what does a gyro do

[balsakkie]

Hello there

im just about to enter the world of remote (electric) hellies and like all my other hobbies mainly RC (nitro) cars, I did my research and asked questions of how the cars worked and what the parts did

now that im entering the world of hellies its obviously a whole new ball game, battery packs, chargers and other bits. Ive just bought the latest issue of rotor world which has a good write up on sims that I plan to get first before I make my mini titan e325 purchase.

NOW. one of the writeups in this months issue mentions a Gyro. and how important it is.

what is a gyro for start
what is its purpose
Ive tried looking for books in WH smith to explain this to me but nothing as for yet, luckily my dad is a engineer so he explained to me all the working of my rc car.

if anyone out there can help me with my questiion and basically educate me on the workings of a gyro and what its purpose is. I think alot of people enter the world of RC and dont know the basic workings of there hobbie. thanks for a great forum

cheers
w

[Mactac]

One of possibly Four people that spring instantly to mind will be along presently to explain the. Device.
I too dabbled in pocket heli's but with my limited patience it was almost certain to end in tears.

I shall bookmark this thread for refference anyway keep us posted

[nurburgring1]

It seems to stabilise the tail rotor so the tail is kept where you want it and the model is stopped from spinning round. ( I think )

[The_Jackal]

It is a small box of tricks that senses movement around a particular axis (for example the way the tail boom moves around the central rotor). It also has a connection to the servo that controls the angle of the tail rotor blades.
So when it senses a twisting to say the left, it increases the angle of the tail rotor blades to cancel out the movement.

This is the only way a heli can stay pointing in one direction. If you are going with a mini titan, dont skimp on the standard of gyro and especially the tail servo. the 401 gyro seems to be the gyro of choice and the servo needs to be super quick rather than high torque (the opposite way to how you choose servos in nitro buggies). Dont be surprised to pay over 100 quid for a gyro/tail servo combo, it will determine how easy your heli is to fly.

[Amused2death]

For every action there is an equal and opposite reaction, so as the main rotor increases pitch (to generate lift), the body of the helicopter wants to move in the opposite direction. The tail rotor is set up to compensate for this, but is only a rough setup. There are two types of gyro, heading hold and non heading hold. The main difference is a non heading hold will drift nose in to the wind from a perpendicular position. Whereas a heading hold will do that relative to its position, ie turn it 30 degrees, let go of the rudder and it will stay there ( if set up right)

I started with non heading hold, it was cheaper, but went to heading hold on one of the helis, they did fly differently, non heading hold seemed easier in fast forward flight and general aerobatic flying, but if you get into 3D flying, then you need a heading hold gyro, and preferably a matched servo to suit. Non heading hold compensates to a movement, whereas a heading hold will try to keep the tail where it is until told otherwise. sort of reactive and pro-active forms of operation

[S4simon]

Getting back to basics. The first gyroscopes were fitted on aircraft to provide stable platforms. Originally (back in the 50s - 70s) three gyroscopes (US$35k each) were fitted to a gimballed system. Each gyroscope has a spinning mass and once up to speed (approx 20k rpm) this gyro would keep the gimbal assembly level to the earth's surface, even when the aircraft is pitching, rolling or yawing. On this gimballed system would be a number of accelerometers (x3). Each of these sense accleration in one axis (pitch, roll or yaw). Now with the accels always level with the earth's surface (thanks to the gyroscopes) they would only sense aircraft acceleration (and not false gravity). Now when these aircraft accelerations are fed into a computer and integrated with time the computer can then work out velocities and distance travelled over a certain time period. If a known starting reference point is inputted into the computer (lat / Long), then over time the computer can then determine the exact postion of the aircraft at any time + also work time to go to a certain postion etc... During the 80's Laser gyros (US$40k each) were invented which utilise two contrarotating laser beams (no moving parts). These laser gyros are fixed to the aircraft (do not need a stable platform) and they can sense aircraft rotation. The optimum pathlength for these lasers was 28cm and as such the actual device was about 20cm square and about 6cm high. Around the year 2000 they developed the fibre optic gyro suitable for the avionic industry. Instead of lasers they now used two coils of optic fibre. Size, power consumption and price dropped dramatically as well as higher reliability. One of the first fibre optic clusters was installed on cruise missiles. From memory the guidance cluster was around US$50k - which was a very cheap expendable but relaible piece of engineering. Nowadays gyroscopes are on a microchip and these are very cheap and provide a suitable output. The A380 was the first aircraft to have fibre optic gyros fitted as standard.

Hope that's not to heavy for you all.