Ed, The prop was overhauled by Maxwell Aircraft Services, of Hopkins, MN, specializing in propeller overhaul. I assume they twisted the prop correctly. My A&P checked the tracking of the blades a number of times. I brought up the possibility that Maxwell may have done a bad job of twisting the blades and he said they were a respected house and doubted there were any errors in the twist.
I have been following the conversations on vibration over the past year and it appears that all the Ercoupes have some vibration at some RPM,s. My C-85 has the 0-200 crank STC raising the horsepower to aprox 100HP. Is this higher horsepower causing a more pronounced vibration then the 85HP and is it also causing the wide range of 2000 RPM to 2500 RPM? Al Flora N94748 (HYR) Al Flora ----- Original Message ----- From: Ed Burkhead To: 'ercoupe-tech' Sent: Sunday, April 19, 2009 5:22 PM Subject: [ercoupe-tech] excess vibration Alberto, Congratulations on the first flight after so much work. Those performance numbers make me drool. I've changed the subject line and included your original post so our vibration experts could take special notice of your questions below. My one special thought is, do the two blades of the propeller track exactly the same and have exactly the same pitch at each station down the length? Ed ------------------------------------------------------------------------------ From: [email protected] [mailto:[email protected]] On Behalf Of Albert Flora Sent: Sunday, April 19, 2009 11:52 AM To: ercoupe-tech Subject: [ercoupe-tech] First Flight All. First I want to thank everyone for all the assistance. A special thanks to Hartmut Beil for his suggestion that I put a 71/52 prop on my coupe. It worked out well. I received the coupe on November 30, 2007. It was delivered in a pickup truck. Now 17 months and an additional $12,000 later; I flew it for the first time this past week. I learned quickly to not coordiante a right bank with the break pedal. Stepping on air for a left bank did little to assist the turn. The C-85 with the 0-200 crank STC put out plenty of power. It handled the 71/52 prop with ease just as Hartmut said it would. The flight was at Boyceville, WI (3T3). Elevation 967 MSL. At run-up the full power ststic RPM was a healthy 2250. Had excellent acceleration and jumped off the runway at 60 MPH going to 80 MPH and climbing at 700 FPM for 1000 ft. with close to the 1320 gross. Made a full power level run at 1960 MSL with a temp of 40F and the engine maxed out at 2500 RPM. This is a fresh engine and prop not yet broken in. Here's his problem with vibration --------------------------------- The only negative impression I have so far is the moderate vibration from 2000 RPM on up to 2500 RPM. My AP/AI changed the prop position to 3 locations and found the best location which helped a little. He also did a dynamic balancing that helped a little more but not much. He said the vibration may show a slight improvement when the engine is broken-in. I hope so. It reminded me of the old C-119's. I did not like the vibration then and do not now. Thank you all again!! Albert Flora N94748 (HYR)
