Lightning Protection of Revolving Aircraft Turrets
Summary:
Honeybee Robotics (New York, NY) has developed a hardware solution that eliminates the need for conductive slip rings or brushes in rotating equipment, using instead an assembly of spoked wheel-like rings to transfer current efficiently into or out of rotating machines. MDA funded the company with a Phase II SBIR award to develop a lightning protection system for the revolving nose turret in the Airborne Laser (ABL) program. The hardware being developed under the project ultimately should find new applications in mechanisms for boat radars, printing presses, and other industrial machinery.
Technology Description:
Honeybee's technology uses spoked, wheel-like rings made of beryllium copper (BeCu) spring material. The rings sit slightly compressed between two larger rings in an assembled mechanism. The assembly resembles a planetary-gear arrangement, in which smaller planet gears rotate around a central sun gear.
Electricity passes from the outer ring, through the BeCu wheels, and into the inner ring, delivering power to a rotating machine. As one ring turns inside the other, the BeCu wheels roll along between them and, due to the spring compression, are constantly in contact with both the inner and outer rings.
The design offers a cleaner and more reliable solution than brushes and slip rings, according to Honeybee. The ring design does not result in particle generation or other significant debris. Additionally, the approach eliminates concerns over significant wear, since the lack of serious friction means that the rings involved in this mechanism should last longer than brushes and slip rings. The rolling motion of the wheels also means that the devices using them could operate more quietly and also generate less electrical noise.
The spoked-wheel/planetary-gear-like arrangement of the wheels and rotating rings offers versatility. Wires or rods could be used in the hubs of the spoked wheels to control their positions and keep them from straying when using many wheels or multiple layers of wheels and rotating rings. Moreover, engineers could tune the dimensions and shapes of the spokes as well as the thickness of the wheel surface, effectively controlling the stiffness of the wheel as needed for the task at hand. By adding spokes and leaving the wall thin, an engineer could increase stiffness without adding stress to the ring system. Spokes also could act as a current-carrying path, theoretically cutting in half the resistance in the wheels.
The design of the wheels also can provide a higher current-carrying capability than might be achieved with brushes and slip rings. The wheels can be compressed to a greater degree to increase surface contact area between them and the rings. The increased contact area of the surfaces should translate directly into high current-carrying capability.
MDA Origins:
MDA funded the company with a Phase II SBIR award to develop a lightning protection system for the revolving nose turret in the Airborne Laser (ABL) program. The ABL project will put a movable high-power laser on the nose of an airplane, allowing the plane to strike at missiles from the air. Honeybee envisions its wheels embedded in the turret, allowing the turret to channel a sudden electrical surge and avoid damage to equipment in the nose due to lightning striking the aircraft.
Honeybee's proposed rotary lightning-protection system (RLPS) for the ABL combines the existing metal mesh/coating approach to lightning-strike mitigation with a rotary-band contact (RBC) concept to provide a ground path for rotating composite structures. The RLPS design would not only protect the mechanisms that produce the required rotary motion but would also protect any sensitive equipment within the ABL by providing a direct exterior path away from the rotating member directly to ground. Honeybee plans to design a lightweight system compatible with nose-mounted ball turrets such as the one employed by the ABL Boeing 747-400.
Spinoff Applications:
The Honeybee technology applies to mechanisms that involve rotary motion and require electricity. Such mechanisms could include boat radars, industrial power washers, and printing presses, as well as other industrial machinery. The company continues to seek help discovering new applications for the technology.
The Honeybee solution would be appropriate for applications in which dust/debris, wear, and noise are concerns. Slip rings and carbon brushes in rotating equipment can generally produce abundant dust, noise, and wear. Moreover, in operation, electrical and acoustical noise associated with slip rings can be significant.
For boating applications, the company has envisioned a handful of appropriate uses that would require the ability to handle 100 amps of 12 volts. Honeybee's ring assembly could offer a solution—especially for users who want to mount such a wear-resistant device on a hard-to-reach mast and who take no pleasure in replacing or repairing slip-ring/brush assemblies atop a mast. In such applications, the company has considered reducing development costs by integrating its hardware perhaps with some of the existing hardware atop a mast or similar construction—thereby reducing complexity, cost, and bulk of the overall structure.
Commercialization:
Honeybee continues to face a challenge in determining its commercial strategy for this technology. The company has been working on a commercial version of the technology for a customer interested in improving the performance of a power sprayer that would normally require a slip ring. The customer will test Honeybee's offering and could place hundreds of orders with Honeybee if the product shows promise.
More broadly, Honeybee is leaning toward using licensing agreements to commercialize the technology but has not ruled out producing hardware in volume on its own. Honeybee has patents on a related technology and has a patent pending on its current MDA-funded design. The company definitely sees commercial potential for its new ring technology, especially given the pervasiveness of slip-ring use today.
Company Profile:
Located in West Midtown Manhattan in New York City, Honeybee Robotics creates robots, flight subsystems, automated drills, custom micro-actuators, piezoelectric transmissions, and other machines for use on Earth, Mars, and beyond. Founded in 1983 as a systems integrator using off-the-shelf robots, the company has gained a reputation for its design skills and creative problem solving. Honeybee received its first NASA contract in 1986 and has subsequently worked on more than 90 others, in addition to completing projects for the Department of Defense and companies such as Coca Cola, Con Edison, 3M, Nike, and IBM.
The company initially started working in the commercial sector, but most of its work today is in the government realm. The company designed and built one of the instruments that was included by NASA on the Mars planetary rovers—a rock abrasion tool (RAT).
Honeybee is a privately held company that is headquartered in New York City. It is a NASA-approved provider of space flight hardware. Owners include Steve Gorvan and Chris Chapman. The company has 50 employees.
Contact Information:
Mr. Jeff Feddersen
Honeybee Robotics
460 West 34th Street
New York, NY 100101
Tel: (646) 459-7836
Fax: (646) 4597898
web: www.honeybeerobotics.com
email: feddersen@honeybeerobotics.com
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