Matronics Email Lists Forum Index Matronics Email Lists
BBS Forum Interface to the Matronics Email Lists
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Dynamic prop balancing

Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Pulsar-List
View previous topic :: View next topic  
Author Message

PostPosted: Tue Jan 24, 2017 3:38 pm    Post subject: Dynamic prop balancing Reply with quote

I have always wanted to dynamically balance my props but never even static balanced them. I mentioned on this list that I’d like to see prop balancing discussed at our next Lawrence fly-in and a gracious and trusting reader offered to loan me his DynaVibe balancing system. The system requires mounting an accelerometer in vertical orientation near the front of the engine and an optical sensor pointing at the back of the prop or backplate, registering each pass of a reflective tape.

During my fire rebuild in 2009, I changed from an Ivo 3-blade inflight adjustable prop to an Airmaster 3-blade constant speed prop. The Airmaster came static balanced, evidenced by an AN3-4A bolt, area washer & AN365-1032A nut (9.5 grams <42.75 gram inches>) in the 240 position. The Airmaster backplate came with 3/16” holes drilled every 30 at 4.5” from center. I referenced the hole directly behind blade #1 as 0 and measured increasing degrees in the same direction as prop rotation.

The DynaVibe instructions suggested not changing any static balance weights. I ran the engine in the initial (static balanced) configuration at around 1840 rpm prop speed (~4,500 rpm engine speed) and registered the magnitude of vibration as 0.26 IPS (inches per second) at 196. According to what I’ve read, anything above 0.25 IPS is considered rough, down to 0.15 IPS is fair, 0.07 is good and 0.04 is excellent. The identified degrees is the heavy point. Since I didn’t want to remove weight (grind away metal) at the heavy point, I added weight 180 opposite the heavy point. Only having holes every 30, I chose to add 10 grams <45 gram inches> (AN3-4A bolt, area washer, #10 thin washer and nut) at 30.

Running in this configuration produced 0.06 IPS at 82. I added 1 gram (#10 thick washer) to the original static balance location (240), bringing the total mass balance at that location to 47.25 gram inches and ran the engine again, registering 0.02 IPS at 54. It was a windy day so I’ll verify the final reading in calmer conditions but I think that’s where it will stay.

I believe the DynaVibe balancing unit will be at Lawrence so maybe we can demonstrate the process on someone’s plane and remove a few vibes in the process.


- The Matronics Pulsar-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
Back to top
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> Pulsar-List All times are GMT - 8 Hours
Page 1 of 1

Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum

Powered by phpBB © 2001, 2005 phpBB Group