Saturday, February 10, 2007

Aircraft Icing and the Researchers of the Icing Branch at NASA Glenn Research Center

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It's the season for icing here in the midwest. As some instrument-rated and other pilots can tell you, few things have higher pucker factor than looking out at your wings while you're in the clouds and seeing ice begin to form. Most general aviation aircraft don't have de-icing equipment on board and even those that do often aren't certified for flight into known icing conditions.

For most GA pilots, that means avoiding icing in the first place - and that requires the development and use of the most effective anti-icing tool you have. Your noggin.

Few are more qualified to provide authoritative information about icing than the professionals on the Icing Team and in the Flight Operations team at NASA Glenn Research Center in Cleveland, Ohio. We had the opportunity recently to talk to NASA Glenn pilots Kurt Blankenship and Bill Rieke and researcher Dr. Judy Van Zante, a contractor with ASRC Aerospace.

Bill Rieke is chief of aircraft operations at the NASA Glenn. He began his flying career with the U. S. Navy in 1966 and flew with Fighter Squadron 74 aboard the USS Forrestal and later flew tactical aircraft with the U. S. Air Force (Air National Guard). He also flew as a captain for the Standard Oil Company before joining NASA. He has flown research and test missions for NASA since 1981.

During his time at NASA he has been the lead project pilot for numerous projects ranging from zero-gravity flight to advanced cockpit technology for the U. S. Air Force. He has also been deeply involved in airborne icing research since 1982.

Bill has an airline transport certificate, five type ratings and 12,000 hours of flight time. His military flight experience was almost exclusively in tactical jet aircraft.

Kurt Blankenship is an NASA Icing Research Tunnel Operator, NASA Glenn Research Center Pilot and the Center’s Aviation Safety Officer. He served in the United States Marine Corps as a CH-53 Helicopter Crew Chief from 1981 to 1985 and then worked for Continental Air Lines as a mechanic. He then attended Bowling Green State University and was a flight instructor and director of maintenance for the school’s flight department during that time. He was a corporate pilot and mechanic from 1990 to 1994 and has been with NASA Glenn since 1994. He holds commercial, flight instructor, and airline transport pilot certificates and, in addition to flying NASA Glenn’s icing research aircraft, he is type rated in Learjets and has over 1,000 hours of flight research time.

Judy Van Zante is a researcher and project lead for the pilot training aids at NASA Glenn and has also done flight test engineering. She holds a Ph.D. in Aerospace Engineering. She flew on the icing research aircraft and did substantial other research as part of the NASA/FAA Tailplane Icing Program.

NASA Glenn's icing research aircraft is a modified DeHavilland DHC-6 Twin Otter. It is powered by two 550 hp Pratt & Whitney PT6A-20A turbine engines that drive three-bladed Hartzel constant speed propellers. Its relatively large size makes this aircraft a versatile test bed for in-flight icing research reaching speeds of 150 knots with a range of 500 nautical miles with a maximum fuel load. The Twin Otter has been modified to carry a full complement of sophisticated instruments that measure and record important properties of icing clouds. A stereoscopic camera system documents ice accretion characteristics of the aircraft in flight.

Most test flights are conducted below 10,000 ft., but the Otter has an oxygen system onboard for flight up to 16,000 ft. Research flights are performed with two pilots and up to three research personnel on-board. The ice protection system on the Otter is a combination of pneumatic boots, electrothermal anti-icing, and electrothermal de-icing. NASA has added pneumatic de-icing boots to the vertical tail, wing struts, and main gear struts. The high level of ice protection allows safe flight into known icing conditions, as well as the ability to selectively de-ice aircraft surfaces. By selectively de-icing, it is possible to evaluate the performance, stability, and control effects of ice on various surfaces. The Twin Otter supports the Icing Research Tunnel research and new icing protection systems. It has two experimental sites, the overhead hatch and the wing cuff, that subject test models to the icing environment while the aircraft remains clear of ice through de-icing. This aircraft is currently being used to acquire extensive experimental data about icing effects on aircraft flight. The aircraft has been used for, and is adaptable to other flight research projects.

Those who aren't pilots or who haven't undertaken instrument training might be a little mystified by some of the terminology that you're about to hear, so here's a quick glossary.

MEA: Minimum Enroute Altitude ( or "MEA") is the recommended minimum altitude that an aircraft should fly on a segment of an airway in instrument meteorological conditions. Flying at or above the MEA ensures clearance from terrain and obstacles, ensures reception of signals from ground-based navigation aids and, in a radar environment, makes it so that relevant air traffic controlfacilities can see the aircraft on radar.

Pirep: A pilot report. It is a report of weather conditions given by a pilot of an aircraft that is aloft. Pireps for turbulence, icing, and visibility are considered particularly valuable pireps.

STC: A supplemental type certificate. Aircraft that have type certificates (such as most production airplanes) must conform to the specifications in their type certificates or be registered as experimental or not flown. You can't mess much with an aircraft without losing the type certificate. An STC issued by the FAA permits the owner of an aircraft to make the covered modifications while maintaining the aircraft's type certificate. Frequent subjects of STCs are engine modifications and de-icing systems. There are also several STCs that allow installation of ballistic recovery parachutes in various production aircraft.

So on to the interview with NASA Glenn pilots Kurt Blankenship and Bill Rieke and researcher Dr. Judy Van Zante.

[Interview audio.]

Thanks to Bill Rieke, Kurt Blankenship, and Judy Van Zante and thanks to NASA Glenn Research Center in Cleveland, Ohio!

With all this talk of icing, it might be easy to forget that NASA Glenn does a lot more than icing research. Space exploration systems, microgravity science, bioscience, aeronautic propulsion, instrumentation, and turbomachinery all form a part of the program at NASA Glenn. For example, many shuttle and space station science missions have an experiment managed by Glenn. The Center also designs power and propulsion systems for space flight systems in support of NASA programs such as the International Space Station, Mars Pathfinder, and Deep Space 1. Glenn also leads NASA' Space Communications Program which included the operation of the ACTS satellite and systems for Cassini. The general public benefits from NASA's investment in the future through the knowledge gained, the inspiration provided and often technology dividends. NASA Glenn has won many awards including an Emmy, a Collier Trophy, and the 1996 Invention of the Year.

Thanks also to Dave Schwartz, an Otter pilot and one of the hosts of Skydive Radio for his contrinbution of background information about flying Otters. You can hear Dave, Stump, and Cory on Skydive Radio by subscribing through your favorite podcatcher or visiting Skydive Radio's website at

More information about the Icing Branch of NASA Glenn Research Center:

More information about Kurt Blankenship:

More information about Judy Van Zante:

NASA print resources:

Information about the icing videos: or

Information about the Otter:

Image address:

Image used per NASA's policy entitled Using NASA Imagery and Linking to NASA Web Sites (October 13, 2005) located at

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