Flite Test | Servos 101

Thanks to Little Bits for sponsoring this episode!
Get your pencil and notepad ready. Class is in session!
Here is an overview of everything you'd want to know about servos, and more!

[firstnamelastname]

Good job Peter! I learned more about servos in 20 mins than I have in 2 years.

[DobyxRC]

Very cool episode. In 25 years I have only taken apart a servo 3 times and each time I frown and toss it in the garbage, this helps me make sense of these wonderful little devices. Thank you for this video!

[manicdee]

Thank you for this awesome instructional video. The Q&A style presentation was great, basically asking the same questions I was interested in asking myself!

Peter did not go too deeply into any one topic and covered a great range of knowledge. I especially appreciated the testing jigs for torque, speed, and browning out.

[NettAirLa]

one of the best episodes I've seen (I like breaking stuff down and figuring out how it works). 
Little Bits are awesome, my 5 year old daughter received a set last year for Christmas and loves them.

[AudaciousRC]

Not sure if this has been mentioned already, or if this is even correct, but i THINK the reason they move the servo 1 inch to measure the torque is because in the U.S. torque units are pounds per foot or 'foot pounds' etc so moving 1 inch is easy to convert to ft/lbs because it is 1/12 of a foot.... i'm just speculating haha i'm not totally sure.

-Colton

[tiagopadua]

Actually the torque is the same, no matter the length of the servo arm. It's the FORCE applied that changes. The torque is a fixed number for the servo.

[wiltonsmith]

“Foot-pounds, inch-pounds, inch-ounces, newton-decameters, etc...”

[digitexstudios]

Here's some basic Motors 101 for you:
There are many types of motors used in almost everything:
Brushed motors
Coreless motors
Induction motors
3-phase motors
Brushless motors
Synchronous motors
Permanent magnet motors
Stepper motors

Almost every motor has three parts: the stator, the rotor, and the commutator.

The stator is the magnet that does not rotate.
In a brushed motor, it is just a permanent magnet, as it is in a coreless or a permanent magnet motor.
In a brushless motor, an induction motor, a stepper motor, or a synchronous motor, it is a set of coils.

The rotor is the rotating element.
In coreless motors, the rotor is just a set of coils.
In an induction motor, it is the squirrel cage assembly.
In a brushed motor or a synchronous motor, it is a set of coils wound on laminated metal.
In a brushless motor, a stepper motor, or a permanent magnet motor, the rotor is a permanent magnet.

And finally, the commutator is responsible for the timing.
In a brushed motor and a coreless motor, the commutator is a brush.
In a brushless motor like that in a computer fan, the commutator uses hall effect sensors. In larger motors like those in drones and planes, the ESC relies on timing alone.
Induction motors have no commutator.
Synchronous motors use slip-rings to provide power to the rotor, but do not use a commutator for timing.
Stepper motors require a special controller and have no commutator.

[incubrian]

oh my god, i have been doing this for 15 years, and man, THIS is the video i have been waiting for!!  seriously, what an amazing job you guys did on this!  please do a servos 102, 201, 301, i will watch all of them :)  love this!

[afterdeth]

So glad you guys keep putting out videos. You're such a help to people just starting to get into the hobby, keep up the good work, and get Peter to do more in-depth technical walkthroughs, it's awesome!

[crossthreadaeroindustries]

All your vids are great and this type of video has its special place. From a techy perspective, one of the best - answers many many questions quickly. Reviews of multicopter controller boards and other components would be appreciated! Thanks, guys.

[joelsterling]

Make more videos! I am so impressed. Never have I ever come across a video that actually explained everything that I had questions about. Very thorough...just the way I like it.

[grumpyjohntxredneckrc]

This Is One of The Most Informative Videos That Flite Test Has Produced & I Have Watched Nearly The Last 7 years Worth Totally! Soo Thanks & Keep Up The Great Jobs Guys!!!

[vipero]

11:30 Alright Torque is the Lever arm length times the Force of the thrust. T=LxF So for a lever arm 1" long and a Force of 100 oz you get T=1 in x 100 oz = 100 oz-in of torque.

Unlike what they say at 11:30 as the lever gets longer the torque doesn't change. The torque is the torque. However as the lever gets longer the force goes down. There is an inverse relationship between the lever length and the max force of the thrust. As one goes up the other goes down.

[TheAdambausch]

Every question I had as a beginner to understanding what a servo is, was asked and answered in that episode!! Great work!!!!

[aerialboy]

So basically you guys didn't get back to magentic induction servo?

[rcflight]

Learnt from experience to always pay extra and get metal gear servos, that way they won't strip and when move up you can just take all your electronics with you.
Best servos for acro I've used so far are the Corona 929MG. Excellent upgrade just to replace the standard 9g servos most planes seem to use these days are dirt cheap ($5.50 per unit from Hobby King).

[Zxenmusic]

Thank you guys. This is the only useful servo explanatory video I've seen - and I've seen scores of them. You have answered all my questions. Thank you!

[zoltanguitar]

Great overview -  Thanks for taking so much time to put such a comprehensive tutorial together.

[AculaRC]

Excellent video and very informative. I've been flying for some time now and this video helped me understand more about servos and thier operation. I love Peters graphs and displays. I'm a visual learner and that helps me out tremendously. Great video fellas!