Navaid Devices, Inc.

The "company mission" is to put autopilots in homebuilt airplanes. The need was recognized a long time ago, but high prices have previously kept them out of reach.

To keep production costs low, we use as many mass-production parts as possible, and we make what we cannot buy. We use a standard gear if we can, modify it if necessary, or make it from scratch if we must. We make front panels, gyro parts, and installation hardware using simple, inexpensive tooling.

We limit selling expenses by dealing directly with the customer. We avoid advertising expenses as much as we dare, relying instead on word-of-mouth communication.

SIMPLE OPERATION

A three-position switch determines the mode in which the system will operate. If this mode control switch is in the center position, only the turn coordinator is active.

Setting the switch to the Wing Leveler mode enables the autopilot. It pulls the wings to level and the airplane goes wherever it is pointed. The autopilot has no heading information, but a fine trim control can be adjusted to make the airplane deviate from a given heading so slowly that changes are needed only once every three to five minutes, depending on turbulence. A turn control may be used for making turns at any rate up to a maximum or about 3 degrees per second.

After intersecting a radial and centering the CDI needle, turn the airplane to the desired heading and set the mode control switch to Track mode. The airplane follows the GPS/Loran course or track in over the VOR.

Position feedback, which Navaid uses in addition to the rate information used by competitors, makes it much easier to match the autopilot to the aircraft. Adjusting a potentiometer setting is much easier than changing a gear ratio.

LIGHTWEIGHT

The autopilot system consists of a panel mounted gyro/computer unit, which we call the AP-1, and a second generation servo actuator designated the S-2. The AP-1 weighs less than the conventional turn coordinator which it replaces, and the S-2 servo weighs less than that of the closest competitor.

If the turn coordinator to be replaced weighs 2 lbs., the weight penalty for adding the autopilot system is only 0.6 lbs. exclusive of pushrod and wiring, or usually about 1-1/2 lbs. installed.

RELIABILITY

Navaid cannot recommend its autopilot for IFR use:

The relatively low price of the product precludes both extensive product testing on a variety of airplanes and a comprehensive production quality control system. A good quality assurance system requires expensive test equipment, testing, and extensive documentation.
The Navaid autopilot has been optimized for cross-country flying by making the servo more than twice as fast as that of a type accepted autopilot. Navaid has no way of insuring that the customer will adjust the autopilot (i.e. the servo slip-clutch breakaway point) in such a way as to insure a moderate roll response in the event of a hard-over failure. Such a failure, no factor at altitude, can be dangerous on an IFR approach.

An accelerated life-test on the position feedback potentiometer in the servo indicated a gradual deterioration that might become noticeable at 2000 operational hours. We tested the life of the gyro by continuously cycling the gyro on for 1 hour and off for 5 minutes. The first sign of wear occurred at 1700 hours in the form of a temporary increase in armature current, but it was fully operational beyond 5000 hours. Actual life will be less because no outside forces were applied to the gyro during this test.

THE GUARANTEE

The customer has 60 days in which to return the equipment for a full refund. During this time, the customer may install and use the autopilot. In the case of a flying airplane, we start the clock on the date of purchase. In the case of an aircraft under construction, the clock starts whenever you start flying; we take your word on that date.

Navaid will repair at no charge any equipment returned for service during the first six months from the start of the clock.