Auction Archive

Futaba Gyro SMM GYA 351 AVCS RATE GYRO

 Up for bid is a brand new in the box GYA 351 Dual Servo Support Gyro. See the specs below. Lots of people may think that “gyros are nonsense for airplanes”.　For those people, I’d like to explain the GYA351 gyro so that they will understand the great benefits of using these gyros tuned exclusively for model airplanes.Here are the secrets behind GY Series gyros: SMM (Silicon Micro Machine) Essentially, it's micro-machining mechanical parts and systems right on a silicon chip a first in the hobby industry. This results in unprecedented levels of functionality, reliability and sophistication. AVCS (Active Angular Velocity Control System) This feature is the equivalent of heading hold, except that it utilizes a gyro sensor that's more accurate and less susceptible to vibration than conventional piezo gyros. It continually sends control signals to the servo , even when the tail is not moving, for extremely low temperature drift and more positive control for hovering and flying in crosswinds.  SMM-GYRO GYA 351 manufacturers description SMM aileron gyro for fixed-wing models, with outputs for 2 aileron servos. The virtually drift-free SMM sensor system is vibration-resistant and offers high gyro gain. It provides a "Heading Hold" (AVCS) function for fixed-wing model aircraft in addition to the familiar "normal" stabilisation mode. In this mode the gyro maintains the set heading in the air with great accuracy, compensating constantly for sidewinds, gusts and turbulence. In AVCS mode circling in thermals becomes a pleasure, as the gyro maintains the set angle of bank automatically. A very good choice for scale and large models generally, but also for gliders. On the landing approach the SMM gyro holds any model in a stable attitude automatically. Naturally, the ailerons can still be used as landing flaps, and the stabilisation system does not affect the flap function. If an auxiliary channel is available, the pilot can adjust gyro gain from the transmitter, and also switch between Normal and AVCS modes. Automatic neutral point calibration when you switch on the gyro. Neutral points for Normal/AVCS can be adjusted in flight via an auxiliary channel. Introducing the GYA350/GYA351 Gyros Lots of people may think that “gyros are nonsense for airplanes”.　For those people, I’d like to explain the  GYA351 gyros so that they will understand the great benefits of using these gyros tuned exclusively for model airplanes. The GYA351 is a single-axis rate gyro exclusively for controlling an aileron and is capable of handling a dual-servo flaperon. This gyro works even while the air-brake is being operated. Both gyros have two selectable operation modes, the AVCS and Normal modes. I’d like to explain how to use these modes, and how you can take advantage of their features. What is the AVCS mode? The GYA351 are the first airplane gyros that have the AVCS mode. Some people may not be familiar with the word “AVCS”. It works like a headlock gyro which is used for tail control of helicopters. Let me explain the difference between the AVCS mode and the Normal mode. In the Normal mode, the gyro sends control signals to the servo only when the attitude of an airplane is changing, and it works to stop the change. The AVCS mode is the mode in which the integral control is added to the Normal mode. It works to not only stop the attitude change but also correct inclination or direction of the airplane. For example, during a knife-edge flight, you generally have to apply aileron and/or elevator controls in order to maintain the attitude of the airplane. However, in the AVCS mode, the gyros, implementing “Auto-trimming,” automatically apply aileron and/or elevator controls to maintain the attitude of the airplane. For instance, even an airplane with extremely misaligned trim can fly straight and level in the AVCS mode without trim adjustment from the transmitter (this is just an extreme example which is not recommended! It is only an example to demonstrate the excellent control ability of the AVCS mode). In the AVCS mode, the gyro senses attitude changes and finds its own neutral position. This is the unique feature which distinguishes the AVCS mode from the Normal mode and is a point to remember when using this mode. Here are some examples where the gyros can really make a difference. Easy Take-off and Landing For beginner and intermediate-level flyers that are able to control mid-air flight but are not confident with takeoffs and landings, the gyro can be a great help. It really makes takeoff and landing much easier. It shows its maximum effect especially in scaled airplanes which commonly suffer from instability. To be precise, manual operation for the aileron and elevator will be reduced by about half during takeoff and landing, the gyro mostly controls the airplane’s inclination when landing. To land the airplane safely, you only need to gently pull the elevator up shortly before landing. In addition, the gyros dramatically reduce the amount of drifting of the airplane caused by weather conditions such as cross-winds at high altitude allowing you to feel more comfortable about flying the airplane high up in the sky. * Please be sure to use the Normal mode for taking off and landing. This mode will give you sufficient stability. With the special features mentioned above, the AVCS mode is recommended only for highly experienced flyers who already know how to safely land their airplanes. Improved Airplane Performance Even after adjusting the trim at level flight, you may still find misaligned trims in upward climbing, knife-edge or inverted flight. In the AVCS mode, any misalignment in trims due to attitude change can be automatically adjusted in accordance with the changes in the circumstance. Therefore, in inverted flight, manual down throw operations are not required, and also in knife-edge flight, manual operation of aileron and elevator sticks are not needed. This means 4-point rolls can be performed quite easily. The gyro automatically removes all bad tendencies of the airplane; usually a skill that only top class flyer's possess. Once the gyro is mounted, you may notice that controlling the airplane feels slightly different. The gyro works in a way different from previous ones, especially when in the AVCS mode. Understanding the dynamics of gyros in general will help you to put gyro-effects to even better use. Points to note when using GYA351 gyro. 1. What to do when the aircraft stalls. During normal flight conditions, the gyro stabilizes the attitude of the airplane. You may notice that the steering feels heavier when you try to change its attitude, or that the airplane is stabilized, but other than that, controlling the airplane would feel no different than before the gyro was installed. However, special care is needed when the airplane enters a stall condition while flying in the AVCS mode. When you lose control of the airplane as it is about to stall, the gyro overreacts and actually causes the airplane to stall. In a stall condition, you cannot depend on the gyro’s stabilizing effect. If a stall happens in the AVCS mode, switch to the Normal mode or immediately accelerate the engine to recover control of the steering. 2. Where to use the AVCS Mode. It is very effective to use gyros for the aileron axis and the elevator axis in the AVCS mode. Imagine the airplane is climbing at an angle of 45 degrees, for example. Even after the elevator stick is returned to the neutral position, the airplane continues climbing with its attitude maintained exactly at the same 45 degrees because the AVCS mode firmly controls the airplane’s flight attitude. The same goes for flights such as inverted flight and knife-edge flight. Once the airplane is set at the attitude for each of those flights and the sticks are returned to their neutral positions, the same attitude will be maintained. 3. What kind of servo to use. When a change occurs in the attitude of an aircraft, a gyro detects its movement and transmits a signal to the servos to move the aircraft in the opposite direction. To achieve this, you need high-speed servos that can respond to the gyro’s signal as quickly as possible. With this in mind, digital servos are most suitable for this application because of their high-speed response. Increasing the gyro’s sensitivity improves control efficiency. However, if the sensitivity is set too high, oscillation (which is also known as 'hunting') will occur. Since digital servos are less prone to hunting, you can set the gyro sensitivity 20 to 30 percent higher for digital servos than for analog servos. 4. How to set the sensitivity For airplanes which respond well to your controls, set the gyro sensitivity to low. For high-speed airplanes, you should set the gyro sensitivity to low, while for low-speed airplanes, the sensitivity can be set too high. For some proportional transmitters, it is possible to adjust gyro sensitivity even during flight. In such cases, you can make the most of the gyro’s performance by selecting different sensitivities depending on the speed of the airplanes: low sensitivity for high-speed flight and high sensitivity for takeoffs and landings. The best thing to do is to fly the airplane at 50% gyro sensitivity at first and then raise the sensitivity gradually to find the maximum value where hunting does not occur. If the airplane hunts heavily due to excessive sensitivity, the airplane or the servos may become damaged. Therefore, it is safer to always start with a lower sensitivity. Gyro sensitivity should be determined not only by airplane speed but also by rudder size and linkages. 5. How to mount the gyro When mounting a gyro on an airplane, it is necessary to align the axis of the gyro with one of the axes of the airplane you wish to control. If the two axes are not correctly aligned, the gyro will detect motion from the other axes of the airplane, causing the airplane to roll badly (not roll on its axis). Please ensure that the alignment difference between the axis of the gyro and the axis of the airplane falls within ±3°. To use a gyro for aileron axis, the gyro should be mounted so the gyro’s bottom surface is vertical to the center line of the fuselage. In most cases, the central part connecting the left and right wings of the airplane has beams extending perpendicularly to the centerline of the fuselage. In such case, mount the gyro on this part. To use a gyro for rudder axis, set the gyro with its base parallel not only to the centerline of the fuselage but also to the horizontal tail. Most airplanes are equipped with a servo bed parallel to the centerline of the fuselage. In this case, mount the gyro for the rudder axis on this side. To use a gyro for elevator axis, set the gyro with its base parallel not only to the centerline of the fuselage but also to the vertical tail. It is recommended that you mount something like a thick balsa block in a way that the balsa block is vertical to the servo bed and parallel to the centerline of the fuselage, before mounting the gyro for the elevator axis on the balsa block. In fact, the gyro can be placed anywhere on the airplane. But considering the center of gravity and linkages, it is the best to install gyros close to the center of gravity. However, try to avoid places where the gyros may be affected by engine vibration. If a servo hunts during engine start-up, the gyro is being affected by engine oscillation. In such a case, please solve the problem by reinforcing the area the gyro is mounted on.