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Engine basics => Engine set up tips => Topic started by: frank mccune on July 11, 2014, 08:18:04 AM
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Hu:
Will this harm the engine?
Tia,
Frank
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No, but in my experience (with the LA 46) it won't hold the setting that way -- it'll either start out at the speed you want in a 4-stroke then get richer & slower, or it'll start out at the speed you want and run away into a 2-stroke.
4 second laps on 65 foot lines with a 50 ounce plane are interesting, but not fun.
What are you trying to achieve by running it in a 4-stroke?
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Hi Tim:
Thanks for the reply.
I asked for a friend of mine who is doing this type of flying. He is using a Brodak ARF Smoothie that flies very well and quite fast.. I timed him and he was turning 4 second laps on 60" lines. I suggested that he get rid of the 10X6 prop and try a 3.5 or a 4 inch pitch 11 inch prop. If this thing would lean out, he could fly combat with it! Lol
I thought tht these enginse should be operated in a wet 2 cycle mode to prevent premature engine wear. I should check to see if he has a AAN p&C before I make any more suggestiions. It may be an iron and steel setup.
Stay well,
Frank
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I thought tht these enginse should be operated in a wet 2 cycle mode to prevent premature engine wear. I should check to see if he has a AAN p&C before I make any more suggestiions. It may be an iron and steel setup.
I've been told that, but I've run my LA 46 slobbery rich on occasion and have not worn it out yet. Doing it that way all the time may be a different story.
As far as running it -- yes, I think he'll be happier running a flatter, bigger prop at a higher launch RPM. There are conflicting stories, and I've never run an unmodified LA 40, but my understanding is that they are more touchy about settings than the LA 46. Perhaps the best thing to do is to get a good, lightly used RC '46, swap all the RC stuff onto the 40, then sell it, and use the 46 for CL!
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Hu:
Will this harm the engine?
No. It will harm the performance of the airplane, but not the engine. The "don't ever run it rich!!!!!" advice stems from George Aldrich, who ruined his first ST X29 ABC because he thought it was way too tight, and proceeded to take out all the taper to loosen it up on his Sunnen Honing machine. Of course it was worthless after that. Then he got the idea behind it, and then went hard-over the other way, setting his engines up tighter and with more taper, which might have been a good idea for a racing engine (some of which *glow a dull red* when they are running), it was a disastrous idea for a stunt engine, since it never got hot enough to loosen up. You probably can damage a ST X29 running it rich, and I know that many of the GMA ABC engines were eventually damaged by running them normally for stunt. Interestingly, the cylinder and piston was durable enough, but the crank wasn't - jamming the piston into the taper with it *squeaking in flight*, 240 times a second, was a bit stressful.
The 40LA doesn't have enough taper nor is it too tight to run in a 4-stroke. You probably don't want to, for performance reasons, but it almost certainly won't hurt anything.
Brett
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Hi Tim:
Thanks for the reply.
I asked for a friend of mine who is doing this type of flying. He is using a Brodak ARF Smoothie that flies very well and quite fast.. I timed him and he was turning 4 second laps on 60" lines. I suggested that he get rid of the 10X6 prop and try a 3.5 or a 4 inch pitch 11 inch prop. If this thing would lean out, he could fly combat with it! Lol
I thought tht these enginse should be operated in a wet 2 cycle mode to prevent premature engine wear. I should check to see if he has a AAN p&C before I make any more suggestiions. It may be an iron and steel setup.
Stay well,
Frank
No OS .40LA (or any other OS LA series engine) comes with ABC, AAC or iron/steel piston & liner setups. They are all ABN, have very little cylinder taper, and are made that way to be (pretty much) idiot proof. The 11x4.5 Thunder Tiger Cyclone prop (from Tower Hobby) is a very good prop for the .40LA and lots of other .36/.46 engines. Maybe not the best, but really hard to beat...and cheap and consistently good. H^^ Steve