No Magic About Catto...

[David-aviator]

....the prop simply does its job, even the 3 blade original version. A new 2 blade will do better.

On Thursday this past week, I broke cabin fever and launched after 8 days of rather high wind conditions around here. It was still blowing but not at 30 knots.

Climbed to 8500' at WOT and let 'her rip for a few minutes, running about 50F ROP.

North leg was 144 knots ground speed.
East leg was 196 knots.
South leg was 207 knots.

An internet TAS calculator came up with 174.44 TAS (200.74 mph).

Dynon D10A computed 172 knots (198 mph) with its IAS/OAT/Density Alt info. Power may have been a bit less than 75% as the indicated DA was 9140'.

Van's advertised number for the 7A with CS prop is 198 mph at 75% power.

Not too shabby at all. Go light weight, go Catto.

[hevansrv7a]

My TAS at anywhere from 6k to 10k, WOT, is exactly the same, done with GPS 3 way and the NTPS spreadsheet. Catto 3-blade, pitched to come near the redline at 8K. Repeated tests, same results plus or minus half a knot.