Heading Hold
This describes a type of Gyro which senses rotation, and maintains direction. This is accomplished by sensing the rate of motion, and the time of motion, then compensating for the distance. While this sounds complicated, the effect is that if you have the model dialed in, and point the nose north, with a heading hold gyro on the yaw axis the model will continue to face north until you command it to yaw. See also Heading Lock. This is not recommended for aircraft use while in flight due to the requirement to use YAW (rudder) command to turn the model. Often used for ground use only for perfect take off and landing runs.

Heading Lock
Slang term for Heading Hold Gyro.

Helicopter Radio
A remote control radio system designed specifically for use with helicopter models. The helicopter radio differs from an aircraft radio in a few ways. First, the heli radio needs mixing functions specific to helicopters, and usually a minimum of five channels. Collective mixing for collective pitch helicopters is a necessity. Second is the throttle stick, which is ratcheted in airplane transmitters, will not have the clicking feel on the heli version. This is due to the precise control needed on the heli collective stick to achieve and sustain a controlled hover. The specific radio requirements will vary from user to user, and the parameters used will vary from helicopter to helicopter. Note that many radios produced have both airplane and helicopter programming in a single radio.

Hit (or to be hit)
Sudden radio interference which causes your model to fly in an erratic manner. Most often caused by someone turning on a radio that is on your frequency, but can be caused by other radio sources miles away.

Horizontal Stabilizer
The horizontal tail surface at the back of the fuselage which provides aerodynamic pitch stability to the airplane.

Hover
To maintain a stationary position in which the model is not climbing, diving, rolling or yawing.

Hovering offset (Heli programming only)
Adjusts the center point of the pitch curves, including the hovering pitch curve, to fine-tune the hovering point when it is not exactly center throttle stick position.

Hovering pitch (Heli programming only)
This is a pre-programmed hovering-type mix which gives an in-flight adjustment to the pitch curve at and around center stick (or the hovering point if that point is not at center throttle stick, then the center-point of this feature is adjusted with the hovering offset command) to give very fine-tuning for easiest hovering.