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Engine basics => Engine set up tips => Topic started by: Clint Ormosen on March 04, 2007, 03:28:04 PM
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How much prop will a 25 LA spin? I'm starting with a Rev-Up 10-4 cut down to 9 1/4". But would a Zinger 10-4 be too much. I want to run this motor in a rich 2-cycle.
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Clint, I have been running an OS 25 FP on a 9x5 APC and it runs ok. I tried an APC 10x4 and it ran but not as good as the 9x5.
I have also blocked the boost port and hemi shaped the head on the FP so that might be considered.... H^^ H^^ D>K
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I believe the LA 25 can turn the Zinger 10-4 if you slick the prop up a bit. Wouldn't hurt to get e couple and cut them down to 9 3/4 and maybe 9 1/2. It *might* like a "5" pitch in the wood! They can be "soft" on pitch a lot of times.
Fitton runs a stock FP 25 in a wet 2 on a 10-4 APC if that helps any........
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How does the power of the LA 25 compare with the FP 25? I have run the FP but this is my first LA.
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When I flew a "light" Brodak Lightening Streak as a beginner, my LA25 seemed to do fine with a 10-4 prop. However when I began flying the full pattern with a heavier Ukey 35, the 10-4 seemed to be too much for the LA25, so I dropped to a 9-4. I think the longer flight coupled with a heavier plane was too much of a load for the LA25 and a 10-4 prop.
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Thanks for the replies, guys. I think I have enough to go on.
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FWIW, Joe Just flys a Primary force ARF on a LA25, I beleive he uses an APC 10x4. I fly my Ukey 40 (500 inchs of wing) on an LA25 with an APC 10x4 and it performs wonderfully even at 95 degrees and 300 foot altitude. It really is a great little engine! I have thought about how it would do on a Nobler or Oriental.
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I used a 9x4 on a LA25 flying an ARF Streak. No muss no fuss.
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Clint,
As several of the posts suggest, "how much prop" may not be what to look for.
The LA runs very nicely on a light load. It, like most mass produced recent engines, was influenced more by RC usage than by ours in CL. The LA25 has a long range in 2-cycle, where it can be happy. A light load, low pitch prop at more than usually expected RPM works great.
You get the power by running up nearer to the engine's rated peak RPM, and the lower pitch keeps airspeed and laptime reasonable. General recommended fuel seems to be 10/22 (half and half synth and castor) for many of the ABC-type engines.
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Lou,
The higher RPM range is exactly why I put this engine on the plane. This particular model had an OS 35-S that was shaking the nose off the thing. Apparently, I hadn't built a strong enough nose to put a 4 cycling motor into. But, I noticed that when run in the 2 cycle mode, vibration was much less. So thats why I chose a modern engine, to run it like you say. In a rich 2 cycle. Kinda like the FP 20 BBTU set-up. Just wasn't sure about the prop so I took a survey.
My fuel is indeed 10/22 50/50 mix.
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11x4 APC with 20% nitro.
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"11x4 APC with 20% nitro."
What a hacker! This is so wrong on so many levels it ought to be against the law.
Everybody knows that when using an APC 11-4 on the 25LA the proper fuel is 63% nitro, 7% propylene oxide, 20% Klotz KL-100, balance methanol. I sincerely hope this settles the issue once and for all.
I continue to believe that a box-stock 25LA--including use of the stock muffler--run on pretty much any brand of 10%- to 15%-nitro fuel, is a pretty decent combination, especially for those new to CL Stunt, just coming back, and/or not wanting to spend much money.
But my prop of choice is the APC 9-4. Have yet to see anything better.
A friend has an Oriental with a 25LA fitted. I don't particularly care for this specific model, but that has more to do with personal taste than anything else, I suppose. He likes it just fine, and the motor has more than adequate power.
Dan