The operation of a fuselage helicopter...

Flex Shafts

The operation of a fuselage helicopter with a flexible shaft requires special care when designing and assembling / installing the shaft in the fuselage.

The flex shafts usually have a higher breaking load than the built-in plastic bevel gears. Awkward installation can tend to swing during hard maneuvers or very pointed tail gyros.
However, a flight style adapted to the scale model usually creates a low load. The originals are far from having the excess power like most models.

The normal mode also leads to a more suitable for the scale Airplanes image.


Criteria and installation:


The Flex shafts run in a special guide tube / hose, using either a plastic tube or a metal tube.
The plastic tube is used in smaller helicopters, where the load on the shaft is smaller.
The metal tube is a coiled guide tube, the sheathed has externally fitted an additional rubber coating.


All guide tubes must be filled before operation with grease (multipurpose grease), then the flexible shaft will be screwed into spiral direction.
In this way, also the spaces between the shaft are filled with grease.
The grease will be hot during operation and thereby it will flow.
When plastic hose and for coated metal tubing it may be leak through both ends.
In the open metal tube it may also leak through the spiral.
Thus, the grease must be refilled from time to time

For installation, we recommend the use of aluminum pipe from the hardware store.
This can be bent without the shaft in the proper curvature before the assembly, and will then be set in the fuselage.
It also serves for the open metal tube as a seal, so that grease can leak only at the ends.
When using no additional tube, the guide tube must be set multiple times in the fuselage, so that it can not vibrate freely.


The guide tube has a lot of excessive amount in internal diameter, with less contact points form the shaft.
Our shafts are typically used for drives in Industries and come from an experienced Swiss company.
They are at least twice coiled, but should nevertheless not be used against there direction.
Among other things, a test, which is rotated at the tail rotor and the main transmission is blocked, leading to the destruction of the flexible shaft!

With our shafts in the shop are the details of the permissible torques and bending radii. For comparison, the torques of conventional bevel gears are shown in the helicopter models.

The direction of rotation of the shaft is always viewed from the direction of the actuator toward the driven member.
A normal (right) rotating T-Rex therefore need a CCW shaft.

The installation aids (600-700) determine the outer tube and can include an additional bearing for the adapter, thereby the required game will not converted in vibrations. These adapters fit directly into the tail boom holding a T-Rex 600 or 700
Other adapters can also be customized.



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