I'm building a small prop that needs to flap wings. It is about 6 to 7 inches long. Figured to use a servo, fairly standard stuff... attach the servo arm to the wing and it flaps.
Is there a micro servo that anyone can recommend please that does not require a controller to swing, just battery power? Or a very good continuous rotation servo that can run off coin cell? I am afraid with a controller board it will be too large to fit inside.
The Arduino Pro Mini is fairly compact and easy to work with. You can buy the official ones from SparkFun in either the common 5 V model or the 3.3 V, which might be more suited to battery power:
You can also get Chinese clones or derivatives of the Pro Mini on eBay and Aliexpress for less if you don't mind waiting forever for shipping from China. The SparkFun ones are quite reasonably priced but I actually prefer to use a specific Chinese derivative that manages to squeeze in an ICSP header and has the A4-A7 pins on-grid:
The only trick with the Pro Mini is that you need to use a separate programming adapter. That could be a USB to TTL serial adapter board like the FTDI FT232 module:
I think there are some other boards that are even smaller than the Pro Mini but I don't have experience with these. For your application, you don't really need as much memory and IO as the Pro Mini provides. You could get by with an ATtiny.
Search for 360 degrees servos. They can be of same size as a hobby micro servo (let's not start that stupid argument about what a servo is!) which turns only 180 degrees. But 360 degrees doesn't mean it can turn only 360 degrees. It means it spinns like a motor continuously and you can control its speed and direction.
Weight will be the biggest problem . Have a look at some of the indoor flying web sites .
You actually mean to flap the wings, not operate flaps ? If you are flapping the whole wing up and down , you might be better off with a simple motor to save weight and give you speed . Have you google this stuff - people have made this sort of thing before
halloweenchris, can you clarify what you are trying to do?
You mentioned you are making a prop. But when you are talking about wings and servos, it is easy to think that you are talking about a flying model.
What are you trying to do?
There are plenty of small servos. Many can be modified to run continuously. How will continuous rotation be translated into wing flapping?
Most coin cells will not power a servo for very long. How long depends on how much load there is on the servo.
