[rebel-builders] SR-2500 Prop Location
Posted: Sun Feb 19, 2012 4:31 pm
Thank you!
Cheers!
Jacques Dionne
283SR
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Mike Kimball
Sent: Friday, March 14, 2008 3:16 AM
To: Rebel Builder's List
Subject: [rebel-builders] SR-2500 Prop Location
I finally got the SR-2500 prop location info from MAM uploaded to the
SR/Moose - Misc section of the archives. MAM passed on another tidbit
that
was crucial in building the engine mount. They told me that in addition
to
the thrust location shown on the drawing, the thrust vector should be
slightly to the right and down. OK. How much? They told me they used
a
3/8 spacer (of some sort) in the upper, left (pilot's side) engine mount
location on the firewall. A little math gave me a 0.55 degree offset to
the
right and a 0.91 degree offset down. The mount was built with these
offsets
in place. The mount was built with the entire engine rotated
appropriately,
keeping the C of G in the middle. In addition, there are lots of
dimensions
identifying the location of all four firewall engine mount locations
among
other things. After my firewall was riveted in place I double checked
those
measurements. Mine was very close but there were a couple of
measurements
that were slightly off. I'm talking 1/32, or 1/16 off in a couple of
places. Tiny, but taken into account when making a firewall mockup out
of
steel plate to begin the mount construction. Lastly, the engine C of G
location for the Chevy is different than what's identified on the
drawing.
I found the C of G (fore and aft) by the simple means of balancing the
engine on a piece of tubing on a table. Not precise, but precise
enough.
The good news is that the C of G of my Chevy is about 3 inches closer to
the
firewall than the Lycoming even with a generous amount of space between
the
water pump and the firewall, helping to offset the greater weight.
I also did a huge amount of research on Lord mounts. I finally settled
on
one that is used in an aerobatic airplane used by a Canadian team with
as
much horsepower as my plane and regularly pulling unbelievable Gs. I
don't
have the part number handy, nor do I remember the plane it is used in,
but I
can dig out that information if anybody is interested. One nice thing
about
the Lord mounts I chose is that both halves are the same and they are
oriented vertically, one above the other. The weight of the engine
rests on
the lower half with the upper half not doing much of anything unless I
fly
poorly and exert lateral forces on them. If I manage to fly the plane
enough to start wearing out the bottom ones I can probably just switch
them
around. I believe there are Lord mounts where one half is different
than
the other and you must get them in right and can't swap them later.
Everything came together very well. Because of troubles I've run into I
have had the unfortunate experience removing and later remounting the
engine
twice now. Performing this feat on the tarmac using an automotive
engine
hoist takes less than three hours for removal and the same to remount,
including cowl removal/replacement and all hookups. It's a good thing
the
plane isn't an inch taller or my engine hoist wouldn't reach high
enough.
:-)
Mike
-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------
-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------
Cheers!
Jacques Dionne
283SR
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Mike Kimball
Sent: Friday, March 14, 2008 3:16 AM
To: Rebel Builder's List
Subject: [rebel-builders] SR-2500 Prop Location
I finally got the SR-2500 prop location info from MAM uploaded to the
SR/Moose - Misc section of the archives. MAM passed on another tidbit
that
was crucial in building the engine mount. They told me that in addition
to
the thrust location shown on the drawing, the thrust vector should be
slightly to the right and down. OK. How much? They told me they used
a
3/8 spacer (of some sort) in the upper, left (pilot's side) engine mount
location on the firewall. A little math gave me a 0.55 degree offset to
the
right and a 0.91 degree offset down. The mount was built with these
offsets
in place. The mount was built with the entire engine rotated
appropriately,
keeping the C of G in the middle. In addition, there are lots of
dimensions
identifying the location of all four firewall engine mount locations
among
other things. After my firewall was riveted in place I double checked
those
measurements. Mine was very close but there were a couple of
measurements
that were slightly off. I'm talking 1/32, or 1/16 off in a couple of
places. Tiny, but taken into account when making a firewall mockup out
of
steel plate to begin the mount construction. Lastly, the engine C of G
location for the Chevy is different than what's identified on the
drawing.
I found the C of G (fore and aft) by the simple means of balancing the
engine on a piece of tubing on a table. Not precise, but precise
enough.
The good news is that the C of G of my Chevy is about 3 inches closer to
the
firewall than the Lycoming even with a generous amount of space between
the
water pump and the firewall, helping to offset the greater weight.
I also did a huge amount of research on Lord mounts. I finally settled
on
one that is used in an aerobatic airplane used by a Canadian team with
as
much horsepower as my plane and regularly pulling unbelievable Gs. I
don't
have the part number handy, nor do I remember the plane it is used in,
but I
can dig out that information if anybody is interested. One nice thing
about
the Lord mounts I chose is that both halves are the same and they are
oriented vertically, one above the other. The weight of the engine
rests on
the lower half with the upper half not doing much of anything unless I
fly
poorly and exert lateral forces on them. If I manage to fly the plane
enough to start wearing out the bottom ones I can probably just switch
them
around. I believe there are Lord mounts where one half is different
than
the other and you must get them in right and can't swap them later.
Everything came together very well. Because of troubles I've run into I
have had the unfortunate experience removing and later remounting the
engine
twice now. Performing this feat on the tarmac using an automotive
engine
hoist takes less than three hours for removal and the same to remount,
including cowl removal/replacement and all hookups. It's a good thing
the
plane isn't an inch taller or my engine hoist wouldn't reach high
enough.
:-)
Mike
-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------
-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------