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Bob, The other comments already posted seem good. Here are my thoughts. My C-85 Coupe carried my 250 lbs pretty well off some pretty short fields and climbed very well. I had a 7146 prop with is past the 7148 which most people consider climb prop. The limits in the type certificate A-787 for the metal McCauley 1A90CF or 1B90CM prop are For D, E & G with C-85: not under 2025 and not over 2225 For later models with C-90: not under 2250 and not over 2375 The limits in the type certificate A-787 for the metal McCauley 1A105/SCM 7153 prop on the A2 with C-90 engine: not under 2250 and not over 2375 I don't know where you got your values of "Rated at Static RPM 2175-2275" but I suspect those values should be checked. My C-85 with the 7146 prop got static rpm of exactly 2225 or perhaps the needle width higher. This gave me pretty good take-off and climb (for a Coupe) but limited my speed at max continuous cruise (2400 rpm on the C-85) to 100 mph. (I could go faster if I let it spin up toward the redline though I did not do that except for a couple of tests. Even then, I wasn't straining the engine since the flat prop didn't take as much power to spin to those rpms as it would have with a coarser prop.) You said your static rpm before the take off was 2150. That's 75 rpm less than I was getting on my C-85. There are, I think, some compression differences between the C-85 and the C-90 so I can't say definitively that you were getting less take-off power than I got on my C-85. I DON'T think you were getting as much power as you ought to. Comparing your static rpm of 2150 with what the type certificate says the two listed metal McCauley props should have, you're turning 100 rpm below the MINIMUM for that engine and 225 rpm below the maximum allowed rpm. Your engine will never develop 90 hp on takeoff. That's a power you only get when you're at redline. It is however the official number for the engine. The power you DO get depends as much on the prop as on the engine design and health. Suggested possibilities: 1. See if there's an engine related problem causing such low static rpm. (I'd put some effort into this since you've already (supposedly) got a 7150 prop.) 2. Borrow a flatter pitched prop such as a 7148 for flight and static rpm tests. 3. Make sure your prop really is a 7150 and not a higher pitch. Please keep us posted on your progress and we'll try to help. Ed Burkhead http://edburkhead.com/ [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Monday, April 14, 2003 10:52 AM To: [email protected] Subject: [COUPERS-FLYIN] Re: Digest list: Ercoupe Hangar Flying ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- Need some input from anyone that ownes a Alon A2. I purchased this aircraft last fall and have not been able to fly it again til yesterday due to operating out of a grass strip that has not been suitable until now due to the weather. I did mke about 5 take off's and landings out of this airstrip in the fall prior to the bad weather. My problem is this: I took off yesterday into a 8 - 10 MPH quartering head wind on a near level 2000' grass runway (grass about 3-4" high) with 60' trees 50 yrds off the end off the runway. It took me over 1000' to get 65 MPH and in the air and I had to turn to the left to avoid the tree tops ( needless to say it scared the hell out of me). This plane is a 1996 A2 w/ C90-16F Contnetal engine w/ a McCauley 11390/CM7150 prop Rated at Static RPM 2175 -2275 Max Engine 2475 RPM - Aircraft TT 2898 TTSMO 1085 At time of take off I was indicating 2150 RPM - The Temp 60 deg - Field Elv 715' Barm.Preasure 30.2 LOADING :Full fuel and me @ 250 lbs According to the manual I should not need more then 5 -600 feet for takeoff. I have flown this aircraft off a paved runway with the pervious owner at gross weight prior to purchase in 90 deg summer heat and it performed better then this. If I would have had any additional weight on board I do not think I would have gotten out. In fact in retrospect I should have aborted the takeoff. My question is, is this the type performace I should expect or do I have a problem. Like needing a longer runway or worse a new engine. ( Don't say loose some weight off your lard ass, I already thought of that) I thought I should be seeing close to red line at full thottle 9on take off roll like I did in my 182. The 182 required a power reduction as soon as you established a climb to avoid going past the redline. The Alon will not even get near the redline. Is it possible to be showing listed 2175 static RPM at full throttle and not developing full rated horsepower Any constructive comments would be apreciated. Bob Bullock Alon A2 N5621F Maryland ========================================================================== == == To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers/ ========================================================================== ==== To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers/
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