I wrote:
FWIW, the poplar one weighed 1.25 pounds. The nearly-identical oak one
weighed a half-pound more... a 40% weight penalty.

[Answering three responses to this message]

On Tue, 04 Nov 2003 05:53:13 -0600, Bob U. wrote:

SO?????

Won't your Fly Baby carry a half-pound?
If not, fly barefoot and save 300% or more. g

Ah, BOb, it's one of them engineering things. Like to get things as
efficient as I can.

However, I did provide the worst-case view of the actual numbers. The
half-pound difference above was just for the wood that went into the basic
structure of the new battery box. By the time the removable bottom,
various anchor nuts, aluminum mounting flanges, mounting bolts, etc. were
factored in, the difference wasn't as strong. With poplar as the basic
structure, the all-up, ready-to-use box weighed 2.5 pounds. So if I'd used
the oak, the penalty would have really been only 20%.

The box I replaced (the old box was for a standard aircraft battery, the
new one was for an Odyssey drycell) weighed five pounds. So even with oak,
I would have had a 2-pound savings.

FWIW, here's the numbers for my conversion from a Gill G-25 to the Odyssey
PC680:

Battery:
Gill G-25: 20 lbs
Odyssey: 14 lbs, including metal case
Battery Box:
For Gill: 5 lbs
For Odyssey: 2.5 lbs

Total weight savings was 8.5 pounds...less than I expected, because I had
anticipated the Gill battery was heavier. Still, the weight saving was a
secondary reason for the conversion. The old battery box and the large
battery only allowed access from above, and a box containing most of my
avionics actually mounted atop the battery. This meant that I had to
disassemble my electrical system *live* to access the battery far enough to
disconnect the cables. Ron didn't like that.

New, flatter battery is mounted on its side, accessible (and
disconnectible!) from below the aircraft. To get access to it, I cut a
1'x3' hole in the belly fabric and install an access panel. But then, I
had to do fabric work anyway because I had to glue down the loose edges of
the fabric on the rudder when I cut away the gaps seals to remove it to fix
the dry rot in the tailpost, which I discovered when I started to install a
modified tailwheel spring support bracket.

Let's just say I've had a busy two months.

On Tue, 04 Nov 2003 05:57:32 -0700, Ed Wischmeyer
wrote:

]I'd have thought you'd use spruce, it's even more poplar... :-)
]
]Ed Wischmeyer

Poplar was oakay fir my purposes. Besides, they don't sell spruce at Home
Depot Aerospace. :-)

Chuck S. posted:
}I kinda like either Black Walnut or Balsa :-) But I also think the
}subtle hues of Cherry can blend into a harmony of tones that are a
}feast to the senses....

Last year, I noticed that my wing "arrows" (wooden dowels tied to the wing
bracing wires to damp vibration) were a bit dry-looking and needed
revarnishing. I have a ton of stuff from various wood projects sitting
around, so I used some cherry stain on the arrows before varnishing them.
I like the effect, but it gets a few strange looks at fly-ins....

Actually, a buddy of mine says my old box was made out of Beech. Ed will
probably get a lot of mileage out of that one....

Ron Wanttaja