Re: Jim-Bob 6-pack article


Bob Farnam <bfarnam@...>
 

Peter,

Probably the belcrank approach might maintain the tailwheel cable tension
better, but only marginally so. It has slightly better geometry when the
tailspring flexes. I doubt that it would make much difference in the real
world. Kittleson's old airplane is now owned by Geoff Rutledge who shares my
hangar. It seems to work every bit as well as mine. In the plans version,
the cables are tensioned first by the pedal return springs, and extra
tension comes from the pilot.

Bob F.
N200QK

-----Original Message-----
From: Peter Harris [mailto:peterjfharris@...]
Sent: Monday, January 10, 2005 1:58 PM
To: Q-LIST@...
Subject: Re: [Q-LIST] Jim-Bob 6-pack article


Bob in relation to the two different cable mods , which method will best
maintain tailwheel cable tension during the ground run when the tail spring
is flexing ? In the plans version the tension is taken up by the pilot at
the pedals.
Peter
----- Original Message -----
From: Bob Farnam
To: Q-LIST@...
Sent: Tuesday, January 11, 2005 5:23 AM
Subject: RE: [Q-LIST] Jim-Bob 6-pack article




Bob F.
N200QK

-----Original Message-----
From: raynergang [mailto:rayners@...]
Sent: Friday, January 07, 2005 11:11 AM
To: Q-List
Subject: [Q-LIST] Jim-Bob 6-pack article


Bob, I have just received today (the Atlantic is big) the Q-Talk and I
just want to say thanks for the article. It's good to see all the
information on these useful (necessary) modifications in one place with
enough detail to get to work. I'm pleased to say I have built most of
them
mods into my Q - except the toe brakes (kept the hand operation, based
on
advice from an experienced friend) and the bellcrank for the rudder/tail
wheel cables.

I have a question about the bellcrank: you say that Al Kittleson's
approach is equally good and it's the way I was expecting to do the job.
Is
there any advantage to the bellcrank method, because otherwise it seems
to
be more complicated (so less reliable?) for no reason? Another simpler
way
could also be to use two cables from the link on each side - with the
suitable turn-buckles and springs as necessary.

Chris,

The advantages to the belcrank method over Kittleson's approach is
that it
was easy to make it strong. It is also convenient to adjust the rudder
pedal/rudder/tailwheel ratios easily. It is not as easy to modify the
lower
rudder bearing to take the 600 or so pounds of load that I wanted it to
take. The US Air Force physiology handbook says that 150 lbs of load is
reasonable to generate with your foot. The rudder pedals multiply that
by 2x
each giving a total of 600 pounds load easily possible. If you can make
it
safe for that load, Kittleson's method is simpler and is what is used by
most certified taildraggers.

The problem with the two cables originating at the link without the
belcrank is that the loads still end up at the rudder bearing, because
the
tailwheel springs will stretch, thereby transferring the load to the
rudder.
Better to use either Kittleson's approach, or the belcrank approach.

Re hand brakes v. toe brakes, I chose toe brakes because that is what
I
was used to plus I wanted both hands free for throttle, stick and
reflexer.
I understand that in Europe, hand brakes are much more widespread than
in
the US. Both clearly work, so use whatever you are comfortable with. The
important thing is to get the differential braking which is such an
important part of control of any taildragger.

Bob F.
N200QK



I already used a beefed-up lower rudder bearing (I saw a Q with a
broken
original one) and so it is now the same 3/4" phenolic as the elevator
centre
mounts. Is that beefed up enough do you know?

Thanks for the info.

Chris Rayner (Q-200; painting and decorating it)

PS - to Doug, welcome to the hot seat. You've got your work cut out
to
better the Richardson team (so thanks to them also), but I'm certainly
looking forward to good things. Get printing those decals - I expect to
claim one!





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