---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Sat 07/26/03: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:01 PM - Re: RV4-List: Fixed Prop Balancing (Emrath) 2. 06:23 PM - Re: RV4-List: Fixed Prop Balancing (Archie) ________________________________ Message 1 _____________________________________ Time: 05:01:43 PM PST US From: "Emrath" Subject: Re: Engines-List: RV4-List: Fixed Prop Balancing --> Engines-List message posted by: "Emrath" We had a gentleman do prop balancing at one of our EAA Chapter events. He mounts a reflective tape on the prop and and transducer on the engine to measure vibration. Run the engine without the cowling on at several different RPM settings recording the amount of vibration. Somehow he deduces how much weight is needed and where in relationship to the prop blades. He then mounted some weights on the flywheel using a AN bolt in one of the holes in the circumference. Remeasures the vibration for a check. Takes 30 min. and some Cash. Pilots who have done this notice lower noise levels while flying and less fatigue after a long flight. I'll be getting mine balanced once I begin flying. Side benefit was you can tell if your tachometer is accurate or not at the various RPM settings. Marty in Brentwood TN ________________________________ Message 2 _____________________________________ Time: 06:23:19 PM PST US From: "Archie" Subject: Re: Engines-List: RV4-List: Fixed Prop Balancing --> Engines-List message posted by: "Archie" ----- Original Message ----- From: "Emrath" Subject: Re: Engines-List: RV4-List: Fixed Prop Balancing The method you described is a single-plane balancer, which is quite effective. The trend is to use dual planes, and believe I have convinced MicroVib to supply a second accellerometer and readout as an option. When a prop is being balanced, it also tends to correct some engine imbalance on that end. A dual plane unit can differentiate a couple from a force imbalance, and if a lot of weight is required to correct the prop, it is possible that the engine may be the greater culprit. A large variation in prop bolt/washer combination or spinner hardware will also do it. Will be doing a basic dynamics seminar, I believe, on Tues, or Wed. at OSH. If you are there, I may be able to elaborate rather than write a novella here. Archie