Re: stall indicator - Phil's response


One Sky Dog
 

In a message dated 11/1/2006 9:34:01 PM Mountain Standard Time,
britmcman@... writes:





In a message dated 10/30/2006 6:23:53 P.M. Pacific Standard Time,
_dmperry1012@dmperry1012_ (mailto:dmperry1012@...) writes:

I don't really understand why anyone wants
to install an AOA or a stall indicator of any type on a Quickie or Q-2xx
other than curiosity

I 'll take this one. Mike, I always wanted to know precisely what was the
best L/D glide angle as a glider aircraft. In the event of any "engine out"
scenario, one could hypothetically set up on best angle of attack and thus
be
at an optimum condition for flying the farthest distance over the ground
regardless of weight conditions. I suspect that the best glide speed may
vary
based on how the aircraft is loaded. If the aircraft is loaded to about 900
pounds the best glide may be some amount faster or slower than if the
aircraft
is loaded to 1350. Regardless of what the aircraft load happens to be, the
pilot could set upon best angle and have the greatest opportunity to make a
greater radius to a potential field.

I experienced a broken prop at 9500' MSL (9000 AGL). By the time I found
nearest airport, it was still about 12 NM out. I wished I had such a tool.

Cheers,

Phil
N87TQ Tri-Q
Q-2 Rev






Phil,

Every angle of attack coresponds to a paticular airspeed in a steady state
calm atmosphere.

The L/D of your airplane does not change due to weight. If you have 10 to 1
and are loaded heavier then the sink speed increases and the forward speed
increases. So if you run trial glides at minimun loading and gross weight you
have two speeds that are your best L/D speeds. They are not that far apart any
spam can POH has the numbers so you can go to your local FBO and read a few
in the book stor area and get a feel for the speed differences due to load. A
Cessna 152 is 65 mph if I recall right. My Dragonfly and most other
Dragonflies the best L/D is at 100 mph. It is very close to Vy climbout speed on most
planes.

How far you are going to get depends a lot on which way the wind is blowing
and wheather your in a high pressure or low pressure area. If your trying to
make an airport upwind in a high pressure area you are not going to go very
far even if you have a good L/D and you need to fly faster than best L/D.
Conversly if you are flying downwind to the airport in a low pressure area you
want to fly slower than best L/D like at minimum sink speed. Those are the 2
extreems in actual conditions you will experiance everything in between. A L/D
meter is not a substitute for glider experiance when the engine qiuts or the
prop flys off.

Regards,

One Sky Dog

500 hours unpowered, 500 more underpowered

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