Aerial horizon is an onboard gyroscopic device used in aviation to determine and display the longitudinal and transverse angles of inclination of an aircraft ( pitch and roll ), that is, orientation angles with respect to the true vertical. The device is used by the pilot to control and stabilize the aircraft in the air.
This device is of great importance when flying according to Instrument Flight Rules (IFR), but it is not used much when flying according to the rules of visual flights (PVP), except in emergency cases when the pilot loses spatial orientation.
Content
Classification
Distinguish between autonomous and remote horizons.
Autonomous Horizon
In an autonomous horizon, the measuring device and indicator are made by a single unit. Only power is supplied to it, which can be electric or pneumatic [1] . There are foreign horizons equipped with a battery. An autonomous horizon, having a mechanical connection between the gyroscopic sensor and the display system, is able to maintain operability in the event of a power loss during the run-time of the gyro rotor (about 3 minutes).
Remote Horizon
The concept of "remote horizon" refers mainly to electromechanical horizons, in which the measuring device and indicator are made in the form of separate units, and does not apply to modern [ when? ] navigation systems, built on the basis and strapdown inertial navigation systems .
The measuring instrument in remote horizontal horizons is the gyro-vertical (such as the central gyro-vertical — the central gyro-vertical, the small-scale gyro-vertical, etc.), and the indicator is the so-called horizon indicator, which is often a complex indicator that shows a ton of parameters and performs several functions - flight-command device (control panel, also gearbox). The use of a remote horizon allows you to position the gyro vertical as close as possible to the center of gravity of the aircraft, which reduces the error of the device.
Indication
According to the principle of indicating the roll and pitch angles, the horizon horizons are distinguished into a “view from the aircraft to the ground” (direct, air force), a combined (mixed) view of the horizon (mixed, KAG) and “a view from the ground to the aircraft” (reverse, VSZ).
Air Force (direct display)
The most [1] common display system in which the orientation of the aircraft is given by a background image that rotates in pitch and roll. The background image is a line located at the border of two areas of different colors (usually brown and blue or light gray and black in obsolete). This line is the line of the artificial horizon. In front of the background image is a simplified silhouette of the aircraft, which is fixed motionless relative to the device or has limited pitch adjustment. The current roll angle is read by the pilot from the scale , drawn around the circumference of the front panel of the device, with a marker on top (in Soviet devices - below). The pitch angle is determined by the intersection of the center of the silhouette of the aircraft with a scale on a moving background (cartouche). Each line of the scale corresponds to a 5 ° or 10 ° pitch.
Horizons with such an indication are mainly used on low-maneuverable aircraft and helicopters.
KAG (combined or mixed indication)
In kAG type horizons, the pitch angle is displayed as the All-Air Force, and the angle of heel is shown by rotating the silhouette of the aircraft as if the plane was being observed from the ground from behind, i.e. by type view from the ground of the VSZ. A movable screen with a pitch scale in these devices has only one degree of freedom and can only move up or down. The angle of heel is determined on a scale located around the circumference of the hull, relative to the moving silhouette of the aircraft. This type of indication was implemented in many Soviet horizons.
VSZ (reverse indication)
In the VSZ type horizon an indication of the VSZ type is realized both in pitch and roll. The pitch indicator is an arrow with a view of the silhouette of the aircraft from the side with a pitch angle reading on a special scale against the nose of the silhouette of the aircraft. The roll indicator is the silhouette of the aircraft with a rear view and with a roll angle reading on a special scale against the wing of the aircraft. This type of indication allows simplicity and clarity of perception, speed and high accuracy of reading, and most importantly from the point of view of safety, the error-freeness of the pilot's first actions in special flight situations.
Technical limitations
By kinematic restriction distinguish between “knocked out” and “unkillable” horizons. “Horizon knocking out” occurs when the rotation axes of the gyroscope rotor coincide with one of the gimbal suspension frames (when the pitch angle is ± 90 °), while the gyroscope loses one degree of freedom and, accordingly, its ability to maintain orientation in space. To prevent this, mechanical restriction of the angle of movement of the gyroscope frame along the pitch is introduced into the construction of the horizon. Better ways to ensure “unbreakability” is to use a gyro-stabilized platform (see. Gyrovertical ) or an inertial navigation system as a measuring device.
All existing spatial position measuring systems are limited by the maximum angular velocity.
Characteristics of Soviet / Russian Horizons
| AGK-47 | AGI-1 | AGB-2 | AGB-3 | AGB-96 | AGB-98 | AGD-1 | AGR-144 | AGR-29 | AGR-81 | AGR-72 | AGR-74 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Type of indication | KAG | Air force | Air force | KAG | Air force | Air force | KAG | Air force | KAG | KAG | Air force | Air force |
| Type of installation location | autonomy. | autonomy. | autonomy. | autonomy. | autonomy. | autonomy. | distance | autonomy. | autonomy. | autonomy. | autonomy. | autonomy. |
| Range of indication on a roll, hail. | ± 95 | ± 180 | ± 80 | ± 180 | ± 180 | ± 180 | ± 180 | ± 180 | ± 180 | ± 180 | ± 180 | ± 180 |
| Working pitch angles, deg. | ± 85 | ± 90 | ± 60 | ± 80 | ± 85 | ± 85 | ± 90 | ± 90 | ± 90 | ± 90 | ± 85 | ± 85 |
| Ready time, min | 3 | 3 | 3 | 1.5 | 2 | 2 | 2 | 2 | 2 | 3 | 3 | |
| Accuracy of indications roll, deg. | one | one | one | 1 (at angles up to 30 degrees) | 1,5 | 1,5 | 0.25 | 1.5 (at angles up to 30 degrees) | 1,5 | 1,5 | 1,5 | |
| Pitch error, deg. | one | one | one | 2 (at angles of more than 30 degrees) | 1,5 | 1,5 | 0.2 | 2.5 (at angles of more than 30 degrees) | 1,5 | 1,5 | 1,5 | |
| Overall dimensions, mm | n.d. | 120 x120 x170 | n.d. | 119.5 x 119.5 x 234 | 105 x 105 x 250 | 85 x85 x250 | 110 x110 x195 | n.d. | 105 x 105 x 250 | |||
| Weight, kg | 2.2 | 2.6 | 2 | 4.2 | 2,5 | 2,5 | 7 gyro sensor , 2.6 indicator | 4,5 | 3,5 | 2,5 | 2,5 | |
| Objects of application | An-2 , Li-2 , IL-14 , Ka-26 , Mi-2 , Mi-4 , Mi-6 , Mi-10 | Yak-18A , MiG-15 , MiG-17 , MiG-19 , Su-7 , Yak-52 , An-28 | Tu-104 , An-10 | Yak-40 , IL-62 , Mi-8 | Tu-204 /214, IL-96 | Ka-226 | Yak-18T , L-29 , L-39 , An-12 , An-24 , Tu-134 | Tu-144 | Yak-52M , Yak-152 , | Ka-50 | Tu-154 , IL-86 | An-28 , An-38 , An-72 , An-74 , An-124 , Tu-154M , Mi-34 , Ka-32 |
Literature
- Automatic on-board control system ABSU-154-2. Technical operation manual. Part 2
- Passenger aircraft IL-18. Technical description. Moscow, Oborongiz, 1961
Notes
- ↑ 1 2 Aerial horizon - an article from the Great Soviet Encyclopedia .