Peter Sripol!
“Smooth, crisp, and clean. With no caffeine.” - Peter
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I just logged in to see if anyone had posted this. When I saw the prop that he was using I was like “nooooo - not a ppg prop! The speed range is wrong!” He must have been hovering just above stall the whole time.
the propeller fits his project perfectly. it has a pitch speed of around 85 km / h. many ul projects, electric sailplanes use similar propellers. all are very efficient in level flight in the range of 55-75 km / h. so he does everything right 
Your numbers are the right numbers to aim for but I don’t think that’s what he had. The first one (the two blade) huffed out on him around 55kph and most ultralights stall around 40kph leaving a very narrow margin to fly in. The second one seemed a little better, but I think he said he was straight and level with 11kW of power - which seems too much, like he was still flying on the backside of the curve.
Ya i just gave him a few different props to try, the first one was a 150cm by with a 14kw rating, then the only other more pitchy prop i had was a 140cm tri with a 17kw rating. I ordered an a adjustable pitch prop 150cm bi-prop we will see if that’s nicer.
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Good plug for you guys.
Paul or Bratwurst, do you know specifically what prop Peter ended up using?
Kind regards,
Mark