April Tests In Olney, TX, Called A Success

Over the last several days, Jay Carter's wild band of innovators relaunched the Carter Copter Technology Demonstrator into the air with a new rotor blade and other significant changes. So far, the tests seem entirely successful, and Carter engineers are poring over the test data to see what comes next.

"We're gonna tweak it... it may go faster!" Chief Test Pilot Larry Neal promised Aero-News. Faster, he meant, than the previous rotor. And faster, already, than any other gyroplane flying.

The advanced compound gyroplane flew in January and February at speeds up to 163 mph, before being returned to the plant for work that included a new rotor, shielded flight computer, and other systems.

The rotor is the soul of any rotorcraft, even one that is meant to fly on its wings at high speed, and the newest Carter rotor incorporates a batch of new ideas. It is longer than the previous one, and it is easily distinguished visually by its integral "spinner" or "hub fairing." Less visible to the naked eye, but of benefit to the durability of the new rotor, the hub also features integral droop stops. Underneath the fairing, the new design of rotor has also allowed elimination of the stabilizer bar used on previous versions.

The rotor is constructed of advanced composites with a carbon fiber spar, as is normal for Carter rotors.

The fairing is not a styling feature; it's meant to help cure a specific drag problem with the CCTD as the test program explores ever-higher speeds. While this is the first time the fairing has ever had physical existence, it's interesting to see that the earliest design renderings of the CCTD that appeared on the Net in the 1990s included such a feature. Sometimes life takes a while to imitate art, perhaps.

Larry Neal praises the new rotor, "Smoother than ever!" and notes that they are flying consistently at higher Mu values. Mu is the ratio of reverse flow to forward flow on the retreating blade: the long-pursued goal for the CCTD is to achieve a Mu of greater than 1.0, which is literally impossible in conventional rotorcraft, and has been called "the Mu 1 barrier."

In February with the old rotor they were maxing out in the Mu 0.8 neighborhood, familiar territory for the CCTD. The Carter engineers are confident that the new rotor will bring the program to a Mu of 1.3. Larry did not quote specific Mu values; the engineers are still reducing and reviewing the data.

There are some other changes -- the machine's a bit heavier, but better balanced (no more great wad of ballast in the nose), the ballistic chute is improved, and the flight control computer has been shielded against interference. Between the Feb. flights and these April flights they also made two mods to try to resolve a yaw condition that was cropping up at high speed (160mph) back in February. There is no word yet on whether the modifications, a reduction in rudder area along the trailing edge, and pilot-controlled rudder locking, somewhat like the tailwheel locking on large taildraggers, have solved the uncommanded-yaw problem.

One improvement in the 2005 iteration of the CCTD, which was already in place for the January and February flights, is in the propeller.  It's got the same GM crate motor putting out 350/380 HP, but the new propeller has made a real difference. The prop is putting out 1850 lbs thrust vice 1400 on the last one, which is a pretty significant improvement. The Carter scimitar propeller is one of the most revolutionary parts of this unconventional aircraft, combining the rigidity of carbon fiber with a variable-pitch mechanism that works by applying torsion to the propeller's spar.

With test pilots Larry Neal and Brad King away at sport aviation events for the next several weeks, the engineers and technicians have time to tinker with the CCTD. And the Mu-1 Barrier and the history books will be waiting when they get back.

Aero-News thanks Carter Aviation Technologies for the use of their copyrighted photos in this article.

FMI: www.carteraviationtechnologies.com