One more suggestion, when you are doing your practice at altitude try climbing with various flap settings and see what you get. Somebody mentioned it but out climbing the treeline may be more of a limiting factor than runway length at some airports.
If drag with flaps at low speeds is such a big deal why don't you see 747's starting the takeoff with 0 flaps, then extending them starting at some speed that would give them TO flaps by the time they reach Vr?

porterjet wrote:If drag with flaps at low speeds is such a big deal why don't you see 747's starting the takeoff with 0 flaps, then extending them starting at some speed that would give them TO flaps by the time they reach Vr?

Because 747's are not intended to be operating out of short strips
Because 747's have a very large amount of excess thrust
Because 747 crews have too many other things to manage during a takeoff roll
Because 747's don't have propeller blast over the flaps to create extra drag
(there is a gap between the flaps for the engine exhaust and bypass air so it doesn't blow the flaps off the wing)

Unfortunately I'm not an aero engineer, but if there are any trained aero's here perhaps they could calculate the reduction in takeoff distance a 747 would enjoy if it were mechanically possible to wait until rotation speed and deploy the flaps instantly (like you can do on a Pacer). I'll bet it's several hundred feet.

With all due (and sincere) respect to the professional jet pilots on this group, I think the more relevant question is... why do so many old grizzly bush pilots feel that this technique shortens their takeoff distance?

A significant number of pilots who do not use this flap technique may be making that choice not because it doesn't work, but because of other safety and control factors (visibility, directional control, pilot restraint system)... for which there is now a good solution... ahem

Fern-hopper,
This may seem odd, but look under the horizontal stabilizer and see if there are VG's installed on the trailing edge if the stabilizer. The only reason I say this is that when I had my engine overhauled, I installed the VG's on the wings. We got the engine on the aircraft and got a ferry permit to get it to the mechanics shop before I got the VG's on the underside of the horizontal stabilizer. We had very little (almost None) elevator response at slow speed. I have also heard that if you do too much to the short wing it can make the plane fly slower than the tail feathers are designed to operate. When Pacers are modified to have bigger wings like the producer or the bushmaster, they usually install super cub tail feathers as they are bigger than the ones on a stock pacer.

Keep at it, Pacer flying is Fun!!


Mike

pacerflyer wrote:Fern-hopper,
This may seem odd, but look under the horizontal stabilizer and see if there are VG's installed on the trailing edge if the stabilizer. The only reason I say this is that when I had my engine overhauled, I installed the VG's on the wings. We got the engine on the aircraft and got a ferry permit to get it to the mechanics shop before I got the VG's on the underside of the horizontal stabilizer. We had very little (almost None) elevator response at slow speed. I have also heard that if you do too much to the short wing it can make the plane fly slower than the tail feathers are designed to operate. When Pacers are modified to have bigger wings like the producer or the bushmaster, they usually install super cub tail feathers as they are bigger than the ones on a stock pacer.

Keep at it, Pacer flying is Fun!!


Mike

I flew again this week and there are VG's only on the wings, none on the horizontal stabilizer. The plane still has the stock pacer tail feathers after the wing swap. Played with slow speeds, both in 3-point landing config and wheel landings. Very little elevator response like you said.

Thanks,

Matt

fern_hopper wrote:......there are VG's only on the wings, none on the horizontal stabilizer. The plane still has the stock pacer tail feathers after the wing swap. Played with slow speeds, both in 3-point landing config and wheel landings. Very little elevator response like you said. ....

Whose VG's are on that airplane? Not sure who else has STC'd VG's for the Pacer, but the MicroAero website sez their kit for both the PA-20 & the PA-22 includes VG's for the horizontal. They're not the only kit out there but seem to be the most common. You might wanna check your paperwork.

VG's on my Maule are also under the horizontal... I had them on my Tripacer and they were on the under side of the horizontal also... better check... Got them from Micro Aero...

also Maule has elevator gap seals which are just clear plastic tape that goes on the elevator... Helps immensely with slow speed elevator control... May not be stc'd for the pacer but it's a thought. after all the Maule was developed by B>D after he was at Piper...if I still had my Tripacer knowing what I know about the Maule Gap seals I'd put them on and forget about it...but then that's me...

EZFlap wrote:

porterjet wrote:If drag with flaps at low speeds is such a big deal why don't you see 747's starting the takeoff with 0 flaps, then extending them starting at some speed that would give them TO flaps by the time they reach Vr?

Because 747's are not intended to be operating out of short strips
Because 747's have a very large amount of excess thrust
Because 747 crews have too many other things to manage during a takeoff roll
Because 747's don't have propeller blast over the flaps to create extra drag
(there is a gap between the flaps for the engine exhaust and bypass air so it doesn't blow the flaps off the wing)

Unfortunately I'm not an aero engineer, but if there are any trained aero's here perhaps they could calculate the reduction in takeoff distance a 747 would enjoy if it were mechanically possible to wait until rotation speed and deploy the flaps instantly (like you can do on a Pacer). I'll bet it's several hundred feet.

With all due (and sincere) respect to the professional jet pilots on this group, I think the more relevant question is... why do so many old grizzly bush pilots feel that this technique shortens their takeoff distance?

A significant number of pilots who do not use this flap technique may be making that choice not because it doesn't work, but because of other safety and control factors (visibility, directional control, pilot restraint system)... for which there is now a good solution... ahem

I've used this often in Idaho both with my tripacer and the Maule.... A little harder to do with the Maule as I have to reach farther to pull flaps... Get going to about 45 or 50 and yank full flaps... .Both planes LEAP off the ground.. then blead flaps up slowly as you gain airspeed... Don't do it as much with the Maule cause it's a taildragger but with the Tripacer I always wanted to get that nose gear off as soon as I could and that technique worked best...

iceman wrote:VG's on my Maule are also under the horizontal... I had them on my Tripacer and they were on the under side of the horizontal also... better check... Got them from Micro Aero...

No VG's on the horizontal. The wings are not stock pacer wings, i believe they came off a cub. I rent the Pacer so i don't have the STC paper work. I am flying it on Sunday so I will see if I can get some more info. It would make sense why they low speed control issues started after the new wings.

I live in Midcoast Maine and want to fly up to northern Maine this spring and summer to camp and fish. I would like to be able to use some of the remote strips up there.

Hey Mike do you have any info on the various airstrips in Northern Maine? I am very fond of Maine, I used to vacation there with my family when i was a kid. The back country of Maine is lot more in reach of a East Coast pilot, than is the American west. That would be awesome to have some info on locations and strips in order to one day plan a adventure. Any of them public? Any websites that disclose further information on them?

Thanks.

iceman wrote:
A little harder to do with the Maule as I have to reach farther to pull flaps...

Don't do it as much with the Maule cause it's a taildragger

If you want to have that lost STOL performance back, while still enjoying the advantages a Maule and a tailwheel, you can contact me via PM or e-mail info ) at( ezflaphandle )dot{ com.

For some advice from a knowledgeable BCP member (regarding how he solved these issues on a Maule) there's rumors of a retired firefighter from Oregon who you might ask

BTW, which Maule are you flying? Looks like an M-4 from your avatar picture?

My point was this, if Boeing (or Airbus, Gulfstream et al.) could legally shorten the takeoff distance using this technique they would. It would be interesting to see if they have tested it.
Perhaps there is a requirement for flaps to be set before starting the takeoff roll written into part 25, I do know there is a takeoff configuration alarm that will scream at you with full power so you wouldn't want that going off early in the takeoff roll.
Anybody have an opinion if this technique works because of lower drag early on, or because of the sudden change in wing shape? Does it work with electric flaps?

porterjet wrote:My point was this, if Boeing (or Airbus, Gulfstream et al.) could legally shorten the takeoff distance using this technique they would. It would be interesting to see if they have tested it.
Perhaps there is a requirement for flaps to be set before starting the takeoff roll written into part 25, I do know there is a takeoff configuration alarm that will scream at you with full power so you wouldn't want that going off early in the takeoff roll.
Anybody have an opinion if this technique works because of lower drag early on, or because of the sudden change in wing shape? Does it work with electric flaps?

John,

Imagine selecting flaps just prior to V-1 and having assemetrical flaps extend just as you rotate and at that very moment....... an engine fails!

Bob

I've had a flap follow thru cable failure giving me split flaps in a C207 while turning base to final. It was violent, and woulda been ugly closer to to the ground.

Does pulling flaps during the take-off roll really shorten distance? Or does it just pop you up into ground effect and get you mushing along a few feet up, which you can do with a healthy yank on the elevator with flaps already set prior to the run. I dunno. I've tried it, but it's not something I think of when pulling stuff out of the bag of tricks.

Gump

porterjet wrote:Anybody have an opinion if this technique works because of lower drag early on, or because of the sudden change in wing shape? Does it work with electric flaps?

The laws of physics are what they are, like it or not. Flap deflection creates drag proportional to the speed at which the air is flowing over them. If your airplane is tied down to the ground and wheels chocked, the air blowing rearward from the propeller would "hit" the flaps and create some amount of force trying to pull the flaps rearward off the flap tracks and hinges. That amount of force will oppose the acceleration of the airplane when you remove the chocks and tiedown chains.

Also, any time you create lift you are creating drag. Flap deflection produces lift, and thus drag. So delaying these sources of drag until the last moment means that the airplane will accelerate faster than if you had the flaps out from the start. It's the same as if you had your feet lightly pushing on the brakes.

The un-answered question is how much drag do they create, and how much do they slow down the acceleration. Some people will say that it is a miniscule amount of extra drag. Some will say it is a medium amount. I have not measured it, but I feel a small difference in my under-powered airplane. Being in the business of selling a flap control modification , I have had the experience of speaking to hundreds and hundreds of pilots about this at trade shows from Alaska to Florida. I can guarantee that a lot of pilots use the "wait till you hit 48 mph and then pop off the ground with the flaps"

Another factor is that (on the Cessna) when you lower flaps the airplane pitches forward, and requires more back-pressure on the yoke to raise the nose. So it is completely possible that you have more "rotation" authority from the elevator with the flaps retracted. So you might be able to rotate a bit sooner and with a bit more authority "clean" than you would with the boards out. So it is easy to imagine that accelerating a little bit faster, being able to rotate harder and a hair sooner, would allow you to get off the ground faster.

Electric flaps are so damn slow you would be hard-pressed to document much of a change. But the laws of physics work on airplanes with electric flaps too. You would eventually be able to measure some slight improvement but it would be very very small.

EZFlap wrote:

iceman wrote:
A little harder to do with the Maule as I have to reach farther to pull flaps...

Don't do it as much with the Maule cause it's a taildragger

If you want to have that lost STOL performance back, while still enjoying the advantages a Maule and a tailwheel, you can contact me via PM or e-mail info ) at( ezflaphandle )dot{ com.

For some advice from a knowledgeable BCP member (regarding how he solved these issues on a Maule) there's rumors of a retired firefighter from Oregon who you might ask

BTW, which Maule are you flying? Looks like an M-4 from your avatar picture?

it is a M4 and I haven't lost any stol performance... I just don't have to do the procedure as much with a taildragger...as soon as my tail is up i'm flying... If i yank full flaps after about 35 mPH I'm airborne...but I don't need it that much...any more money that goes into my Maule goes to the new extended heavy duty gear from ABW, when they become available and maybe a set of 29x11x10's all from Wup....

lowslow79,

my e-mail is [email protected], send me an e-mail and I'll give you a couple of spots that you can go to. We've found some spots that get you fairly close to some fishing.

Mike

GumpAir wrote:I
Does pulling flaps during the take-off roll really shorten distance? Or does it just pop you up into ground effect and get you mushing along a few feet up, which you can do with a healthy yank on the elevator with flaps already set prior to the run. I dunno. I've tried it, but it's not something I think of when pulling stuff out of the bag of tricks.

I played with this a fair bit in my 170, and the conclusion I came to was that any increased shortfield performance from a delayed flap pop-up is all the mind of the pilot. Whether you start the roll with 20 deg flaps out and break ground early, then slowly mush along and accelerate toward Vx while gaining some altitude, --or-- whether you pick up airspeed zooming along the ground clean then pop flaps for a dramatic POP off the ground and fast but short-lived climb, you end up in the same spot if you map distance/altitude over time. It's just that the second option is a lot more fun, and feels more effective since it occurs over a short period.

In my opinion, the drag of the flaps in the initial roll is negligible in the total performance of the takeoff. Personally, I always started with 10 deg flaps (in my Cessna) then popped 20 to feel that rapid transition. You clear the bushes either way.

I read(so it must be true, actually outa Sparky's book, so, pretty good source) that the dif. is insignificant between putting them on before you start your t/o roll, or popping them on later.

Personally, I like the idea of putting them on(20*) before I start my t/o roll, just so I don' have to mess with it again 'til I get in the air. I like keeping things simple.

I have on occasion in a fairly strong crosswind pulled on another10* as the plane is geting ready to fly, just to get me off the ground a little quicker with some positive control, so I'm not working my waydown the runway, almost flyin.

Gary

Looks like the discussion on this is winding down, but looking through the PA22 flight manual, the recommended procedure is to begin with 1 notch of flaps, then add the second before rotation (not verbatim). It does specify that this technique reduces ground roll by 20%.
This is how I was taught in a PA22/20.
I can quote the exact wording if anyone is interested.