josok a crit :
> Do you really advise here to get rid of a safety feature?
>
> In case of a broken throttle cable or piano wire, you might end up with a very
silent engine. The problem here is too tight routing of a throttle cable. Change
the inner cable with a solid wire, and things will improve, probably until,
because of the same tight routing the wire breaks sooner then might be
expected.
>
> Aircraft carburettors have springs to pull full throttle in case something
> goes
wrong with the linkage. Please be careful when changing the basics!
>
Jos,
Thank you for responding.
Not all aircraft rely on spring tension to open the throttle against the
friction in the outer case. Some have a push-pull cable and the throttle
valve will stay where it is, should the control fail.
Hundreds of MCRs have been flying for years with a piano wire to replace
the stranded cable and spring, without any problem whatsoever. The
linkage is far far safer with a push-pull control than with a flimsy
stranded cable and puny spring. You can even keep the spring for your
peace of mind !
You mentioned the real cause : inadequate routing of the cable with
tight turns. This leaves you with no option to open the throttle. There
are frequent reports of buckling cable in such setups.
Do not hesitate to reroute the offending cable until it has only large
natural sweeps instead of turns. The usual place for breaking a cable is
at a wrongly rigged portion between throttle lever and cable case. So a
careful design of this portion, and some provision for pivoting is key.
Regards,
Gilles
http://contrails.free.fr
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