I was walking among the thousands of airplanes at Oshkosh this week and noticed a subtle, but significant transformation; that square tip on the end of the prop of yore is giving way to a more scimitar looking device. Where a few years ago there were a few to be seen, now they are the dominant form on LSAs, especially those from Europe. What had been 4 inches inches wide and square on the end is now 1.5 inches and rounded. The air has not changed; horsepower is horsepower. So why the transformation?
The answer to this was offered in a seminar on the subject of propeller design hosted by Jack Norris, who knows of what he speaks when it comes to the subject as his book explains in lay-terms. In a nut, all this knowledge is being rediscovered.
Yes, rediscovered. Look at, for instance, the prop used by Glenn Curtis on the last of his seaplane racers–its look is suspiciously similar to these “new” designs. Why this knowledge was lost and then found again will be the subject of further discussion in KITPLANES.
There are some amazingly simple things you can do to your airplane, and you can modify your flying technique to significantly stretch that increasingly expensive gallon of gas. Hint: fly with the throttle wide-open until… More on that later.