FLAPS 2 Notches VS. 3

[davidmorris]

I've almost always used full flaps while landing. While recently riding with a friend he only used 2 notches on a relatively short strip. I ask him why he didn't use full flaps and he stated the 3rd. notch does not really make a difference. Since then I've been trying both 2 notches and full flaps and really can't tell much of a difference.

What say you?

David Morris
N508DM

[Jim Harper]

In my experience, unless one is really trying to make it short, two versus three isn't a lot of difference. The airplane is amazing and has a lot of capibility. However, if you want to make it short and REALLY use the capability, three notches is the way to go. It is staggering how much you can slow down of final (or the pattern, really, but my attention span is too short...

Jim

[Dan L]

This is a subject I like. I have a Word file that I wrote up a few years ago on the subject so I thought I'd paste it here. It is a bit long winded and I would consider my techniques as high performance. But after 2500 or more landings in my EX this is what has worked the best for me. I use the following for 98% of my landings when on wheels.

My short answer is yes to 3-notches of flaps on landing.

My landing technique in the Carbon Cub is as follows.

I’ll approach the landing zone on final from a fairly high altitude (500-600’ AGL) and keep the plane in front of the power curve most of the way down. When I’m 200-300 feet AGL I’ll transition into a nose high attitude by pulling back on the stick. I’m using full flaps at this point; 3-notches. Usually power can be left as is or close to where it was. More power may be needed as the plane settles farther behind the curve. During this phase of flight the GPS ground speed will start in the high 40’s and transition down to the low 40’s in a no-wind condition and a +/-4000’ DA.

I’ll pull in the first notch of flaps when I’m a ways out and/or at 500’ or so AGL. With any amount of flaps the plane will need to be trimmed nose down. I like to trim to a full nose-down position requiring me to pull back on the stick to maintain level flight. If the stick was released when trimmed like this the nose would immediately pitch down. (After flying the FX2 on a demo with Brad Damm I found this pitch change with flaps to be almost insignificant.)

I like full nose-down trim for a couple of reasons. As the plane slows down in the behind-the-power-curve attitude less rearward stick pressure is need until at the point of touchdown very little is needed and it makes it easier to stab the stick forward at touchdown and keep the tail up. I also like the feel in the stick with this trim condition. Also on take-off with full nose-down trim position makes it easier to get the tail up quickly.

With 31” AK Bushwheels and 3” extended gear it is easy to get close to the ground in a tail-low attitude and have the mains touch first. Just prior to touchdown I’ll either give the engine a few hundred RPM’s for a short burst to flatten the round-out and/or push the stick forward depending on speed and wind conditions. The goal and challenge is to roll the mains on at close to 40 mph without bouncing and hit the predetermined touchdown spot. Immediately after touchdown I’ll push the stick forward to raise the tail from its initial tail-low position. On many touchdowns I will be on the brakes before or just at touchdown.

Then depending on the ground conditions, length of the strip and wind I’ll either continue to push the stick forward to keep the tail up as long as possible or more likely I will be getting on the brakes for a short stop. With hard braking it is necessary to pull the stick back right away. Brake pressure will keep the tail up and reducing pressure will allow the tail to fall. I try to keep the tail up with brakes until almost stopped and then gently let it fall by releasing the brake pressure. Sometimes adding a little power (with the tail up and braking) will help keep the tail up or down depending on the need and stick position.

Take-off technique:

I pull two notches of flaps prior to starting the ground roll. No flaps on take off results in a much increased ground roll. With two notches of flaps and trim in the full nose-down position or fairly close to that, I’ll get lined up with the runway and smoothly push in full throttle. (I used to hold the stick to the full forward position to get the tail up but now I often let it come up on its own.) Once the tail starts up I’ll smoothly transition the stick back to keep the tail fairly low but keep it off of the ground. Over-the-cowl visibility is good with this attitude, the tail is out of the rough stuff and the wing has a good angle of attack. Shortly thereafter, as the airspeed needle flashes through about 25 mph indicated I’ll smoothly pull back on the stick and up we go. Once I’m a couple hundred feet AGL I’ll ease off on the flap position and immediately roll in some nose-up trim.

I’ll make variations of this technique with changes in weight and balance and wind conditions. Higher wind speeds along with gusty and turbulent conditions require a flatter deck angle on approach and landing. Those types of conditions would also get me to raise the tail more on takeoff and hold it down on the mains longer before pulling back on the stick.

The Carbon Cub lands and takes-off very similar to my previous 160 hp Super Cub. The flaps on the Carbon Cub seem more effective that a PA-18’s. On short final, when I’m rolling in full nose-down trim in the Carbon Cub I probably would not have trimmed as much in the PA18. I think this is due to the simple fact that it is easier and quicker to use the electric trim in the Carbon Cub as opposed to the manual trim in the PA18.

Landings:

The Carbon Cub seems to be able to land a little slower than the PA-18. Maybe 2-3 mph slower. I see some GPS ground speeds in no-wind conditions at our typical 4000’ density altitude in the high 30’s. I rarely if ever saw a touch down ground speed under about 41 mph in the Super Cub without wind on the nose.

In a crosswind condition I’ll wheel land with a flatter deck angle and higher speed and touchdown on the windward side wheel. Aileron deflected into the wind and rudder and braking as needed to keep a straight track. The overhead flap handle in the Carbon Cub is really nice with a left crosswind as compared to a PA18 trapping the left leg between the stick and flap handle.

Take-offs in the Carbon Cub are much quicker and it is able to hold Vx or Vy much longer than the PA18. I’m sure this is due to the higher horsepower and overall lighter weight. And I suspect that the zero-thrust line motor mount helps too.

My Carbon Cub weighs 1002 pounds empty and my Airworthiness Certificate is for a normal amateur-built experimental (EAB) with an 1865 pound gross, not an ELSA. I have the 44 gallon fuel tanks and extended baggage. With approximately half fuel, 4000’ density altitude and just me (165 pounds) in the front seat plus my normal survival gear, small tool kit, gallon of water and few other odds and ends, I’ll take off in 200’ and about the same distance for landings. When I’m lighter and/or with a decrease in density altitude will shave off 50’ or more from landings and 100’ from take-off’s. And if there is any headwind, as there often is it gets even better. I have little experience flying close to sealevel.

Skis on the snow are a different scenario. Those landings are all 3-point unless laying tracks first. With cold temperatures and a resulting density altitude close to sea level I can see touchdown ground speeds in the 36-38 mph range with no headwind. My shortest takeoff ever was on my straight skis with below zero temperatures and a good headwind. I slid about one ski length which is about 6 feet.

A comment about landing with full nose-down trim: It takes some progressive experience getting used to wheel landing with the trim set like this and especially when braking. Sneak up on it if you want to try it. There are times when full back stick and some power are needed to keep the tail from rising. When I’m out playing on the gravel bars and ridges my weight is in the low to mid 1300 pound range. And my CG is around 72”.

Full flaps and full-nose down trim will allow me to land the shortest. Two notches of flaps and the trim left where it was for landing generate the shortest take-offs for me. Your mileage may vary.

DSCN2333.jpg

[ceslaw]

Dan:

Enjoyed reading your post. Suspect you would use a bit more 'traditional' approach landing on a hard surfaced runway?

Chuck

[Daveembry]

After reading this post last night, today I went out and did some testing. Today I did stalls with 2 and 3 notches of flaps with power off. With 2 notches my stall speed was around 32. With 3 notches it went UP to 38. I did it twice to confirm it was correct.

I didn't do any with power on yet.

With 2 notches of flaps, I could maintain level flight with an airspeed in the high 20's with about 1500 rpm.

Interesting. Has anyone else noticed this or have the same results?

[ATXCubDriver]

After reading this post last night, today I went out and did some testing. Today I did stalls with 2 and 3 notches of flaps with power off. With 2 notches my stall speed was around 32. With 3 notches it went UP to 38. I did it twice to confirm it was correct. My flaps are 1st notch 20; 2nd notch 38 and 3rd notch 50 degrees. (Don't know why I have 50 on full flaps as the g-series it's suppose to be 46 I think).

I didn't do any with power on yet.

With 2 notches of flaps, I could maintain level flight with an airspeed in the high 20's with about 1500 rpm.

Interesting. Has anyone else noticed this or have the same results?

With or without your gap seals? If with the seals pop them out and see what that does to your data.

[Daveembry]

With or without your gap seals? If with the seals pop them out and see what that does to your data.

Yes Mike, with gap seals. I'll try without.

[Pete D]

After reading this post last night, today I went out and did some testing. Today I did stalls with 2 and 3 notches of flaps with power off. With 2 notches my stall speed was around 32. With 3 notches it went UP to 38. I did it twice to confirm it was correct. My flaps are 1st notch 20; 2nd notch 38 and 3rd notch 50 degrees. (Don't know why I have 50 on full flaps as the g-series it's suppose to be 46 I think).

I didn't do any with power on yet.

With 2 notches of flaps, I could maintain level flight with an airspeed in the high 20's with about 1500 rpm.

Interesting. Has anyone else noticed this or have the same results?

Those two things are probably related. You may have the non-g series flap ratchet.

A little bit of power will likely change things too.

[Daveembry]

Those two things are probably related. You may have the non-g series flap ratchet.

A little bit of power will likely change things too.

Yes we had thought of that piece being the non G-series flap ratchet but I checked the shipping slip and it showed the correct part number. Perhaps the slip was different from the actual part. I may get one and compare.

Yes, no doubt that power makes a HUGE difference. 1500 rpm kept it level around 28 mph or so IAS. If I dropped it back to around 1300, it would give a 300 fpm descent at that same speed with 2 notches. (38 degrees).

[Dan L]

Dan:

Enjoyed reading your post. Suspect you would use a bit more 'traditional' approach landing on a hard surfaced runway?

Chuck

Hi Chuck,

I use the same methods if I'm landing on a paved surface. If it is a big airport I'll pick the taxiway exit I want and land right there to keep the taxi to a minimum.