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Gyros? - wondering about pitch stability

R/C Submarine modelers

Postby 112-1053369592 » Mon May 19, 2003 3:30 pm

ok you sub guys, a surface modeler is wondering how to use gyros for stabilizing pitch. I just finished a 1:72 Sea Shadow (the Navy's SWATH stealth ship), which is basically an a-frame affair sitting atop two torpedos. While very stable in roll, it has no stability in pitch... the real one uses computer controlled horizontal stabilizers to maintain pitch attitude, and my lack of stability shows why... low speed, it goes ok, but goose it and it dunks the stern; let off the gas, and the bow noses under in a rude reaction.
I doubt that static fins will fix this; looks like an opportunity to use a gyro. I've heard that subs sometimes uses these to maintain level operation... should work for me too. Do you use regular old R/C helo gyros? Any particular type? Any tips?
Thanks, PM
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Postby ThierryC » Mon May 19, 2003 5:14 pm

Hello

Most subs use some sortf of pitch stabilisation device, or APC (automatic pitch control).
They are different than regular helicopters gyros (don't ask me why I have no clue, I think the heli gyros are not sensitive enough)
There are currently 3 APCs manufacturers out there, SubTech, Engel, and Thor Design
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Postby Ramius-II » Tue May 20, 2003 12:55 am

Hi Pat:
There are several types of pitch control devices. The most basic and common uses a three wire system so that a small pool of mercury makes contact between the center and one of the two pins. So you have pin...common...pin. As things move, the mercury flows in one direction and this flow is used to provide a connection which is the input to a PIC (Programmable Intergrated Circuit). The PIC then tells the servo which way to move. Most common PIC is the 16F84. If you look closely at a pitch controller you will typically see this format of number.

In Helicopters, you are attempting to stablize three directions at once thus a simple pool of mercury won't do it. While mercury is not the only means, it is most common due to it's elecrtical characteristics. You can accomplish the same results with a capacitance type device however, the circuitry is a bit more complex.

Thierry's recommendations are the easiest to use and you could probably "y" connect two servos to the APC. Al at SubTech tells me you do not need to control the APC with the radio, it operates stand alone.

Hope all this helps,

Best Regards, Ed

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Postby KOEZE » Sun May 25, 2003 1:56 pm

Dont forget Norbert Bruggen
http://modelluboot.de/
He has some great APC's

EJK
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you get older because you stop playing.
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Postby witchblade » Tue May 27, 2003 11:19 am

Being a ex-modelheli builder I couldn't resist.

A modelhelicopter uses a gyro only on the tail rotor. It counteracts the change in force which is generated by the mainrotor, and only that. It doesn't read out the tail, else you could use it. Perhaps the newer Heading Hold gyro's can be used, but costing over 250 dollars (or Euro's here in Europe),it is more costfriendly to go with the normal submarine devices.

Jst a thought,

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