Why bother with flaps on takeoff?

[N659HB]

Flaps? What's that?

 

[455 Bravo Uniform]

Another factor is consistency for safety and reduction of human factors induced errors. I would think that means same flap setting every time. Then when you need it, there is nothing to change. And when you don't need it, so what.

-Taxi with control wheel all the way back every time? I do
-Flaps 20 every time? I do
-Soft field TO every time? I do (it's more fun)
-Lights on every time? Sure why not

I'm not saying this is right, I'm just saying it's something to discuss cuz this is POA and its our virtual hangar...

-Vx climb every time? Now that maybe pushing it (no pun). I'll take Vy

Passenger comfort may or may not play into it (their safety is more important than their comfort?).

Fly your plane, be safe, enjoy.

 

[midlifeflyer]

I guess it depends on the airplane. In a Cessna 120, I never bothered with flaps at any time.

Of course it does. One of the funny ones is, after flying a bunch of Skyhawks, pilots tend to think the Cutlass is exactly the same, but, unlike the Skyhawk, the Cutlass short field takeoff says:

 

[Pilawt]

Of course it does. One of the funny ones is, after flying a bunch of Skyhawks, pilots tend to think the Cutlass is exactly the same, but, unlike the Skyhawk, the Cutlass short field takeoff says:

View attachment 56965

The amplified portion of the 172RG "Normal Procedures" section also says, "At takeoff weights of 2550 pounds or less, 10˚ flaps may be used if desired for minimum ground roll or takeoffs from soft or rough fields." 172RG ("Cutlass RG") MGW is 2650; 2550 is the same as the MGW of the fixed-gear 172Q Cutlass and 180 hp Skyhawks.

I'm guessing the 172RG can't meet the certification standard for climb rate if 10˚ flaps are extended > 2550 lb. Nor, for that matter, could a fixed-gear 172 with 180 hp.

 

[azure]

In general:

Flaps- Off the runway sooner, but shallower lower rate climb off the runway

No flaps- Longer on the runway, but steeper higher rate climb once off

Probably model dependent. In my Cardinal, you are both off the runway sooner and the climb is steeper, both in angle and fpm, with flaps. Every once in a while after not flying for a few weeks, I forget to set the flaps on takeoff, and I'm immediately aware of it. The POH recommends 10 of flaps for all takeoffs.

 

[frfly172]

Longer takeoff roll without flaps, prefer to be off the ground as soon as possible.

 

[GRG55]

I guess it depends on the airplane...

My Aztec has a specific checklist item to make sure the flaps are UP before starting a take-off. Always.

 

[Pilawt]

Bonanza no, Cherokee Six yes, Cheetah no, Sport Cub yes, ...

And the beat goes on.

 

[Sac Arrow]

Leave it to POA to have a flap over this subject.

 

[Stewartb]

Flap effectiveness is fun to toy with in a tail dragger. Do a wheel landing with full flaps and hold the tail up as you slow. Retract flaps and the tail will drop. Flaps help keep the tail light at slow speeds. Or, make a takeoff run and hold the speed back to where the plane's just on the verge of flying. Pull out a couple of notches of flaps and it'll fly away without adding more power. Conversely that's why tail dragger pilots "dump" flaps during short landings and in testy winds. We want the plane to stay on the ground and retracting flaps helps that. You nose dragger guys should recognize that flipping your flap switch up immediately at touchdown makes brakes more effective? Most high performance tail dragger guys (and float guys) start the takeoff run at half flaps but will pull more flaps to pop the plane into the air. Most will nurse them back to half for the initial climb out if there aren't obstructions to clear. If there are obstructions? Leave the flaps down until you clear the hurdles. Flap knowledge in whatever you're flying is good to have in your quiver but it requires familiarity, especially for control feel differences and changes to normal trim settings.

 

[CC268]

That’s standard. Same for a Skyhawks. But not every airplane is a Cherokee or a Skyhawk. Some, including Mooney’s, call for flaps for normal takeoff as SOP. The manual even refers to them as "takeoff flaps." Different airplanes, different POH-recommended procedures,

Yea I was in no way shape or form stating that my Cherokees POH applies to all airplanes lol

 

[CC268]

Why did you find it interesting? I don't think any of the PA28s call for flaps as normal technique unless short field.

Idk cause I did?

 

[RudyP]

Haven’t seen this mentioned yet so I will - there is a small impact to the tires/wheels/landing gear as well. These things aren’t designed for super high speeds, especially on bumpy, not very smooth runways. Is it a huge deal to go 10mph faster? No, not in most cases, but since you don’t have to, I prefer to be off the ground a bit sooner, especially if the runway surface isn’t terrific. Remember those last X kts of speed to get to liftoff speed are the slowest to gain so it can be an extra few seconds on the ground that aren’t necessary. Again, not a major deal but why not optimize?

Also, this may be obvious but the faster the plane, the bigger the difference. It may not make much difference on a Cessna 172 or Cherokee but it starts to be a bigger deal on traveling GA planes and of course, no jet pilot would take off without the best possible configuration.

 

[GRG55]

...You nose dragger guys should recognize that flipping your flap switch up immediately at touchdown makes brakes more effective?...

LOL. Now that is amusing.

Might surprise you taildragger guys that most of us know that?
And unlike you taildragger flyers, who keep the stick back after touchdown so you don't flip the airplane on to its nose, we do it to put weight on the mains for more effective braking.

 

[Let'sgoflying!]

who cares how fast you get off or climb?
Its all about wear and tear!
What is easier and cheaper to fix (and, consider the likelihood of needing it in each case); flap components or landing gear components?
I don't have the answer, and it may be different for different airplanes.
Just want to direct some emphasis to the mx side.

 

[Fearless Tower]

Leave it to POA to have a flap over this subject.

No kidding. Whatever happened to reading the manual?

 

[GRG55]

No kidding. Whatever happened to reading the manual?

Reading? Manual??
Isn't there a video phone app for that?

 

[dmspilot]

Even different years of Skyhawks have different procedures regarding flaps on takeoff. I always wondered if it was something with the airplane's design that changed or if Cessna just changed their minds.

 

[Bill]

You nose dragger guys should recognize that flipping your flap switch up immediately at touchdown makes brakes more effective?

Sure we do, but there is no free lunch. Putting flaps up immediately removes the aerodynamic drag, and that requires more braking.

 

[Salty]

No kidding. Whatever happened to reading the manual?

I already knew what the manual says. I wanted to discuss why.

 

[Salty]

who cares how fast you get off or climb?
Its all about wear and tear!
What is easier and cheaper to fix (and, consider the likelihood of needing it in each case); flap components or landing gear components?
I don't have the answer, and it may be different for different airplanes.
Just want to direct some emphasis to the mx side.

If your flaps are wearing out when you use them, you just may be doing it wrong.

 

[steingar]

I can think of two reasons why I use flaps on take off. The first is the POH says to do so. POH also says to keep it a 25 square on take off. Lots of folks say this is nonsense, but I've heard anecdotally that Mooneys burn les oil if you do that. Then again, the POH also says to use carb heat on landing, which I never do. Wasn't trained that way, and to my understanding Lycomings don't make ice as readily as Continentals.

The other is more subtle. Tiny tires and rubber shock discs. These are both wear items, and if you have to do the whole deal on the doughnuts it doesn't come cheap. Taking off that much sooner at a lower speed will reduce the wear and tare on the gear. Enough to make a difference? Dunno.

All that said, I've taken off without flaps (by accident, the result of a touch and go [anyone on Mooneyspace will get the joke]) and not even noticed. Now, for those who aren't familiar with Mooneys, there is a down side to takeoff flaps. They have to come out at 105 mph. That's the flap speed on the M20c's. Not a big deal, but something else to do on an already busy time of your flight.

Will you really break the airplane if you blow through the flap speed with the flaps hanging out? My mechanic says you can deform a spring. One pilot told me he accidentally left the flaps down for a cross country trip and didn't damage a thing. I believe it, Mooneys are stout.

 

[kgruber]

The flaps affect the airflow around the horizontal stabilizer. In a low wing extending the flaps will reduce the down load on the tail, causing the nose to go down (because the tail is going up).

In a Hersey Bar PA28, yes. In the "Cessna" copy PA28 wing, the nose goes up with flaps.

 

[ktup-flyer]

Now you're gonna tempt eman with his new mobo, or bomo, whatever he has.

Moonanza. Zoom climbs are fun

 

[dmspilot]

In a Hersey Bar PA28, yes. In the "Cessna" copy PA28 wing, the nose goes up with flaps.

It doesn't in my experience. And it shouldn't make a difference. How and why would it?

 

[Salty]

I can think of two reasons why I use flaps on take off. The first is the POH says to do so. POH also says to keep it a 25 square on take off. Lots of folks say this is nonsense, but I've heard anecdotally that Mooneys burn les oil if you do that. Then again, the POH also says to use carb heat on landing, which I never do. Wasn't trained that way, and to my understanding Lycomings don't make ice as readily as Continentals.

The other is more subtle. Tiny tires and rubber shock discs. These are both wear items, and if you have to do the whole deal on the doughnuts it doesn't come cheap. Taking off that much sooner at a lower speed will reduce the wear and tare on the gear. Enough to make a difference? Dunno.

All that said, I've taken off without flaps (by accident, the result of a touch and go [anyone on Mooneyspace will get the joke]) and not even noticed. Now, for those who aren't familiar with Mooneys, there is a down side to takeoff flaps. They have to come out at 105 mph. That's the flap speed on the M20c's. Not a big deal, but something else to do on an already busy time of your flight.

Will you really break the airplane if you blow through the flap speed with the flaps hanging out? My mechanic says you can deform a spring. One pilot told me he accidentally left the flaps down for a cross country trip and didn't damage a thing. I believe it, Mooneys are stout.

I've always considered the white line the limit for max flaps not any flaps.

 

[kgruber]

It doesn't in my experience. And it shouldn't make a difference. How and why would it?

Your experience differs from mine. It differs because it does.

 

[Palmpilot]

The POH for the Brazilian LSA that I used to rent (a Paradise P-1) recommends two notches of flaps (16 degrees) for both takeoff and landing, and I discovered that other flap settings don't work nearly as well. What I found is that the recommended settings give much better pitch control. I found that if I used full flaps (36 degrees) for landing, I was always running out of elevator authority during the flare, so that I couldn't get the nose up enough before touchdown.

 

[midlifeflyer]

Even different years of Skyhawks have different procedures regarding flaps on takeoff. I always wondered if it was something with the airplane's design that changed or if Cessna just changed their minds.

Sometimes they just change their minds. An example is the Mooney J. After a certain year, they removed the high performance short field takeoff from the POH altogether.

 

[Let'sgoflying!]

If your flaps are wearing out when you use them, you just may be doing it wrong.

Possibly. But a large number do wear out given normal use. Not the control surface itself usually although I've had to patch holes where the gear shot rocks into them (mine are fabric) Ever changed the flap tracks out on a Cessna? Ugh. The rollers are also a known wear item. The use of the electric motor is not a gift; they burn out too even if used only in the white arc. In my model the cables are known to break under tension.
However, I hear your point; you prefer to use the flaps and save the gear. A valid opinion.

 

[Checkout_my_Six]

Sometimes they just change their minds. An example is the Mooney J. After a certain year, they removed the high performance short field takeoff from the POH altogether.

lawyers.....

 

[midlifeflyer]

lawyers.....

Too easy a cop out.

 

[Checkout_my_Six]

Too easy a cop out.

who do you think writes the PoH.....marketeers?

 

[GRG55]

The POH for the Brazilian LSA that I used to rent (a Paradise P-1) recommends two notches of flaps (16 degrees) for both takeoff and landing, and I discovered that other flap settings don't work nearly as well. What I found is that the recommended settings give much better pitch control. I found that if I used full flaps (36 degrees) for landing, I was always running out of elevator authority during the flare, so that I couldn't get the nose up enough before touchdown.

So why did they build it with 36 degrees of flap when 16 degrees is the maximum they recommend for landing?

 

[Salty]

Possibly. But a large number do wear out given normal use. Not the control surface itself usually although I've had to patch holes where the gear shot rocks into them (mine are fabric) Ever changed the flap tracks out on a Cessna? Ugh. The rollers are also a known wear item. The use of the electric motor is not a gift; they burn out too even if used only in the white arc. In my model the cables are known to break under tension.
However, I hear your point; you prefer to use the flaps and save the gear. A valid opinion.

I had no point, just being a smart aleck. My mooney with hydraulic flaps would be hard pressed to wear, but electric definitely. I still probably wouldn't drive my decision to use them with that though.

 

[vanman]

We only have two friends in flying. Altitude is first and speed is second. Our objective should be to get as high as possible as fast as possible without compromising our safety and our equipment (mainly the engine). The first issue is the ground roll. There are two area which slow the airplane down, the drag from the wheels on the ground and the aerodynamic drag of the plane (including the flaps if they are down). There's a lot more drag with the wheels than the plane. Compare an air hockey puck to a rolling bike. Once in the air, you have to clean up the airplane. So, it's retract the gears and flaps up. Fly Vy to whatever your safe altitude is.

In the Cirrus SR22 which I fly, it flaps 50%, rotate at 70 kts and flaps up at 80 kts. By the time I rotate, look outside or at the instruments to make sure I'm level and look back at the airspeed, it going past 80 kts. I then let it accelerate to Vy and hold it at Vy until I get 500' AGL and then accelerate to about 120 kts for better cooling.

There is actually a third friend we high performance AC have and that's power. If I were to do the same takeoff in our SR20, to maintain 80 kts with retracting the flaps, I probably be in a slight descent. So, the procedure in the SR20 is to retract flaps at 85kts.

So to answer your question, I think flaps down to get off the ground as soon as possible. Flaps up as soon as you can safely do it.

 

[Palmpilot]

So why did they build it with 36 degrees of flap when 16 degrees is the maximum they recommend for landing?

It's not the maximum that they recommend for landing, it's just what they recommend for a normal landing. They recommend full flaps for a short field landing. (See attachments.)

I don't know the reasons for their design decisions. If you want to ask the manufacturer, there's contact information on their Web page. You might need a Portugese translator, though!

http://www.paradise-ultraleve.com/

 

[MauleSkinner]

... no jet pilot would take off without the best possible configuration.

At least on the GA/135 side of the jet world, "best possible configuration" usually means "normal". It's a fairly low percentage of takeoffs that require a different configuration for a shorter runway (more flaps) or a steeper climb (less flaps and/or speed increase).

As @455 Bravo Uniform noted, consistency can be a significant safety factor.

 

[Dana]

That makes me want to ask another question. I know this is a logically sound statement, but, if this is true, then why do you have to trim up for each notch of flaps in a mooney?

Two reasons. One, flaps increase the wing's camber and thus the [negative] pitching moment, and two, they increase drag below the aircraft centerline, causing a pitch down.

 

[azure]

I've always considered the white line the limit for max flaps not any flaps.

He didn't say 105 was the white line, he said it was the maximum speed for takeoff flaps. I assume the white line is lower. That said, I'm surprised that takeoff flaps have such a low limiting speed in a Mooney, though it could be because they recommend more than 10* for takeoff (gathering that from his mention of two notches). In my Cardinal, takeoff flaps are allowed up to 130 kts... but they're only 10* and I usually try to stay well under that when using that first notch of flaps.