Cadets seek to improve combat airdrops

Published March 4, 2010
By John Van Winkle
U.S. Air Force Academy Public Affairs

U.S. AIR FORCE ACADEMY, Colo. -- Aeronautical and systems engineering management cadets from the Air Force Academy's Department of Aeronautics are working to improve the safety and accuracy of combat airdrops with remotely piloted aircraft.

In 2009, U.S. Air Forces Central identified an urgent operational need for a true single-pass airdrop capability for C-17 Globemaster III and C-130 Hercules aircraft. Air Mobility Command has articulated a similar requirement. An essential part of that capability is collecting near-real-time wind data to compute accurate airdrop release points that account for wind drift.

Learning of the need, the Department of Aeronautics redirected its aircraft design courses with just a few days' notice to seek real world solutions using an RPA.

"We've been treating the aircraft design classes like a miniature RAND corporation for about a dozen years now, doing real work for real Department of Defense and NASA customers," said aircraft design instructor Dr. Billy Crisler. "By expecting second-lieutenant level work from the cadets in real world projects, we give them valuable experience in the same way 'Top Gun' school works for fighter pilots."

While much of the work is done in the Aeronautics labs and classrooms, Dr. Crisler brought his cadets to the 731st Airlift Squadron here Feb. 9 to see firsthand the challenges of dropping cargo to friendly ground units in contested or denied territory and in mountainous terrain. The 731st AS visit showcased the Joint Precision Air Drop System, or JPADS, which exploits autonomous GPS-aided guidance and a steerable parafoil instead of a conventional unguided parachute to provide extra stand-off range and enhance precision.

JPADS data can also greatly improve accuracy for conventional, unguided airdrops that use the long-serving Container Delivery System, or CDS. These Improved CDS, or I-CDS, drops exploit wind data collected and used by the JPADS system, and they're so effective that they can be used for almost all airdrops that don't require extreme precision or standoff drop points. They also cost much less.

A key component of any precision airdrop is releasing a dropsonde over the drop zone to collect near-real-time wind data. The size of a sports drink bottle, the dropsonde collects wind drift data and transmits it back to the aircraft so the aircrew can compute the ideal drop point. Precision is critical in denied or contested territory or mountainous terrain: putting the cargo as close to the intended drop point as possible minimizes the risk to friendly ground forces, prevents damage to the cargo and denies misdirected cargo to enemy forces.

But there's a drawback to using the dropsonde for I-CDS drops, said Cadet 1st Class Cheng Tay, an aeronautical engineering major and international exchange cadet from Singapore.

"Now (aircraft) have to make a pass over the drop zone to deploy the dropsonde and return over that site to actually drop their cargo. That second pass increases the risk of getting shot at, so we're trying to mitigate that risk with an unmanned aerial vehicle," Cadet Tay said.

Alternatives to dropsondes include new modes for the radar in the plane or adding another radar. A stopgap alternative is to fly lower, using wind forecasts instead of near-real-time wind data. Neither alternative is attractive: developing the radar is feasible but will take time and money, and flying lower makes the airlifter a prime target for small-arms fire.

"It reminds me of the B-29 raids on Japan during World War II," Dr. Crisler said. "They fly too high and they lose accuracy. They fly to low and they get toasted. Not much has changed over the years."

The cadets hope to change that age-old equation by using an RPA to fly ahead of the airlifter and deploy the dropsonde while the airlifter is still approaching the drop zone. This would provide a true one-pass capability.

"We have two teams looking at small and medium (RPAs), and two teams looking at large (RPAs) and rockets as a method of deploying the dropsonde," Cadet Tay said.

The cadets will wrap up their design and trade studies by the end of this semester. If their work suggests that an RPA solution is feasible, future work will examine a specific RPA and re-packaged dropsondes to meet this need. Dr. Steve Brandt, the Aircraft Design Course director, said he hopes that the cadets can make an immediate impact.

"If the cadets find a solution that's approximated by an existing RPA, it would be fairly easy to demonstrate this capability," Dr. Brandt said. "We can modify an existing RPA faster and cheaper than creating a new one from scratch, but we can help find the answer, no matter which way it needs to go."

Department of Aeronautics capstone aircraft design classes and research projects have contributed to several other DOD development programs, including a project initiated by the Operational Test and Evaluation Center as well as projects for the Air Force Aeronautical Systems Center, Air Force Special Operations Command and the Air Force Research Laboratory's Air Vehicles and Weapons directorates.

Cadets seek method to improve combat airdrops