Harmonic dampner

[tridge]

Has anyone used Mark Landoll's harmonic dampner for Lic. engines. It bolts to the flywheel. It functions the same as dampners do on nearly all other engines manufactured.

[dan carley]

i've used marks balancer on my rv-4. works great

danny
RV4
N14FT

[DanH]

<<It functions the same as dampners do on nearly all other engines manufactured.>>

The rubber-and-inertia-ring dampers as found on most automotive engines? Sorta similar in operating principle, but application matters too. Note their location at the accessory end of the crank as compared to a location at the prop hub; consider the distribution of inertias and resulting crankshaft vibratory modes. Hard to get much torsional vibratory damping from a damper located near a node. Put another way, it looks like a good damper crippled by a poor location.

I suspect positive reports are mostly due to the additional effective propeller inertia...additional flywheel, so to speak, and quite different from damping. If true, a solid steel disk would serve as well.

[tridge]

Originally Posted by dan carley

i've used marks balancer on my rv-4. works great

danny
RV4
N14FT

What prop are you using? Did you do a before and now comparison?

[Flyrod]

Tridge,

I use one on a IO360 w/ electronic ignition and AFP injection. The prop is the Whirlwind 151. If you use a light composite prop such as the 151 (29 lbs), the extra inertia comes in handy at idle speeds. The prop is very smooth. I purchased the aircraft and have never flown without it, so I am not sure if there is a big difference without it.

The 11 lbs on the nose could be an issue depending on how your aircraft is set up. The combination of extensive electronics behind my aft baggage compartment and light prop on the nose affords me plenty of latitude on my center of gravity. In fact, the builder had to put both batteries up front to get a better balance.

The dampener appears to be a quality product. The company that actually builds them is in California and specializes in building dampeners for top fuel dragsters. Everyone I have talked with, including Vans, say they make a difference. As long as your CG can take it, I dont see how it could do any harm.