Submitted by: Mike Penketh, IAC #3213 & Sean DeRosier, IAC #187992
"I dunno," that’s probably an honest answer. I know we’ve all tried or flown behind different propellers but its not often we have the same airframe/engine combination and several composite constant speed propellers available for evaluations. Several years ago the Hoffman propeller off my Zlin 50 made an extended visit to the prop shop, a borrowed a MT propeller gave me a rare chance to compare two aerobatic composite constant speed propellers on the same aircraft, the Zlin 50 powered by an AEIO-540/260hp.
So ... what did I find out?
In this early comparison the take-off, climb and cruise were all about the same, no marked difference. Slow speed pushes and pulls revealed a noticeable difference. The Zlin 50 is a remarkable aerobat; it flies well at slow speeds such as found in the vertical S described below.
Using the original equipment Hoffman propeller starting at about 160mph in level flight using full power and no more than a 3G pull the 1st half of an inside loop was completed. Hanging upside down I would hesitate a moment looking for a minimum of 85 mph, then with no more than – 3G I could push over the top and the 1st half of an outside loop was completed; all this with a very solid feel to the aircraft. I then switched to the MT propeller, using the same technique. All was the same until I reached the vertical phase of the half outside loop. Shutter, shutter, shake, shake and the maneuver was all over. Even an evaluation as simple as this is uncommon. Below we’ve tried to go a step further and expand the comparison paramaters.
For the ya-buts, what-ifs and nit-pickers ...
We have tried to be as consistent as possible in our comparative evaluations. The same pilot, same aircraft and same procedures have been used in comparing five different composite aerobatic propellers.
The following composite aerobatic propellers were compared:
The following comparisons are offered for information only. They represent real numbers. Hanger flying, dreaming or salesmanship is not a factor. We are not in the business of selling propellers. The final decision is yours.
|Propeller:||GSPD (1)||RC (2)||VMAX (3)||VMAX (4)||VMAX (5)|
2 blade; 52 lbs. 78" diameter A/C EW 1037 lbs.
|210 mph||1957 fpm||210 mph||195 mph||1800 ft|
2 blade - 200 Series; 45 lbs. 78" diameter A/C EW 1030 lbs.
|207 mph||1836 fpm||205 mph||195 mph||1500 ft|
2 blade - 200C Series; 46 lbs. 77" diameter A/C EW 1031 lbs.
|210 mph||2000 fpm||210 mph||193 mph||1800 ft|
3 blade - 400 Series; 65 lbs. 74" diameter A/C EW 1050 lbs.
|204 mph||1682 fpm||202 mph||190 mph||1500 ft|
3 blade; 59 lbs. 76" diameter A/C EW 1044 lbs.
|202 mph||1764 fpm||202 mph||193 mph||1400 ft|
There are numerous distributors for Hartzell and MT propellers, these can be found in publications such as SPORT AEROBATICS, SPORT AVIATION or TRADE–A-PLANE. Whirl Wind products are only available from the manufacturer and our authorized distributors.