>We are fitting Graham Singleton's XS rudder modification and having
>difficulity establishing the position of the CS29 push rod fitting
>in the rudder
Jim - can't say for certain about the pushrod clearance slot. I
SHOULD know, as I've just been examining the rudders of several
Europas at Kemble in order to confirm the positioning of my own CS29.
I think that the slot was visible at neutral on at least some of
them, but wouldn't stake my life on it. No doubt others will respond.
My own concern was about the vertical positioning. The Classic manual
reprint shows a measurement from the bottom of the rudder. which I've
already rounded off to clear the tailwheel spring. I noted the
position of the pushrod WRT the bottom hinge, and then checked the
positions of the hinges WRT the top & bottom of the rudder. All this
gave me confidence that my own measurement (from where I'd
extrapolated the bottom of the rudder to be) was pretty satisfactory.
>When deflecting the rudder to port, we find the push rod hits the
>port side of the rudder leading edge before the new steering arm
>gets to the stop. We are able to get more than 32 deg of movement
>to stbd.
This leads me to suspect that no matter how much of a slot you cut,
you won't get 30 degrees deflection to port. I say this because in
addition to the above, I was wondering how critical the positioning
of CS29 port & starboard was. I've got the XS version of the kit and
the appropriate flavour of Graham's mod to suit. I gather for Classic
fuselages Graham uses the original tailwheel pivot, but for the XS
supplies a bellcrank which mounts on trunnion brackets affixed to the
bulkhead at FS171.
I drew up the whole thing in CADintosh and found that the Graham
Singleton bellcrank would have to move through over 89 degrees to get
60 degrees (ie 30 each way) rudder movement (>96 degrees for 64
degrees rudder). This is based on the measured lever arm of 1 25/32"
on Graham's bellcrank, and assuming the rudder lever arm of 2.5"
specified in the Europa manual (p28-4, 17 Jan 96, issue 1).
When I assembled the bellcrank on its brackets, the stops limited the
deflection to about 88.5 degrees, so obviously something would need
slight adjustment.
At first I thought of moving the CS29 starboard slightly to reduce
the rudder lever arm. I found that having the CS29 hole centre 2.35"
---From the rudder hinge centre gave just under 32 degrees rudder
deflection.
Then I read Graham's instructions again (YES! I know! When all else
fails ...) and he suggested changing the thickness of the sleeves
which act as stops for the bellcrank. He had supplied 1/4" ID, 3/8"
OD tube, but I just happened to have some 4130 tube (1/4" ID, 5/16"
OD) left over from the outrigger pivot mod. When I substituted the
thinner tube and redid all the sums, things looked just fine, giving
about 61 degrees total rudder movement with the 2.5" rudder arm.
On the strength of all my comparison measurements, I took my courage
in both hands and hacked a hole in the rudder LE. I find that with
the CS29 firmly against the inside of the port skin, the lever arm is
2.5" (as close as I can measure). A couple of layers of BID will tend
to reduce that slightly, giving me a bit more leeway for increased
rudder deflection, should other things not turn out exactly as
expected. Thus, I'm happy to bond in the CS29 without checking the
physical deflection available. I intend to ensure correct balance
between port & stbd deflections by facing the pushrod to length when
fitting.
And why am I doing all these sums instead of "fit and try" as
suggested in the manual? I want to get all my foam parts post-cured
in a batch, but don't want to wait for that until I have got the
fuselage ready to hang the rudder. (I reckon the bit of the rudder
that gets carved away at the top LE corner to clear the fin flange
will survive without post-curing.)
>If we move CS29 further forward, the stbd edge of CS29 will be above
>the surface of the rudder skin.
I'm pretty sure you don't want to be doing that!
Sorry I can't help much with your original query, but would be
interested to know, when you get it all sorted and working, if your
deflection measurements support my calculations.
regards
Rowland
--
| Rowland Carson PFA #16532 e-mail <rowil@clara.net>
| 640 hours building Europa #435 G-ROWI
|