Prop obsevations
Posted: Tue Aug 02, 2016 12:13 amI thought I would share the differences between two props. I now have 36hrs on my plane, Jab 2200 ( 3300 rpm redline). Up until a couple of weeks ago I had been using a Sensenich
60X46 prop that I purchased from Jabiru. The prop was on special and advertised as a climb prop. The flight test paperwork that came with the prop showed that when being tested on a Jabiru J120, At 3350 rpm the aircraft was doing 112 knots.
I found the prop to be very good in climb usually seeing 1000-1100 FPM climb solo at 80 knots (700 with a passenger), 3100 rpm.S&L, 2900 = 105 knots, 3300 = 120 Knots, WOT I saw 125 at3350 but backed off although the engine would have revd more. Whilst flying I had to be careful of those revs as a powered descent would push the revs to high. Straight away you can see how slippery the Sonex is compared to the Jab which is not bad aircraft anyway.
A friend was selling a 20hrs old 56X48 Brent Thompson prop, a New Zealand manufacturer, the company has since changed hands a couple of times so I can not comment about the quality now.(This prop was too much for the Corby Starlet he had it on)
The numbers for the new prop (only a few tests so far), climb solo most certainly down, 700 fpm at 80 knots 2850 rpm. S&L 2900= 122 knots WOT 3150 =138 knots. With a 80kg passenger the climb is a pathetic 550 fpm but in cruise the numbers were only a few knots down to solo performance.
The other strange thing with the smaller diameter prop is the amount of extra yaw it creates on climb, I would have bet money the opposite would have been true.
These tests were done at YMIG, field elevation 2000' plus its cold here at the moment 10 deg C.
60X46 prop that I purchased from Jabiru. The prop was on special and advertised as a climb prop. The flight test paperwork that came with the prop showed that when being tested on a Jabiru J120, At 3350 rpm the aircraft was doing 112 knots.
I found the prop to be very good in climb usually seeing 1000-1100 FPM climb solo at 80 knots (700 with a passenger), 3100 rpm.S&L, 2900 = 105 knots, 3300 = 120 Knots, WOT I saw 125 at3350 but backed off although the engine would have revd more. Whilst flying I had to be careful of those revs as a powered descent would push the revs to high. Straight away you can see how slippery the Sonex is compared to the Jab which is not bad aircraft anyway.
A friend was selling a 20hrs old 56X48 Brent Thompson prop, a New Zealand manufacturer, the company has since changed hands a couple of times so I can not comment about the quality now.(This prop was too much for the Corby Starlet he had it on)
The numbers for the new prop (only a few tests so far), climb solo most certainly down, 700 fpm at 80 knots 2850 rpm. S&L 2900= 122 knots WOT 3150 =138 knots. With a 80kg passenger the climb is a pathetic 550 fpm but in cruise the numbers were only a few knots down to solo performance.
The other strange thing with the smaller diameter prop is the amount of extra yaw it creates on climb, I would have bet money the opposite would have been true.
These tests were done at YMIG, field elevation 2000' plus its cold here at the moment 10 deg C.