Dynamic Propeller Balancing for your Homebuilt aircraft 

The accelerometer should be mounted so its longitudinal axis runs through the center of the crankshaft or in your case the prop shaft. When you say it should be mounted perpendicular to the cylinders, that would be true when talking about traditional horizontally opposed aircraft engines where you would mount it at the 12 o'clock position as close to the prop as possible. But since you are not balancing the cylinders but rather the propeller the relationship to the prop and the shaft that spins it is the most important. In your case, the same 12 o'clock position holds true with the longitudinal axis of the accelerometer running through the center of the prop shaft. Think about the unbalanced propeller spinning in circles the heavy side of this rotating mass is trying to pull the engine to the outside as it goes round and round. So the front of the engine moves in a small circle following the heavy side of the rotating mass, this is the vibration you and the entire airframe feel! This vibration radiates outward from the center of the rotating mass and the accelerometer that senses acceleration along its longitudinal axis when misaligned with the source of movement (vibration) will have reduced accuracy. Now if you will, think about landing your aircraft in a quartering crosswind. As the wind hitting your aircraft moves off of the wing tip toward the front of the aircraft it has less effect of pushing the aircraft off the side of the runway. So, with the accelerometer's side case pointed at the source of the vibration the effect of the vibration is reduced to the point that it only senses the rotational force created as the engine follows the unbalanced rotating mass in circles. I would bet that if you had the exact same setup except with the accelerometer being pointed toward the prop's center of rotation instead of away from it by 80 to 90 degrees your ips reading would be considerably higher!

That Photo sensor seems a long way from the prop. Question, why not do what the machine says instead of putting a weight on first, seems like a backwards way round of doing things?

Good tip keep them coming I enjoy all your tips and find most very useful. Thanks

Great information. Thank you for posting.

Great video! Thanks for sharing your knowledge with all of us 😄

Great video 😊

Good job my friend

Hello, plz tell me where I can get fore sell engine n secondhand propeller

Do all airplane spinners have to go certain way? and if I put it back a different way can that cause vibration on the plane? Thank you

I wonder about the mass and arm of the tape on the blade... are you supposed to use a long strip like that?

Great video. What about balancing the blades?

i am working on a car engine to a fly one how can i attach it pls suggest some information

What kind of engine is it ? What type of aircraft is it ?

did he turn the engine backwards at 5:30? oh my!

goooood. may I study.?

I'd love to watch your video, but the damn dog barking is somewhat of a major distraction.......