The Murphy Builders Site

I have decided to do a couple of small mods, based on the 3500 upgrade plans
that I just received, to upgrade specific areas of the fuselage that are
simple and require little disassembly of already assembled parts. I am
planning on installing the V-brace that ties the top of the firewall to the
front spar carrythrough. Where the V-brace attaches at the top of the
firewall I am planning on installing some kind of fitting for a safety cable
to attach to the engine. Then, there are some bracing channels that I will
add to the gear box structure. Lastly, I want to do the mod that beefs up
the attachment point on the fuselage for the front spars.

Since I am still planning on using the Chevy LS-1 or possibly the newer LS-6
aluminum block engine, which will be anywhere from 350-405 HP for a 450
pound engine, and I hope to find a constant speed, three bladed prop to use,
what are your opinions about the need to beef up the tailfeathers. Murphy
repeatedly mentions the importance of the tailfeather mods when using the
M14 radial because the airflow over the tailfeathers from the big prop
induces a lot more stress than the original 250-260HP Lycoming swinging a
two or three bladed prop.

Mike Kimball
SR #044




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Hi Mike,
I started the 3500 mods with the easy ones first. Since it was hard for me
to drill out good rivets it took a month of staring at the instructions
before drilling the first rivet. All the mods to the elevator, stabilizer,
fin, wing attach, v brace went fast and are very straight forward. I am
taking a lot longer doing the landing gear mods but one side is fitted and
finally going back together.
When I started the mods I had second thoughts about the value of the
upgrade. At this point I am very glad that I have made them.
The v brace mod attaches to the M14 engine mount, since I'm using an IO540
and there is no mount at that point I made a firewall doubler and bolted the
v brace bracket to the firewall. I am curious about the safety cable you
mentioned. What is the purpose and where are you attaching to the engine?
I've seen cables on racers but I thought those were in case of a prop blade
loss at high RPM.
Al
SR#26
----- Original Message -----
From: "Mike Kimball" <agt@mosquitonet.com>
To: <murphy-rebel@dcsol.com>
Sent: Friday, October 12, 2001 10:04 AM
Subject: Tailfeather Mods for my SR


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The list archives are located at:
http://www.dcsol.com:81/public/default.htm
username: rebel password: builder

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I have decided to do a couple of small mods, based on the 3500 upgrade

plans

that I just received, to upgrade specific areas of the fuselage that are
simple and require little disassembly of already assembled parts. I am
planning on installing the V-brace that ties the top of the firewall to

the

front spar carrythrough. Where the V-brace attaches at the top of the
firewall I am planning on installing some kind of fitting for a safety

cable

to attach to the engine. Then, there are some bracing channels that I

will

add to the gear box structure. Lastly, I want to do the mod that beefs up

the attachment point on the fuselage for the front spars.

Since I am still planning on using the Chevy LS-1 or possibly the newer

LS-6

aluminum block engine, which will be anywhere from 350-405 HP for a 450
pound engine, and I hope to find a constant speed, three bladed prop to

use,

what are your opinions about the need to beef up the tailfeathers. Murphy
repeatedly mentions the importance of the tailfeather mods when using the
M14 radial because the airflow over the tailfeathers from the big prop
induces a lot more stress than the original 250-260HP Lycoming swinging a
two or three bladed prop.

Mike Kimball
SR #044

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The purpose of the cable is to keep the engine attached to the airplane if
it decided to break loose of its engine mount. One very good scenario, as
you mentioned, is the loss of a prop blade. Since I am using an automotive
engine that has never been vibration tested with any prop, it seemed prudent
since there could be hidden harmonics created that could induce prop
failure. Plus, I may end up with one of the available experimental props
out there to save weight and cost. Who knows what I might be messing with
then. I wanted the added comfort of knowing I would at least have a shot at
a dead-stick landing if my experimental engine/prop test bed goes astray.
Where would I attach to the engine? Who knows? I don't have the Chevy
LS-1/LS-6 V8 I am planning on using yet. I will find a place somewhere.

Mike

-----Original Message-----
From: murphy-rebel@dcsol.com [mailto:murphy-rebel@dcsol.com]On Behalf Of
Al & Deb Paxhia
Sent: Friday, October 12, 2001 4:12 PM
To: murphy-rebel@dcsol.com
Subject: Re: Tailfeather Mods for my SR


*-------------------------------------------------------------------------*
The list archives are located at:
http://www.dcsol.com:81/public/default.htm
username: rebel password: builder
*-------------------------------------------------------------------------*
Hi Mike,
I started the 3500 mods with the easy ones first. Since it was hard for me
to drill out good rivets it took a month of staring at the instructions
before drilling the first rivet. All the mods to the elevator, stabilizer,
fin, wing attach, v brace went fast and are very straight forward. I am
taking a lot longer doing the landing gear mods but one side is fitted and
finally going back together.
When I started the mods I had second thoughts about the value of the
upgrade. At this point I am very glad that I have made them.
The v brace mod attaches to the M14 engine mount, since I'm using an IO540
and there is no mount at that point I made a firewall doubler and bolted the
v brace bracket to the firewall. I am curious about the safety cable you
mentioned. What is the purpose and where are you attaching to the engine?
I've seen cables on racers but I thought those were in case of a prop blade
loss at high RPM.
Al
SR#26
----- Original Message -----
From: "Mike Kimball" <agt@mosquitonet.com>
To: <murphy-rebel@dcsol.com>
Sent: Friday, October 12, 2001 10:04 AM
Subject: Tailfeather Mods for my SR


*-------------------------------------------------------------------------*

The list archives are located at:
http://www.dcsol.com:81/public/default.htm
username: rebel password: builder

*-------------------------------------------------------------------------*

I have decided to do a couple of small mods, based on the 3500 upgrade

plans

that I just received, to upgrade specific areas of the fuselage that are
simple and require little disassembly of already assembled parts. I am
planning on installing the V-brace that ties the top of the firewall to

the

front spar carrythrough. Where the V-brace attaches at the top of the
firewall I am planning on installing some kind of fitting for a safety

cable

to attach to the engine. Then, there are some bracing channels that I

will

add to the gear box structure. Lastly, I want to do the mod that beefs up

the attachment point on the fuselage for the front spars.

Since I am still planning on using the Chevy LS-1 or possibly the newer

LS-6

aluminum block engine, which will be anywhere from 350-405 HP for a 450
pound engine, and I hope to find a constant speed, three bladed prop to

use,

what are your opinions about the need to beef up the tailfeathers. Murphy
repeatedly mentions the importance of the tailfeather mods when using the
M14 radial because the airflow over the tailfeathers from the big prop
induces a lot more stress than the original 250-260HP Lycoming swinging a
two or three bladed prop.

Mike Kimball
SR #044

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For assistance contact mike.davis@dcsol.com

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Mike, I know why you want to do it, but, if the prop failure busts the
engine from it's mounts, breaks the mount and/or removes the engine mount
from the firewall, do you really think a safety cable is going to keep the
engine with you! I DON'T KNOW THE ANSWER FOR SURE, but if it's that
catastophic I have some doubts unless it is a VERY, VERY large cable/strap.
Also, where would you connect it to the airframe to take that thrashing
load, to make sure that it stays up front and doesn't swing under the cabin
which would definetly make CofG matters worse? I know of 2 guys that lived
after a J4 lost the engine/prop. Both guys got as much of their bodies as
they possible could up against the windshield and glided it in! Wasn't
pretty but the lived!

A very recent prop loss on a 80 H.P. 912 Rebel (that will stay anonimous
unless the owner tells the tale himself!) during takeoff, broke the lower
engine mount tubes, damaged the firewall/cowling and threw the carbs right
off the engine. Luckily the engine stay attached to the aircraft and the
owner/pilot was able to safely glide it into a field without further damage
to his aircraft. If an 80 H.P. engine can do that much damage throwing 4
pounds of wood GSC blades, imagine what 350 HP would be like throwing one 25
pound blade out of the set of 3!

Best regards,
Wayne G.O'Shea
www.irishfield.on.ca

----- Original Message -----
From: "Mike Kimball" <agt@mosquitonet.com>
To: <murphy-rebel@dcsol.com>
Sent: Friday, October 12, 2001 8:48 PM
Subject: RE: Tailfeather Mods for my SR


*-------------------------------------------------------------------------*

The list archives are located at:
http://www.dcsol.com:81/public/default.htm
username: rebel password: builder

*-------------------------------------------------------------------------*

The purpose of the cable is to keep the engine attached to the airplane if
it decided to break loose of its engine mount. One very good scenario, as
you mentioned, is the loss of a prop blade. Since I am using an

automotive

engine that has never been vibration tested with any prop, it seemed

prudent

since there could be hidden harmonics created that could induce prop
failure. Plus, I may end up with one of the available experimental props
out there to save weight and cost. Who knows what I might be messing with
then. I wanted the added comfort of knowing I would at least have a shot

at

a dead-stick landing if my experimental engine/prop test bed goes astray.
Where would I attach to the engine? Who knows? I don't have the Chevy
LS-1/LS-6 V8 I am planning on using yet. I will find a place somewhere.

Mike

-----Original Message-----
From: murphy-rebel@dcsol.com [mailto:murphy-rebel@dcsol.com]On Behalf Of
Al & Deb Paxhia
Sent: Friday, October 12, 2001 4:12 PM
To: murphy-rebel@dcsol.com
Subject: Re: Tailfeather Mods for my SR

*-------------------------------------------------------------------------*

The list archives are located at:
http://www.dcsol.com:81/public/default.htm
username: rebel password: builder

*-------------------------------------------------------------------------*

Hi Mike,
I started the 3500 mods with the easy ones first. Since it was hard for

me

to drill out good rivets it took a month of staring at the instructions
before drilling the first rivet. All the mods to the elevator,

stabilizer,

fin, wing attach, v brace went fast and are very straight forward. I am
taking a lot longer doing the landing gear mods but one side is fitted and
finally going back together.
When I started the mods I had second thoughts about the value of the
upgrade. At this point I am very glad that I have made them.
The v brace mod attaches to the M14 engine mount, since I'm using an IO540
and there is no mount at that point I made a firewall doubler and bolted

the

v brace bracket to the firewall. I am curious about the safety cable you
mentioned. What is the purpose and where are you attaching to the engine?
I've seen cables on racers but I thought those were in case of a prop

blade

loss at high RPM.
Al
SR#26
----- Original Message -----
From: "Mike Kimball" <agt@mosquitonet.com>
To: <murphy-rebel@dcsol.com>
Sent: Friday, October 12, 2001 10:04 AM
Subject: Tailfeather Mods for my SR

*-------------------------------------------------------------------------*

The list archives are located at:
http://www.dcsol.com:81/public/default.htm
username: rebel password: builder

*-------------------------------------------------------------------------*

I have decided to do a couple of small mods, based on the 3500 upgrade

plans

that I just received, to upgrade specific areas of the fuselage that are
simple and require little disassembly of already assembled parts. I am
planning on installing the V-brace that ties the top of the firewall to

the

front spar carrythrough. Where the V-brace attaches at the top of the
firewall I am planning on installing some kind of fitting for a safety

cable

to attach to the engine. Then, there are some bracing channels that I

will

add to the gear box structure. Lastly, I want to do the mod that beefs

up

the attachment point on the fuselage for the front spars.

Since I am still planning on using the Chevy LS-1 or possibly the newer

LS-6

aluminum block engine, which will be anywhere from 350-405 HP for a 450
pound engine, and I hope to find a constant speed, three bladed prop to

use,

what are your opinions about the need to beef up the tailfeathers.

Murphy

repeatedly mentions the importance of the tailfeather mods when using

the

M14 radial because the airflow over the tailfeathers from the big prop
induces a lot more stress than the original 250-260HP Lycoming swinging

a

two or three bladed prop.

Mike Kimball
SR #044

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with "unsubscribe murphy-rebel" in the body of the message.
For assistance contact mike.davis@dcsol.com

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