lml@lancaironline.net Mailing List Archive

In a message dated 4/13/2005 12:47:04 A.M. Central Standard Time, JIMRHER@aol.com writes:

I have the MT 4 Blade on my L4P. the difference in vertical decent with the engine at idle and going form Fine pitch to Course pitch is 3500 fpm. A giant difference. With the 4 blade it is like a brake at fine pitch. However, others have told me that at course pitch they calculated a glide ratio of up to 25 to One. amazing but the speed it up there. I needed a glide number to put in the SFS EFIS because it shows a blue glide range around the airplane, corrected for wind and terrain. We all agreed on a more realistic 15 to One.

Jim,

Interesting. In my Lancair 320 with a Hartzell 2-blade CS prop, at flat pitch and a 1500 fpm descent with a best glide of 107 KIAS (10836 fpm) the ratio is 7.2:1 and at coarse pitch, the 500 fpm descent is a 21:1 ratio. Being generally befuddled and brain weak, I use a conservative rule of thumb of 10:1 (assuming that I can get it into coarse pitch most of the time), thus flying at 5500 AGL should give me about 10 NM to find something level or soft.

Hmmmm........, maybe I can cross Lake Michigan at 15,000 MSL yielding enough glide range to handle the 25 NM to the point of no return if I fly from Manitowoc to Luddington routed from land bulge to land bulge. Once back to the shoreline, the beach becomes a touchdown possibility. Nah.... It's more comforting to fly the shoreline at the south end.

Scott Krueger AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL (KARR)

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