Light Weight Bellcranks With
||Our carbon bellcranks are molded with high-temp epoxy and
continuous carbon tow. The weight of these bellcranks are between 7
and 8 grams each. This weight is for the bellcrank without the
leadouts and pivot post. The installed weight will depend on how
long the pivot post is and the type of leadout material used. The
leadout holes are bushed with 3/32 inch ID brass and the pivot post is 1/8
inch music wire. The pivot bushing is oil impregnated bronze to
provide a smooth long lasting bearing surface without any wobble to last
thousands of flights. The pushrod bushing is machined to tight
tolerances from phosphor bronze to provide a slop free fit with 3/32 inch
music wire. If a Rocket City ball link is used the pushrod bushing
can be tapped to accept the 4-40 bolt. The bellcrank is positioned
on the pivot post by two retainers. The large retainer supports the
bellcrank from the bottom while the small retainer is at the top.
The best way to install the retainers on the pivot post is to use JB weld
epoxy. When solder and flux is used there is the chance of
contaminating the bearing and pivot post with flux. If the flux is
not neutralized it will cause the music wire to rust. JB Weld is
a high temp aluminum filled epoxy that adheres well to steel.
The low weight and tight tolerances of this part make it a natural for
today's modern aerobatic aircraft.
||This is the same bellcrank except that the 19 strand 1/32
inch diameter stainless steel leadouts are attached. The breaking
strength of these cables are 185 pounds. Since there are two
leadouts the breaking strength will double to 370 pounds. The
leadouts run through a brass tube to provide a smooth bearing
surface. Whenever cable leadouts are used it is important that they
are bushed to prevent them from sawing through the bellcrank
material. The crimping ferrules will withstand the full breaking
strength of the cable. This cable is extremely smooth and flexible
and will provide thousands of flights.
||This close-up of the
bellcrank assembly shows the positioning of the retainer bushings with the
small turned bushing on the top and the large flange bushing supporting
the bellcrank from the bottom. These retainer bushings are a tight
slip fit to allow them to be positioned during assembly. The best
way to install the retainers on the pivot post is to use JB Weld epoxy.
When solder and flux is used there is the chance of contaminating the
bearing and pivot post with flux and a risk of corrosion or rust exists.
JB Weld is a high temp aluminum filled epoxy that adheres well to
steel. Remember to clean the area where the epoxy is to be applied
with 320 grit sandpaper.
A spool of carbon
tow and the finished product.
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