MT Props w/Electric Pitch Control

Anyone care to comment on using one of MT's composite blade props with
electric pitch control?

Eggenfellner seems to really want you to use this prop with his Subaru
setup.

I'm a bit concerned both with a composite prop and an electric pitch
control.

On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote:

Anyone care to comment on using one of MT's composite blade props with
electric pitch control?

Eggenfellner seems to really want you to use this prop with his Subaru
setup.

I'm a bit concerned both with a composite prop and an electric pitch
control.


I don't think there's anything wrong with a properly made composite
prop, and MT is one of better known prop manufacturers. They make
LOTS of props, many of them for certified airplanes.

What's your specific concern?

Corky Scott

On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote:

Anyone care to comment on using one of MT's composite blade props with
electric pitch control?

Eggenfellner seems to really want you to use this prop with his Subaru
setup.

I'm a bit concerned both with a composite prop and an electric pitch
control.
++++++++++++++++++++++++++++++++++

snort

You worry about the wrong end of the propulsion system.
Get your priorities straight.

Be far, far more concerned with the Soob application..

Signed,
N.E. Juan

"Corky Scott" wrote in message
...
On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote:

Anyone care to comment on using one of MT's composite blade props with
electric pitch control?

Eggenfellner seems to really want you to use this prop with his Subaru
setup.

I'm a bit concerned both with a composite prop and an electric pitch
control.


I don't think there's anything wrong with a properly made composite
prop, and MT is one of better known prop manufacturers. They make
LOTS of props, many of them for certified airplanes.

What's your specific concern?

Corky Scott

I don't know anything about using composite construction for a propeller. I
do know a little about fiberglass and carbon fiber composite, just from an
"educated layman" point of view. So bearing that in mind, I would be
worried about:

1) Would continual flex/unflex cause fatigue and how would you detect it if
it's internal? (I think in the research environment they basically CAT scan
parts to look for internal fatigue?)
2) How could you tell a trivial rock ding from a potentially disastrous one
(again, hard to see what's inside)?

Again, I'm not all all claiming these things happen, I just am asking if
people know of any gotchas. Of course, there are lots of testimonials that
basically say "I've had mine for X years and it hasn't broken yet", but
that's not really data.

Secondly, does the electric system work automatically (so that you don't do
anything), or is there a control that works like manifold pressure (i.e.
"governed" so that changes in RPM cause automatic changes in blade pitch),
or is there just a blade pitch control? Why would it be better/worse than
hydraulic?

Does anyone out there have one who can ring in on this?

I can tell you that they make composite props for military applications that
include dirt strip transport planes ( I think some C130's are using MT's ).

A composite prop is not like a composite wing. What you see is what you
get. There is no wondering what stresses are going on inside anymore than
there is with a metal prop. Most dings can be fixed by filling up and
building up with epoxy, then sanding. If the ding meets a certain size,
then it has to be inspected by MT or someone specially trained.

Advantages of composite props are reduced weight and noise along with a
shock absorbing kind of flex. Disadvantages are that little dings that
would only scratch a metal prop will require epoxy repairs (but they are
easy and cheap repairs.

Given that most homebuilts will never fly enough hours to make a difference
in the maintenance costs, the MT is not a bad idea at all. Mine is smooth
and quiet, and I like it.



"x" wrote in message news:TcIac.45575$gA5.568680@attbi_s03...
"Corky Scott" wrote in message
...
On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote:

Anyone care to comment on using one of MT's composite blade props with
electric pitch control?

Eggenfellner seems to really want you to use this prop with his Subaru
setup.

I'm a bit concerned both with a composite prop and an electric pitch
control.


I don't think there's anything wrong with a properly made composite
prop, and MT is one of better known prop manufacturers. They make
LOTS of props, many of them for certified airplanes.

What's your specific concern?

Corky Scott

I don't know anything about using composite construction for a propeller.
I
do know a little about fiberglass and carbon fiber composite, just from an
"educated layman" point of view. So bearing that in mind, I would be
worried about:

1) Would continual flex/unflex cause fatigue and how would you detect it
if
it's internal? (I think in the research environment they basically CAT
scan
parts to look for internal fatigue?)
2) How could you tell a trivial rock ding from a potentially disastrous
one
(again, hard to see what's inside)?

Again, I'm not all all claiming these things happen, I just am asking if
people know of any gotchas. Of course, there are lots of testimonials
that
basically say "I've had mine for X years and it hasn't broken yet", but
that's not really data.

Secondly, does the electric system work automatically (so that you don't
do
anything), or is there a control that works like manifold pressure (i.e.
"governed" so that changes in RPM cause automatic changes in blade pitch),
or is there just a blade pitch control? Why would it be better/worse than
hydraulic?

Does anyone out there have one who can ring in on this?

We are an MT dealer and have sold quite a few of the electric controlled units
along with a bunch of hydraulic standard and aerobatic as well as a few fully
reversable units. The props are by far first rate pieces with more engineering
behind them than most auto conversions or kit airframe designs. We have worked
with MT to obtain STC's for props on certified airplanes and I was amazed at
the huge amount of data they gather for every prop they build. The build the
props we recommned for our kit aircraft as well as have built special one of a
kind props for us.

The blades are wood core with a special high strength compressed wood at the
root. The blades are epoxy glass covered and have stainless steel leading
edges bonded to them for errosion protection. The blades are extremely duarble
and approved for flight in rain. The wooden core have near limitless fatique
cycle.

The electric control unit is a panel mounted device with a display and knob
used to set the desired RPM much like the Beech electric prop we had on our old
bonanza. IT works as any constant speed prop to hold the RPM at the pilot
selected point.

Feel free to email me directly if I can answer any other questions for you.

Kevin Kimball

On Wed, 31 Mar 2004 23:09:43 GMT, "x" wrote:

"Corky Scott" wrote in message
...
On Wed, 31 Mar 2004 19:51:59 GMT, "x" wrote:

Anyone care to comment on using one of MT's composite blade props with
electric pitch control?

Eggenfellner seems to really want you to use this prop with his Subaru
setup.

I'm a bit concerned both with a composite prop and an electric pitch
control.


I don't think there's anything wrong with a properly made composite
prop, and MT is one of better known prop manufacturers. They make
LOTS of props, many of them for certified airplanes.

What's your specific concern?

Corky Scott

I don't know anything about using composite construction for a propeller. I
do know a little about fiberglass and carbon fiber composite, just from an
"educated layman" point of view. So bearing that in mind, I would be
worried about:

1) Would continual flex/unflex cause fatigue and how would you detect it if
it's internal? (I think in the research environment they basically CAT scan
parts to look for internal fatigue?)
2) How could you tell a trivial rock ding from a potentially disastrous one
(again, hard to see what's inside)?

Again, I'm not all all claiming these things happen, I just am asking if
people know of any gotchas. Of course, there are lots of testimonials that
basically say "I've had mine for X years and it hasn't broken yet", but
that's not really data.

There are a number of businesses making composite props in the world
today, some of them making props for extreme aviation endeavors. MT
and Hoffman make composite props that are used in unlimited aerobatic
competitiions. In the world of props, metal props are the most
dangerous in that they can and do vibrate in sympathy with the engine
harmonics and can rapidly fatigue and fail. Some conditions are so
dangerous that the airplane/engine/prop combination has a plackard
requiring that the pilot avoid operations at a specific rpm. Wooden
props are at the other end of the spectrum, they actually deaden
vibrations. Composite props are somewhere in between those two
extremes. MT and Hoffman are big time players in the world of
certified and experimental props, and their prices reflect that.

Secondly, does the electric system work automatically (so that you don't do
anything), or is there a control that works like manifold pressure (i.e.
"governed" so that changes in RPM cause automatic changes in blade pitch),
or is there just a blade pitch control? Why would it be better/worse than
hydraulic?

Does anyone out there have one who can ring in on this?

Electrically controlled props may or may not also be governed. Some
just adjust pitch, others adjust pitch and govern rpm. If you have an
electric adjustable prop in mind, the best thing to do would be to ask
the vendor what it's designed to do.

Corky Scott