B225
DESIGN: SynchroLite ~
Control - Flight - Collective
Outside Helicopters
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Web page by Paul Cantrell |
UltraSport:
Indian Helicopter:
1" of movement at the end of the collective lever produces 1 degree (actually .95 degree) of pitch. This collective lever is 17" long.
Bell 47:
The Bell 47 collective lever is about 14" long and moves from 30 degrees off the horizontal to 90 degrees. It would visually appear that the pitch only changes 10-18 degree for full collective lever travel.
Kaman Huskie:
E-mail from E.M. former Huskie pilot: I do remember the control power with the servo flaps was very weak, and a normal power landing usually required overspeeding the rotor because the collective pitch travel was so limited.
We also had fatalities when one rotor on an HTK went into high collective pitch (uncommanded in any way), and the other rotor didn't.
Re Helicopters in Prouty's book:
The average 'up' value of the best 11 helicopters is +17.52 degrees.
The average 'down' value of the best 11 helicopters is +1.95 degrees.
The average collective range of all helicopters is 16.42 degrees.
The greatest collective range of all helicopters is 25.0 degrees.
The Robinson R22 is +1.5 to +14.5 (13 degrees).
SynchroLite
For the SynchroLite use +17º -3º; total of 20º. (Note: -3 is large because of -1.4 zero lift angle?)
Mount the collective lever and all linkage on the power train, so that the dimensional changes caused by oscillations between the fuselage and the power train does no effect the collective's contribution to blade pitch. Mind you, this migh put some oscillations in to the stabilator/ruddervator and into the lever.
The pitch linkage is attached to the trailing edge of the blade, therefore lifting the collective will cause all six rods to be lowered.
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Last Revised: October 26, 2001