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Post by olderndirt on Jan 12, 2015 13:18:02 GMT -5
Need some thoughts about increasing horsepower/propeller performance - in the acft.cfg? On my recent trip to Launumu, PNG, the Pacer was turning only 2300 rpm at takeoff (mixture appropriate) - a long way from the 2700 that makes 180 hp. There's no 'power' scalar per se in the .cfg so what can I do with the prop?
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Post by Deleted on Jan 12, 2015 13:42:39 GMT -5
Elevation of Launumu is around 5000' isn't it? Could that be part of the problem?
Latitude -9.1333
Longitude 147.6833
Altitude (feet) 4954
-Not Glenn
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Post by Deleted on Jan 12, 2015 14:05:15 GMT -5
Hmmnn, not sure. As crash mentioned, the altitude is pretty high up there so you aren't getting the air sucking through the system that you would down low (which you already know). With a constant speed prop you'll get the same rpm down until you can't get more than 15" of manifold pressure, but with that engine, you are going to lose rpms right off the bat. Also, what happens right after you get airborne? The max rpm's I get out of the A2A 172 (which is very accurate) is about 1900 to 2000 at SL when standing still holding the brakes, but by time I'm up to 45 to 50 kts indicated, I'm developing about 2400/2450 (whatever redline is). So your static rpm's are going to really suffer at that altitude. I guess I'd be reluctant to play with settings too much using that airport as a reference because when you get back down to SL, you're going to blow your engine into tiny little pieces (exaggeration, but you get the idea  ). Probably not a lot of help. I can look tonight to see what parameters control the prop, but I'm not that conversant with this end of things in terms of engine dynamics. |
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Post by olderndirt on Jan 12, 2015 16:14:10 GMT -5
What I need here is the .cfg equivalent of a climb prop rather than cruise. Appreciate the comments about mixture - that's a red knob isn't it?
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Post by Deleted on Jan 12, 2015 17:22:04 GMT -5
OK, 2700 rpm then. I was going from memory in the midst of trying to get 3 ELT's out the door ASAP  . No, it's not a mixture thing (didn't say anything about the mixture). It's that the engine simply can't pull enough air in to turn the engine at full power. Is your plane doing the same thing at sea level? If it is, then you have a problem. If it's losing it at that altitude, then it's environment. Hell, even at Cooking Lake, Alberta (2200 ft asl) the 172 I flew on floats there wouldn't get up to redline until after in the air and leveled off. At 5,000 ft, it's going to be that much less powerful, and with a fixed pitch prop, you're going to see it in rpm's, even leaned to the max. Either way, I've never tweaked the prop dynamics so anything I tell you in that regard is pure guess work. |
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Post by Bushpounder on Jan 12, 2015 17:47:38 GMT -5
See if she'll turn 2700 in Miami.
BP;)
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Post by olderndirt on Jan 12, 2015 20:46:44 GMT -5
Unregard - I'll use a different plane.
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