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Carter Copters with Slowed Rotor/Compound (SR/C) technology

News International-French

4 Dec 2015

Carter has designed, built, and flown several prototype aircraft to develop and demonstrate their slowed rotor technology.

Their original CarterCopter Technology Demonstrator was the first aircraft to achieve Mu-1. The Personal Air Vehicle incorporates many of the lessons learned during the years of flight testing the CCTD.

At its core, SR/C™ Technology represents the simple yet elegant hybridization of airplanes and rotorcraft through remarkable innovations in engineering design. The extraordinary performance capabilities of this technology (1) have been developed and honed over nearly twenty (20) years, (2) have been independently verified by NASA, the U.S. Army, and the nation’s top Center for Rotorcraft Excellence at the Georgia Institute of Technology, (3) were first demonstrated by the CarterCopter Technology Demonstrator (the "CCTD"), and (4) are being demonstrated by the SR/C™ 4-Place Personal Air Vehicle / Proof-of-Concept demonstrator (the "POC"). While performance testing of the POC remains ongoing – for the purpose of expanding the high-speed envelope – these two prototypes have proven the ability of SR/C™ aircraft to outperform the speed, range, service ceiling, and efficiency of any rotorcraft (or other VTOL aircraft), while retaining their VTOL capability.

Among other things, aircraft incorporating SR/C™ Technology:

  • offer cruise speeds from 100 knots at low altitudes to 450 knots at 40,000 feet;
  • have the ability to operate without runways at low cost, which will revolutionize regional civilian air transportation;
  • are the only aircraft capable of transporting large payloads over long ranges to sites requiring VTOL, where local fuel is either very expensive or unavailable; and
  • are inherently safe and capable of flight even if all electronic systems fail, and, in the event of fuel exhaustion, normal landings remain possible.

In no uncertain terms, this game-changing technology is fully capable – and on the brink – of emerging and taking hold in both the fixed-wing aircraft and helicopter markets.

As SR/C™ Technology pertains to the fixed-wing aircraft market:
SR/C™ aircraft are essentially fixed-wing aircraft; the difference being that SR/C™ aircraft utilize a very simple rotor as an extremely efficient high-lift device for vertical through intermediate-speed flight. As speed increases, more and more of the weight of the aircraft is transferred from the rotor to the wing. At cruise speed, the rotor is slowed to the slowest safe rpm to decrease the rotational drag. During high-speed flight, we are able to make the rotor all but disappear (from a drag standpoint) by slowing it down. In order to do this, Carter Aviation has identified and overcome no less than ten (10) technical issues – each of which has to be addressed before the rotor can be safely slowed and advance ratios (Mu) of 0.75 – and well beyond – can be achieved. These innovations comprise a significant portion of our patent portfolio.

Since the wing of an SR/C™ aircraft is sized for efficient cruise, the wing area can be much smaller than that of a comparably-sized fixed-wing aircraft. The result is substantially increased efficiency, range, speed, and service ceiling (conservatively up to 25,000 feet, and more like 35,000 feet, with the current prototype and up to 45,000 feet with a follow-on SR/C™ 6-9 Place Business Aircraft).

Thus, incorporation of SR/C™ Technology affords aircraft the ability to retain the speed, range and efficiency of a fixed-wing aircraft, but with the added benefit of VTOL.

As SR/C™ Technology pertains to the helicopter market:
SR/C™ aircraft are fully capable of satisfying the requirements of the vast majority of helicopter missions, without the added cost, complexity and weight inextricably intertwined with systems having full hover capability, e.g., heavy gearbox, complicated heavy rotor-head / swash plate system and counter-torque device. This is because the extreme inertia that can be stored in the rotor allows SR/C™ aircraft to hover for approximately ten seconds based on the maximum in flight rpm and fifteen seconds based on maximum takeoff rpm. (By using stored rotor inertia to drive the rotor, the need to counter the torque associated with extended hover is eliminated.)

Landing Gear Capabilities
Put into the context of offshore operations, the ability to hover for ten seconds will allow SR/C™ aircraft to make safe approaches / landings on oil rigs and ships. The ability to land on floating structures is further facilitated by Carter Aviation’s patented lightweight extreme energy absorbing landing gear. The configuration used on our current prototype is capable of absorbing a twenty feet per second landing. On the right is a video containing footage showcasing the capabilities of Carter Aviation’s landing gear system. With minor exception (such as search-and-rescue and logging operations), SR/C™ aircraft are well-suited to serve the market currently served by conventional helicopters. SR/C™ aircraft with limited hover are even more appealing because of the fact that they can be lighter and have more than twice the speed and three times the range of a comparably-sized conventional helicopter.

And, minor modifications (e.g., the addition of a small efficient wing, horizontal stabilizer and propeller – the use of twin propellers would eliminate the need for a tail rotor altogether) to helicopter designs will permit the retention of full hover capability, but with the added benefit of efficiencies and speeds approaching those of fixed-wing aircraft.

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