Flaps on take-off?

[PTK]

Consider for a moment rotation and cruise airspeeds of different airplanes, while I get some more pop-corn.

Different airplanes fly at different airspeeds, both takeoff and cruise.

For example, in my Mooney I rotate around 60 KIAS and cruise at say 160, (a ratio of 0.35). A C150 rotates at say 55 and cruises at around 110, (a ratio of 0.5). A jet liner on the other hand may rotate at say 130 KIAS but cruise at 600, (0.22). This relationship is affected by cruising airspeed much more than rotation speed. IOW cruise speed is roughly double that of rotation in a C150 whereas in a jetliner cruising speed roughly quintuples!

This shall be called the P number! (named after yours truly!)

So the Mooney is able to rotate and fly at reasonable runway lengths with no flaps. A jet liner will need to use an unreasonably huge length of runway or not be able to take off at all with no flaps.

Point is, use of some degree of takeoff flaps depends on the airplane and its P number. The higher the cruising speed the lower the P number and the greater the need for takeoff flaps.

As this ratio increases the more flexibility we have in the decision on use of takeoff flaps, and therein lies this "debate." As the P number gets lower there is no "debate". Better use some takeoff flaps if you want to takeoff!

[Super Dave]

What's settled? That you should consult your POH for takeoff configuration? That was settled with fantom's post on page 1.

I was being sarcastic with "that's settled". My point is that "because my POH says so" is not a very good argument.

[Super Dave]

Hey! We made it to page 10!

[N201MKTurbo]

If we would have used flaps we could have airborne by page 4

[flyboy0681]

Why so much flap over flaps?

[DS1980]

 My point is that "because my POH says so" is not a very good argument.

Now I get that sarcasm.

[pinerunner]

Am I still considered a Mooniac if I continue doing no-flap takeoffs on 5000'+ runways, as I've done for 500+ hours?

Why do I like no-flap takeoffs under (normal for me) conditions?

1. The plane is less squirrelly while on the runway (especially in windy conditions)

2. One less thing to forget during climb out.

3. ..............to be determined.

I agree with point number 1.  I've noticed a few times my plane getting light on its feet a bit early in the TO run and skittering sideways just a touch in a crosswind. I think its ground effect and I tried a few no flap takeoffs on long runways to get a cleaner break with the runway, the idea being that ground effect would be more pronounced with flaps down. Still I mostly use flapson takeoff, even on fairly long runways.

[pinerunner]

This thread may set a record for number of pages! I have a thought/question to inject. If you should want a moderately steep climb-out (but not so steep as to require flaps) could the use of flaps give you better engine cooling for that angle of climb required? The reason I wonder about this is because an earlier post mentioned that our old guppy mouth cowlings give poor cooling at high angles of attack. Using flaps increases drag of course but lets you use a lower angle of attack to get the same angle of climb. I usually waste no time getting them up minimize chance for exceeding the flap extended speed but maybe there's a reason not to be in such a rush.

 

Something new to check out.

[scottfromiowa]

Now I get that sarcasm.

It's O.K. It takes Sheldon a while to "get it" too.

[scottfromiowa]

Here is the deal. Some have made the issue of using take off flaps an absolute...based on a POH one line reference. I get that. If you want to say that it is not open for debate...using no flaps on a take-off...then you are not able to understand why this thread has gone 9+ pages.

For those that can't see outside of the box on this one and feel that I, an owner/operator of a short-body Mooney completing hundreds of take-offs sans flaps cheated death...I am sorry.

I had one bad take-off departure...with flaps. The rest were non-events. My fault, yes.

[DS1980]

Here is the deal. Some have made the issue of using take off flaps an absolute...based on a POH one line reference. I get that. If you want to say that it is not open for debate...using no flaps on a take-off...then you are not able to understand why this thread has gone 9+ pages.

For those that can't see outside of the box on this one and feel that I, an owner/operator of a short-body Mooney completing hundreds of take-offs sans flaps cheated death...I am sorry.

I had one bad take-off departure...with flaps. The rest were non-events. My fault, yes.

I like how you imply that those who operate within the limitations set forth by the manufacturer and printed in the POH are lesser people than those who do not. How much does Mooney pay you to be a test pilot?

Maybe I won't understand the number though since it may be outside the box in which I fly. Bazinga!

[scottfromiowa]

I like how you imply that those who operate within the limitations set forth by the manufacturer and printed in the POH are lesser people than those who do not. How much does Mooney pay you to be a test pilot?

Maybe I won't understand the number though since it may be outside the box in which I fly. Bazinga!

Not my intent.  Your interpretation.  I respect all with possible exception of a Texas pilot...

 

How much do you get paid for taking off or landing with winds over 15 knots?  You daredevil testpilot you.

[scottfromiowa]

^{I like how you use Bazinga}

[DS1980]

Saying that someone is not able to understand and can't see outside the box leaves nothing to interpretation.

[Hank]

Some people think that their individual POH/Owner's Manual is how all airplanes should be flown.

 

Seeing is believing, right? Even in Missouri? Check this out, ye unbelievers! I prefer "As desired" myself.

[scottfromiowa]

Apparently it does.

[DS1980]

Some people think that their individual POH/Owner's Manual is how all airplanes should be flown.

 

Seeing is believing, right? Even in Missouri? Check this out, ye unbelievers! I prefer "As desired" myself.

A POH is how that airplane should be flown.

Other models have a specific take off flap setting, others say "as desired."

[scottfromiowa]

Or Mooney learned that it is not critical under a lot of circumstances and modified later models POH's to reflect this.

[gregwatts]

Even the LOP guys didn't use this many pages to make their case!

[SkyPilot]

Lol....I did leadville this summer. 12,800DA. No turbo 77j. 100lbs girl friend and 33gallons of fuel and bags..........1/2 down the runway was thinking please fly please fly pretty please......ah screw this I should have bought a turbo.....fly please

Where did you find a 100 pound girlfriend

[flyboy]

Welcome to page 11

 

I take off with the wheels in the down position and the flaps in the down position (partial)

 

Guess I am a real drag,

[DS1980]

Yes, we went to 11!

Let the Spinal Tap references begin!

That's all I was going for. I'm done.

[Bob_Belville]

I'm betting they use flaps to get that 747 out of KAAO later today. Maybe they can stay in ground effect over to KIAB.

[Jamie]

You guys act like a long thread is a bad thread.

 

This kind of conversation is us figuring out the problem. Note that there are exactly zero threads on whether or not flight is possible. That's a settled issue. But flaps (among other things) are one aspect of a very complicated machine who's owner's manual is woefully short on "why".

 

There are lots of things about flying that ARE understandable, but are very subtle and prone to misinterpretation (like the relationship between throttle, pitch, speed and altitude).  Flaps are (is?) one of them. We're told "DO: THIS" but not told why, and one day we forget and don't do it, and we don't die and then we're left wondering "Well, wait a minute... I didn't, and it worked, so either I'm being lied to, or there's more to this than the 40+ year old book is telling me."

 

As long as we keep science and fact foremost in the discussion, there's nothing wrong with a 100+ page thread. If it degrades into a holy war with entrenched sides and no progressive understanding, I'm outta here. Until then: party on.

[N201MKTurbo]

Way back in 58 someone was designing the flap position indicator and made a couple of marks in the silk screen. They didn't want to waste them so they became the takeoff flap setting.