Re: G-BXOY Rudder Horn & Intermediary device

Clive Clapham


Your welcome. Always nice to be appreciated.

Let me know how you get on?

How about posting some pictures?


Thanks Clive, I appreciate the description and pictures.

I have to rebuild the tail/tailwheel area. I am looking to run the
cables to the rudder then to the tailwheel -- Your approach seems better
than how I was planning to do it. Still in the thinking stage (current
project is the canard).

Mike Perry

gobxoy@... wrote:

Hi Mike

Glad to see someone's awake.

I will upload some more pictures shortly.

The idea came to me whilst I was replacing the tail spring, welded a
1.1/4" hole saw to same sized 15" tube to make a 18" deep hole saw ran
it up the remains of the tail spring only took an hour including
welding etc. Leaves a hole just right to flox in a new one.

I knew that if you lost the tail wheel you also lost rudder control as

I looked at the JimBob bell crank, and felt there was an easier
cheaper and lighter way to get all the benefits.

Forty years ago my brother had a control line model aircraft that had
a triangle with a hole a each point. That sort of did something close
to what I wanted.

After a bit of playing around I came up with a small s/s triangle.

Bolt on the rudder horn mine is taped so the nut is a lock nut and a
small spacer to stop the thimbles contacting the horn. The other
holes, one connects directly to a shortened normal rudder cable. The
remaining rearward connects to the tailwheel horn.

This was repeated on the other side.

I only needed about 30" of extra cable(cheap or what).

The Triangle articulates to accommodate the differential action/spring
compression etc. Brilliant.

Disconcet one or both cables to the tailwheel rudder works just fine
all that happens is the foot controls in the cockpit move forward
about 1/2". This is because the triangle is neutral(ish) under normal
operation and displaces forward when the tailwheel cables are
disconnected. It's all tensioned by the bulkhead springs and pilot as
normal. You need to take care to maintain the peddle position.

To keep it all lined up I cut out the penolic and used a 5/16" or 3/8"
version of the elevator pin bolted to a 1/8" thick 1" X 1.1/2" steel
plate, all glassed in with 3X Bid, there is no pull back on the
rudder. The horn tube was lengthened so to remove the rudder you push
the weldment up rather than down.

Lightweight and cheap, as it saves the extra duplicated cable run and
bell crank. Cannot jam from something inside the tail cone easy to
inspect as all external.

Clean and sanitary looking.

Never did like the spring tensioning arrangement cobbled up by QAC.

My test pilot thought it was c__p but asked me to make him the bits to
convert his when he had flown it.

Obviously the usual disclaimer applies you copy you test it your risk.


Hello Clive:

I am very interested in how you did the rudder horns and rudder pivot.
I would appreciate more photos and/or more description.

Thanks -- Mike Perry

gobxoy@ wrote:

Hi Guys


As you already have the bell crank, there's not much point changing,
in the UK I came up with an alternative used on two Quickies. It's
simply a small triangle of SS sheet with three holes on each rudders
horn. Which is lowered and the pivot moved to inside the rudder horn
much like a larger elevator outer pivot, we ditched the pesky
inadequate penolic bearing. It achieves a similar result, in that the
ratios can be independent. It still gives rudder if the tail wheel is
dangling in the air. Still reliant on the same number of splices, but
simpler and lighter and easy to inspect, doesn't have anything inside
the fuselage. There is a picture in the gobxoy album. Can add clearer
shot if anyone asks.

The Gall essay is exemplary. Well worth reading.

Clive Clapham gobxoy

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