Sender: <marv@lancaironline.net> (Marvin Kaye)
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Date: Wed, 08 Sep 2004 15:35:42 -0400
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From: <donaldgordon@bellsouth.net>
Subject: RE: [LML] Re: MT Propellor
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Steve,

	I am running the 3-blade, electric MT propeller on my Lancair
320 with an O-320-E2D engine.  I started with an Aymar-Demuth wood
propeller.  The constant speed propeller has many advantages over the
fixed pitch propeller identified below.

	o Slower taxi speed (less residual thrust)
	o Shorter takeoff distance
	o Faster climb
	o Much faster descents (fixed pitch is RPM limited)
	o Shorter landing distance (less residual thrust)
	o Lower RPM cruise with reduced cabin noise
	o Decreased vibration (over a 2-blade propeller)

	In cruise, I am faster below 8,000 feet since I am not RPM
limited like I was on the fixed pitch propeller.  Although, the 3-blade
is theoretically less efficient than a 2-blade (a single blade propeller
is the most efficient).  I don't believe the 3-blade is significantly
slower than the 2-blade in cruise although I don't have any data to back
this up.

	The MT propeller has a wood core with a fiberglass out shell.
The wood core dampens the vibrations and provides for a smooth running
propeller.  Make sure they statically balance the propeller before they
send it to you.

	The electric propeller changes pitch slower than a hydraulic
propeller.  However, I find the pitch change speed more than adequate
for my flying.  Generally, it takes about 3 seconds to change the pitch
from 2700 RPM to 2450 RPM in cruise.  The pitch is controlled by dial on
the controller mounted in the cockpit.  A round dial with markings in
RPM up to 2700 RPM allow you to control the speed.  In addition, you can
toggle a switch on the controller and manually control the blade pitch
yourself.  In an engine-out emergency, you can manually change the pitch
to full coarse and dramatically improve your glide range, as discussed
previously on the LML list. A failure on the controller or propeller
pitch motor will leave the propeller in the last commanded position.  An
LED indicator illuminates when the propeller has reached the stops in
fine pitch.

	The installation is remarkably simple.  The hardest part of the
installation is finding real estate on your panel to mount the
controller.  You will also need a manifold pressure gauge.  However, the
controller does not interface to the MP gauge.  The controller is about
1" high by 5" wide.  The spinner is supplied with the propeller.  A slip
ring must be attached to the back on the flywheel.  Two brushes ride on
the ring supplying power to the pitch motor.  You will need to make room
in the baffling front bulkhead for the brush assembly.  The propeller
does not come with an installation manual but with a little head
scratching, you can figure it out and/or call the MT factory.

	Since I had the new seals put in the propeller, I haven't had
any problems.  I haven't flown in heavy rain so I'm not sure how the
paint will hold up.  It does have a steel leading edge which should help
with erosion problems.  The propeller has a 2000 hour TBO.  During
overhaul, they recondition the blades.  Overhaul, the last time I
checked, was about $2,500.

	You can buy your propeller direct from MT in the U.S. and
negotiate your own deal.  Contact them at:

* MT-Propeller USA, Inc. *

1180 Airport Terminal Drive
DeLand, Florida 32724
Phone: (386) 736-7762
Fax: (386) 736-7696
E-mail: mtprop@bellsouth.net


Hope this helps,


Don Gordon
Orlando, FL
Lancair 320 - N320DS (800 hours TT)
donaldgordon@bellsouth.net