I've not used this prop yet so I can't offer much.

Here is what I think.
These little engines put out minimal power So I am not sure how I would justify  a 14 percent thrust drop from a combo that as you say you have grown fond of.

I would personally (soley based on the info given) put the extra revs to use gained by the smaller dia. to going up with the prop pitch. In other words try the 5.5 by 3. The engine will not have lost power. You might find you will have a better thrust overall.

When it comes to choosing a prop, you cannot count on a math equation to solve it for you. Believe you me it is mostly a matter of personal preference in the long run when it comes to props. Talk to a lot of guys and you might be surprized what they use.  Moreover get a wide range of props and try them to see what you like best. Keep in mind that whatever you do like best will most likely change when you go to a different plane.

When I say a wide range don't go over 6 inch dia.

I do have a question. Why only 2 inch pitch?  I think this is fine for learning to fly but most like flying faster unless you are on unusually short lines.

Robert
   

Ray I will agree with what you say but I would that carry the same over to an AP .061 and call it equal?
 I have not owned one of the APs so I find it hard to say more.

Robert

Graham , i use both props 6x2 and 5.5x2 on my norvels, depending on the weight and airfoil of the plane. Both work well, i have used them both on 48 ft. lines with no problem, depending on how fast you want to fly.

Thanks everyone for your input. I am going to get a couple of the 5.5 x 2 props and see how they work.

APC has quite a list of props including a 5.5 x 2.5 which I might try and get a couple of as well. Sometimes I think I spend far too much time tinkering with different props and glow plugs but it sure does add to my overall understanding. I never would have thought that using a prop with 2" of pitch would work as well as it does but it does. These smaller planes and engines require a difficult approach than the larger ones.

So, for now the 6x2 on the .061's is my first choice until I do some testing and prove otherwise - who knows, maybe the 5.5 x 2.5 will end up being a better choice on windy days?

As to the AP 061 and Norvel comparison - I think the Norvel has a slight edge overall, especially with the revlite cylinders. However, the AP061 is the only one of the two currently available off the shelf, has proven itself to be pretty good value for the money and using the Cox TD Venturi, Galbreath head and Nelson plug (or turbo plug button head and plugs) it does work quite well. The Brodak/CS .061 is not quite in the same league RPM wise but with a Nelson or Turbo plug head, a good and proper break-in and the right prop choice, also works quite well. I have a little 1/2a trainer type that I have been flying this summer. It has CS .061 on it and I have using the APC 6x2 prop. This plane has been flown with a Cox TD 049/051, Norvel 049 and 061, AP 061, PAW 049 and now has the CS 061 and Using these various engines and a variety of line lengths from 30 feet to 42 feet and lines of .008 to .012 braided steel, spiderwire and Sullivan Tuff strand. It has never flown any better that it does now with the CS 061 and 6x2 prop on 35 foot .012 lines (I generally fly on a rough stubbly grass field and not very .008 friendly). I do intend to give .010's solids a try at 42 foot and pending my tests may become my new 1/2a choice as well.

cheers, Graham

I flew my Sky Sport with the Holuszko venturi equipped AP Wasp and the 5.5x2.5 prop.  That is a very nice combination.  On 47' lines the lap time is quite manageable, and the pull solid everywhere.  I am pretty sure that I have the stock AP plug in the engine, and am running 10% Nitro.  Does the full pattern on about 22 cc of fuel.