Subject:
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Re: Helicopter rotor in 8856... unrealistic?
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Newsgroups:
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lugnet.technic
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Date:
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Thu, 13 Feb 2003 23:05:50 GMT
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Viewed:
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563 times
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In lugnet.technic, Pehter Abrahamsson writes:
> Dean Hystad wrote:
>
> > The rotor design for the 8856 and 8444 would not allow the helecoptor to
> > move forwards backwards or sideways. If you tilt the rotor (as is done in
> > these sets) the only thing that happens is that the fusalage of the
> > helecoptor tilts. In a real helecoptor the blades's pitch varies as it
> > rotates around the hub. The stick controls the pitch of the rotor.
>
>
>
> It has already been made by Lego in 1977, 852 Reconnoitre Helicopter.
> Wonder why they did not do that later on also?
> /Pehter
The rotor design in that set isn't quite right either, though its closer to
real life. In the 852, the control stick changes the pitch of the rotor
blades, but the pitch angle stays the same as the blades spin around the
hub. In a real helicopter the rotor blades have to change pitch as they
rotate about the hub.
When you pull back on the stick in a real helecopter, the angle of attack of
each rotor blade is greatest when the blade is pointing forwards, and least
when the blade is pointing backwards. This generates more lift in front of
the helecopter and less in the back. The imbalance causes the entire
helecopter to tip backwards (nose lifts and tail dips). With the helecopter
oriented this way, the lift from the rotor is aimed slightly backwards,
causing the helecopter to travel in that direction. The opposite occurs
when you push the stick forward. Sideways motion is achieved in a similar way.
Dean Hystad
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