The Murphy Builders Site

Are you referring to the elevator spades? Mine seem to be fairly straight.
At least, I can look through the tooling holes in one spade and see those in
the other lined up pretty well dead on. However, you might want to consider
a more a more extensive modification, and here I'm only repeating what I've
been told by Sean White. It seems the Elite elevators are kind of twitchy.
He is proposing to address this by cutting the spades in half, span wise.
i.e. the entire elevator span will be reduced by 4" at each tip. He is also
rounding the tips of the spades a little. He expects to have flight test
results in a few weeks. My elevator has still to be closed, so I'm going to
wait until I hear how his mod. works out before completing it.

Al.
----- Original Message -----
From: "Roger Cole" <rcole927@earthlink.net>
To: <murphy-rebel@dcsol.com>
Sent: Wednesday, June 04, 2003 10:27 PM
Subject: Elite Elevator Horn Problem

After completing the elevator for Elite 709, I attached it to the H-stab
with some temporary bolts and leveled everything to check for twist. I
found that the centerline at the tip of the right elevator horn was 1/4

inch

lower than the centerline of the elevator. The elevator, itself, has only

a

small amount of twist (1/32 in in 13 inches, or 0.13 degrees), which is

more

than I would like but probably acceptable. The H-stab has a smaller

amount

of twist (1/32 in 16 inches, or 0.11 degrees).

What is the best way to correct the misalignment of the elevator horn? I

am

thinking that one way might be to replace the horn with new parts. Only

the

two tip ribs (EL-402) and the tip skin (EL-408) would have to be replaced.
The problem is how to get the holes in the tip skin properly aligned with
the holes in the elevator skin. How can I do that?

What is an acceptable amount of twist in the elevator and H-stab? I would
like to keep it under 0.10 degrees, which is as good as an electronic

level

can measure. What can be achieved with reasonable care?

Thanks in advance for your expert answers.
--
Roger Cole <rcole927@earthlink.net>
Elite 709

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Hi Al !

Glad to hear that issue being addressed - I'd have some
reservations about reducing the total span of the elevator, though !
I'd strongly suggest he keep the leading edge extended in front
of the horns, not bring them forward, like the Rebel...
Making those kind of changes might really jump the heart rate on
the test flight ! ;-)
Rounding the tips of the horns sounds like an excellent idea, in
any case - and might help a lot.

Be very interested to hear how it all works out - please
keep us posted !

.....bobp

----------------------------------orig.-----------------------------
At 10:50 PM 6/5/03 -0400, you wrote:

Are you referring to the elevator spades? Mine seem to be fairly straight.
At least, I can look through the tooling holes in one spade and see those in
the other lined up pretty well dead on. However, you might want to consider
a more a more extensive modification, and here I'm only repeating what I've
been told by Sean White. It seems the Elite elevators are kind of twitchy.
He is proposing to address this by cutting the spades in half, span wise.
i.e. the entire elevator span will be reduced by 4" at each tip. He is also
rounding the tips of the spades a little. He expects to have flight test
results in a few weeks. My elevator has still to be closed, so I'm going to
wait until I hear how his mod. works out before completing it.

Al.
----- Original Message -----
From: "Roger Cole" <rcole927@earthlink.net>
To: <murphy-rebel@dcsol.com>
Sent: Wednesday, June 04, 2003 10:27 PM
Subject: Elite Elevator Horn Problem

After completing the elevator for Elite 709, I attached it to the H-stab
with some temporary bolts and leveled everything to check for twist. I
found that the centerline at the tip of the right elevator horn was 1/4

inch

lower than the centerline of the elevator. The elevator, itself, has only

a

small amount of twist (1/32 in in 13 inches, or 0.13 degrees), which is

more

than I would like but probably acceptable. The H-stab has a smaller

amount

of twist (1/32 in 16 inches, or 0.11 degrees).

What is the best way to correct the misalignment of the elevator horn? I

am

thinking that one way might be to replace the horn with new parts. Only

the

two tip ribs (EL-402) and the tip skin (EL-408) would have to be replaced.
The problem is how to get the holes in the tip skin properly aligned with
the holes in the elevator skin. How can I do that?

What is an acceptable amount of twist in the elevator and H-stab? I would
like to keep it under 0.10 degrees, which is as good as an electronic

level

can measure. What can be achieved with reasonable care?

Thanks in advance for your expert answers.
--
Roger Cole <rcole927@earthlink.net>
Elite 709

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Thanks Alan.
I'm halfway through my Stab, but the Elevator will be next and I appreciate
your "tip" in advance. Thanks
Nigel
745E
G-ONIG

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Alan Hepburn
Sent: 08 June 2003 11:06
To: murphy-rebel@dcsol.com
Subject: Re: Elite Elavator Horn Problem


Roger:

Further to my last on this, you asked how to ensure that the horns (or
spades) don't come out twisted relative to the elevator. I said mine
were pretty well spot on, but couldn't remember how I'd done this. It
seemed that plain good luck couldn't have been it, particularly when
building anything with "Murphy" in the name! Well, now I remember, and
you're going to kick yourself, it's so darned simple. You draw a line
on a piece of nice rigid, straight material long enough to reach from
the tip of the spade to the elevator tailing edge. Then you drill 4 #
11 holes along this line, spaced to line up with the tooling holes on
the elevator and spade ribs. You then cleco or bolt this material to in
place, and remove it when the spade is finished. I used some aluminum
channel I had around, but I guess plywood and AN3 bolts would also do
fine.

I can't help thinking they did the same when they built the prototype,
and they just left out this little tip to challenge the student. You'll
find this is typical as you move through the thing. Never take the
instructions as being full and complete.

For example, you're going to encounter much the same thing on the rudder
spade, which it turns out I built first. I'd figured out the above
trick, but for lateral positioning I simply relied on the material being
straight, and confirmed with a square that the spade was at right angles
to the leading edge. Close, but I'd have been better to take a more
thorough look at that website with all the Elite photos, where they
recommend temporarily installing the rudder on the fin to set up the
alignment. Then you can set up a spare at root and tip of the spade to
get it dead parallel with the top of the fin. Mine diverges about 1/16"
of an inch (fortunately, it would have been pretty tight if it had been
the other way). I'll always notice this, though probably nobody else
will. Another real basic one - save the cutoff stringers from the stab,
and use them on the fin. The guy I bought my kit from had chucked them
out, and I wound up having to buy extra stringers.

Howvere, as I say, you may want to consider a design change here, and
Sean's idea sounds like it may work. Well see yow the initial flights
go. I just don't know enough about areodynamics to say whether a 10%
reduuction in elevator area will be critical. I suppose it depends how
much elevator authority the thing has to begin with. Anybody out there
with Elite experience, do you tend to run out of elevator in the round
out at forward CoG locations? Alternatives, such as shortening the
spades chord-wise would be much more complicated.

I do happen to have a couple of spare EL-402s which must have been in
the kit, if that's any use, but I think you can probably use the
originals and just replace the spade skins. Just drill a key #30 hole
to take the tip cleco, then offset all the other holes from their
original position by 5/16". Not quite a regular drill pattern, but good
enough for all but the perfectionists.

Regards, Al.



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