Hot day, max load, should I use flaps on takeoff

dmspilot said:
Excess thrust or power
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dmspilot said:
On the other hand the garbage you spewed about power required and power available was logically and factually incorrect.
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I would like to agree with you to avoiding hurting your feelings but then we would both be wrong.

You are getting very boring so on to another topic. My time is extremely valuable.
 
Back to the subject, I'm still confused by so many of these comments. To clarify. Are some of you saying you should take off on a hot day at max load, short field, without flaps, even when the POH procedure is to use them?
 
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Snowmass said:
I would like to agree with you to avoiding hurting your feelings but then we would both be wrong.

You are getting very boring so on to another topic. My time is extremely valuable.
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:rolleyes: Did your shrink give you your diagnosis yet?

Fact, what you wrote was completely wrong. If you don't agree, that's your problem, not mine. My feelings are not affected by your inability to see through your own arrogance.
 
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Salty said:
Back to the subject, I'm still confused by so many of these comments. To clarify. Are some of you saying you should take off on a hot day at max load without flaps, even when the POH procedure is to use them?
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How about compromising: takeoff flaps to get you off the ground, retracting flaps while staying in ground effect, then climbing out?
 
Salty said:
Back to the subject, I'm still confused by so many of these comments. To clarify. Are some of you saying you should take off on a hot day at max load without flaps, even when the POH procedure is to use them?
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I think the flaps up argument is primarily revolving around around how to achieve Vx, as defined in the POH, after liftoff. Also, whether the flaps should be retracted before or after clearing obstacles, since it seems Vx is typically (always?) published for flaps up.

According to the PA-28-181 POH, flaps should be retracted while accelerating to Vx; however, it seems that Cessna and many other publications say to retract flaps after clearing obstacles. I was always taught to retract after clearing obstacles as well but the POH contradicts this.

That's my interpretation and summary of the discussion.
 
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DogoPilot said:
I think the flaps up argument is primarily revolving around around how to achieve Vx, as defined in the POH, after liftoff. Also, whether the flaps should be retracted before or after clearing obstacles, since it seems Vx is typically (always?) published for flaps up.

According to the PA-28-181 POH, flaps should be retracted while accelerating to Vx; however, it seems that Cessna and many other publications say to retract flaps after clearing obstacles. I was always taught to retract after clearing obstacles as well but the POH contradicts this.

That's my interpretation and summary of the discussion.
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Thanks. Why would anyone want to fly Vx after they clear obstacles?
 
Salty said:
Thanks. Why would anyone want to fly Vx after they clear obstacles?
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If you carefully read what they are saying, they want you to make sure you gain speed as you retract the flaps and accelerate to Vy. Vx clean is the obvious optimum target.

Salty said:
Are some of you saying you should take off on a hot day at max load without flaps, even when the POH procedure is to use them?
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That is exactly what transport category aircraft do, with the AFM's blessing. However, the reason isn't "obstacles to clear" it's to meet a climb gradient set by performance regulations.
 
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Salty said:
Okay, I figured you’d say that. But you lose me there. A mountain is an obstacle, and best angle of climb is best angle of climb.
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If you're asking why the climb speed depends upon the distance of the obstacle from the takeoff point, I addressed that already, in posts 71 and 94.
 
dmspilot said:
If you're asking why the climb speed depends upon the distance of the obstacle from the takeoff point, I addressed that already, in posts 71 and 94.
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Thanks for the slow walk. At least now I’m following your argument. I’m still not convinced that Vx is always better with no flaps. Otherwise, I’m with you.
 
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DogoPilot said:
I think the flaps up argument is primarily revolving around around how to achieve Vx, as defined in the POH, after liftoff. Also, whether the flaps should be retracted before or after clearing obstacles, since it seems Vx is typically (always?) published for flaps up.

According to the PA-28-181 POH, flaps should be retracted while accelerating to Vx.
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The POH says the flaps should be retracted after reaching Vx. Even though it doesn’t say it, when accelerating (45-54 depending on weight) to the 64kts Vx flaps up, I think you’re probably in the flaps in Vx just before that. But the point has been made that getting the flaps off is most advantageous for angle for this aircraft, and per Dtuuri, all aicraft.
 
MajorTurbulence said:
The POH says the flaps should be retracted after reaching Vx. Even though it doesn’t say it, when accelerating (45-54 depending on weight) to the 64kts Vx flaps up, I think you’re probably in the flaps in Vx just before that. But the point has been made that getting the flaps off is most advantageous for angle for this aircraft, and per Dtuuri, all aicraft.
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Ah yes, that's correct. I think the main point of confusion in this thread stems from the fact that some POHs and publications state that flaps should be retracted after clearing obstacles, which seems contradictory to the definition of Vx. I think other posts have covered the reasons for this apparent contradiction but it is definitely a bit confusing.
 
Not confusing to me as a high wing guy. I routinely use Vx to clear obstacles. If I have a short strip with tall trees I use 2 notches of flap and accelerate in ground effect before pitching up. In my 180 if I tried at any point of that short run to retract flaps I’d be in the trees.

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Stewartb said:
Not confusing to me as a high wing guy. I routinely use Vx to clear obstacles. If I have a short strip with tall trees I use 2 notches of flap and accelerate in ground effect before pitching up. In my 180 if I tried at any point of that short run to retract flaps I’d be in the trees.

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That's how it feels in the Archer. Retracting from 25 to 10 doesn't give me much of a sinking feeling but going from 10 to clean feels like I lose lift quite rapidly. I assume this is because I'm not adequately compensating for the change in angle of attack as the flaps are retracted.

Due to this feeling, I have always climbed out without touching the flaps until clear of obstacles, which is how I was taught, even though it contradicts the POH and much of what has been discussed here. Where I fly in Minnesota, I haven't had to deal with clearing close-in obstacles so it has never been an issue, but this discussion does have me pondering my technique.
 
DogoPilot said:
That's how it feels in the Archer. Retracting from 25 to 10 doesn't give me much of a sinking feeling but going from 10 to clean feels like I lose lift quite rapidly. I assume this is because I'm not adequately compensating for the change in angle of attack as the flaps are retracted.

Due to this feeling, I have always climbed out without touching the flaps until clear of obstacles, which is how I was taught, even though it contradicts the POH and much of what has been discussed here. Where I fly in Minnesota, I haven't had to deal with clearing close-in obstacles so it has never been an issue, but this discussion does have me pondering my technique.
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I definitely understand your reluctance and for those with electric flaps, but the mechanical flap handle on the Archer gives you the ability to feel the synchronization of increasing angle of attack as you slowly reduce the flaps. When you learn to do this, you will feel more confident without losing lift. The airplane feels like it is rotating about an axle of constant lift during the transition.
 
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With a high DA, keep the wing clean, unless you are on a really short field.

frfly172 said:
First notch for takeoff in a Cherokee.
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Is a myth I'll never get. At least in PA28s.

hindsight2020 said:
A Hershey bar Arrow is a -II or -I. My Arrow II has the auto extender, and thence doesn't do what yours does, which is in agreement with both the Arrow II POH and the turbo IV description. Never heard of a -II having a circuit for the flaps. Yours is the first I hear of it. I am to assume your Arrow II didn't come with an auto-extender from the factory? If so, that seems in agreement with the description in the turbo IV POH.
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You haven't disabled the auto-extender?

unsafervguy said:
<flame suit on> i find it interesting that a bunch of internet people think they know better that the engineers, and test pilots that designed, built, and documented and validated the performance data for the FAA. bottom line, fly it the way the book says.
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You sound like the kind of person who thinks max demonstrated crosswind is some sort of unsafe, hard limit.
 
N1120A said:
With a high DA, keep the wing clean, unless you are on a really short field.



Is a myth I'll never get. At least in PA28s.



You haven't disabled the auto-extender?



You sound like the kind of person who thinks max demonstrated crosswind is some sort of unsafe, hard limit.
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No, I understand English. Demonstrated is not a hard word to understand. I also probably have more understanding of performance calculation and testing than most of the people on this board. performance numbers and methods are spelled out in The fars and the cars. All manufactures want the best numbers they can get for marketing reasons, so the are not going to leave anything on the table when they write the poh. If there is a configuration that will give better performance they will use it. The equipment used to determine performance will give data more accurate than you will ever be able to. Bottom line is joe pilot will not beat the performance that the manufacture will document. Fly it the way the poh says.
 
Couldn’t disagree more. A good pilot with seat time in just about any airplane can beat the book numbers most of the time. But not many performance-minded pilots are flying a bone stock airplane so that muddies the water. To counter that not many pilots are flying a brand new airplane with a new engine and prop and perfectly rigged, so that’s another factor to consider.

I think the POH is written so that a competent pilot unfamiliar with the type can get into it with a good idea of standard performance and limitations. Give that guy a thousand hours in it and I bet he exceeds them.
 
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The flip side of this.. if you're so concerned about your plane's performance that you are ignoring POH procedures and coming to an internet forum to discuss a hot, heavy, high DA takeoff then maybe don't put yourself in that position in the first place.

There's a video out there of a Bonanza that, per the POH, can make a takeoff, and while it certainly *does* it is a remarkably nerve wracking video to watch as they barely leave the runway and dodge a few trees off the departure end

**in my experience, unless a plane *specifically* calls for flaps during takeoff (IE, SR22, etc.) then flaps in my experience add a lot more drag than lift. They might help you get off the ground faster, but climb performance sucks. Don't you want the least amount of drag possible so you get air moving over the wing and have it perform better?

**while some people in some planes might be able to beat book figures, for the vast majority of sub 100 hr/year pilots just read and follow the POH.. it's written by the people who designed, built, tested, and ultimately developed the plane. Always funny to me when people develop their own practices with their own rational for why it works. Some of these people eventually end up in an NTSB report, like the guy who took off with flaps in a loaded C172 and crashed on departure (AOPA gave some pathetic excuse that it was because the pilot was used to flying SR20s.. which makes absolutely no sense).
 
Tantalum said:
There's a video out there of a Bonanza that, per the POH, can make a takeoff, and while it certainly *does* it is a remarkably nerve wracking video to watch as they barely leave the runway and dodge a few trees off the departure end
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And that wasn't even hot and/or high. Concrete WA, elevation 267', Mears Field.
 
steingar said:
This one isn't difficult. You look at your POH, or whatever you've got. You're at gross, and not over, RIGHT? If so, you look up your performance for those conditions or something similar. Either you have it and you go, or you don't and you stay. Had this very issue with a landing the other day at a strip that was shorter than what I've done in the past. Book said I could do it under the conditions with a sizable margin, off I went. Turned out to be a nothing burger getting in and out, and I had a great day.
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Same, took my Saratoga to Oceano today, 2,200’.

I did the numbers and I had plenty of margin, ended up being a non event.

Fly by what the book says.
 
Jamie Kirk said:
Oceano
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Oceano is an awesome spot. And that little campground there is great too.

The fun starts when you have a 6K+ airport elevation and it's a 9K DA.. you're at max gross, and terrain around you. Situations like that call for "go - no go" points on the runway.. "POH says I should lift off by X feet, runway is Y feet long.. so if I'm not off (or hit some speed threshold) by taxiway Z abort" <- or something like that. I've yet to have to abort.. and thankfull Big Bear, Kearn Valley, and Tahoe all have big beautiful lakes you can climb over!
 
unsafervguy said:
Demonstrated is not a hard word to understand.
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<snip-a-roo>

unsafervguy said:
The equipment used to determine performance will give data more accurate than you will ever be able to. Bottom line is joe pilot will not beat the performance that the manufacture will document. Fly it the way the poh says.
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Donno about all y'all and my name ain't Joe, but I, for one, have certainly beat the published "Maximum Demonstrated Crosswind" values in numerious Cessna airplanes over the years¹... Not sure where they got the numbers from originally, but they are not very accurate.

¹ Yes, to the PTS/ACS standards of "Touch down at a proper pitch attitude, within 400 feet beyond or on the specified point, with no side drift, and with the airplane’s longitudinal axis aligned with and over the runway center/landing path."
 
smv said:
<snip-a-roo>



Donno about all y'all and my name ain't Joe, but I, for one, have certainly beat the published "Maximum Demonstrated Crosswind" values in numerious Cessna airplanes over the years¹... Not sure where they got the numbers from originally, but they are not very accurate.

¹ Yes, to the PTS/ACS standards of "Touch down at a proper pitch attitude, within 400 feet beyond or on the specified point, with no side drift, and with the airplane’s longitudinal axis aligned with and over the runway center/landing path."
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demonstrate

verb
English Language Learners Definition of demonstrate


: to prove (something) by showing examples of it : to show evidence of (something)

As I said, I understand English. Demonstrated crosswind is the maximum the manufacture has shown during testing. If it were the aerodynamic limited crosswind they would call it that.
 
smv said:
Dunno about all y'all and my name ain't Joe, but I, for one, have certainly beat the published "Maximum Demonstrated Crosswind" values in numerious Cessna airplanes over the years¹... Not sure where they got the numbers from originally, but they are not very accurate.

¹ Yes, to the PTS/ACS standards of "Touch down at a proper pitch attitude, within 400 feet beyond or on the specified point, with no side drift, and with the airplane’s longitudinal axis aligned with and over the runway center/landing path."
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You really certain about that? What was the actual crosswind when you were touching down? On a blustery day that number is nearly impossible to come by.
 
smv said:
<snip-a-roo>



Donno about all y'all and my name ain't Joe, but I, for one, have certainly beat the published "Maximum Demonstrated Crosswind" values in numerious Cessna airplanes over the years¹... Not sure where they got the numbers from originally, but they are not very accurate.

¹ Yes, to the PTS/ACS standards of "Touch down at a proper pitch attitude, within 400 feet beyond or on the specified point, with no side drift, and with the airplane’s longitudinal axis aligned with and over the runway center/landing path."
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Same, My max steady direct x-wind in the skywagon is 20knots. I've done 37 knots indirect... and it's a taildragger. Published max is 12. Tricycle gear? Meh keep upping it.
 
steingar said:
You really certain about that? What was the actual crosswind when you were touching down? On a blustery day that number is nearly impossible to come by.
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I am. Ran out of rudder at Delaware county with the PA28. It was a steady state 30+kt direct. Had a bit of side load when landing because, well, ran out of rudder to keep it aligned and had to drift it onto the runway.
 
EdFred said:
I am. Ran out of rudder at Delaware county with the PA28. It was a steady state 30+kt direct. Had a bit of side load when landing because, well, ran out of rudder to keep it aligned and had to drift it onto the runway.
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Yeah, I've been there too. I speed up, more air over the control surfaces. Need a long runway to do that in the Mooney.
 
steingar said:
Yeah, I've been there too. I speed up, more air over the control surfaces. Need a long runway to do that in the Mooney.
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Except the plane still lands at the same speed, so the extra speed only helps keep you aligned on approach, when you go to actually touch down, you're still going to have the same sideways vector. You can't force airplanes to land.
 
EdFred said:
Except the plane still lands at the same speed, so the extra speed only helps keep you aligned on approach, when you go to actually touch down, you're still going to have the same sideways vector. You can't force airplanes to land.
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All true, but usually when you're landing in a low wing aircraft the crosswind decreases markedly as you get into ground effect. At least that's been my experience.
 
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