Mechanical Gyro

[ahmedrehan]

Dose any one have an idea were to find electro mechanical spining gyro the one used in heli before piezo and mems.

These gyro give very accurate slow speed turn rates like 2min turn and you even dont need kalman filter on there output.

Ahmed

[dmgoedde]

I have one on an old .30 heli from 1995. Maybe on E-bay others have theirs for sale?

Wouldn't you still need the Kalman filter to fuse together the gyro data with accelerometer to track attitude? Also, I'm not sure how easy it is to extract rate data from an old gyro like mine.

[ahmedrehan]

I have one on an old .30 heli from 1995. Maybe on E-bay others have theirs for sale?

Wouldn't you still need the Kalman filter to fuse together the gyro data with accelerometer to track attitude? Also, I'm not sure how easy it is to extract rate data from an old gyro like mine.

these type of gyro have linear magnatic sensor which will give voltage output proportional to turn rate if you change the spring to low tension it will give you good analog output for 2min turn need for airplane to turn without going into spiral adding a height hold will give a very reliable stablizer even for bigger uav. this trick was used in bta autopilot.

But i dont think these gyro are produced any more.

[dmgoedde]

So the supposed advantage of the old-style mechanical gyro is it doesn't have a complex bias to correct for like a MEMS gyro?

Maybe go on the Heli section of RCGroups, put out a new thread asking if anyone has a mechanical gyro from 10+ years ago that still works. You are bound to get a hit or two.

[ahmedrehan]

So the supposed advantage of the old-style mechanical gyro is it doesn't have a complex bias to correct for like a MEMS gyro?

Maybe go on the Heli section of RCGroups, put out a new thread asking if anyone has a mechanical gyro from 10+ years ago that still works. You are bound to get a hit or two.


Yes the bias drift is not there or very minimum as the center of gyro is hold with spring also the actual aircraft use to have attitude indicator based on mechanical gyros still many of the aircraft use them . 2 min turn indicator in aircraft also uses mechanical rate gyro.

any way i have an idea to fabricate these gyro using outruner brushless motor held in gimbal as the weight of outruner body will act as gyro if need can put extra weight on it. and sensing through optical encoder or magnatic sensor optical encoder has an advantage that the output is digital and no analog conditioning is required.

[ios]

I have one of these old BTA electro mechanical automatic piloting systems. Its quite a big unit and actually humms when its on!! :D As far as I can tell, it works the same way as the FMA Copilot, but using a gyro instead of thermopiles. When the Tx sticks are released, plane flys staight and level, when sticks a pushed in a given direction, the plane will either roll or pitch proportionally - but will not allow inverted flight or very steep descent.

Why is the electro mechanical version different to the piezo and mems version?

[ahmedrehan]

I have one of these old BTA electro mechanical automatic piloting systems. Its quite a big unit and actually humms when its on!! :D As far as I can tell, it works the same way as the FMA Copilot, but using a gyro instead of thermopiles. When the Tx sticks are released, plane flys staight and level, when sticks a pushed in a given direction, the plane will either roll or pitch proportionally - but will not allow inverted flight or very steep descent.

Why is the electro mechanical version different to the piezo and mems version?

The hum is due to rotating weights. BTA electro mechanical is a very good stablizer found in 80s and 90s but discontinued now the new version AS-07 uses piezo gyro and pressure sensor but is not good as the older version because the pizeo gyro is not good in detecting low rate of turn also the pressure sensor is less senstive the old version has rubber diaphram type sensor which was very senstive.

the copilot or light type sensors are also very good for small aircrafts with dihedral but if you go to bigger airframe with less spiral stability it will not work also copilot is heat senstive

The piezo and mems are temperature senstive so the bias drift and you have to condition through kalman or other filter.

However now what i see the future is 6axis micro magnetic sensors which can give good results such sensors are now being produced for commercial applications.

[gkamysz]

I've never used the older AS-05 or AS-06 BTA systems. I've seen them and owned an AS-05 briefly. If they flew better than the AS-07 I have now, that would be incredible. The old pressure sensors were hand made and failed after a period of time (5-10 years) due to the rubber deteriorating. The mechanical gyros worked just fine, but drew a significant amount of current. The older systems were also analog and the AS-07 is digital.

I have an old mechanical gyro that was sold by Kalt for the Whisper electric heli many years ago.

Greg


The hum is due to rotating weights. BTA electro mechanical is a very good stablizer found in 80s and 90s but discontinued now the new version AS-07 uses piezo gyro and pressure sensor but is not good as the older version because the pizeo gyro is not good in detecting low rate of turn also the pressure sensor is less senstive the old version has rubber diaphram type sensor which was very senstive.

the copilot or light type sensors are also very good for small aircrafts with dihedral but if you go to bigger airframe with less spiral stability it will not work also copilot is heat senstive

The piezo and mems are temperature senstive so the bias drift and you have to condition through kalman or other filter.

However now what i see the future is 6axis micro magnetic sensors which can give good results such sensors are now being produced for commercial applications.

[dmgoedde]

the copilot or light type sensors are also very good for small aircrafts with dihedral but if you go to bigger airframe with less spiral stability it will not work also copilot is heat senstiveWould you elaborate on what effects you saw that indicated CoPilot is heat sensitive? I'm not going to say "huh uhh! You are wrong!", I am just curious what you saw.

[ahmedrehan]

Would you elaborate on what effects you saw that indicated CoPilot is heat sensitive? I'm not going to say "huh uhh! You are wrong!", I am just curious what you saw.

I dont mean drift but the problem i faced is ir flare put on the drone will cause it to malfuntion as the ir flare generate too much heat .

[ahmedrehan]

I've never used the older AS-05 or AS-06 BTA systems. I've seen them and owned an AS-05 briefly. If they flew better than the AS-07 I have now, that would be incredible. The old pressure sensors were hand made and failed after a period of time (5-10 years) due to the rubber deteriorating. The mechanical gyros worked just fine, but drew a significant amount of current. The older systems were also analog and the AS-07 is digital.

I have an old mechanical gyro that was sold by Kalt for the Whisper electric heli many years ago.

Grloeg

How is your experinece with AS-07 and what is the type of plane you are using ? i had one old bta 05 which worked fine till 2006 was bought in late 80s i think this type of life for rubber is good for its value. I agree old versions were analog and new AS-07 is digital i wish if you had got a chance to compare you will see the difference your self.

[gkamysz]

I've been using the AS-07 in an Ultra Stik Lite from Hangar 9. I actually flew it with many of the beta versions of the software when I worked for the US distributor. I think it works well, wing leveling is excellent. Pitch is very good most of the time. I made several changes with motors and have a huge hole in the bottom of the fuse. I never really optimized the installation in regard to pressure in the fuselage. The only issue I run into is that the gyro neutral point can drift if I leave the AS-07 in the sun when I have the wing off. As it cools in the airplane after calibration it will tend to turn the aircraft. As long as I pay attention to that it works very well. I have their homing navigation system and that works very well also. They guys at the flying field have been impressed by how it works.

Greg

[ahmedrehan]

I've been using the AS-07 in an Ultra Stik Lite from Hangar 9. I actually flew it with many of the beta versions of the software when I worked for the US distributor. I think it works well, wing leveling is excellent. Pitch is very good most of the time. I made several changes with motors and have a huge hole in the bottom of the fuse. I never really optimized the installation in regard to pressure in the fuselage. The only issue I run into is that the gyro neutral point can drift if I leave the AS-07 in the sun when I have the wing off. As it cools in the airplane after calibration it will tend to turn the aircraft. As long as I pay attention to that it works very well. I have their homing navigation system and that works very well also. They guys at the flying field have been impressed by how it works.

Greg

Piezo gyro has problem with temperature . Also during the calibration startup the aicraft should not yaw these problem was not there is AS-05 /6 but i will never trust my bigger crafts with AS-07 . Which version of software you last tested?

[gkamysz]

I had a few version prior to and including the release. There were really only a few minor changes. The analog versions needed to be trimmed mechanically for servo neutral position at installation. The AS-07 eliminated that, but has the temperature drift issue. There are systems far more advanced than BTA's setup today. I think they were trying for a more user friendly version for modelers. In general I think it works very well.

Greg

[Jack Crossfire]

Don't throw in the mechanical gyros without some vacuum tubes for the complete retro experience. You can probably equal the mechanical goodness by adding weight to piezo gyros.