1st performance report from B&B Sport Aviation in August of 2000

 

"On our RANS S-12XL Trainer, it is now possible to fly without the helmets or intercom - At Cruise Power settings, we can actually hear the wind whistling by!

 

Report filed on August, 2000

PERFORMANCE FIGURES OF NEW PROP:

 

TEST AIRCRAFT:

RANS S-12 XL Partial enclosure, Rear Cabaine Fairings, No Flap Filler, 582 C box 3:1 ratio, new composite prop & spacer **13.25 degrees pitch, 200 lb. Pilot.

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                INDICATED CRUISE SPEED

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      NOW                                       *BEFORE

 

5500 rpm 70 mph                        55 mph

5650 rpm 77 mph                        60 mph

5800 rpm 79 mph                        65 mph

6000 rpm 80 mph                       70 mph                Level Flight Highest Achievable Indicated Airspeed 85 mph

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* Same S-12XL, only w/ 582 B box 2.58:1 Ratio and 3 blade Powerfin propeller

**Maximum achievable rpm 6150

 

CLIMB: 40deg. Angle, at 3000 feet msl, Temp. 60 deg.:

5900 rpm  No Flaps  750 fpm @ 50mph

5900 rpm  1  Flaps    900 fpm @ 45mph

5900 rpm  2  Flaps    600 fpm @ 45mph

 

FURTHER PERFORMANCE FIGURES:

**New Pitch Setting at 12.5 degrees

 

CRUISE:

5600 rpm  65 mph

5800 rpm  70 mph                                                 Level Flight Highest Achievable Indicated Airspeed 90 mph

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CLIMB: 40deg. angle, at 3000 feet msl, Temp. 52degrees

6350 rpm  No Flaps   800fpm   @ 50mph

6350 rpm  1  Flaps   1100fpm   @ 50mph

6350 rpm  2  Flaps    750fpm    @ 50mph

 

**Maximum achievable rpm 6400

NOTES: After decreasing the pitch from 13.25 to 12.75, the noise level naturally increased slightly. Cruise settings however, are still very comfortable. The sound has a mellow like deepness to it.  Again, this is the quietest combination that I have ever experienced on any S-12. The Turbine like smoothness and noise reduction alone make this combination a must for any Rotax powered aircraft, especially the Pushers. The Powered Chute and Trike guys should really find this a great benefit…especially with the 5 blade!

 

  The tool used for setting the pitch angle is very unique and simple to use. I have also found it to be very exacting. As you torque down the prop bolts the blades maintain the established setting with zero drifting.

 

Although this prop has yet to be named, it’s gaining a good reputation around here. We sold 4 of them to 4 different pilots, with one demonstration!

 

 

 I think I've found the perfect propeller for the S-12. The prop itself is a little unusual because it has a gentle leading edge curvature that begins half way down, tapers and ends at the tip with a nice round curve instead of the usual "hacked off" square tip. It also has forward dihedral. Initially I had decided to not only switch to the C gearbox (3.00:1 ratio), but also to install a 2.5" prop spacer. This combination would not only slow the prop down but also give the air (as it separates from the flaps) a chance to clean up a little before reaching the prop. As it turned out the 2.5" spacer was also needed in order to keep the prop from striking the fairing on the rear strut. The initial pitch reference was set at 13.25deg. This was the quietest setting but only achieved 6150 max. rpm. It sure was quiet though! For the first time ever, I could hear the wind whistling by! Leveled off at 5600 rpm I took off my helmet/headset and the could hear the gentle drone of the engine and prop working together as the wind whistled through the cracks between the windscreen and the Lexan doors. I said out loud, "This is GREAT!" and I heard myself!"

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