Alerion Reflex?

[Skunkworks85]

All,

I was watching a video on youtube on a CTSW in the UK, What struck me as odd, as what appears to be level flight the alerion tip did not align to the droop tip like my CTSW, 

 

It appears that this CTSW has about an inch of reflex in level flight on the alerions, 

 

I know they are coupled to the flaps, and they(not US) get -12° , but I do not see how the alerion could still have this much reflex.

 

What are your guys thoughts?

 

 

 

 

[GrassStripFlyBoy]

Interesting point.  I looked at that channel and they have videos on another SW as well as a 2K model.  This airplane is an 07 registration G-CEKD, and on another video it shows an IAS of ~ 96N  at power setting of 4420 rpm, looks rather level in the video but VSI might be in decent.

[Skunkworks85]

On 10/15/2020 at 1:06 PM, GrassStripFlyBoy said:

Interesting point.  I looked at that channel and they have videos on another SW as well as a 2K model.  This airplane is an 07 registration G-CEKD, and on another video it shows an IAS of ~ 96N  at power setting of 4420 rpm, looks rather level in the video but VSI might be in decent.

Vertical speed shows about a 700 fpm decent.

I know Rodger preaches that -12 flaps does not add much. But if the coupling mechanism is different on the EU airframes, and reflexes the ailerons more than LSA airframes, I wonder if that is where the claimed higher cruise speeds come from.

 

 

[Roger Lee]

I've run 4 CT's with -12. The mechanisms inside are the same and only need a little adjustment to allow the extra angle. It isn't worth it.

[GrassStripFlyBoy]

I once ran flaps manually beyond the -6 setting, did not measure what angle they became but estimate -9 to -10 range, it was a few degrees by eye.  At altitude cruising along, slowed and cranked into manual full up setting, and resumed same power setting, and maybe 2 - 3 knot increase in cruise.  Not enough gain to ever go back into the manual full up mode.

[Roger Lee]

If your plane is set up for -6 it can not physically go past about -7 / -8 because of the restricting limit cable inside even if you're in manual. The cable will prevent it from going past its limit.

Plus -12 makes it harder to hold altitude when flying high at 11K+ when you have a heavier load. I've had to fly in zero at times at high altitudes with a plane that has -12. This cable is one item that has to be relocated to get any additional movement.

[GrassStripFlyBoy]

As it's been many months since I investigated this, I went out to hanger and ran the flaps.  Not busting out a protractor here, simple high level visual observations.  0 degrees aligns the flap edge to the inboard fuselage detail, raising to -6 the edge goes up what appears to be around ~ inch +/-

Leaving at the standard -6 switch detent setting, shut off battery switch, adjust flap control to manual neutral setting, battery back on, then driving to max up.  The flap edge goes up nearly an equivalent amount further up from the fuselage detail.  When aligning the ailerons to neutral nearly all the trailing edges of ailerons and flaps then become darn near a straight line with the wing tip details.

Now, I'm not looking to use manual flaps and fly around like this, sort of curiosity here.  In aircraft with 12 degree flaps, do all trailing edges align with the wing tip detail, or do they drive up further beyond the droop detail as shown in the initial post in trail here?

[gorilla]

Hi Darrell,

With my 2006 UK CTSW on -12 flap and flying so that the ailerons are completely symmetrical, both ailerons are slightly higher than the edges of the flaps at the flap/aileron junction when viewed from inside the cockpit and flying at 100 knots.  In solo flying mode, I find my aircraft rolls very, very slowly to the left.  I counter this with a miniscule amount of pressure on the stick to the right - usually with my left thigh or I just use a gnat's whisker of right rudder every now and again to get back on track.  In the UK, we do not have the luxury of an aileron trimmer! 

With a passenger, the aircraft tracks as straight as an arrow with the ailerons in that same symmetrical position.

  

[Madhatter]

I have done a lot of rigging over the years, all planes are different.  My CT when the ailerons are level it significantly. rolls to the right. To compensate for this when all else is correct the flaps are slightly adjusted to compensate for the roll. A lot of CT'S were hand built and even a small difference will show up in flight. This is routine on aircraft with no adjustment capability for angle of incidence.  On a low wing plane a slight down angle on the ailerons will actually give a slight speed increase. Rigging takes time and is trial and error. 

[FlyingMonkey]

Good point, rigging is important.  All airplanes are essentially hand-built, and different wings on the same airplane can have small variations in dihedral, washout, etc.  Control rods that are supposed to be symmetrical can have a millimeter or two (or more!) different lengths.  Control cables can have different tensions, or tensions far off factory spec.

Assuming no gross mechanical defects, I'd more concern myself with how the airplane flies and handles than where the surfaces sit in level flight.  Many RVs and other types have a flap intentionally run a rod end turn or two out on one side to compensate for a heavy wing.  Sure it's adds drag,  but it sure beats having the airplane always trying to fly in a circle! 

[sandpiper]

On 10/17/2020 at 3:42 AM, GrassStripFlyBoy said:

I once ran flaps manually beyond the -6 setting, did not measure what angle they became but estimate -9 to -10 range, it was a few degrees by eye.  At altitude cruising along, slowed and cranked into manual full up setting, and resumed same power setting, and maybe 2 - 3 knot increase in cruise.  Not enough gain to ever go back into the manual full up mode.

I have played with this a few times over 14 years of ownership. Consistently gives 2-3 KIAS increase. In a 4 hour flight this would put you 12 NM further along max. That's about 6 minutes. Not enough to make much difference and since most of my flights are way less than 4 hours............

The only time I put it to practical use was when trying to keep up with a neighbors RV-12. Wasn't much good then, either.

[Madhatter]

Many years ago there was a company that guaranteed a 20 mph increase in speed on a beechcraft bonanza. It was done primarily by extensive rerigging and flown for many hours and also using a chase plane to analyze control positions. It worked but was expensive. There were a few aerodynamic mods but it was mostly rerigging.