Fuel and prop selection
 

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.

RE: Fuel and prop selection
 

Don't stress too much about it. Follow the break-in instructions and later you can experiment with props for your type of flying.

In the beginning, the break-in prop will be fine for your trainer. VERY soon after you solo, you will want to scrap that engine for something bigger....and eventually move to gas.

After-run oil is for people who fly less than once every 3 months or so. It's a waste of money, time and effort. If you buy a year's worth of oil, you have likely paid for 2 OS .46 AX engines.

I put nearly 20 gallons through my MAGNUM .46, (a lower quality engine than OS), and could have gone much longer had I taped-in my crystal. Glow motors are just not very complicated. BUT keep your investment in glow to a minimum. Gas is FAR better, FAR cheaper, and the planes are FAR more capable.

GOOD LUCK!!

agexpert

RE: Fuel and prop selection
 

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!

RE: Fuel and prop selection
 

First of all, you made a good choice in engines. I have pretty much gone to OS exclusive after I had a bout of problems with others. In my opinion, they are reliable and consistent performers. If you follow what Big Ed said above, you will have an engine that will last a while. No, don't scrap it as suggested... :D it's a great engine.

As far as fuel is concerned, go to your LHS and see what he has on hand. Any good quality nitro fuel designated for aircraft is just fine. I have used several types and brands, all name brands, by the way, (S&W, Bryon, and so on) because they are probably the most consistent in their blending. I started out with 15% nitro content and have had no reason to change. Not that it's better, or worse, it's just what I get and use and it seems to perform just fine.. so if it ain't broke, why fix it.

Big Ed said something that I think should be clarified. 80% oil... well, the blend consists of 80% castor and 20% synthetic... that's not to be confused by a total of about 20% oil in the gallon of fuel which consists of 80% castor and 20% synthetic... or some such blend. The fuel consists of Ethanol, Nitro Methane, and an oil blend. If 15% nitro, then the gallon contains Ethanol blended with 15% nitro-methane, and 20% oil blend. That's if you get 15% nitro. If you get 10% nitro...well, just change the figures. What's important here is to get what is recommended by the engine manufacturer, try it, and adjust it as you feel is necessary. If you have any questions, perhaps it's best to talk to the 'pro' at the field and see what he/she uses and try that.

At the beginning phases of your flying, if you use a good quality fuel, you won't have to worry about it and you can focus on your flying.

As far as props are concerned, go with what is recommended by the plane/engine manufacturer and keep it simple. Once you do, and find that you have the prop you like, then buy about a dozen of them. :D

CGr

RE: Fuel and prop selection
 

Excellent choice of both trainer and engine. They are both top notch. As long as you use good, brand name fuel, you shouldn't have problems. I would start with 10% nitro as suggested, and fly with the suggested break in prop. Since props don't have a very long lifespan when you first start out, I would buy a few 11x5's and 11x6's to try out after you break your first prop.

I don't really agree with agexpert that you will want to scrap your engine for a bigger one "VERY soon after solo..and eventually move to gas". This engine will last you for years, and will fly this trainer perfectly. You will probably want to start looking for a second plane sometime after you solo, but you'll probably want to keep your trainer intact. As for moving to gas, I see very few guys who do this. A lot of guys are happy flying glow engine planes for their whole lives.

Good luck and enjoy!

RE: Fuel and prop selection
 

Good point. I still have a trainer and fly it regularly... they are fun and basic flyers.. great to bore holes in the sky on a lazy afternoon.

RE: Fuel and prop selection
 

I have found in Florida, living 9 miles from the beaches, the salty air makes my engines require after run oil the same day I come home from flying. Inspect the engine by removing the backplate and see what your bearings looks like. They should have a clean silver shine to them. If I let my engines sit even indoors for a few days, my bearings would be showing rust developing. After run oil is very cheap insurance from a bearing rebuild. Do it after each use, it can never hurt and it's very inexpensive to use.
A whole chapter on maintenance is in a Harry Higley book that's available for $24.95 at most hobby shops, and they state to use after run oil all the time, not just for storage. Good habit to get into and have no regrets. The book suggests to flush the engine as the nitro is the corrosive that damages bearings, regardless of castor content, the nitro is still there. Oils that people have used regularly with success are transmission fluid, Marvel Mystery Oil, air compressor tool oil (I use this as it's cheap from Walmart) and the retail Hobbico type after run oils.
Most 2 stroke .46 sport engines like the AX after break in require a 10X7 prop to properly load the engine keeping it in the rpm range it was designed to run at. I wouldn't use the .40 10X6 after break in is complete, and on a AX it's just 3 tank fulls typically. You can go up to 11 inches and drop one pitch number, so a 11X6 is the correctly prop to use on a trainer as a starting point. Varying factors allow you room to make adjustments such as temperature, altittude, nitro content of the fuel, and weight of the plane among other things. Even choosing APC or Master Airscrew, wood or nylon, makes a rpm difference and the plane behaves differently with these variety of prop materials due to flexibility that causes change in pitch, especially at full speed in the air. You can learn a lot about props from the pylon and combat racers in this forum. You won't be in your trainer long and you'll be off into some other area of the hobby, either pattern, scale, sport, 3D, low wing trainer, biplanes, etc. and each has it's own fuel and prop category to generally follow. But they all typically use after run oil after each flying day.
OS is flexible on nitro content. I have used FAI 0% because it only costs $10 a gallon here. I have used Byrons 5%, Wildcat 10%, Cool Power 15%, and even 30% heli fuel in my OS engines and it runs on all of them. I've changed plugs going hotter and colder when making drastic changes. So 5-10% is fine and common with OS owners for what you're doing. But there isn't anything wrong with other fuels, synthetic or castor based. Some say the castor builds up residue quicker and shellacs the engine too much. Usually I've found by that time, the engine is well seasoned and wiped out anyway. I prefer castor based fuels to help seal the engine, and the castor properties protect the engine better should you have lean run for whatever reason, in an OS ABN engine as yours.

RE: Fuel and prop selection
 

Marvel Mystery air tool oil is $1.99 a bottle. I have 16 glow engines that I used it on this fall and still have 2/3s a bottle left.

Gas is a no brainer for me to work on, as I`ve been a mecanic all my life and am familar with gas. Had to learn the odds and ends of glow, which was a little bit of a learning curve.

RE: Fuel and prop selection
 

Great plane and engine choice!

I've found that a 10x6 is too little prop for this engine. Mine swings an 11x6 at over 13.3K, 10x6 will be well over 14K, too fast for good longevity.

Good prop options for this engine would be 10x7 (fast flyin'!), 11x6 (sporty!), 11x5 (thrusty, slower!) or 12x4 (3d thrust!)

Any decent fuel, 10-15% with castor/synthetic mix would be great. I use Omega 15%, others will work as well.

J

RE: Fuel and prop selection
 

Some fliers here use a pipe and 9X6 prop on the FX turning it up quite a bit over 13.3k, and 5 years later, still running strong. I've got at least three Rossi .45 engines that routinely turn 16,500 rpm with 9X6 props too, and perform like new. Short lived engines isn't from RPM as much as a lean run, dirt/FL sand sucked inside the carb, lack of after run care, and of course, crashes. OS rates the .46 FX and AX to withstand RPM over 13.3k...GMS .47 even lists the 9X6 prop on the tower site for pylon applications. Proper fuel, care, and mixture, the engines should outlive us.

RE: Fuel and prop selection
 

Once again you all came through for me. Thank you for all the detailed advise. I've found this forum to be the best resourse for all of my r/c questions. Especially the differing points of view.
Good arguments make for good research!

RE: Fuel and prop selection
 

The next person I see jump right from A glow to A gas engine will be the first one. I still fly with both. At the moment I'm out of big planes so I have been just flying my glow powered planes. For fuel I have always used Power Master 15% but tried several others and they have all performed very well. I even run my YS engines on the 15% and they run just fine. After A day at the field I do run my engines dry but because I fly several times A week I don't use after run oil, that and I live in A desert so there isn't A lot of moisture to worry about. Any engine that is going to sit for A while I do use the after run. NEVER in A YS engine though!!!! It destroys the pump system. You really did buy A nice engine, never had A problem with any of the OS engines.