MJD
Posts: 1703
Joined: 5/27/2003
From: Orangeville,
ON, CANADA
Status: offline
|
quote:
ORIGINAL: longdan
My take on it is, that I basically have (almost) a 100% guarantee of not ruining a 1/2A engine under normal sport flying use if I use 100% castor (and don't run it lean), but is this guarantee reduced if the castor content drops to 50% of the total oil content?
I do not believe so for one minute. Offering my personal opinions on the subject:
- A sensible fuel for 1/2A's with ball and socket joints has 50% of castor as minimum in it's oil package, and the balance synthetic.
- I think it is smart to have at least 20% total oil. Is 22-23% "best"? Maybe. 20% might be best. Doesn't hurt.
- I also think it is acceptable to run 18% 50/50 syn/cas if that is all you have available. I have done so a lot, in .049 reedies, and enjoyed long life and good performance. The caveat is to know how to set a 1/2A needle with some respect for the engine.
- Too much oil degrades performance and doesn't add to longetivity, at least not enough to warrant the negative issues.
- The 20% castor/80% synthetic rules apply to typical larger sport engines, ringed or not, with plated cylinders esp. although a broken in lapped engine might be happy too but whatever - I don't own many of those. Anyhow, 1/2A's work on different rules of thumb.
- 1/2A's with bushed conrods are probably content on 20% castor/80% synth, but maybe 50/50 is better for the other benefits castor offers.
- The conrod and specifically the bushing/bearing design and metallurgy have lots to do with overall oil requirements, both in type and percentage. So don't be surprised by the special needs of the ball-and-socket engines.
Digressing from oil a bit while I'm at it:
- This is not an oil issue, but 15% is the minimum nitro content for Cox .049's, and 25% for .020's and especially .010's. Below these levels, from my experience, they start to run like crap and will p- you off eventually. And I don't care about Texaco engines, or the the occasional guy who insists they run 10% in their .049's and "that's all they need", because I think it is BS. While you might be able to needle them to the point they stay running, why be a miser when the only return is marginal performance and handling? 25% is ho-hum everyday sport fuel for 1/2A's and smaller - the numbers are just different with these guys.
- Don't put Armor-All in your fuel. The silicone oils poison the catalytic action of the glow plug element over time with deposits, and shorten plug life. A better idea is to a good job balancing props and the tank installation. Many fuels contain anti-foaming additives anyway.
- Balance your props with all the care and skill you have at your disposal.
- Keep everything to do with the engine and fuel cleaner than clean.
As I said, these are my personal opinions! But I've run just a few of these guys in my lifetime. Way more than many, and way less than some. But they always seem to run well for me and I still love small engines, so something must be working.
MJD
< Message edited by MJD -- 6/24/2008 4:38:07 AM >
|
Printable Version
All Forums >> RC Airplanes >> "1/2 A" & "1/8 A" airplanes >> 100% castor vs 50/50 castor/synthetic 
100% castor vs 50/50 castor/synthetic - 
Along with my Andersons, Hollands,K&B's etc. I wouldn't use synthetic in any of them, because they weren't made for it. I even up the castor in my fuel, like Fox did. So far they're all running,.. years & years later. For the new Norvels AP's ThunderTigers...I think synthetic may be fine, but the few I have get real castor. I also go by history. The Germans, in WWI had a hard time getting castor for their rotary engines during the middle to end of the war, and switched to a synthetic blend. They had more planes fall out of the sky due to engine siezure than enemy gunfire...I've been taught, If you don't learn from history, you're doomed to repeat it.... Bob
