The American Helicopter Museum (AHS), though not one of the biggest aerospace museums I've ever visited, is none the less worth a trip to learn about the history of rotory wing flight in the U.S. I've been to the museum several times (its not too far from where I live) in the Philadelphia suburb of West Chester, PA, and it has a nice collection, both indoor and outdoor, of rotorcraft on display. This seems to be an appropriate location for what I believe is the largest helicopter-only museum in the U.S. That's because some very significant early development of rotory wing flight took place in the Philadelphia area. This included the work of Harold Pitcairn, who developed and built several autogyro designs in the 1930s, and Frank Piasecki, the inventor of the first successful tandem rotor helicopter in the 1940s and 50s. (See my previous blog entry on the passing of Piasecki.) Today there are still a number of helicopter companies in the area, including Boeing Helicopter, AugustaWestland USA, Keystone Helicopters, Piasecki Aerospace and Carson Helicopters.  In fact, many of the volunteers at the museum who help in restoration and education activities are retirees from some of these companies. You can see the enthusiasm in their eyes as they recall their personal involvement in the design or manufacture of a particular helicopter model in the museum collection during a guided tour. Besides the interesting rotorcraft such as the prototype Bell/Boeing tiltrotor V-22, Pitcairn PC-1A autogyro, and Bell 47 (better known as the bubble cockpit helicopter seen delivering casualties in the tv show "MASH") the AHS has some nice educational displays and hands-on exhibits for kids.

The AHS is located at the Brandywine airport, so if you are a pilot you can fly in and walk right to the facility. Being on an airport also allows the AHS to hold an annual helicopter-only airshow, called Rotorfest, usually in October. The show features civilian and military flight demonstrations, and helicopter rides are provided to the general public for a fee. Though you won't see the flashy aerobatic displays or high speed flybys of military jets at Rotorfest, it is fun to watch the various helicopters display there unique capability to hover, fly sideways and backwards, and demonstrate rescue techniques that no other aircraft can perform.

I have a personal connection to one of the most unique items at AHS, the third prototype Bell Boeing V-22 Osprey tiltrotor. The prototypes ware assembled and first flown at the Boeing facility south of Philadelphia in the late 1980s, and I was an escape systems engineer with the U.S. Navy at the time. Since the V-22 was going to be the largest tiltrotor design ever flown, there were a lot of unknowns about the flight characteristics. So the military and civilian test pilots assigned to the program requested the the first prototype V-22s have ejection seats for the early part of the flight test program. As an ejection seat engineer, I was part of the government/Boeing team tasked to investigate installing an escape system in the first V-22 prototypes. Typically a helicopter can't have ejection seats because of that large, rotating blade right above the cockpit that would make mince meat of anyone who tried to eject upwards. However, with the V-22, the two large propellers/rotors that provide lift and/or forward thrust, depending on how they are positioned, are located outboard on the ends of the V-22 wings. Even in the hover mode, the "disc" created by the spinning props were outboard just enough to let the pilot and copilot eject straight up. That's of course if the V-22 was in a normal level hover at the time of ejection and wasn't doing any wild gyrations. We ran ejection seat computer trajectory simulations that showed if the titltrotor had any type of roll rate at the time of ejection, then there was a good chance the seat with the crew would hit one of the rotating blades. We showed these sims to the test pilots, but they still wanted ejection seats, so we finally tested and qualified a version of the Martin-Baker SJU-5 ejection seat, which was in the Navy F-18s at that time. Even though there were some tragic crashes of V-22s later in the development program, the early prototypes never encountered any major problems, so fortunately the test pilots never had to use the ejections seats. You can still see the Martin-Baker seats (the seats are disarmed, of course) in the prototype V-22 on outdoor display at AHS.