What torque for gyro servos

[baronrouge]

Hello,
What torque is necessary for a gyro like A of A Kellet (or similar size), equiped with DC Head?
I read that this head don't need powefull servos (see E.Pinilla with his Cierva), or in others forum that is necessary to use high torque servos.
Who believe? What is you experience in this size of gyro?
Thanks,
Jérôme

[britinoz]

G'Day Jerome. I have myself used ''standard'' servos for this type of job ,but only once, because they did not last very long.
I would suggest that you use a Metal Geared ball race servo to handle at least 8-9 Kilo.
If you look around you will find some for a good price.
Happy Landings
Chris

[Boneswamped]

Jérôme,
Hello, I also reccomend High torque metal gear servos. The fixed pitch blades, and DC heads we use in our R/C autogyros place a fairly high load on the servos. You mentioned Cierva; his control mechanisms were cyclic in nature, while our models are DC. A standard servo might work for a while, but the plastic gears WILL fail eventually.

Here is a link for various servo torque ratings that may help you to choose a servo compatible with your system:
http://www.fatlion.com/sailplanes/servochart.html#top

Regards,
-Mike

[baronrouge]

Hello,
Thank for the details. Actually, I've equiped my Cierva (modified in french version Lioret et Olivier C-30 and built whit E. Pinilla plans) with 2 digital Multiplex Royal MCV2 (5 kg/cm of torque on 4.6V); they work together, mixing them with classic delta or elevon program on radio. So there is 10 kg/cm of torque for roll and elevator fonction on the hub.
This rotor head is a copy of spanish system i've seen in "Patrulla abejorro" web page. In attachment, my gyro, with detail on the head.
Rotor span may be 65", weight about 2.7 kg and APS 70 4T powered.
Jérôme

[britinoz]

G Day Jerome.
That's a fine looking machine you have there.Have you flown the model with those servos???
Happy Laandings
Chris...........

[Norfolk Flyer]

Hi Jérôme,

I understand it like this...

The servos do not have to move the rotor disc directly. They only have to flex the plate in one direction and alter the blade angle of incidence at 90 deg. to this, and let the blades fly to their new position. The more flex there is in your head / blade system, the less load on the servos.

Regards
John

[baronrouge]

---"The more flex there is in your head / blade system, the less load on the servos."---

Ok I've understood. My rotor head is a triangle of epoxy fiberglass (not G10) so it is very stiff (and it is only 1/16" thick) because of the little lenght.
I will put stronger servos.
thanks
Jérôme