Another way to measure fine speed changes is to set your WAAS GPS to set your distance units to Km and, whilst under AP altitude hold control in level flight, make the flap change with any trim adjustment as required and wait the 3 minutes to record the new speed.  KM/hr is more than twice as fine as Kts.

Grayhawk 

 

 

Steve,

For small deflections you can use: sin(3 deg) * (flap chord)

My flap chord at the root is 10.75", so 0.56"  - Another option is a digital level.

 

The faired-in position is pretty accurate at -7 degrees.  When I calibrated my flap position transducer, I had to make a full size template to locate 0 degrees.  The fuselage fairing ended up right at -7.0, so it is a good reference.

 

When measuring speeds greater that 120 KIAS, I recorded each point for at least three minutes. I found that it took about 2 minutes to reach a truly stabilized speed after a power or flap setting change.   The speed decay is so slow it isn't really detectable by starring at the airspeed indicator.  Imagine trying to see average needle movement of 1kt/min.  Fortunately the two minute settling time is very consistent.

 

I think it would be quite valuable and educational to repeat the same series to of tests on a small tail 320/360.  I would be more than happy to go over all the details with anyone interested in volunteering.  I think the biggest hurdle is mounting the alpha/beta probe.  I was able to grab onto the mounting provisions for my wingtip lens with a fiberglass 'lens' to mount the probe.  The internal transducers are relatively simple.

 

Chris Zavatson

N91CZ

360std

http://www.n91cz.net/

 

From: steve <n5276j@aol.com>
To: lml@lancaironline.net
Sent: Monday, September 30, 2013 5:59 AM
Subject: [LML] Re: Lancair 320/360 performance and stability

 

Chris,   I'm going to re-just my flaps to -10 reflex and see what happens. What would you guess the measurement is up from the trailing edge of the faired in position?

            Thanks for all your work. Do you need a small tail 360 for more testing?

 

Steve Alderman   N25SA

-----Original Message-----
From: Chris Zavatson <chris_zavatson@yahoo.com>
To: lml <lml@lancaironline.net>
Sent: Sun, Sep 29, 2013 8:54 pm
Subject: [LML] Re: Lancair 320/360 performance and stability

So I happened to be looking for something unrelated in the FB manual and came across this on page 10-24:

 

"Lancair flaps are full electric actuated.  They are designed to run from +45 down to -10 up (reflex).  Note that the 'faired in position' for flaps is actually a -7 deg reflex position. ....."

 

My standard build manual is in storage so I could not compare.  It would appear the intent was to be able to go to -10 degrees after all.

 

Chris Zavatson

N91CZ

360std

http://www.n91cz.net/

 

From: Christian Meier <lancair@meier.cc>
To: lml@lancaironline.net
Sent: Tuesday, September 24, 2013 3:19 AM
Subject: [LML] Re: Lancair 320/360 performance and stability

 

Chris,

 

today I made a picture during Cruise with Autopilot at 7500ft with following configuration:

770 kg  40l in header, 20l in each wing (80l total), 75kg and 83kg for pilot and co.

Flap was on 7° reflex  CG 26,20"  

My design CG is 22,8  -  30,3 from firewall back,  horizontal was installed - 0.6°

 

So it looks like if I would add more reflex than 7°, I would need more down elevator.

So the gain with the higher reflex would be lost with the down elevator....

 

Christian

 

 

 

 

 

 

 

 

 

 

--
For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html