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- Newsgroups: rec.models.rc
- Path: sparky!uunet!iphase!iex!usenet
- From: djones@iex.iex.com
- Subject: Re: Props
- Message-ID: <1992Jul30.220600.2381@iex.uucp>
- Sender: usenet@iex.uucp (USENET news)
- Organization: IEX Corporation Inc.
- References: <1992Jul22.222910.27329@iex.uucp> <1992Jul23.153612.20836@rtsg.mot.com> <1992Jul27.225145.1783@iex.uucp> <1992Jul28.230434.26635@rtsg.mot.com>
- Date: Thu, 30 Jul 1992 22:06:00 GMT
- Lines: 68
-
- In article <1992Jul28.230434.26635@rtsg.mot.com> svoboda@rtsg.mot.com (David
- Svoboda) writes:
- >Prop load is prop load. I would use it in any case.
- >
- Makes sense.
-
- >A 11x6 prop would be similar in engine loading to a 10x8. That is, you would
- >realize approximately the same engine rpm *at a given airspeed*. Now,
- remember
- >that a lower pitch will give you a lower airspeed, but more static thrust.
- Think
- >of it as a "lower gear". Thus, a low pitched large diameter prop is good for
- >a naturally slow airplane, and will give you a good climb. A higher pitch
- prop
- >will have less climb or acceleration, but will pull the airplane with a faster
- >top speed (and a faster cruise speed, for that matter). If you are
- underpowered,
- >a larger, lower pitch propeller would be a better use of the engine's
- horsepower,
- >but you have to limit that becuase that airplane will have a minimum speed,
- and
- >an extremely low pitched prop would not pull it faster than that (stall on
- takeoff).
- >
- Also makes sense. I have also been the victim of this!
-
- >A higher loading prop will lug the engine, which makes the mixture very hard
- to
- >adjust. You can easily have a lean run, and have it masked.
- >
- Oh Boy! Sounds like a trashed 4 c if a guy ain't careful!
-
- >I'm not any sort of 4-stroke guru (well, with motorcycles, maybe, but not
- model
- >airplanes :-), but that sounds like a good method of protecting your engine.
- I
- >would further suggest that you peak the engine with the nose pointed at the
- >sky, rather than level. And listen and look at it flying--some engine just
- seem
- >to change mixture in the air when they unload.
- >
- I will and I do. Except when the unmuffled gas burners are flying!
-
- >
- >Sure there is. Try an alternative, and see if it works.
- >
- I did. I bought a bigger engine! A wimpy way out of the problem
- but on our field there is very little room for error. Our asphalt runway is
- about 300' feet long but is only 20 - 25' wide. It has a maze field on two
- sides
- and a fence on one. I love scale, but am not confident enough to sweat
- out the take-off's! So I took the easy way out and sold the 40 Surpass
- and bought a 48 Surpass.
-
- Thanks for your help!
- Doug
-
- PS
- There is a very good article on props in the August Model Builder.
-
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