I have a brand new 46ax, with 4 tanks through it. I modified the muffler and am getting 15100 rpm with a apc 10x6 and 15% powermaster. This one runs better than my first 46ax. And its not even all the way broke in. What are your tach numbers?

sounds good!! i remember i liked the 11x6 apc for sport flying http://www.rcuniverse.com/forum/m_50...tm.htm#5043356

I used the 11x6 too.

i have 11X6 apc as well I love it, I have the 11X7 in the box to try to move up to but dont know if i need to. I think tach numbers were around 13-14k but its been a few months and it was still under the first gallon or so when i tached it last

I always used a 12.75 x 3.25w on mine.....

(i may have the numbers backwards...)

OK then, let me rearrange them for you: 57.21 x w5.23 .........[sm=idea.gif]

No wait......... you got 'em right.

Back in the day, 10x6 props were the standard on 35s. Today's engines are more powerful. That 10x6 is probably jest a mite bit light for that sucker.

What do you use that engine on? The use has a lot to do with the choice.

I would agree that 10x6 is too little prop for that one. I use the 10x6 on an old 40 FP, I use a 11x6 or 11x7 on the 46 FX.

I loved a 12x5 on my 46AX spinning at 12000rpm.

12 x 5??? That seems a bit large to me. We use a 10.5 x 6 as the smallest prop. A 10 x 7 or 10 x 8 are goodies for trainers or other sport aircraft that aren't intended for 3D-type flying. If you prop the engine so that it turns 12,500 RPM or above when leaned to just rich of peak, you'll find the engine performs very, very well. However, it will be quite a bit noisier than if you run larger propellers.

LOL!

Well I just put a 10x7 mas and was still pulling 15100 rpm. Same fuel, and glow plug.

You've just seen your first example of how undependable the propeller identification system is for model propellers.

Both a 10x6 and 10x7 turning the same revs, right.

In fact the id system is not to blame. Our belief that it's perfect is. The blade area and airfoil have a lot to do with how they work. The id system just suggests what to expect, nothing much better can be counted on.

What you've just seen is why you should try more than one prop. Best thing to do with a new airplane is to figure on testing at least 3 props before picking one. Start with what you see at the field on your engine. Get that size and one the next diameter up. It's often worthwhile to get the same dia/pitch but in a different brand, especially if it looks a lot different. Different blade area can do wonders. Different tip shape is worth trying.

Say your engine is on a couple of models at your field, one turning an 11x6 and one a 12x5. Look at the planes those engines are on. Figure to try the prop that's on the model most like yours. Say it's the 11x6. When you're getting your 11x6, look at the 12" props and pickup a 12x5 or 12x6. If there aren't any, get a 10x8 or 11x7. Or just get another brand of 11x6.

See the plan? Try something, anything, that's close to what looks to be the best match.

If we are talking about an APC prop those numbers are backwards should be 12.25 X 3.75 unless their making a new one again!!! You would not get those kind of rpms in Denver with out changing the comp. ratio. I would say that one's a keeper.
jerrysu29 Call Sign Wild Man

The plane flies awesome with the 10x6 apc. Oh the plane is a modeltech luckystik. The 10x7 ought to make her a little faster. With a 10x6 apc she is already really fast. I have always known you lose rpm with apc props. I have another os46ax and it does not run this good.

from my experience you may lose RPM with APC props but you gain performance....

I was running an 11x5 for the first half of the summer, getting no more than 12,500 rpm. At one point I tried the 12x5 and it was a little too much for the engine. I kept the 11x5 for a little while longer, then tried the 12x5 again and got over 12,300 peak RPM. The engine sounded and ran great, and the prop did very well on my Venus .40 and my Phoenix Dolphin.

I believe my O.S. 46 AX tached at about 12,500rpms with a 11x7 MA prop, last time I check. Its only got 5 tanks at the most, so it still has that new engine smell. One small question,does anyone know if a pitts muffler does anything to the rpms. The 46 has a pitts muffler ( first one I've owned) and I just didnt know if it is effecting the performance.

Hi!
9x7, 10x7, 11x6 11,5x6 ,12x4,12x5 or 12,25x3,73 , or 13x4 all APC works good but for different planes of course!
Avoid the white tipped MA props. They are lousy performers and just put out a lot of noise compared to APC , RAM or Graupner Cam-prop which are the props of choice!!

As people are noting, different props give different amounts of performance. As a guide, the O.S. Max .46AX should be propped to turn in the mid-to-high-12,000's when leaned to just rich of peak RPM. If your prop will allow the engine to turn that RPM level AND fly the airplane in the manner you like, you have chosen the "correct" propeller. It doesn't matter what brand or size is on the prop. The bottom line is how the airplane flies. Da Rock had it right....what works the best IS the best, and you'll find people with the same airplane/engine combo using different props because of the way they like to fly the model. However, it's good to remember that the engine likes to turn up at full throttle, so work from there.