New Aluminum tail spring, etc.

Mike Davis · Post by **Mike Davis** » Fri Feb 17, 2012 5:19 pm

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To: <murphy-rebel@dcsol.com> (Murphy Rebel Builders List)
From: Bob Patterson <bob.patterson@canrem.com>
Subject: Re: New Aluminum tail spring, etc.
Message-Id: <E10zivw-0007XR-00@mail4.toronto.istar.net>
Date: Thu, 1 Jul 1999 11:39:28 -0400

Hi Brian,

It will be interesting to see how it works out in your comparison.
Others
have found that the square tips work best in both situations, and that is
why
I recommended that shape. I believe that the tapered tips were originally
developed for 2 stroke engines that couldn't produce enough torque for the
full blade..... But then, the tapered tips suffer smaller loads, so may be
more
durable .... And that shape has proven better for glider wings ...

In any case, I suspect that Warp Drive prefers to sell the tapered tips,
as they are more expensive :-)

Any and all feedback on performance differences with the different blades
will really be a help to all of us - anybody else tried both ???

.......bobp
-----------------------------------orig.------------------------------------
--
At 06:11 PM 6/30/99 -0400, you wrote:

Hi Bob

I think that I mentioned that the Warp Drive factory still recommends
square tips for float operation but the tapered tips for wheel ops.

Hope to find out soon myself what the difference is. We should have a good
basis of comparison as Ron Barber is about ready to fly with a similar
setup with square tips and myself with tapered tips. We both have 'modern'
0320 engines. What a marvel of 1930's technology they are!

Regards

Brian #328R

At 05:27 PM 28/06/99 -0400, you wrote:
I had almost forgotten the earlier aluminum springs - we used one for a
season. It went flat after repeated bumps .... (aluminum is not a great
material for 'springs' :-) )

If you can use a thinner spacer, that would be great. As I mentioned,
some have added a thin piece of rubber between the spacer and the spring.
The spacer is only to get a good angle for the spring, and to distribute
the loads from the spring to the tail post over a larger area, so making
it thinner shouldn't hurt.

If you do go to the Scott tailwheel, you will likely find that it
doesn't fit the spring. You can grind the spring a bit, and there are
spacer blocks available to help with the fit. Have a look through the
archives of this list - I think someone described these a few months ago.
I think Scott make different size attachment fittings.

You can move your battery back to adjust the C of G - several here
have used a long, narrow battery (about 3 1/2" thick, by about 10 - 11"
long). These can be positioned on the right side of the fuselage, between
the bulkheads, leaving the floor open for sleeping. Just move it back

until

you get the desired position....

The Murphy kick-out tailwheel works GREAT, once it is broken in. Be
sure to grease it regularly, especially the pin at the top. There should
be a grease fitting there for it, but it's not in the design, so you just
have to stuff a glob of grease into the underside with your finger, at
least once a month....

If you haven't already, you can save a LOT of weight up front by going
to the B & C lightweight starter, and a lightweight alternator, (over 30
lbs),
as well as the (now-almost-standard) 3 blade Warp Drive 72 inch prop with
17" of metal on the leading edge, and SQUARE tips !

Sounds like you're making good progress - keep at it. It's worth it !!

.....bobp

-----------------------------------orig.----------------------------------
At 09:04 PM 6/27/99 -0700, you wrote:
Bob, my Rebel had an aluminum tail spring which was even before the
composite
one. My serial # is 107R. With the newer replacement tail spring, an
additional
spacer TS-7 was added on top of the extra thickness of the new tail

spring,

which is what lowered the strut attach bracket. I am not sure what
purpose it
served, so I removed it, leaving only the original TS-2 spacer in place.
That
gained back some altitude on the strut bracket, and now I have only 1/4
inch
negative dihedral. Do you think this is still a problem? I could replace

the

TS-2 with another spacer that is 1/8 inch less thick, and that would
bring me
back to the original stab height. I am using the Murphy tail wheel
modified to
kick out on a sharp turn. I hope it works. I am almost ready to do a
weight and
balance, so might still go for the heavier Scott tail wheel if I have a
problem.
I am using an O320.

Bob Patterson wrote:

use

outside

strips,
spring,
fit
stability,

spacer -

fit

cheaper,
-----------------------------orig.-----------------------------------------
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The Murphy Rebel Builders List is for the discussion
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Archives located at:
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*----------------------------------------------------*

*----------------------------------------------------*
The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm
*----------------------------------------------------*