From a personal position I believe far too many people are placing too much emphasis on rpm counts and not actual in flight performance. I've had too many props with lower rpm counts than the "other guy" that truly out perform the higher rpm prop in every area. Camss69 is doing the experimenting the right way and looking to the the way the plane performs, not just to the numbers. Another thing that troubles me is that so many people want to run a larger prop than an engine can effectively handle. This is the case with many 50cc engines and most 23" props.

Unless the larger diameter is pitched down from a 22" prop there will be a substantial loss in rpm AND available power. It lugs them down and takes them out of the rpm band where they perform the best. The larger props also promote faster engine heating where in many cases the excess heat cannot be shed due to poor baffling or indaquate air flow through the engine. Having the correct mixture settings becomes even more important when swinging "over size" propellers.

This brings up an area that troubles me with the Vess propellers. They use an "A" and "B" sizing instead of numerical pitch, which means that nobody has anything useful to work with in sizing. I know one person that cooked off a ring and cylinder using one thinking that it was of a size and pitch that would suit the engine. So ended the use of Vess props for that individual, and many that he associates with. Sort of like electric motor manufacturers where everyone uses a non standard method of sizing a motor, causing a lot of consumer frustration and mulitple purchases to reach an end.

Bottom line is the fact that performance is not just in the numbers, but how the plane actually performs. The truth of that can be found with most stock Zinger and Top Flite props. They'll provide a high rpm count but generally poor flight performance in sizes useful for most gassers. The type and size of any given propeller is determined by the type of flying desired and the engine/airframe combination it's attached to. That performance can only be found through actual trial and error since one prop will not fit all performance ranges for any given engine. The rpm count obtained by others using the same engine and prop is not a good gauge of performance in many cases since there are so many user influenced parameters.

Back to the 3mm-53. It's a real good engine and with normal care it should perform extremely well over a very long period of time. Like any other engine just don't take it where it should not go. That includes hitting the ground and using excessively large props. That's my perspective anyway.