Specifications

Autorotation
A controlled, unpowered helicopter descent (and landing). A helicopter is a brick with a ro-
tor, so it doesn't glide well when unpowered. The autorotation is the closest to gliding pos-
sible. The autorotation consists of a steep descent using negative pitch to keep the rotor
blades spinning followed by a slight flaring performed with positive pitch to convert the mo-
mentum of the blades into lift to soften the landing.
Autorotation Gear
Autorotation gear. A gear with a one-way bearing so the motor can only drive the main
shaft in one rotational direction. Required for performing autorotations.
AR Gear
See Autorotation Gear
ATV
Adjustable Travel Volume. This is the amount of servo travel from one servo endpoint to
the other. This can be reduced or increased by changing the servo endpoints. This is also
used to avoid binding.
See also EPA
AUW
All Up Weight. The weight of the heli when ready to fly, including batteries.
AVCS
Angular Vector Control System. Basically Futaba's own terminology for "heading hold".
Their website describes it as "an advanced version of heading hold which doesn't have the
temperature related drift problems of most of the older HH gyros."
B
Backlash
The play in the mesh between two gears. Too much backlash and the gears can slip or
break the teeth, too little backlash can cause excess friction, heat and wear. The common
guideline is to allow the thickness of a sheet of paper between gears to achieve the correct
amount of backlash.
Balance Charger
A charger which automatically equalizes the amount of charge in each cell of a multi-cell
battery pack. This is particularly important for lithium-polymer battery packs to prevent cell
bloating or cell ignition.
Ball Link
A connection that allow for adjusting controls using a ball on one end, and a link that
"snaps" onto the ball on the other.
Ball-Link Pliers
A special plier made especially for handling ball links. It can quickly remove the ball joint
from a ball link without damaging either part. One jaw has a U-shaped cut in it and the oth-
er jaw has a small cup on it to hold the ball joint.
Glossary
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