Date: Wed, 25 Aug 2010 16:00:04 -0800
From: rebel-builders-d@dcsol.com
Subject: [rebel-builders-d] DIGEST - rebel-builders-d
To: rebel-builders-d@dcsol.com
Digest of list: rebel-builders-d Total messages in digest: 5
1 Date : Tue, 24 Aug 2010 20:33:27 -0400
From : g.alan.hepburn@gmail.com
Subject: RE: [rebel-builders] ATTENTION All Murphy Elite Operators: Cracks Found
2 Date : Tue, 24 Aug 2010 20:10:58 -0800
From : kpierson@dcsol.com
Subject: Re: [rebel-builders] Elevator deflection angle
3 Date : Tue, 24 Aug 2010 20:17:27 -0800
From : kpierson@dcsol.com
Subject: Re: [rebel-builders] Motor mount
4 Date : Wed, 25 Aug 2010 08:09:45 -0400
From : klehman@albedo.net
Subject: Re: [rebel-builders] Elevator deflection angle
5 Date : Wed, 25 Aug 2010 10:39:39 -0700
From : rshannon@cruzcom.com
Subject: Re: [rebel-builders] Elevator deflection angle
---------- Digest Message #1 ----------
Date: Tue, 24 Aug 2010 20:33:27 -0400
From: g.alan.hepburn@gmail.com
To: rebel-builders
Subject: RE: [rebel-builders] ATTENTION All Murphy Elite Operators: Cracks Found
Checked my Elite. No sign of any cracks. Total time is 130 hrs.
Al Hepburn
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of John &
Lee
Sent: Sunday, August 22, 2010 2:57 PM
To: rebel-builders@dcsol.com
Cc: murtech; kits
Subject: [rebel-builders] ATTENTION All Murphy Elite Operators: Cracks Found
In Horizontal Stab
Service Difficulty Report:
Date: 21 August 2010
Model: Murphy Elite
Serial #: 549
Built: 2004
TTSN: 273 Hours
Damage History: None, all time on wheels (tail dragger) except last 33 hours
on Murphy 1800 amphibs (installed end of June 2010).
Preliminary Findings:
Cracks were found during pre-flight (21 Aug 2010) beside both the left and
right outboard elevator hinges. Some appear to be hairline fractures in the
rear spar extending from the outboard hinge bolt holes to the outboard edge
of the horizontal stabilizer rear spar. The hairlines were difficult to
detect without a magnifying glass. I routinely applied spray lubrication
to the hinges, and this (plus dirt accumulation) covered over some, but not
all of the cracks. After removing some lubricant from the area, I
took photographs and have posted them at
http://www.dcsol.com/murphy-rebel/ under
Files>Elite>301 E-Horizontal Stab.
Murphy Aircraft Mfg Ltd Technical Support and Patterson Aero Sales were
advised on 21 August and photographs were sent to them (awaiting action by
Murphy Mfg Ltd.). I tried to list findings at Transport Canada's Service
Difficulty Reports Web Site but was unsuccessful.
Has anyone else found something similar? I am in the process of hiring an
AME to work with me to conduct some disassembly and further inspection work
this coming week. I will provide further inspection findings when I am
able.
Take Care
John Garstang
Ladysmith, BC
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---------- Digest Message #2 ----------
Date: Tue, 24 Aug 2010 20:10:58 -0800
From: kpierson@dcsol.com
To: rshannon@cruzcom.com
Subject: Re: [rebel-builders] Elevator deflection angle
Ron: Thank you for your response to my inquiry, although I'm glad
to receive that information, but to have a stabilizer with a nose up
attitude goes aginst everything that I have ever learned about
stabilizers, but I'll work with it.
Keith P.
On 8/23/2010 3:48 PM, rshannon@cruzcom.com wrote to rebel-builders:
-> The manual calls for 1 deg. up angle of incidence, so you're probably in the
-> ballpark. Some have used less.
->
-> Ron
-> N254MR
->
-> On Mon, Aug 23, 2010 at 1:01 PM, <kpierson@dcsol.com> wrote:
->
-> > Recently while trying to figure out the thrust angle for a motor mount
-> > I measured the horizontal stabilitor and found that it was 1.5* NOSE UP
-> > when the airframe is level. Are all Rebels built that way, or was mine
-> > put together wrong?
-> >
-> >
->
---------- Digest Message #3 ----------
Date: Tue, 24 Aug 2010 20:17:27 -0800
From: kpierson@dcsol.com
To: klehman@albedo.net
Subject: Re: [rebel-builders] Motor mount
Ken: Thanks for that information, I'll try to look in the archives
Keith P.
On 8/24/2010 1:56 PM, klehman@albedo.net wrote to rebel-builders:
-> Keith
->
-> I dug up a MAM diagram for the 0-235 and I believe it is the same mount
-> for the 0-320. It shows one degree of right offset and zero down thrust.
->
-> However you might check to see if I put anything in the archives (as I
-> often do) about 8 years ago. Reason is because I measured a conical
-> mount and my less than perfect memory recalls 1 or 2 degrees of right
-> offset and 1 or 2 degrees of downthrust. I can't find anything
-> definitive in my notes. For low power cruise with the soob and wing
-> cuff, the down thrust and offset was a good thing to put in my mount
-> from what I've seen. However I would not hesitate to use 1 or 2 offset
-> and zero downthrust if I was building an 0-320 mount.
->
-> If guys are cruising your configuration with the top of the door opening
-> level then I think that would confirm zero downthrust is perfect. I
-> would aim for the thrust line level when cruising with whatever reflex
-> flaperon you expect to use. So that may be a question to ask the list if
-> you still need the info.
->
-> Ken
->
-> kpierson@dcsol.com wrote:
-> > I have started to build a mount for my 160 hp Lyc. engine,
-> > I have all other dimensions that I need except the down thrust angle
-> > that MAM uses? Does anyone have that information, or know were
-> > I can find it?
-> >
-> > Thank you Keith P.
-> >
---------- Digest Message #4 ----------
Date: Wed, 25 Aug 2010 08:09:45 -0400
From: klehman@albedo.net
To: rebel-builders
Subject: Re: [rebel-builders] Elevator deflection angle
When I queried this, some clever person here reminded us that in the
downwash from the wing, one degree up on the stab was still likely
providing down force on the stab.
I believe I set around .6 up on my stab. For my particular airframe
(wing cuff and soob engine) at 80 knot economy cruise, I would set it to
zero if rebuilding.
Ken
kpierson@dcsol.com wrote:---------- Digest Message #5 ----------Ron: Thank you for your response to my inquiry, although I'm glad
to receive that information, but to have a stabilizer with a nose up
attitude goes aginst everything that I have ever learned about
stabilizers, but I'll work with it.
Keith P.
On 8/23/2010 3:48 PM, rshannon@cruzcom.com wrote to rebel-builders:
-> The manual calls for 1 deg. up angle of incidence, so you're probably in the
-> ballpark. Some have used less.
->
-> Ron
-> N254MR
-
Date: Wed, 25 Aug 2010 10:39:39 -0700
From: rshannon@cruzcom.com
To: rebel-builders
Subject: Re: [rebel-builders] Elevator deflection angle
You're right, it is counterintuitive, given the role the stabilizer is
supposed to play. Whether it's the wing downwash, or unique prop corkscrew
effect, or whatever -- or whether necessary at all (e.g., preference from
Ken and others for zero incidence) -- it does seem to work reasonably well
for the Rebel.
Whatever the rationale, as was discussed in an earlier post on this topic,
the down force of the stabilizer is wasted energy, insofar as it contributes
to drag but not lift. With that in mind, minimizing stabilizer downward
force is one key to speed optimization (drag reduction) which is why the
Reno racers are always trying to fly at the edge of controllable aft CG.
Ron
On Tue, Aug 24, 2010 at 9:10 PM, <kpierson@dcsol.com> wrote:
----------Ron: Thank you for your response to my inquiry, although I'm glad
to receive that information, but to have a stabilizer with a nose up
attitude goes aginst everything that I have ever learned about
stabilizers, but I'll work with it.
Keith P.
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