AGB-3

 

AGB-3 air horizon (bomber air horizon, similar to AGI-1 - fighter) — the most common[source not specified 4425 days] aviagorizont. The display type is "from the ground to the plane". Designed for heavy non-maneuverable aircraft (bombers) Design-autonomous. Due to the lack of an additional tracking frame of the gyroscopic sensor, the operating range of pitch angles is limited to 80 degrees. It has the following modifications AGB-3 (illumination with ultraviolet rays, used on aircraft OKB Myasishchev 3M, M-4), AGB-3B (white scale illumination), AGB-3K (red scale illumination, the most common modification as it is used on Mi-8/17, Yak-40, Il-76). From 1992 to the present, the 3rd series of the device (AGB-3K series 3) has been produced. It is used on airplanes AN-24, AN-26, AN-32, Yak-40, Il-62 and Mi-8/17family helicopters. The sensitive element of the aircraft horizon is a gyroscopic sensor that does not have a mechanical connection with the pointer mechanism along the pitch channel, but has a mechanical connection along the roll channel. This scheme, according to some sources, was copied from the captured American air horizon.

Basic technical data

Parameter	Meaning
Ready time, min, max	1,5
Current consumption in steady-state mode. And no more than: a) from an AC source with a voltage of 36V 400Hz: in phase III in phases I, II b) from a 27 V DC power source	0,8 0,9 0,3
Error of air horizon readings, including stagnation and instrumental scale error, at angles from 0 to 30 ' deg, max.	±1
Gyroscope precession rate along the roll and pitch axes under correction, ' / min	1.8-5
Care of the gyroscope with the correction turned off on the swinging base in 5 minutes, deg, no more by roll by pitch	±2,5 ±4
Operation of the power failure detector in the event of an open DC power supply circuit and one of the phases of the AC circuit:	a check box should appear before the pitch scale
Weight, kg, max	4.7

Operating principle

The gyroscopic system of the AGB-3 air horizon (AGB-3K) is a gyroscope with three degrees of freedom, the main axis of which is supported in the vertical position (that is, perpendicular to the plane of the true horizon) by an electric pendulum correction system. As is known, the main axis of an uncorrectable three-stage gyroscope will deviate from the true vertical position of the seat over time due to the daily rotation of the Earth and the movement of the aircraft in flight relative to the ground, as well as under the influence of friction in the gimbal supports, residual unbalance of the gyroscope, and a number of other reasons.

Electric pendulum correction, consisting of two uniaxial liquid pendulum sensors and correction motors, determines the true vertical and creates moments on the gimbal axes of the gyroscope that cause precessional movement of the main axis of the gyroscope to the vertical direction.