Spar Dimensions for J-3 and/or Aeronca Champ

[Ron Wanttaja]

We've got some Fly Baby builders who are considering building the Hevle
Classic tandem Fly Baby. We're trying to work out what would be a good
thickness for the spruce spar. My thought was that comparing it to that of
a production plane would be a good start.

So, can anyone tell me the thickness, height, and length of the wooden
spars for the J-3 and the Aeronca Champ?

Ron Wanttaja
www.BowersFlyBaby.com

[jls]

"Ron Wanttaja" > wrote in message
...
> We've got some Fly Baby builders who are considering building the Hevle
> Classic tandem Fly Baby. We're trying to work out what would be a good
> thickness for the spruce spar. My thought was that comparing it to that
of
> a production plane would be a good start.
>
> So, can anyone tell me the thickness, height, and length of the wooden
> spars for the J-3 and the Aeronca Champ?
>
> Ron Wanttaja
> www.BowersFlyBaby.com



Ron, the wood spar dimensions for the BC12D model Taylorcraft are as
follows:

The front spruce spar measures ¾ inch thick by 5-11/16 inches tall

The rear spruce spar is 5/8 inch thick and 4-3/8 inches tall.

So far, no AD's on the Taylorcraft's spars, knock on wood.

For wood specifications Grain, knots and moisture content refer to following
FAA website

To look in the Advisory Circular 43.13 found at:

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular
..nsf/0/CCFE0D58D41D2C8086256A55006C6B67?OpenDocument&Highlight=wood

[Ron Wanttaja]

On Mon, 22 Mar 2004 08:02:25 -0500, " jls" > wrote:


>Ron, the wood spar dimensions for the BC12D model Taylorcraft are as
>follows:
>
>The front spruce spar measures ¾ inch thick by 5-11/16 inches tall
>
>The rear spruce spar is 5/8 inch thick and 4-3/8 inches tall.

Thanks much, this helps. The single-seat Fly Baby spars are almost exactly
the same, except the aft spar is 3/4" like the front. No one is sure how
much margin is in the spar itself, though an entire wing was static-tested
to 6Gs in Finland. The gross for the two-seat Fly Baby is about 500 lbs
higher; the need to upgrade the bracing wires was obvious, but the issue
about the spar thickness wasn't.

Thanks again....

Ron Wanttaja