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To: <murphy-rebel@dcsol.com> (Murphy Rebel)
From: Bob Patterson <bob.patterson@canrem.com>
Subject: Re: Bungee gear --> spring gear
Message-Id: <E0zbHHP-0006gh-00@mail2.toronto.istar.net>
Date: Wed, 4 Nov 1998 23:44:20 -0500
Thanks for the explanation of 'panting' - bulges like pants
that are too long !! :-)
Several builders have seen this effect in the area you mention,
also in the panel right under the doors. One fix has been to re-make
that panel in .032 - if you haven't already rivetted it on. They have
also stiffened that panel by adding short vertical L or C channels
bent up & rivetted inside between the bottom & the door frame.
I have also seen pieces of wing stringer used as stiffeners -
this is a great idea - they're light & strong & small enough to slip
in almost anywhere. A piece of stringer on an angle, perhaps almost
parallel with the witches hat in that side panel might solve your
problem. (or an extra piece of witches hat ...)
The corner wraps were thickened up because they were TOO
sensitive to denting - I was one of the first victims ! The original
owner of our third Rebel had removed the wings in a hurry (don't ask !!),
and left his son holding the wing tip while he removed the BOTTOM (!)
strut bolt. When the wing tip dropped, he grabbed the strut & lifted
it so it dented the corner wrap.
This was a minor blemish (i thought) - after a hundred or so
hours of flying, it was apparent that the 'dent' was flexing - it
eventually opened up into a 2" crack !! At this point, the corner
wraps were replaced with the heavier .025 versions. Since then,
the factory decided that, since they were using .032 for the heavier
Elite, thay would make THAT (.032) the standard - not a bad idea !!
This sort of thing applies to ALL aircraft that use a stessed-
skin (semi-monocoque) construction, and all corner wraps on the Rebel,
including the rear fuse. If anyone out there has a dent in the wraps,
the wrap MUST be replaced to maintain strength & durability !!
If the smoking rivets are on the doorpost, there is a "newer"
addition to the 'float fix' AD (since Oshkosh 1998). It calls for
an extra row of larger rivets, staggered between the existing rivets,
all the way up the doorpost. Please check with MAM for the exact
details. Anyone out there looking at heavy float usage would be well
advised to do this while building..
This was the result of 'field experience' - someone decided
to fly in waves that were MUCH larger than MAM originally intended
(nobody else ventured out of the seaplane base !) I agree that these
things sound dramatic, but again - NO ONE was hurt, and the Rebel flew
away the next day. Not a big problem, just one more minor improvement.
There are always several aircraft damaged at Oshkosh
- there WERE over 14,000 aircraft there !!, and not <all> the landings
were perfect !! :-) or :-(
I'm sure your gear bolts were not loose because of hard landings,
which would have stretched them. There are many areas where the bolts
do slacken slightly after a bit of flying.
We were flying to Florida with No. 001, in March, a long time
ago ( ~ 1991) when we found the horizontal stab quite loose on a
preflight in Ohio. The bolts fastening it at the root had slackened -
after about 60 or 80 hr. of flying !! Now I always double check them
on my walkaround - along with many other spots .... part of my
'ongoing maintenance program'. :-)
Here we have an initial 25 HR. test flying period with various
restrictions - once completed, you can fly anywhere & carry passengers.
The end of this period is an EXCELLENT time to go over the whole
aircraft, checking & lubricating everywhere. You might be surprised
- i saw one Rebel that had ONE rivet missing on top of the wing -
it was never installed !!
I love your descriptions of flying & hunting there !!! God,
I WISH I could fly along on one of those - it sounds BEAUTIFUL !!
Sigh !! Maybe we'll come up on the lottery one day & come to visit !!!
Glad you're enjoying the Rebel as much as the rest of us :-)
....bobp
-------------------------orig.---------------------------------
At 09:42 PM 11/4/98 +1300, you wrote:
Hi again,
Thanks for the info, I was speaking to Grant from Murphy today and he
backed up what you say, he said Darral reckons to run about 12lbs in the
tyres.
I'd come to that conclusion in the last few days and have tried it, it
certainly softens the ride and appears to take some of the loads away from
the fuse.
Panting of the skins is a term used over here to indicate flexing of the
skins in certain situations.
I do have the latter kit with the stronger floor area, the problem is not
in the twisting forces with braking etc. but with the dissipation of the
loads through the fuse resulting from the flexing of the spring gear ( ie
weight bearing loads)
The panting I am getting is just ahead of the front door post,down low just
above where the corner rap meets the side panel, it occurs when the
undercarriage is working. It is causing the 'smoking' of the rivets down
low on the front door post.
It is of some concern, and obviously a fix is required, stronger rivets in
the area concerned would probably do the job, but I do wonder if a doubler
over the area that is 'panting' may be the best long term option,
especially with all the off airfield work that I do.
Murphy have been beating around the bush in regard to a fix for the
problem, but they have said that the front corner raps have been increased
in thickness to 35thou. ( I wonder why!)
Yes, the aircraft has only done 35hrs to date, but I am using the way it
should be used!! It has to hold up thats why I built it!!
And yes, I had to re-torque the under carriage bolts fairly early on, as
they had loosened.
Also remember that if you are fitting an 0-320, or a heavier motor, to do
the floatfix bulletin promulgated by Murphy, I found out the hard way, all
the taxiing over rough ground caused the top of the firewall to flex
creating some cracking of the firewall around the top mounts on either
side, this happened within 20hrs!!!
This all sounds very dramatic, but it isn't really, I just look at these
problems as just part of the shake down period, we'll sort this out and be
off like a rocket!
It is the neatest aircraft to fly, and you can go to the greatest places.
The other day my son and I tossed some camping gear and a rifle in the back
and headed off for the mountains, an hour and twenty later we dropped into
the headwaters of the Wilkins river on to an old deer hunters strip (Alt.
2000ft, 280 metres long and two metres wide!). We were surrounded by 8000ft
peaks.
We had an evening hunt in the most beautiful country possible, slept under
the aircraft, up early and away for another hunt then back for a late
breakfast. Toss the gear in the plane and off home, all in under 24 hrs!
What a way to travel!!
The only problems I am getting with the aircraft is associated with the
rough and undulating terrain that I am operating off, in the air the
aircraft has been faultless, I have full confidence that these issues will
be worked through reasonably quickly.
Cheers
Alister Yeoman
----------??From: Bob Patterson <bob.patterson@canrem.com>
To: Murphy Rebel <murphy-rebel@dcsol.com>
Subject: Re: Bungee gear
Date: Wednesday, November 04, 1998 5:05 PM
I run the fat tires - 8.00 x 600. They aren't very heavy-duty, but
they ARE inexpensive !! :-)
Normal pressure is around 20 lb - but i have run them as low
as 10 lb. The only danger if they're too soft is that they TURN on the
wheel, and pull the valve stem out of the tube !! :-(
Very fancy method - add air, then put a foot on the tire & push
on top - look for a little flattening (1/2" bulge ??) at bottom, and a
little side to side wiggle. Seems to give nice landings that way ....
It's unusual to see problems with the spring with such low time
- how many hours on the Rebel ?? What's 'panting' of skins ????
You might want to re-torque the bolts that hold the spring
gear on - I've heard of several that loosened up in the first 50 hours -
and there were one or 2 that had sheared bolts.
Were the rivets that are smoking dipped in epoxy when installedlittleYou <could> paint some epoxy on inside & out now ... might help.
I hate to say this, but "the EARLY" spring gear kits were a----------------------------orig.-----------------------------------------weak in the floor area. Newer ones have several doublers with 'fingers'
that are supposed to spread the loads much better, preventing the waves
in the floor. It might be possible to add doublers inside or out, even
now. It would depend where the problem is. I'm sure the factory could
help, if you sent photos of the problem spots ... (Hope you can get
someone to scan photos of your Rebel for us - we're all curious !)
.....bobp
Apologies to those who've heard "the Early" too often !!
someAt 07:16 PM 11/3/98 +1300, you wrote:Hi Bob,
You state that the tyres are the primary shock absorbers, I am havingfusetrouble with my spring gear in that the loads are transferring to thewasand causing some panting of the skins and minor smoking of some rivets.
What tyre pressures are you running?
Cheers,
Alister Yeoman yeoman@voyager.co.nz
----------idea.bungeespindlebungeetension.inre-readingthatPlease??willtheboltsnewforway risk of directions ortotheyou
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