REFLECTOR: Aileron Cable Problems and Solutions

[Terry Miles]

Dear Al, and all,

 

Thanks for all the input on aileron cables.  Al, you had it right.  My cable
throw was 2.75 or so.  The book calls for 3 inches, so I sent it back for
another that came back at 3.125 inches, and that gave me most of what I was
lacking for control surface displacement.   

 

I still have just under the book value.about 2.35 to 2.4 inches up and down.
Others might know of this already but:  There is unpreventable slack within
the system so the control surface displacement measurement it is actually a
range +/- 1/8 inch or so.  Measure using the stick.  Then measure grabbing
the wing root bell crank (or slam the stick to the stops) and you can see
this slop factor.  Air loading will give you the lesser value.  

 

I also am taking this measurements direct from trailing edge to trailing
edge.  If you rig up a right angle measurement (rather than the hypotenuse)
the numbers are smaller.  The book doesn't say.  

 

New related topic:  By drilling a new hole in the bellcrank it is a possible
to get greater aileron travel.  I have another set of bell cranks with
altered drill points maybe one hole diameter closer to the pivot.  It gave
me maybe 3/16 inch more control surface throw.  Doing this shortens stick
throw and increases friction.  I don't know how much left and right stick
travel is ideal, before the control stick becomes too sensitive to pilot
displacement.  Jorge, your earlier point about hardware assembly is a good
one.  I'll add that as you assemble all of this stuff (plus the autopilot
roll servo) and put on the wide area washers it is easy to have a
washer-to-rod end bearing rub if you are not careful to add extra washers
where needed.

 

New related topic:  I hope by now everyone who needs to know, knows that the
dash five wing root bell cranks go in upside down from the non-dash  5
model.  Depending on your drill point thru the firewall you will need a 4
foot 6 inch or possibly a 4 foot 9 inch set of aileron cables.  This is in
addition to measuring the cables in your parts pile to be sure you have full
cable travel back and forth of at least 3 inches.  Somewhere in the course
of things some cables were shipped that were mis-sized by overall length and
other were shipped (as what happened to Al and I) with less than the proper
throw.  

 

If you have a dash five, don't drill your firewall until you inform yourself
on this topic.  As for fire wall real estate planning:  be sure also to save
proper positioning for your autopilot roll servo.  All this stuff has to be
in align, and know even then the bell crank arm will likely have to be bent
some to relieve friction. 

 

 I am going to keep what I have.  I had cut and trimmed the ailerons very
carefully to have full (+) a little aileron travel while also keep the wing
to aileron gap proper.  This cable limitation on aileron travel is a bit of
a disappointment, but I am premature in any gripes until I see how she does
in flight.

 

Respectfully,

Terry

 

 

 

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