Carter Tests Propeller Design for UAVs

One of the things that makes the CarterCopter successful is its efficient use of power. Even though its motivation is Corvette-based, the job the engine is asked to do is a big one: break the Mu-1 barrier. That meant to Jay Carter that the propeller for his gyroplane had to be the best-possible thrasher of air. So, Jay invented a radical new prop.

After a Sun 'n Fun presentation a year ago, ANN's recip engine man, Tim Kern, and CarterCopter genius Jay Carter were talking about the possibilities for some of the new technology embodied in the CarterCopter, and Tim suggested licensing the prop's qualities, separately, for applications that weren't the CarterCopter's own. Well, it's better: Carter is making the props himself. Here's a new press release:

Carter Aviation Technologies, best known for their revolutionary gyroplane technology, is expanding their sphere of development. It is being announced that Carter has designed, built, and bench tested a composite prop with matching spinner to be used on an Unmanned Aerial Vehicle (UAV).

Carter’s new UAV prototype propeller is 28” in diameter with a 9” spinner. Although the 8’ version of the Carter design prop has been flying very successfully on their prototype gyroplane since 1998, the development of this new diminutive prop required new tooling, molds, testing instrumentation -- and the same amount of engineering effort as the original propeller. This development project was completed in record time due to the long hours put in by Carter engineers and technicians.

Stan Clines, Composite Specialist, was in charge of the prop production, Kenneth Hibbs, Electronic Specialist, handled the instrumentation and Mark Robinson, Machinist and Mechanical Technician, built the test stand and readied the prop for testing. Jay Carter, Jr., President and Chief Engineer, headed the overall testing sequence. Bench testing of the prototype began during the first part of January 2003. Testing requirements called for the prototype prop to be bench tested at a tip speed exceeding Mach 1 for a minimum of 10 minutes to prove its strength and durability.

On January 29, 2003, the new prop was tested for the required 10 minutes at 8600 rpm where the tip speed exceeded the speed of sound. Each 4/10 lb blade produced 7400 lbs of centripetal force when the blade tip exceeded Mach. This initial testing also showed that there was a 15% reduction in horsepower required at 7000, rpm when compared to a wood prop currently used on a UAV. Testing will continue. In addition to testing for greater efficiency, Carter will be looking at the noise reduction advantage estimated for their prop.

Jay Carter noted, "This is an extremely important step for Carter. It marks the first time that our patented technology will be focused on a use outside of our own company. We had to develop several different technologies to support our work in gyroplanes. A new, highly efficient, low-cost, lightweight propeller was one of our goals. A unique quality of our propeller design is that it is fully scalable and highly efficient in either a tractor or pusher configuration. Also, with minimal structural, mechanical, static/dynamic, aero-elastic or shape limitations our design allows the prop to be shaped for maximum airflow efficiency."

This announcement suggests that a relatively low-cost, lightweight, retrofitted prop can increase the flight efficiency of a production UAV system by a significant percentage. The new prop features ground-adjustable pitch, low inertia due to its lightweight construction, metal abrasion weather strip on the leading edge, and an ideal planform (large chord at blade root) that improves prop efficiency. If the new Carter prop continues to test as well as it did initially, then every manufacturer of a prop-driven UAV could retrofit this same type of prop.

Carter continued, "To some degree, our propeller technology is an extension of my years spent in engineering wind turbines to garner efficient air movement. It is gratifying that these new propeller tests are beginning to prove our development theories. I believe that our propeller design, when fitted to a specific engine, could improve prop efficiency from 10% – 20% over many other propellers in use today. Plus, our extremely lightweight design provides a high safety factor and with the blade’s flatwise flexibility, gyroscopic loads into the engine and airframe are greatly reduced. This would be a marked improvement for the general aviation industry."

[Hey -- I just got an idea: could your airplane use 10~15% better prop efficiency, quieter running, and possibly lower prop maintenance?]

FMI: www.carteraviationtechnologies.com