L / H Teknisk Ordbog:
Platte: Tip




http://www.matronics.com/archive/archive-get.cgi?Kolb-Archiv...
I don't think I have ever heard of anyone who has improved performance on aircraft of this type by going to a smaller prop, seems like everyone who goes to deeper reduction ratios with more diameter and or pitch, get much better performance.
At the very least by trying the tip change before you shorten your blades, you will be comparing apples to apples when you do shorten them and cut the tips.


http://www.freshpatents.com/High-efficiency-ceiling-fan-dt20...
[0004] When a fan blade that extends generally radially from its axis of rotation is rotated, its tip end travels in a far longer path of travel than does its root end for any given time. Thus its tip end travels much faster than its root end. To balance the load of wind resistance along the blades, and the air flow generated by their movement, fan blades have been designed with an angle of attack that diminishes towards the tip. This design feature is also conventional in the design of other rotating blades such as marine propellers and aircraft propellers.