-6 Flap Setting

[delta4242]

I know this has been discussed at length but thought I’d share my findings today.

I have a 2018 CTLSi. While in the hanger I put my flaps on 0 degrees. Put my level as far inboard as possible and zeroed the level. I then put the flaps on -6 and measured from the reference.

Left side was -5.10 degrees 

Right side was -4.95 degrees

I wonder if this is the reason I’m seeing a little less speeds than others?

 

[Tom Baker]

It could have something to do with it, but prop pitch is normally a bigger factor in the difference between airplanes. Full throttle level flight, what is your speed and RPM? When you check, make sure you give it a little time to wind up unless you are over redline.

Edited to add, how do you know zero is actually zero for your reference?

[delta4242]

8 minutes ago, Tom Baker said:

It could have something to do with it, but prop pitch is normally a bigger factor in the difference between airplanes. Full throttle level flight, what is your speed and RPM? When you check, make sure you give it a little time to wind up unless you are over redline.

Edited to add, how do you know zero is actually zero for your reference?

I put a digital level on the flap and zero out the reading. I then put the flap to -6 and it measured the degree of movement.

[Tom Baker]

1 hour ago, delta4242 said:

I put a digital level on the flap and zero out the reading. I then put the flap to -6 and it measured the degree of movement.

You are assuming that your starting point is zero, but all you have determined is that there is only 5° difference between the two positions. Your starting point could be -1°.

I will ask it again because it is important, what is your full throttle indicated airspeed and RPM? This needs to be determined before you worry about anything else.

[delta4242]

Thanks Tom, I’ll have to check next time I go flying. I did check last week and it was as 5410-5460 rpm at 3000’ but I only waiting about 30 seconds before pulling it back to eco mode.

For the flaps, It very well may be a -1 starting point, however I’d expect a flap movement of 6 degrees between 0 and -6, 15 degrees between 0 and 15, and a 15 degrees between 15 degree and 30 degree settings. Perhaps I’m too literal.

Thanks

[GrassStripFlyBoy]

16 minutes ago, Tom Baker said:

You are assuming that your starting point is zero

Exactly the issue here.  Placing a level on the flap is not intersecting the pivot, in my mind I'm seeing both ends of the level are being raised creating a lower value.  If you're really wanting to measure this make a wedge of wood or cardboard and zero the level with intersect of pivot point, and that may not work precisely either.

I think the question on flaps around top speed is a minor point, 1 degree would not equate to much airspeed difference.  Prop pitch as Tom points out is the big driver. 

And understand in this hotter summer weather indicated airspeed is lower, fly a pattern and confirm average ground speed?

Curious what speed you're seeing.  And understand those reporting speeds around here are often SW's, much lighter, smaller wheel fairings and gear.  AG Lyme had about the same vintage LS and I believe he repitched prop and saw a nice little perk up.  LS's based on those I run with here in MI are not as quick as SW's.

 

[GrassStripFlyBoy]

And for what it's worth, I was curious on the speed difference between -6 and -12 flaps, as I'm able to run manually driven flaps up past -6, somewhere around -10 (I did not measure but it was a marked amount than -6 limit switch stop).  I did not perform extensive air work to study, it was perhaps 2-3 knots faster than the -6, not much there...

[delta4242]

4 minutes ago, GrassStripFlyBoy said:

And for what it's worth, I was curious on the speed difference between -6 and -12 flaps, as I'm able to run manually driven flaps up past -6, somewhere around -10 (I did not measure but it was a marked amount than -6 limit switch stop).  I did not perform extensive air work to study, it was perhaps 2-3 knots faster than the -6, not much there...

Thanks, that’s good news. One less thing to worry about!

I think once I stop flying crooked I’ll pick up a few extra knots. Right now I see around 103-105.

 

[sandpiper]

On 9/4/2021 at 2:33 PM, GrassStripFlyBoy said:

And for what it's worth, I was curious on the speed difference between -6 and -12 flaps, as I'm able to run manually driven flaps up past -6, somewhere around -10 (I did not measure but it was a marked amount than -6 limit switch stop).  I did not perform extensive air work to study, it was perhaps 2-3 knots faster than the -6, not much there...

I get the same 2-3 knot bump on the manual side. 

[Anticept]

Please do not use the manual setting unless it's an emergency.

The microswitch that stops the flap system is a normally closed type. That means that if it malfunctions, there is nothing to stop the flaps from continuing to crank. I do not know the extent of damage that can occur, but I really don't want to find out.

If your flaps are not going to their correct position, get them re-calibrated. Unfortunately, a potentiometer for this application is not very good... but it is cheap, and that's why it's installed.