ORIGINAL: jwingnut1
I am currently 3/4 of the way done building my Eagle 2. I purchased the O.S. 46ax to pull her around and its time to make my decision on fuel and props. Because this is my first plane I'm unsure of what fuel I should be using after break in. OS recommends that I break the engine in with nitro 18% lubricant and a 10x6 prop.
So what fuel and prop should I use after the break in period?
Oh yeah... What do ya'll think is a good after run oil? and is it necessary?
Hopefully my .46 will be around for a while.
Any input is appreciated.
You will likely find an 11x5 prop just about ideal for flying your trainer. The 1" longer diameter will give you faster acceleration while the 5" pitch will prevent the top speed from getting too fast while training. A smaller, higher pitched prop like the 10x6 will spin up faster to maximize top speed, but the shorter diameter will make acceleration take longer.
The O.S. Max .46 AX will run very nicely on 10% nitro fuel, and a blend of 80% synthetic lubrication and 20% castor oil would be ideal for this engine. After break in, you can use 15% nitro fuel with a similar lubrication package if you'd like, but the extra nitro content shouldn't affect performance significantly. Some folks say O.S. 2-strokes run best on 15% nitro, so you should try both and decide for yourself.
After run oil is necessary on a frequent basis only if you fly with 100% synthetic lubrication nitro fuel. Castor oil will help coat and protect the engine bearings to prevent corrosion. Even with some 100% synthetic fuels, anti-corrosion additives will make frequent use of after run oil unnecessary, but your mileage will vary depending on the brand of fuel you use.
After run oil is a good idea when storing a plane or engine away for more than a few weeks at a time. An annual ritual here in Nebraska is to go through all of my engines when winter arrives and put 3-4 drops of after run oil down the carburator and another 3-4 drops down the glow plug hole in the cylinder head and turning the prop over ten times to distribute the after run oil throughout the engine. If you have 3 or 4 glow engines and you treat them like this once or twice per year, a 2oz. bottle of after run oil will last you a decade.
I bought a bottle of Hobbico after run oil a few years ago, and it's still 80% full. Regular old DOT 3 automatic transmission fluid also makes a great after run oil, and I think that's what is actually in the Hobbico bottle.
As for longevity, you should be able to fly your O.S. Max .46 AX for up to 40 gallons of fuel or more before needing to do any serious work to it. This assumes of course that you properly tune it and don't run it too lean.
Good luck and remember, this is a hobby, so if you're not having fun you're doing it wrong!