What technique do you guys use?
Cessna 182
Before I had the Sportsman STOL kit I had the Horton, and I used 20 degrees of flaps, and elevator pulled quite a bit.

After Sportsman STOL kit ,10 degrees of flaps and at 40 mph add 20 more (so 30) pull and starts flying (I didnt invented it, I read somewhere that was the best procedure for this STOL kit).
Its a bit distracting techinque while taking off from a narrow short strip.

A friend of mine has a Cessna 172 XP with Horton and VGs, and is using 20 degrees of flaps and takes for ever, its getting scary.
I dont know what to recommend him.
Any ideas?

Here is a video of him taking off.

With it being a hawk XP and with a stol kit, there is going to be some variability from plane to plane. If it were mine, I'd go to a nice long strip and test it. test it with 20, 30 and see. Mark it off. Next thing is technique, is the tail ready to fly? Does he have a good feel for it?

Lastly....and from the video it's actually the first thing I thought of.....is he getting full RPM? Have it checked. He may not be getting full RPM from a combination of governor setting and/or an inaccurate tach. I had it happen to me and it was like adding 25 HP.

Bill

I'd say that what he needs more than anything is bigger tires. I couldn't tell if he was trying to go flying or just plowing the field for a future crop. Not only is he bogged down in the soft surface, but as one tire bogs down more than the other the airplane side loads, increasing resistance. There was a HUGE amount of drag keeping him from reaching rotation speed, but once airborne he climbs well.

I'm no expert, but it looks to me like he's only using ten degrees of flaps. On my plane there's a huge difference in take off performance between 10 and 20 degrees. It appears he's getting off the ground about as quickly as he can and then milking ground effect, so bigger tires and more flap is all I could suggest.

The XP POH doesn't call for 20 flaps for any take off, only 10. However, some seaplane POH changes call for 20 flaps as a normal proposition. Depending on the density altitude of the strip, it would sure be worth trying 20 in a controlled experiment, i.e., not when the pilot absolutely needs the shortest take off possible. There's a fine line between having the necessary power to use 20 flaps and being so under powered so that the extra drag of the 20 flaps impedes the take off rather than helps it.

If your friend doesn't have the 210hp STC, that would be a worthwhile addition. That extra 15hp doesn't sound like much, but it does give a pretty fair extra boost to the airplane. There's also a 3 blade Hartzell prop which is claimed to add thrust. The engine STC is relatively inexpensive and doesn't require a lot of shop time; the 3 blade prop is pretty pricey, of course.

On the strip shown in the video, the biggest problem is the mushy strip vs. the tire size. If he's going to operate off of that kind of strip, he ought to have bigger tires. There are STCs permitting larger mains and a nose fork change so that a larger tire can be put on the nosegear.

But it also appears that although he had full aft yoke initially, he seemed to have reduced that long before the nose gear was clear of the soft terrain. That caused extra drag from the nose gear and materially lengthened the take off roll. That's exactly the opposite of most botched short/soft field take offs, in which too often the pilot holds the nose much higher than necessary, which causes the excessive angle of attack to add aerodynamic drag. But in this case, I think your friend should have held more up elevator until the nose gear cleared the soft stuff. At that point, reducing up elevator to whatever was necessary to just keep the nose gear above the soft stuff would have been appropriate.

Cary

He has 5.00 x 5 in the nose and 7.00 x 6 in the mains.
Definitely bigger tires makes a difference.
Agreed about 20 degrees , maybe too much drag for the amount of power.
Density altitude is about 6,500 ft.

I agree with Hammer on the twenty degree flap, but the main thing is to get the nose wheel out of the mud. I fully agree with what Cary said on this subject. Does he have the control wheel full back until the nose wheel comes just off? He did good, once off, getting level in low ground effect, but it appeared he could have stayed in low ground effect longer. Like Hammer said, he seemed to climb well, but lots of altitude over the trees is not necessary and can be dangerous slow. Also he could have gained a lot of kinetic energy by making a wings level rudder turn in low ground effect. This is something that needs to be practiced in a large field before getting into the short field situation with a curved departure path.

The only big tires I ever flew regularly were what came on a ten thousand dollar Stearman. I have never flow anything regularly with a STOL kit. I have done seventeen thousand hours of stuff like in the video with normal airplanes with normal stuff. I expect all that stuff and a rocket engine will take care of a lot of short and soft field problems. I just teach and appreciate good technique. If I had an expensive airplane with all the bells and whistles, I would be afraid to fly it.

What Cary said, hold the nose wheel off the ground and he needs to rotate sooner. He could have flown much sooner than when he lifted off if he had rotated sooner. Remember, the objective here is to break ground ASAP, once off the ground, level off in ground effect, build speed and then climb out at Vx or Vy depending what you are trying to accomplish. Milk the flap off while accelerating in ground effect.

Kurt

Cary wrote:The XP POH doesn't call for 20 flaps for any take off, only 10. However, some seaplane POH changes call for 20 flaps as a normal proposition. Depending on the density altitude of the strip, it would sure be worth trying 20 in a controlled experiment, i.e., not when the pilot absolutely needs the shortest take off possible. There's a fine line between having the necessary power to use 20 flaps and being so under powered so that the extra drag of the 20 flaps impedes the take off rather than helps it.

Cary

I'm not sure the POH is relevant after the Horton kit is installed...it's a bit of a different wing now. On my Horton equipped 170B the difference in take off distance between 10 and 20 degrees of flap is enormous. I wouldn't say 20 degrees gets me off in half the distance, but I bet it's 3/4's distance or better. That's just gut feeling stuff there...I've never actually measured it. But I have done a couple take offs when I thought I had 20 degrees of flap and only had 10 degrees pulled, and each time the way I figured it out was wondering allowed why the hell I wasn't flying yet.

Maybe the XP wing is a lot different than mine, Horton kit or not. But if it's similar the extra drag is trivial compared to the performance increase.

Hammer wrote:

Cary wrote:The XP POH doesn't call for 20 flaps for any take off, only 10. However, some seaplane POH changes call for 20 flaps as a normal proposition. Depending on the density altitude of the strip, it would sure be worth trying 20 in a controlled experiment, i.e., not when the pilot absolutely needs the shortest take off possible. There's a fine line between having the necessary power to use 20 flaps and being so under powered so that the extra drag of the 20 flaps impedes the take off rather than helps it.

Cary

I'm not sure the POH is relevant after the Horton kit is installed...it's a bit of a different wing now. On my Horton equipped 170B the difference in take off distance between 10 and 20 degrees of flap is enormous. I wouldn't say 20 degrees gets me off in half the distance, but I bet it's 3/4's distance or better. That's just gut feeling stuff there...I've never actually measured it. But I have done a couple take offs when I thought I had 20 degrees of flap and only had 10 degrees pulled, and each time the way I figured it out was wondering allowed why the hell I wasn't flying yet.

Maybe the XP wing is a lot different than mine, Horton kit or not. But if it's similar the extra drag is trivial compared to the performance increase.

Each airplane, depending on its equipment and load, will be a bit different. That's why I suggested doing a controlled experiment, at a strip with the same density altitude. Just as a for-instance, my airplane (63 P172D) has the stock Cessna wing without any cuff, but with the Madras drooped wingtips. I have a 180hp Lycoming/CS prop conversion. Experimenting at DAs of not more than about 6500', 20 flaps does materially reduce the take off roll, compared to either 10 flaps or no flaps. But much above that DA, 7500' or above, 10 flaps works better. It's a combination of lower available power and less lift at the high DAs that makes the difference in whether 20 or 10 flaps is better.

Cary

Cary

Yes! G44. I missed that. I always rotate as soon as possible, regardless of flaps or surface, and immediately level the airplane in low ground effect once off. Airplanes accelerate much quicker in low ground effect. The design of the airplane is to fly. Regardless of wheel size, power, flaps, gear, slope, surface, or anything else, airplanes fly much better than they roll on any surface.

Soft fields vs. hard dirt, electric vs. manual flaps, and a million other factors probably change the equation from one takeoff to another. Depending on what part of the takeoff you are on, raising the nose just puts more weight (and drag) on the mains... so if you are in soft ground that drag might hurt. Remember you have more "flotation" with three tires instead of two. Rolling along at a high AoA also means the airplane is making more aerodynamic drag, which slows acceleration. Drag is low at the beginning and increases with speed of course. So there is probably a balance between the benefit of keeping the nosewheel out of the mud and keeping the airplane's drag as low as possible. Then again keeping the dirt and rocks out of the propeller is kinda important too. I'll bet there's no one answer that yields the best result for all conditions.

There is one objective, however. Get into low ground effect as soon as possible and accelerate there as long as possible. Short, soft, snow, water, obstructions, crooked departure path, etc., etc. Get up into low ground effect as soon as possible and stay in low ground effect as long as possible. Flying is better than rolling and flying is better than stalling and falling.

What about the technique with the Sportsman STOL kit.
10 degrees to start ,and add 20 degrees more at 40 mph.
It goes up in short distance but it is distracting to add flaps in a narrow short , bumby strip

Any other technique you guys use with this STOL kit?

contactflying wrote:Yes! G44. I missed that. I always rotate as soon as possible, regardless of flaps or surface, and immediately level the airplane in low ground effect once off. Airplanes accelerate much quicker in low ground effect. The design of the airplane is to fly. Regardless of wheel size, power, flaps, gear, slope, surface, or anything else, airplanes fly much better than they roll on any surface.

Yep!

motoadve,

With electric flaps or with hard to find/reach manual flaps, just put the flaps down before you start. KISS.

contact

The COG & lift vector are in front of the MLG. This forces the MLG into the runway when lifting the nose wheel. The aircraft was plowing mud (like an angry pig in heat) during the roll out and rotation. It looks dangerous from the video.

Get bigger tires or risk disaster!

contactflying wrote:Yes! G44. I missed that. I always rotate as soon as possible, regardless of flaps or surface, and immediately level the airplane in low ground effect once off. Airplanes accelerate much quicker in low ground effect. The design of the airplane is to fly. Regardless of wheel size, power, flaps, gear, slope, surface, or anything else, airplanes fly much better than they roll on any surface.

I've been using this technique lately and curious how long you typically keep it in low ground effect before climbing out? Until you reach Vx or Vy?

I have a 182 and before and after big tires depending on how soft it is, i will either start with no flap or no more then 10 degrees and like you mention at 40 knots add 10 degrees and it flies off. With that said when i had the 5-5.00 nose wheel on soft grass (not as soft as that) i would always have to get the nose wheel damn near off the ground even to gain enough airspeed to think about flying, and always get it in the air early and keep in ground effect till it stabilizes and gain air speed to vx. Always once in air take 10 degrees away asap, once you practice alittle you will do it smoothly with no alt loss.

Titus577 wrote:

contactflying wrote:Yes! G44. I missed that. I always rotate as soon as possible, regardless of flaps or surface, and immediately level the airplane in low ground effect once off. Airplanes accelerate much quicker in low ground effect. The design of the airplane is to fly. Regardless of wheel size, power, flaps, gear, slope, surface, or anything else, airplanes fly much better than they roll on any surface.

I've been using this technique lately and curious how long you typically keep it in low ground effect before climbing out? Until you reach Vx or Vy?

Yes, until you reach Vx or Vy and then smoothly transition into the climb. Unless absolutely necessary, climb at Vy (best rate), this will give you some extra speed/energy to lower the nose, round out and flare for an unexpected engine failure low to the ground. It is amazing how fast airspeed bleeds off if the engine quits in a climb. Some of the steep climbs right after lift off I see some doing really makes me cringe, yes, engines do quit right after take off, stack the deck in your favor.

Kurt

Quite often electric flapped Cessna models gauge is inaccurate as far as degrees goes.
Double check the deflection if you are not sure.

A quick method I like is to turn the yoke all the way and match flap deflection to the max aileron down deflection.
It is right close to 20 degrees.

In that soft of stuff you need to get the nosewheel up. While it is true that you have more flotation with 3 wheels in contact with the earth you also have more drag keeping you from getting to flying speed.

On soft beaches I will typically initially leave the nosewheel lightly in contact with the sand just enough to help with steering while the speed is slow then lift it up as speed increases until liftoff.

If I leave the nosewheel in contact with the ground and wait for "rotation speed" as if flying something more along the lines of a jet taking off from a 10,000' paved runway it takes waaaaay more beach.

All of this depends on the slope of the beach and crosswind. Sometimes lifting the nose off right away is appropriate also.

This is while at max gross weight.

The 207 manual calls for 10 degrees flaps. if you use only 10 degrees on the soft you will run out of takeoff area pretty quickly., About 15 works pretty good for me with a Horton.

Each airplane will act differently. Get to know your machine!!!!