Yesterday I tested a new prop on my Hatz. The test is inconclusive, with some oddities (more on that later). The test was a series of climbs with first the old, and then the new prop. The flights were recorded with an old Garmin 60CSx which has a pressure sensor, so it's a lot more accurate than GPS altitude. That data was analyzed with "Trackreader", a windows program I wrote myself:
At the same time, a GoPro was looking at the instrument panel to record time, speed, altitude, rpm (note the tach display on the phone on the right):
Finally, I put the climb date into a spreadsheet. It was a bumpy day, so I really don't trust the numbers:
This is the weird part. Climb vs. airspeed should be a smooth curve with a single high point. The dip at 65 knots shouldn't be there, the strange part is that it's there in both tests. The data at 55kts is suspect, too. If I delete the 55 and 65 knot values, I get curves that, although probably not correct (Vy shold be closer to 55kts), look like what you would expect:
Clearly I need to do more testing under better conditions, though I probably won't put the original prop back on. Once I believe I have accurate data I expect to send the prop back for rework to have some pitch taken out (I was looking for more climb, hopefully without too much loss of top speed).
At the same time, a GoPro was looking at the instrument panel to record time, speed, altitude, rpm (note the tach display on the phone on the right):
Finally, I put the climb date into a spreadsheet. It was a bumpy day, so I really don't trust the numbers:
This is the weird part. Climb vs. airspeed should be a smooth curve with a single high point. The dip at 65 knots shouldn't be there, the strange part is that it's there in both tests. The data at 55kts is suspect, too. If I delete the 55 and 65 knot values, I get curves that, although probably not correct (Vy shold be closer to 55kts), look like what you would expect:
Clearly I need to do more testing under better conditions, though I probably won't put the original prop back on. Once I believe I have accurate data I expect to send the prop back for rework to have some pitch taken out (I was looking for more climb, hopefully without too much loss of top speed).