Virtually the entire structure of The 1929 Hamilton H-47 is covered in corrugated sheet metal, a texture more commonly seen as a part of a building than part of an airplane. Photo by Mariano Rosales

A number of new construction techniques came into vogue as airplane designs evolved from fabric-covered frames into more durable metal structures.

One example of an interesting technique is the 1929 Hamilton H-47 that came to EAA AirVenture Oshkosh 2010. Virtually the entire structure of the craft is covered in corrugated sheet metal, a texture more commonly seen as a part of a building than part of an airplane.

Corrugation provided strength and stiffness qualities different from a flat sheet of metal, and the Hamilton Metalplane Company of Milwaukee, Wisconsin, constructed 29 examples of the H-47 using the unique skins.

Now owned by Pole Pass Airways of Orcas Island, Washington, the Hamilton here is the only remaining flying example of the type. It is making its first AirVenture appearance since 1975, when it won Vintage Reserve Grand Champion.

Although now outfitted in Northwest Airways livery, this particular airplane originally was delivered to the provincial government of Ontario, Canada.

Immediately mated to a pair of EDO YC-6400 floats, the craft flew exclusively off water until it moved to a private owner in Alaska. Northwest did own and fly H-47s, just not this particular one.

As many airplanes that finish their working career do, it fell into disrepair. A group of Northwest Airlines pilots recovered it from Alaska, bought it to Minnesota, and began restoration. Ultimately Jack Lysdale at Fleming Field in South St. Paul completed the project.

The plane flew very little after its award-winning Oshkosh visit. It was, however, impeccably maintained-including continuous annual condition inspections-and was always hangared.

Only a bit of carburetor and fuel line cleaning and a replacement set of brakes were required before taking to the air this past Sunday.
Plans are to put the plane back on the water. The original EDO floats were located in Fairbanks, Alaska, and are currently under restoration, with an expectation of water operations in the spring of 2011.

The airplane flies well behind its 525-hp Pratt & Whitney Hornet engine, according to the Pole Pass pilot that brought it here.

Expectations were that the hard-mounted powerplant would create a lot of vibration, but that does not seem to be the case.

It is, however, very noisy inside.

As is the case with any one-of-a-kind flying artifact, much remains to be learned about power settings, speeds, and other flight characteristics. Opportunities to practice landings came at several airports along the route from Minnesota to Oshkosh.

Once it leaves Oshkosh the H-47 will travel to California, before making its way to its new home in Washington state.