----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
Paul, I've never seen good numbers for any Coupe. I'd treat any published numbers as if they were a diet ad promising to melt away fat. Here are reasons to be suspicious: 1. Your airspeed indicator can be off. If you follow published numbers with a bad airspeed indicator, you could crunch. My second flight in my coupe had gas-line icing and I joined the Coupe glider club. I flew down final to the farm field at 70 indicated, just like it said in the book and the magazine articles. What I didn't know is that on MY Coupe, the airspeed indicator was WAY off and I was really about 55. When I got near the ground and pulled back to flare, the yoke immediately touched the limiter-stop and the plane leaned back a hint and we made a big WHUMP sound when we hit. It was a ploughed field with snow so it was soft. The 30 mph headwind made my forward speed so slow we rolled only 50 feet and didn't nose over. No damage. Moral: A. test your airspeed indicator! B. flight test YOUR plane to determine the critical number (minimum flying speed) with YOUR airspeed indicator. Personally, I'd recommend doing approach at 1.3 times minimum flying speed. C. Plan your flights according to reality, not your airspeed indicator. (For years I wondered why my 120 mph Coupe always had 20 mph headwinds both ways on even short trips.) 2. Current actual gross weight makes a BIG difference to your take-off roll, obstacle clearance and climb rate. Keep it in mind. 3. There aren't any good generic tables for Coupes with the different prop pitches. 4. Condition of the prop is important. Was the prop originally made at that pitch or was it re-pitched later. Are there dressed out dings? (There had sure better NOT be any prop dings that HAVEN'T been dressed out. (Hint: I got multiple dings once when I did my runup mag tests on a spot that had gravel hidden in the grass.) 5. The structure or the controls could be a bit out of rig causing some extra drag (kind of like a cross-control slip). Summary: You ARE the test pilot of your own plane. It can provide some fun flying to go out and do test pilot recording of the numbers for your plane. Here's one number set I will give you. It has some correspondence with reality. On a C-85, you may get something close to these numbers for cruise speed: 7146 100 mph my extreme climb prop (well measured on MY plane) 7148 104 mph normal climb prop 7150 108 mph "normal" prop 7152 unknown cruise prop (I THINK I've seen a Coupe with a 7152 get the same speed as my 7146 albiet with TERRIBLE climb. That plane didn't have the horsepower to spin the prop up to enough speed to get 112 mph so they ended up with LESS cruise power, lower airspeed and dangerously poor climb. Maybe if they were flying very light, they'd get good high cruise speeds. I've never had this prop and these statements about the 7152 should be taken with a salt-shaker's worth of doubt.) For what it's worth. "Your mileage may vary." Ed Burkhead N3802H, Ercoupe 415-D Peoria, IL > -----Original Message----- > From: Paul Tanzar [mailto:[EMAIL PROTECTED] > Sent: Friday, April 13, 2001 12:34 PM > To: 'coupe-list' > Subject: RE: [COUPERS] OK Now for Props !! > > I'm learning more about 'coupes in general, and the > '48 E model I just purchased, through this forum! > Although the previous owner couldn't tell me what kind > of prop the plane has, I figured out pretty quickly on > the flight home that 7148 must mean climb prop. Now Ed > confirms my suspicion. Departing a 1000MSL strip at > 50degF, I was pleasantly astounded to see 800+ fpm on > the VSI. When I only saw 100mph at 2350rpm, I felt > fairly sure that I must have a climb prop. I was > alarmed, however, at seeing only 2250rpm on the > takeoff roll, although acceleration felt good and rpm > was normal in cruise. Now I know why. Are there > published climb prop performance numbers to substitute > for the standard ones in the POH, or am I going to be > a test pilot this summer? > > Paul > > --- Ed Burkhead <[EMAIL PROTECTED]> wrote: > > ----[Please read http://ercoupers.com/disclaimer.htm > > A normal climb prop is 7148. This prop > > is a McCauly 1B90CM > > which is allowed by the type certificate Aircraft > > Specification A-787. > > (propellers and accessories section, paragraph 4) > > With this prop, I get the > > max allowed static runup rpm of 2225. > > > __________________________________________________ > Do You Yahoo!? > Get email at your own domain with Yahoo! 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