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I noticed yesterday after a 1 hr flight in heavy rain.. The first 11 " of my warp drive prop is very polished, Is this normal ? also I installed the external generator on my ss7 with 912 uls and now have intermittent vibrations ?? could that be a load on generator. thanks.. jim
Water is the worst thing for eroding a prop. Even more so than rocks and sand. There is a good chance the prop has gone out of balance.
What do you mean by an "external generator"? Is it under the cowling or the type that hangs out in the air and is driven by a small prop?
Jim,
It's hard to diagnose some things without seeing them in person; however, I have a similar setup to your aircraft so will offer a couple comments. (912uls, warp drive, external alternator)
On your propeller, do you have the nickle edge warp drive blades or plain blades? I have a friend operating a float kitfox who has the nickle edge blades which is designed to prevent erosion from the water. Don't know if that is a factor or not, but if you were flying in heavy rain for an extended period of time, I suspect the exposure to water was more than what a person would get with a few takeoff and landings on floats. Also unsure if the polishing observed was simply changing the normal flat black paint to a shiny surface; or if the white colored substructure under the paint is showing through. In the final analysis, a call to the Warp drive factory is the best way to go - I have found them very helpful - but you have to get the factory, not one of the marketing sites.
On the rotax belt drive external alternator I don't see how this would create a vibration as long as the installation was correct. Might consider if the prop track or individual blade pitch could have been unintentionally affected in the process. Easy enough to check the blade track with a ruler & block and the Warp protractor wouldn't take long to check the pitch of each blade. As an aside, I have the tapered tip warp drive and do the pitch check back from the tip a few inches as the wider part of the blade is easier to get an accurate measurement from.
generator is rotax and is inside of cowling. also no paint eroded on prop just polished only on the tip just thought it was odd for just the tip to get polished I guess it is just that much of the prop doing the work.
Hi James,
The speed of the prop blade surfaces through the air varies from the hub to the tips. The tips are obviously traveling fastest, so they will potentially take more of a beating from the impact of rain drops. Basically, the entire length of the blade is doing work.