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Original Year
 1986
# of pieces
 239
Categories
 Aircraft:  Helicopters
Other: Arctic Action
Dimensions
 32(L)x8(W)x16(H)
without rotor
Features
 Rotating main and tail rotor
Other Views

8640 Polar Copter
iso
revolve
Click the image to download the LDraw file of this model.
Model by Eric Albrecht

Set 8640 was released in 1986 as one of 4 sets in the new Arctic Action theme.  This set features rotating main and tail rotors and one of the new Technic figures with a helmet, skis, and poles.  A very large number (24) of toothed connectors are used in the construction which allows the "bubble" shape of the canopy and also the skid supports.

This is the only Technic set released this year which does not have wheels, and remains one of the very few such to this day.  This is also the first set to feature the new 2 and 3 bladed rotor pieces.

Helicopters have been a very popular Technic subject over the years, and a large number of them have been made.   This example is among the most simple, but is also one of only three to come with a pilot, and is the only one to include any white beams.

Features
Rotors
The rotors' rotation is driven by an input crank on the left side.  This crank drives a set of 16 and 24 tooth gears.  A second 16 tooth gear drives the main rotor of the same 24 tooth crown gear, resulting in a ratio of 1:1.  The crown gear torque passes aft and then into the tail rotor through a pair of 14 tooth bevel gears which results in a final gear ratio at the tail of 1.5:1.

 crank    rotor
 Click for an animation of the rotor in motion.
Skids
The landing skids are constructed from beams and plates supported by toothed connectors.  These are clearly meant to be skis capable of landing on snow.  The left hand skid supports a pair of skis for the Technic figure with a pair of finger hinges.
 Skids
 

Other Views
Side View
side view
 Top View
top view
Front View
front view
Computer Render
render

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