Chris,

 

Great research.

 

In my small tailed 320, increased flap reflex experimentation did not result in increased top end speed.  The nose up pitch was increased, requiring increased nose down trim - probably resulting in greater empennage drag negating any reduction in drag from the greater reflex.  Of course, we would have to discuss the angle of incidence of the small tail and its relationship to the elevator correcting for nose down pitching ( my incidence was at -.9 degrees).

 

By moving weights forward and aft in the same flight, forward CG was better for maximizing speed - unlike some aircraft that see max speed when the CG is at the neutral point, probably a consequence of more standard wing/tail design that saw drag from wing/horizontal +/- lift factors more balanced and minimized.

 

For me, the biggest gain in speed came from adding $140 worth of gap seals to both sides of all control surface and the flaps (remember Greenameyer made his flaps part of the wing in his very fast Reno Legacy - he didn't need no stink'n flaps).  I believe that I lost no speed when I removed the upper seals from the flaps last year. The seals were curved Mylar seals often obtainable for gliders.  The gain was from 6 to 8 KIAS, depending.  Controls were more responsive and the wee rudder was effective about 5 KIAS sooner.

 

I didn't follow up on a cockpit controlled diffuser for managing cooing drag as I saw about 7" H2O upper to lower cowl at about 135 KIAS (climb speed), but 13" at 200 KIAS and such pressure was not necessary as the engine ran cool there.

 

I found the small tail had enough control - I only wanted my little engine to pull everything along as quickly as possible.

 

Scott Krueger

 

In a message dated 9/13/2013 7:32:54 A.M. Central Daylight Time, chris_zavatson@yahoo.com writes:

N91CZ has been a flying laboratory for most of this year.  Below are links to three reports that may be of interest to the Lancair community, in particular 320/360 flyers.

 

The first takes a look at the effect flap position has on total aircraft drag using the NLF(1)-0215.  The numbers are quite impressive in terms of drag coefficients.  In the end, it looks like we could benefit from a little more reflex beyond -7 degrees.

http://n91cz.com/Performance/Cruise_Flap_Report.pdf

 

The second report looks at the neutral point differences and static margins of the small and large tail 320/360 models.  A large portion of the document is a tutorial of sorts on longitudinal stability.  It deals only with static stability, but is a good lead-in to the third report.

http://n91cz.com/Stability/Lancair360_Static_Stability.pdf

 

The third report looks at the stability of the 360 MKII in much greater detail.  It include dynamic stability in both cruise and landing configurations, as well as, stick force gradients and elevator effectiveness all the way down to stall speed.

http://n91cz.com/Stability/Lancair360_Stability_and_Control_Evaluation.pdf

 

 

Chris Zavatson

N91CZ

360std

http://www.n91cz.net/

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