the.........the default one is nice and straight but a REAL C172 would veer left as it was explained to me on here when I first bought the C172 in October last year.

Still, I learned something about flaps as I was using them to climb which is not right so now, only for take off and landing.
Cheers Piper.
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speedy70
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Re: How to gain altitude fast flaps full or not ?

Post by speedy70 »

Styggron do not forget as you have unlimited fuel ticked you will always have the weight of full tanks to contend with.

It would be better to just load the amount of fuel you need plus a little extra for emergencies.

Cheers Chris

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Re: How to gain altitude fast flaps full or not ?

Post by Piper_EEWL »

You're welcome. And yes the default C172 is way off.

But I can only echo what Chris is saying. Turn off the unlimited fuel. Load only as much fuel as you need plus some reserve. If you're not stretching the Skyhawks range you don't need to do a lot of planning. But you're always hauling that dead weight around. Just give it a try.

Happy flying
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Styggron
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Re: How to gain altitude fast flaps full or not ?

Post by Styggron »

Piper_EEWL wrote:You're welcome. And yes the default C172 is way off.

But I can only echo what Chris is saying. Turn off the unlimited fuel. Load only as much fuel as you need plus some reserve. If you're not stretching the Skyhawks range you don't need to do a lot of planning. But you're always hauling that dead weight around. Just give it a try.

Happy flying
The A2A climbs perfectly but I shall heed your words and Chris' and turn off unlimited fuel. It is about time I start fiddling with the fuel.

Thank you all
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Re: How to gain altitude fast flaps full or not ?

Post by Piper_EEWL »

Good choice :wink:

You'll note a major difference in performance with reduce fuel load.
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AKar
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Re: How to gain altitude fast flaps full or not ?

Post by AKar »

Styggron wrote:I thought full gives you the most lift, sure it slows you down but the climb still seems pretty slow. I always seem to have trouble climbing fast.
Great that you've got it sorted out already. :) I just pop in to add an additional comment, because that thinking actually follows from a surprisingly common fallacy, which I would like to help to make straight. It must be understood that:
  • An airplane in (steady) climb does not require any more lift than it would in (steady) straight & level flight.

    To be very accurate, it always requires less lift in (steady) climb than it would in (steady) straight & level flight.
An opposite intuition is an easy pit to fall into, and pops up in quite many places: even in some A2A manuals, where they discuss aspect ratios by a nice-on-its-own story of an RC glider falls logically into this same fallacy (and also into another one, mixing up the climb angle and the angle-of-attack). :)

-Esa

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Re: How to gain altitude fast flaps full or not ?

Post by DHenriques_ »

AKar wrote:
Styggron wrote:I thought full gives you the most lift, sure it slows you down but the climb still seems pretty slow. I always seem to have trouble climbing fast.
Great that you've got it sorted out already. :) I just pop in to add an additional comment, because that thinking actually follows from a surprisingly common fallacy, which I would like to help to make straight. It must be understood that:
  • An airplane in (steady) climb does not require any more lift than it would in (steady) straight & level flight.

    To be very accurate, it always requires less lift in (steady) climb than it would in (steady) straight & level flight.
An opposite intuition is an easy pit to fall into, and pops up in quite many places: even in some A2A manuals, where they discuss aspect ratios by a nice-on-its-own story of an RC glider falls logically into this same fallacy (and also into another one, mixing up the climb angle and the angle-of-attack). :)

-Esa
Absolutely correct (as you already know :-)

Ps rules !

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Styggron
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Re: How to gain altitude fast flaps full or not ?

Post by Styggron »

AKar wrote:
Styggron wrote:I thought full gives you the most lift, sure it slows you down but the climb still seems pretty slow. I always seem to have trouble climbing fast.
Great that you've got it sorted out already. :) I just pop in to add an additional comment, because that thinking actually follows from a surprisingly common fallacy, which I would like to help to make straight. It must be understood that:
  • An airplane in (steady) climb does not require any more lift than it would in (steady) straight & level flight.

    To be very accurate, it always requires less lift in (steady) climb than it would in (steady) straight & level flight.
An opposite intuition is an easy pit to fall into, and pops up in quite many places: even in some A2A manuals, where they discuss aspect ratios by a nice-on-its-own story of an RC glider falls logically into this same fallacy (and also into another one, mixing up the climb angle and the angle-of-attack). :)

-Esa

errrrrr ok this I don't understand. If I am climbing I don't need more lift ? Is it because the throttle pulls me through faster if I increase it ?

So I need less lift in a steady climb than straight and level ?

Ok now I am utterly lost :(
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Re: How to gain altitude fast flaps full or not ?

Post by Oracle427 »

There are 4 forces acting on an aircraft.

Lift and Weight
Thrust and Drag

When you are in a steady state, and the emphasis is on steady, then all 4 forces are in balance.

If you are level, then it can be said that lift is countering all the weight, and thrust is countering all the drag.

However if you pitch up into a stable climb with a stable airspeed, then some of the thrust is providing lift as well. Some of the lift is providing drag. Some of the drag adds to weight. Weight always acts down to the earth.regardless of attitude. By definition, less lift is needed in a stable climb.

Again the emphasis is on the word stable.
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AKar
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Re: How to gain altitude fast flaps full or not ?

Post by AKar »

Styggron wrote:errrrrr ok this I don't understand. If I am climbing I don't need more lift ? Is it because the throttle pulls me through faster if I increase it ? So I need less lift in a steady climb than straight and level ?Ok now I am utterly lost
I broke the issue down into two statements in the earlier post: the first one is the principle you need to realize, the second one is just to make it more accurate in all circumstances.

It comes from the elementary properties of nature and motion that you don't need more lift during climb. Airplanes are not different to any other body in this respect.

Consider an elevator (a lifting device, not control surface). Let it be stationary for a moment. That elevator hangs from its cable, which must support its weight by an equivalent, upwards pull force to balance out. Obviously.

If the elevator was going upwards at steady velocity ("rate of climb"), how would the force on the cable be? It must still be the same! Because the elevator's velocity is steady, the only thing the force of the cable must overcome is still the weight of the elevator, and that is unchanged. So the lifting force is also unchanged.

Vertical motion is not different to any other kind of motion: the body keeps on going at constant velocity (be it zero or not - it makes no difference) when the net force acting on it is zero - that happens if the forces acting on it are balanced. In our elevator, regardless of whether it was at rest or in steady motion, the cable pull must balance out the weight of the elevator, so the cable pull must be the same regardless of whether it was moving or not. Only to accelerate the elevator upwards must the force on the cable increase. That happens when the elevator starts moving, the force on the cable must momentarily be greater than the opposing weight to accelerate the elevator upwards but when it moves at constant rate, the force reduces to be equivalent to the elevator's weight. That's why you feel the pull when the elevator starts to go up, but nothing when it goes up at steady speed.

The airplane is no different to the elevator in this respect. When it climbs at steady rate, the vertical, upwards acting force must balance - and only just balance - the weight of the airplane. Only if we accelerate it upwards, "pull up", the force must be greater. Therefore one can say that the g-meter directly indicates the lift produced when the airplane is in the air. This is true in any attitude and in any kind of flight when the angle of attack is relatively small[*], not just when climbing or something.



The second statement in the earlier post is easy to understand if you realize the first. Only additional thing we need to account for is the definition of lift: in this case we could define that the lift is the component of aerodynamic force perpendicular to our direction of movement through the air. So, looking the airplane flying straight & level from its side, the lift would point towards "up", exactly balancing the weight that points "down", while the thrust points ahead horizontally - the drag, obviously, pointing into the opposite direction. Now, if you pitch the airplane up like in climb, the forces rotate with it: the lift tilts backwards and the thrust tilts upwards. Only the weight remains pointing down towards the centre of the Earth. Now, the thrust actually has some vertical component too, offsetting a bit of the weight - that's why the lift is actually reduced in the climb for the vertical forces together to remain in balance at a constant rate of climb! And that's why you need to add thrust in climb to keep the speed constant: now it doesn't only offset the drag, but it also needs to offset some of the weight too.

In an extreme example, imagine a fighter that steadily goes straight up vertically: now the lift in climb is actually zero! All the weight is supported by the thrust - which of course must also offset the drag, so quite high-performance airplane is required indeed.

I added the second statement earlier to account for this issue. And it is actually important to understand that the lift doesn't need to point up. Lift is not defined by any specific vertical, but by being perpendicular to the flow direction.



[*]Why only at small angles of attack? This comes from the definition of the lift, being perpendicular to the flight path through the air, whereas drag is opposite to the flight path vector. Let us just consider an airplane falling down in flat attitude, at its terminal velocity. The g-meter would indicate one g for the rate of descend is constant, but the force is by definition actually drag - not lift - in this case, even if it was "upwards": this is because it is acting opposite to our direction of movement through the air, we going directly downwards and the drag pointing upwards. Just like with a parachute!

Also, technically any sideways aerodynamic forces, when present, are lift too while not being indicated by the g meter.

But don't worry about these last notes, it has more to do with our definitions than actual understanding!

-Esa

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Re: How to gain altitude fast flaps full or not ?

Post by Oliver Branaschky »

And another extremely valuable post by Esa. Thank you for making those matters seem so easy :-)


Viele Grüße/Best regards
Oliver

Oliver Branaschky

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