Flap settings

[Lsapilot]

I've been able to manually raise the flaps past the -6 position using the flap switch.   There is no indication on the flap viewing screen of any flap position when I do this.   Anyone familiar with this? Could this be a -12 position?  I don't seem to gain much speed doing this, maybe a knot or two. Any safety issues involved?   Thanks for any help...

[FredG]

Are you rotating the flap controller switch to the manual control setting in order to achieve this increase?  Also, what is the year and model of your airplane?

 

Some US-based CTsw flap control systems can reflex a little beyond -6 and are limited to -6 by programming of the flap controller (I have only measured two aircraft, maybe they can all reflex a bit beyond -6 degrees).  When I measured my 2006 CTsw with an accurate digital protractor, I found that the flaps would reflex to about -7.5 degrees with the manual setting and would stop at -6 degrees with the pre-programmed setting. 

 

I would guess that the increased travel you observed is not a -12 setting.  I believe that the reflex position limiting cable (not an electrical conductor but a strong multi-strand cable designed to physically limit total flap reflex travel) will prevent travel much past -6 degrees. Also, before this mechanical stop limits travel, a microswitch near the flap motor will open the circuit to the motor and stop flap travel.  The position of the microswitch appears to be adjustable.  The limiting cable does not appear to be adjustable.

 

If you measure your flap travel using the manual control setting on the switch, I doubt that you will find more than a degree or two of reflex beyond negative six degrees.  But, you wont know until you measure.

 

I have no opinion regarding the safety of flight in the configuration you described.

 

I am not a mechanic and my post is for informational purposes, only.

[Roger Lee]

In manual mode it is possible to get maybe 2-3 degrees more, but only if it is set up that way. Not all do ii. It is not a -12 setting. It just allows for it to pass -6 a couple of degrees. You need to be careful because there is a safety cable inside and if the motor does not stop before it goes tight you will strain the motor and bring its demise. 

This isn't a good practice unless you know the limits.

[Lsapilot]

Yes, I'm using the flap controller switch.  thanks for your input.  I've decided not to use this setting as there wasn't much of a speed increase.  

[Roger Lee]

There really isn't any difference between -6 and -12. I have tested this to nauseum with 6 CT's. I used to hear people's claims so I tested them.

-6 works much better at high altitudes than -12.

[sandpiper]

I can pick up 2-3K when using the left side of the flap selector. When the selector is at 9 o'clock, at least on mine, the flap motor is off. So, I put the flaps up as far as they will go, then keep the selector at 9. That way the motor is off and it will not burn out. I have checked it out on the ground and my cable does not go tight before the motor stops.

 

I rarely do this because the benefit is not significant.

[Roger Lee]

Howdy John,

Hope you and the wife are well.

We are not exact enough as pilots in pitch and aircraft trajectory or our instruments to say 2-3 knots change with almost anything. That can be influenced by the smallest of changes in flight and nothing to do with a flap. Most people's restricting factor is prop setup, trim and personal flying habits. Sometimes even wishful thinking gets you 2-3 knots.

[sandpiper]

Howdy John,

Hope you and the wife are well.

We are not exact enough as pilots in pitch and aircraft trajectory or our instruments to say 2-3 knots change with almost anything. That can be influenced by the smallest of changes in flight and nothing to do with a flap. Most people's restricting factor is prop setup, trim and personal flying habits. Sometimes even wishful thinking gets you 2-3 knots.

 

And that is why I rarely mess with it except when bored.

[Ed Cesnalis]

Howdy John,

Hope you and the wife are well.

We are not exact enough as pilots in pitch and aircraft trajectory or our instruments to say 2-3 knots change with almost anything. That can be influenced by the smallest of changes in flight and nothing to do with a flap. Most people's restricting factor is prop setup, trim and personal flying habits. Sometimes even wishful thinking gets you 2-3 knots.

 

I don't agree. 2-3 knots is 2-3 knots.  My IAS is just as sensitive as my GPS.  I might not know why I'm fast or slow on a given day but I do know how fast I go for my current prop setting and current time of year.  If that 2-3 knots is there most days its a real change. 

[Roger Lee]

Conjecture is not the same as real time testing.

 

You/we are the most in inaccurate item in the plane. Humans are not machines nor are they calibrated. Most people's gauges are not that accurate and most vertical indications are not accurate to hold perfect level flight. Plus you have to fly at different times and weather conditions on each individual flight. I had 8 CT's to pick from and used 4 2006 CTSW's that took off and flew side by side. Real time comparisons. The other big control factor is only one mechanic.

 

Almost all aircraft that come into the shop with a digital and analog airspeed gauge don't even match.

 

 

I have tons of research on this and practical test and experience. Probably more than anyone in a CT. If someone here can duplicate all that then I'm all for. It took me about 6 months to gather this info and 14 props. I had 6 CT's with -12 for comparisons against -6 CT's. 

[Ed Cesnalis]

all that's true Roger but.  I didn't say I can precisely read my airspeed but I can pretty easily sense a 2-3 knot change.  I fly the same flights at WOT all the time and get consistent seasonal results.  Any 2-3 knot change is noticeable to me if I am flying frequently.

 

Its true you can tweak your prop pitch for such a gain only to have it overcome by conditions. 

 

I think about LoPresti speed mods and they make sense when you see them rated in improvements like +3knots but not if you look at an absolute speed like 165knots because before the speed mod any 2 Mooneys might vary 3knots or more.

 

If someone offers me a 2-3knot improvement that's big enough to consider and big enough to sense and even see in flight times.