Bob: I went to the net RE; the discussion about the Tubular spar used as a fuel tank in the American Yankee as designed by Jim Bede, below is what I found.
See the link: http://en.wikipedia.org/wiki/Grumman_American_AA-1 Don Lively Burlington IA -------------------------------------------------------------------------------- >From the Link above---- All models of the AA-1 accommodate two people in side-by-side seating under a sliding canopy and are noted for their exceptionally light handling. The Yankee and its 4-seater siblings, the AA-5 series, feature a unique bonded aluminum honeycomb wing and fuselage that eliminates the need for rivets without sacrificing strength. The wide-track main landing gear struts are laminated fiberglass for shock absorption, and was marketed as the "Face Saver®" design by American Aviation.[1] The Yankee was originally designed to minimize the number of airframe parts used, with the aim of simplifying production and saving money. As a result of this philosophy many parts were interchangeable. Due to the use of a non-tapered tubular spar, which doubled as the fuel tank, and the lack of wing washout, the wings could be exchanged left and right. The fin and horizontal stabilizers were interchangeable, as were the rudder and the elevators. The ailerons and flaps were similarly the same part. While it did succeed in making production easier, this design philosophy produced many aerodynamic compromises in the design. For instance, because the flaps were the same part as the ailerons they were too small to be effective as flaps. The lack of wing washout, necessitated by the wing interchangeability requirement, meant that stall strips had to be installed to produce acceptable stall characteristics for certification. Over time this philosophy of compromising the aerodynamics in favour of a minimized parts count was abandoned. For example, the redesign of the AA-1B into the AA-1C by Gulfstream involved wider-span elevators and horizontal stabilizers that produced better longitudinal stability, but were no longer interchangeable with the rudder and fin. Powered by the same 108 hp Lycoming O-235 engine as the Cessna 152, the original Yankee cruises twenty percent faster thanks to the cleaner wing and better aerodynamics. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- ----- Original Message ----- From: "bob" <b...@wheelerexpress.com> To: "KRnet" <kr...@mylist.net> Sent: Sunday, May 27, 2007 7:07 PM Subject: Re: KR> Rebuilding Wings/tube tanks > Gary Sprunger wrote: > >>Responding to Flesner questioning slosh in tube used fo tank and Ron Wright >>response about the American Yankee >>which used a 6" tube @8' long. >> >>That is correct about the Yankee and also the BD-4. >> >> > The BD-4 does use a 6.8" tubular wing spar, but it doesn't hold any fuel. > I've never heard of anyone changing the original wet wing design to do > so, but it's one of the many fuel tank ideas I've kicked around for the one > I'm building. > > Bob > > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > Post photos, introductions, and For Sale items to > http://www.kr2forum.com/phpBB2/index.php > please see other KRnet info at http://www.krnet.org/info.html >
