This is no surprise to me, I have said on here before that Graupner carbon props are the most efficient props available.
Not only are they a very good tongueless shape, but they have flex designed in that is just not possible with a metal prop, under high loads like hole shots or accelerating out of a corner they flex and reduce pitch which reduces peak currents, as the boat accelerates the prop unloads and the pitch increases.
If you use Graupner carbons to test for prop size, when you find the right prop for your boat, you need to order a metal prop 1 size smaller.
TP's low blade area CNC props are clones of Graupner Carbons, and while they are the second best aluminium CNC props out there (closely behind Tenshock), they give the same speed and less run time than a Graupner that looks and measures the same.
The 51mm prop is flexing and depitching more than the 48 on acceleration, giving similar peak current, but you will find that the average current during a run will still be higher with the 51mm, and you will see slightly higher speeds.
Graupner carbons are very fragile though, when a decent amount of power is put through one hitting the stem of a leaf can be enough to throw a blade, and if you are running big power, just gunning the throttle can break one, as such they are not really suitable for long term use these days, and I would only recommend them as a cheap way to work out what metal prop you need for newbies that don't yet have a box full of metal ones to try and has no access to a friend/clubmate willing to lend them props.
Paul Upton-Taylor, Greased Weasel Racing.
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