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From: Sky2high@aol.com
Full-name: Sky2high
Message-ID: <3814d.12cf3414.3e4ec969@aol.com>
Date: Thu, 14 Feb 2013 18:12:42 -0500 (EST)
Subject: Re: [LML] Full feather prop vs high pitch
To: lml@lancaironline.net
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Ron, 
 
Other than fancy-dancy airpanes, consider these conditions for a single  NA 
engine aircraft equipped with a non-feathering  and non-electric constant 
speed prop controlled by engine oil pressure  boosted by a governor:
 
1 Engine loses power, oil system intact.  Slowly rotating prop keeps  
governed oil pressure high enough to allow it to remain in coarse pitch if  so 
selected.  OK and a significant reduction in drag (for slick  airplanes).  May 
be able to restart engine.
 
2. Engine loses oil while still generating power.  After a short time  of 
operating without oil (pilot leaves power in to extend range), the  engine 
seizes and prop is stopped in flat pitch.  OK, but less OK as drag  is 
significantly less that a windmilling prop but somewhat more than  a coarse pitched 
rotating prop.
 
3. Engine loses oil and power allowing the flat pitched prop to  windmill - 
just like a fixed pitch prop.  Not OK. No where to go but  down rapidly....
 
But during failures, problems 1 or 2 are most likely with 3 a  rarity.  
Such a CS prop is a reasonable cost vs risk and  weight choice.  Everything is 
a compromise.
 
Grayhawk
 
 
In a message dated 2/14/2013 4:38:21 P.M. Central Standard Time,  
cfi@instructor.net writes:

It seems the  discussion on the full feathering prop and non full 
feathering prop vs drag  has kind of missed the whole point behind the full 
feathering prop.  The  full feathering prop will go to full feather when you lose all 
oil pressure,  and the standard prop will go to minimum pitch (high drag) 
configuration with  the lose of oil pressure.  The Prop governors work 
opposite and are not  interchangeable.  The best of both worlds is the "counter 
weighted"  prop.  This prop goes to full coarse pitch with the loss of oil 
pressure  and uses the same gov. at the full feathering prop.  I have the 4 
blade  MT Prop counter weighted and I know Brent Regan and Bob Pastusek have 
them as  well as others, but I'd bet most of the folks out there didn't even 
know they  existed. 
I will be very interested to see how the full reversing prop  works that 
Ronald just ordered.  I'm sure you can go full feather as well  as reverse and 
even if it takes a few seconds to get to reverse, in most cases  this would 
be enough time say in case there was ice on the runway.  It's  always very 
handy to back up from time to time too.  The weight of the  reversing prop 
will be quite a bit lighter than the full feather metal prop  though, so 
there might be some W&B issues in a  IVP. 

Ron

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<DIV>Ron, </DIV>
<DIV>&nbsp;</DIV>
<DIV>Other than fancy-dancy airpanes, consider these conditions for a singl=
e=20
NA&nbsp;engine&nbsp;aircraft equipped with a&nbsp;non-feathering=20
and&nbsp;non-electric&nbsp;constant speed prop controlled by engine oil pre=
ssure=20
boosted by a&nbsp;governor:</DIV>
<DIV>&nbsp;</DIV>
<DIV>1 Engine loses power, oil system intact.&nbsp; Slowly rotating prop ke=
eps=20
governed&nbsp;oil pressure high enough to allow it to remain in coarse pitc=
h if=20
so selected.&nbsp;&nbsp;OK and a significant reduction in drag (for slick=
=20
airplanes).&nbsp; May be able to restart engine.</DIV>
<DIV>&nbsp;</DIV>
<DIV>2. Engine loses oil while still generating power.&nbsp; After a short =
time=20
of&nbsp;operating without oil (pilot leaves power in to extend range), the=
=20
engine seizes and prop is stopped in flat pitch.&nbsp; OK, but less OK as d=
rag=20
is significantly less that a windmilling prop but somewhat more than=20
a&nbsp;coarse pitched rotating&nbsp;prop.</DIV>
<DIV>&nbsp;</DIV>
<DIV>3. Engine loses oil and power allowing the flat pitched&nbsp;prop to=
=20
windmill - just like a fixed pitch prop.&nbsp; Not OK.&nbsp;No where to go =
but=20
down rapidly....</DIV>
<DIV>&nbsp;</DIV>
<DIV>But during failures, problems 1 or 2 are most likely with 3 a=20
rarity.&nbsp;&nbsp;Such a&nbsp;CS prop&nbsp;is a reasonable cost vs risk an=
d=20
weight choice.&nbsp; Everything is a compromise.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Grayhawk</DIV>
<DIV>&nbsp;</DIV>
<DIV>
<DIV>In a message dated 2/14/2013 4:38:21 P.M. Central Standard Time,=20
cfi@instructor.net writes:</DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: blue 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px">=
<FONT=20
  style=3D"BACKGROUND-COLOR: transparent" color=3D#000000 size=3D2 face=3DV=
erdana><SPAN=20
  style=3D"FONT-FAMILY: Verdana"><SPAN style=3D"FONT-SIZE: 12px">It seems t=
he=20
  discussion on the full feathering prop and non full feathering prop vs dr=
ag=20
  has kind of missed the whole point behind the full feathering prop.&nbsp;=
 The=20
  full feathering prop will go to full feather when you lose all oil pressu=
re,=20
  and the standard prop will go to minimum pitch (high drag) configuration =
with=20
  the lose of oil pressure.&nbsp; The Prop governors work opposite and are =
not=20
  interchangeable.&nbsp; The best of both worlds is the "counter weighted"=
=20
  prop.&nbsp; This prop goes to full coarse pitch with the loss of oil pres=
sure=20
  and uses the same gov. at the full feathering prop.&nbsp; I have the 4 bl=
ade=20
  MT Prop counter weighted and I know Brent Regan and Bob Pastusek have the=
m as=20
  well as others, but I'd bet most of the folks out there didn't even know =
they=20
  existed.&nbsp;<BR>I will be very interested to see how the full reversing=
 prop=20
  works that Ronald just ordered.&nbsp; I'm sure you can go full feather as=
 well=20
  as reverse and even if it takes a few seconds to get to reverse, in most =
cases=20
  this would be enough time say in case there was ice on the runway.&nbsp; =
It's=20
  always very handy to back up from time to time too.&nbsp; The weight of t=
he=20
  reversing prop will be quite a bit lighter than the full feather metal pr=
op=20
  though, so there might be some W&amp;B issues in a=20
  IVP.&nbsp;<BR><BR>Ron</SPAN></SPAN></FONT></BLOCKQUOTE></DIV></FONT></BOD=
Y></HTML>
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