I got my carbon fiber aerobatic propeller from Twisted Composites just before the start of the 2012 season. It is a beautiful piece. The surface is perfectly smooth and shiny with woven graphite fibers showing through the epoxy resin matrix. It is 76 inches in diameter with a pitch of 61 inches. The dimensions are the same as the aluminum Sensenich it replaced on my Pitts S1-C. Steve has different pitch versions of this propeller to match engine power. He recommended 61 inches for the 180 HP O-360. A balancing tool is included with the propeller. The static balance was perfect in all positions. This solid core carbon fiber propeller is half the weight of the equivalent aluminum propeller. To maintain the center of gravity within limits, I exchanged the lead acid battery, located behind the seat, for a much lighter lithium iron phosphate unit. The plane is now 35 lbs lighter. I have flown about 45 hours during the summer with this propeller, including 3 contests in Colorado in the sportsman category.
The Pitts is famous for its good flying qualities, not its comfort. There are a lot of vibrations in the cockpit. The new propeller decreased all that shaking considerably. Compared to what I was used to, the plane feels almost smooth. Indicated airspeed is 140 MPH at maximum power, around 3000 RPM, level flight at 8,500 feet, 10 oC. Better than the Sensenich in the same conditions (125-130 MPH). Transitions from idle to full are much quicker. My Pitts used to have very noticeable harmonics between 2150 RPM and 2450 RPM. Vibrations increased considerably inside this range. This is completely gone.
The carbon fiber propeller changed several flying characteristics. Aerobatics contests in Colorado are flown at relatively high density altitude. Before the propeller and battery upgrade, I had a tendency to run low on energy toward the end of the sequence. The weight loss mentioned above resulted in a much easier energy management in the box. Now if I get a little low, I just make the next vertical or 45 up line a little longer. Of course less weight results in better performance, but there is more to it. There is a lot of gyroscopic action in the Pitts due to a very small airframe flying behind a large, heavy propeller. One gets used to it and flies accordingly. Pitch transitions require rudder work and large rudder inputs require pitch adjustments. Competent Pitts pilots have no problem with it. Some will tell you they like it. However, throughout the sequence, this generates extra stick and rudder work. The lighter carbon fiber propeller reduced these flight control inputs significantly. Little rudder input is required now when pulling or pushing into loops and part-loops. However decreasing gyroscopic precession had an unexpected result. It made more noticeable the effects of slip stream, torque and P-factor. As a result, some maneuvers requiring a lot of rudder input like hammerheads and snap rolls have to be flown differently. For example, in the hammerhead to the left, I used to keep full power throughout, full left rudder when approaching zero speed, stick full right and forward a little during the pivot. This does not work at all anymore. It took me awhile to figure out that reducing power progressively to idle when the nose falls through the horizon gives a good consistent pivot. To summarize, the new propeller required some adjustments but it improved performance. The plane feels tighter, easier to fly. My grades improved a lot during this past season. Practice is part of it, but this propeller is a major factor.
Of course an even lighter wooden propeller would do the same. However wooden propellers have many disadvantages including performance loss. The weight advantage may not offset the decrease in performance. Carbon fiber is a little heavier than wood but performs just as well as aluminum. It is probably a better compromise.
Steve includes a pair of “socks” to block UVs when the plane bakes in the sun waiting for the next round. These do not fail to generate questions and jokes about night aerobatics.
Thanks Steve for a great product,
On July 31, 1998 at about 8pm a number of exceptionally violent thunderstorms moved across Phoenix’s East valley and Falcon Field airport where I have my airplane hangared. I did not realize the extent of the damage until the following day when I drove to the airport. Airplanes were flipped over, a DC-3 was blown through a chain link fence, then a block wall; finally coming to stop in the middle of a street. Unfortunately, my hangar was also damaged. The welds on the top rollers failed and the door fell into the hangar. One side of the door scraped the hangar wall and the other came to rest on my (Twisted Composites) propeller. I feared the worst but after examining the propeller it appeared to have only some paint (from the door) and a scratch where the door rested on it. I sent the propeller back to Steve and within a few days it returned with a clean bill of health. I received excellent service from Steve Hill and recommend his product to anyone looking for a high quality, high performance fixed pitch propeller.- Christopher Huey, Laser 200
Prop Stays Together After Gravel Impact on Takeoff
Reno Formula One Gold Race 2010: Invictus departed the runway and chewed rocks. Miss USA aborted and did a nose stand. I could not emphasize enough how well your prop held up in the Invictus ordeal. I told everyone who saw it that the prop may have saved the plane. The pilot continued the take off from the gravel. The damage you saw to the tip was there from take off, and the prop held together for the return to land. Good work, Steve.
- Doug “Jethro” Bodine Pilot of “Yellow Peril” Formula One Race Plane
Pilot Practices Airshow Routine after Prop Strike
A pilot complained of “the tips coming apart” on a brand new Twisted Composites prop after practicing an airshow routine. It was later determined that, unknown to the pilot, the aircraft had experienced a prop strike on a previous hard landing during the same flight. The pilot did a touch and go then went up to practice the airshow routine. Upon landing, the prop tips were discovered to be severely damaged but not enough for the pilot to notice. The damaged tips were cut off, minor repairs were made and the prop is still in use today.