flap setting for take off one notch

[simatos]

In discussion re take off there several references to 0ne notch for take off. The newer 170s the first notch is 10 degrees while the older ones the first notch wil give 20 degrees, is this correct? What do you think about 20 degree of flap for regular, short field and soft field take offs ???Gary

[dacker]

My A model has 10 degrees for the first notch, 20 for the second, 30 for the third, and 50 for the fourth. B models are different. I regularly use 20 for takeoff, and I believe the manual even says something about using 50 for takeoff (I don't have it in front of me). I wouldn't recommend it though since the drag is so high there most likely wouldn't be any benefit.
David

[zero.one.victor]

My ragwing has 4 notches, not the 3 as per the owners manual. I measured full flaps at about 35 degrees, didn't bother measuring any of the intermediate notches.
I almost always use half-flaps (2 notches) for takeoff, seems to break ground a lot cleaner that way. For landing, I always use full-flaps.
I also use half-flaps at about 70-75 mph for loitering (whale watching, etc), and for other low speed op's, such as doing an extended pattern for spacing behind someone who thinks he's flying an airliner ("turning 2 mile final.....").

Eric

[GAHorn]

In discussion re take off there several references to 0ne notch for take off. The newer 170s the first notch is 10 degrees while the older ones the first notch wil give 20 degrees, is this correct? What do you think about 20 degree of flap for regular, short field and soft field take offs ???Gary

B-model Serial Numbers up to 26504 had Four (4) flaps selections available. They were 0, 20,30, and 40 degrees. Aircraft Serial Numbers 26505 and subsequent had an added 10 degree setting.
For many years it was reportedly not approved to add the 10 degree setting to the earlier airplanes without additional basis, but after Cessna ran out of stock/inventory of the earlier flap-ratchets, ...miraculously,... it became "approved" to replace the earlier ratchet with the later Five (5) "notch" ratchet, giving 0, 10, 20, 30, and 40 degree flap settings.

Many operators feel that soft-field takeoffs are better performed with the 10-degree setting, but Cessna performance graphs show no advantage to that. (So the question I have is: Then why did they ever complicate the issue by making the 10-degree setting?)
Some operators have reportedly cut a 10-degree notch in their early ratchets. Without further approval I'm pretty certain that's technically illegal.
Personally I sometimes wonder if 20 degrees isn't a bit much, because the flap retraction after takeoff results in a slight loss of altitude unless the flaps are retracted s l o w l y . This becomes a two-handed manuever with one hand removed from the throttle....a mildly uncomfortable feeling for me while watching the trees at Reklaw loom in the windshield. (My takeoff there was 20-degrees because that was my only option in SN 25713. The wind was really gusty out of the North and I departed Rwy 02, which is a canyon cut out of 200' pine trees. When I reached the upper branches of the trees on the sidelines, the gusty crosswind wind whipping across the tree-tops really stole the lift. For a moment my airspeed indicator fluctuated to zero, the airplane lost altitude and my "expletive deleted" drew a gasp from Jamie (who has led a protected vocabulary experience).
Fortunately my 2200 lb takeoff continued to struggle out of there behind that 7655 cruise prop that I hate on takeoff but like in cruise. But for a moment things were tense. (I may start wearing "Depends" earlier than expected in life.)
Anyway,....sometimes I think I'd like to try a 10-degree setting takeoff, but I suspect it won't really make any difference. I suspect an advantage (if any) of the difference between the early and the late flap ratchet is, not in having the ability to make a 10 degree takeoff, ... but having the ability to select 10-degrees for a short time while accelerating away from a 20-degree takeoff. (As opposed to having to hold onto the flap handle and slowly bleed off the flaps in an effort to avoid a loss of altitude. Of course, in theory, it should be possible to pitch up at the same rate that flaps are retracted and suffer no loss of altitude or airspeed. In theory. Sort of. I think.)

[Jr.CubBuilder]

My owners manual says that the performance numbers for take off with one notch are approximately the same as the numbers posted for take off with two notches. I like the first notch for take offs, it doesn't drag to much and you can fly with that one notch on. Just take my time and keep climbing, then when I am ready for more speed and have some altitude I can lean over and deal with that.

I don't like the drag that two notches introduces, it works but the plane really feels draggy on take off, and I start sweating. One notch seems to give better performance if you keep the speed over 60mph. That's all opinion and conjecture though, so try it, don't take my word for it.

[3958v]

Recently our EAA chapter had Harry Rivlet a noted authority on airfoils give a talk. He actally recomended that flaps be used on all takeoffs because they would reduce the chances of a spin resulting from an inadvertent departure stall. Another interesting point reguarding flap use on takeoff is the recomendation in the ragwing owners manual that for the shortest takeoff flaps be applied just before liftoff. Bill K.

[Jr.CubBuilder]

I'm going to argue that last bit. That applying the flaps just before takeoff bit strikes me as just plane wrong. The last thing a taildragger pilot should be doing on a take off roll is ducking his/her head down to fiddle around with the flap handle. I don't believe there is any appreciable acceleration advantage with a C170 (and I think for most similiar planes) to be gained by leaving the flaps up during the initial roll, then yanking them on after the tail comes up. It sounds good at the bar over a few beers, but I don't see how it will get the plane off the ground any sooner. I do however see how one could initiate a truely spectacular ground-loop by momentarily ducking down to find the flap handle at 40mph while the wheels are on the ground.

[dacker]

Sorry Cub Builder, you shouldn't need to duck your head at all to pull a couple of notches of flaps, or trim, or adjust throttle, or even pull carb heat (well I do steal a quick look at my carb heat ). I pop twenty degrees all the time and it does get me off the runway quicker, but as I have said in other posts, it adds a lot of drag and slows acceleration. It is an approved maneuver (according to the owner's maual). It is one of those things you should experiment with when you feel comfortable, then tuck away into your "bag of tricks".
David

[N3243A]

The last thing a taildragger pilot should be doing on a take off roll is ducking his/her head down to fiddle around with the flap handle.

You NEVER take your eyes off the runway during the take off roll. In order to pop flaps during the roll, you reach for the flap handle by feel. But I agree that use of this technique is pretty limited excepting for a few extreme takoff scenarios, ski flying being one of them when your trying to finesse the airplane out of deep or sticky snow.

Bruce

[AR Dave]

Hey this has a lot to do with your plane, the set up, etc.... I think anyway, cause well I can't think of any other reason!
What is your stall speed and what speed do you fly at!
I was taught to fly 60 mph, with full 40 B flap degs. This is well, well, above my stall speed. I also have an 8043 prop which gives up that 15 mph cruise for a reason. And 8.50 tires and 180 gear legs which all changes the lift attitude on the ground. Maybe all this makes a difference.
If you don't enjoy cruising at 60 mph, I'd think you wouldn't really enjoy pulling full flaps on take off. However, let me assure you that taking off with 20 degs B flaps, pulling to 40 degs flaps at the correct timing, will make me rise like in an elevator. It ain't got nothing to do with acceleration, it's LIFT. I used play and play with getting my short takeoffs fined tuned for hunting camp. I would get the biggest kicks out of showing my friends how the plane could balloon up like a helicopter. But I just kept flying at 60 mph. Trimmed for nose down and the plane was in a level attitude, she would just rise up like on a thermal. However, I tried to show someone this trick once while chatting, we were already 60 or so when I pulled the flaps, nothing happened and there was pressure against the handle.
Also, what are ya'll doing where you're not comfortable with the flap handle while taking off. I pull handle to 20 degs, but at that angle it's like a shifter on the car. Put the throttle to full thrust and then put your hand on the UP LEVER. Hold the nose down cause she's going up, up, and up. Heck, I remember practicing with the flaps up all the way and pulling 40 degs all at once. Guess I just started younger and like to have more fun.
With all that said, my usual is 20 degs flaps and leave em alone. Besides there are better short field take styles.

[Roesbery]

For the stock 170B, you might want to look at the chart in the owners manual. Different conditions require different solutions. For higher HP conversions it's a different ball game altogether.

[zero.one.victor]

I've heard the pull-full-flaps trick called a "jump" takeoff. Works in the ragwing too. I never let go out the handles doing it, though, just immediately start bleeding them back up. I takeoff with 2 notches in mine, sometimes leave it that way for part of the climbout, sometimes bleed them off right away.
I heard someone at Reklaw asked George his best advice for taking off at gross weight behind a cruise prop. He replied "depends....."
Better get that club flattened out before it kills ya, George. I'd rather be a few minutes late arriving, than a few feet too low when I get to the trees off the departure end.....then you can wear your depends because you want to, not because you have to.

Eric

[simatos]

Gentlemen, wow lots of info all of which I read with great interest. Thanks and I will let you know how it all works out om my plane Cheers G

[Jr.CubBuilder]

Ok I confess I was thinking in terms of pulling the flaps on from 0 degrees, which for my stubby little arms requires loosening the shoulder harness and bending way forward. Yanking full flaps from 20 degrees would be just like reaching for the gear shift in a car. I'm still scratching my head though, as I'm not seeing how it's going to get me off the ground faster. Sure it will give an exciting bump in lift, but fourty mph of airspeed with 20 degrees of flaps is going to create the same amount of lift whether they are already down or get yanked on.

[AR Dave]

Theorizing - taking off as clean as possible (no flaps / no drag) will accelerate to that 40 mph faster, then pull in the lift. However, in reality when play time is over (and I honestly havn't practiced that in yrs), I agree there isn't a big enough difference to mess with. If you pull the flaps too early you cost yourself runway and too late means you could have already been in the air.

The 2nd fastest and easiest way to take-off from a short field.
Line up straight and set flaps to 20.
Pick up the tail to 2”.
Let it fly off almost on its own. (slight Pull)
Clean to 10 and accelerate
Clean to 0

Lower the nose and accelerate to 90-100 to develop HP (more speed / more rpm). But if you need to turn tight, use the flaps to increase the rate of turn proportionately.