LMLers,

 

During flight testing of my 320 several years ago, I collected glide ratio data for 3 different configurations as you can see below in the copy of the spreadsheet where I keep this data.

 

Config	Flaps	Gear	Prop	Decent Rate	KIAS	Glide Ratio
Cruise/low drag	up	up	low RPM	600	103	17.3
Approach/low drag	10 deg	down	low RPM	1300	92	7.1
Approach/high drag	10 deg	down	high RPM	1900	92	4.9
NOTES:
	Test aircraft is Lancair 320 MKII, N320DK, owned and flown by Dan Olsen on 8/10/04
	Engine is Lycoming IO-320-D1B, stock, 160hp
	Prop is Hartzell HC-F2YL-8468-14D
	Engine power set to idle (not completely shut off)
	Empty weight		1142
	Pilot		195
	Fuel (36gal)		216
	Baggage		20
	Gross Weight		1573
	Test altitude was 7500' - 9500'
	Aircraft was flown with Jim Frantz's AOA Pro at the best glide AOA and KIAS was then noted

 

It is quite alarming to see the incredible difference between a clean, max glide config and a normal approach to landing config.  Glide ratio goes from 17:1 down to 5:1.  I remember speaking with Orin Riddel at the Lancair factory years ago and him describing that if you were on downwind, abeam the numbers, and your engine quit and you left it in the high-drag congif, you will not make the runway.  First reaction should be to immediately retract the gear, low RPM on the prop and get the flaps up.

 

I practice this scenario regularly and I can always make the runway with the main issue typically being that I land long and have to turn up the RPM to add drag on short final:

·         Fly normal downwind

·         Chop the throttle to dead idle on downwind

·         Low RPM (coarse pitch)

·         Gear and flaps up

·         Pitch for best L/D on the AOA

·         Fly the pattern (tighter than normal)

·         On short final when runway is assured, drop the gear and 10deg flaps

·         Add flaps and increase RPM, as necessary, to avoid landing dangerously long

 

I encourage all Lancair drivers to get some experience with your plane in the various drag scenarios with the engine at idle, especially the dramatic difference that flat vs. coarse pitch on your prop makes.  There is nothing like feeling it for real to teach you some of the “muscle memory” needed to react in a pinch.

 

Upon departing OSH a few weeks ago, I wanted to fly across Lake Michigan to visit my daughter.  Going around is very long and going over is very scary J  So, I was able to take the knowledge from actual glide testing of my 320 to create the following table to show how high above the water I need to be in order to glide to the shore in the case of engine failure at the middle of the lake.  The area of the lake I went across was about 60nm across, so 30nm from center to shore.

 

		Lancair 320
		N320DK
		Glide Ratio
		17	15	12	10	8	7	5
Distance to Glide (nm)	50	17,871	20,253	25,317	30,380	37,975	43,400	60,760
	45	16,084	18,228	22,785	27,342	34,178	39,060	54,684
	40	14,296	16,203	20,253	24,304	30,380	34,720	48,608
	35	12,509	14,177	17,722	21,266	26,583	30,380	42,532
	30	10,722	12,152	15,190	18,228	22,785	26,040	36,456
	25	8,935	10,127	12,658	15,190	18,988	21,700	30,380
	20	7,148	8,101	10,127	12,152	15,190	17,360	24,304
	15	5,361	6,076	7,595	9,114	11,393	13,020	18,228
	10	3,574	4,051	5,063	6,076	7,595	8,680	12,152
	5	1,787	2,025	2,532	3,038	3,798	4,340	6,076
	1	357	405	506	608	760	868	1,215
			Clean Low RPM				Landing Low RPM	Landing High RPM

 

My table shows about 12,500’ above the water (approx. 13,500’ MSL) would get me to the shore (to be conservative I used a 15:1 glide ratio even though my testing showed 17:1 because the engine was still producing minimal power during the test).  So, with approved floatation gear donned, we charged across at 15,500’, giving us a good 5nm of buffer to account for extra weight and other fudge factors.

 

I hope this data is helpful to some of you and encouraging to others to go do this testing and practice engine-out procedures in your Lancair.

 

Regards,

 

Dan Olsen

N320DK – 750 hrs

IV-P in gestation