Doug Fir vs: Sitka Spruce

You cant increase your speed by 20%...but you CAN DECREASE your useful load
by about 12% (if I have my numbers right). Fir is a little heavier than
Spruce.
Dave...D as in "Duh"...A...V...E
"Lou Parker" wrote in message
om...
Del Rawlins wrote in message
...
On 26 Oct 2003 06:24 PM, Lou Parker posted the following:
Can anyone tell me the truth? When I read articles about the
difference between the two woods, the information says that fir is 23%
stronger than spruce. When I talk to people they say only 10%. Anyone
got a handle on this?

The difference between the two, is that sitka spruce will often forgive
less than perfect technique, while doug fir will split if you so much as
think the wrong thoughts about it. Sometimes even if you don't.
Spruce,
on the other hand, is a joy to work with. A few years ago I turned some
unairworthy citabria spars into parts for a canoe. Still hoarding the
one leftover spar for future use. 8^)

----------------------------------------------------
Del Rawlins-
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/


Does that mean that after building my plane with fir instead of spruce
that I should be able to up my cruise speed, max speed and everything
else by 20%?
Lou

On Thu, 30 Oct 2003 17:17:15 -0500, "D Reid" wrote:

You cant increase your speed by 20%...but you CAN DECREASE your useful load
by about 12% (if I have my numbers right). Fir is a little heavier than
Spruce.

I just finished a new battery box for my Fly Baby. Actually TWO battery
boxes, after the first one (made of oak) got laughed out of my EAA chapter.

(Hey, I do a bit of non-aviation carpentry. I *love* working with oak!)

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

Ron Wanttaja

You cant increase your speed by 20%...but you CAN DECREASE your useful load
by about 12% (if I have my numbers right). Fir is a little heavier than
Spruce.

I just finished a new battery box for my Fly Baby. Actually TWO battery
boxes, after the first one (made of oak) got laughed out of my EAA chapter.

(Hey, I do a bit of non-aviation carpentry. I *love* working with oak!)

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

Ron Wanttaja
++++++++++++++++++++++++++++++

SO?????

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


Barnyard BOb --
If flying is the most fun you can have with your clothes on...
How much fun can flying naked be?

I just finished a new battery box for my Fly Baby. Actually TWO battery
boxes, after the first one (made of oak) got laughed out of my EAA chapter.

(Hey, I do a bit of non-aviation carpentry. I *love* working with oak!)

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

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

Ed Wischmeyer

In article , Ron Wanttaja says...

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....
I really liked the use of Oak tho' it was a nice touch.

Chuck S


I just finished a new battery box for my Fly Baby. Actually TWO battery
boxes, after the first one (made of oak) got laughed out of my EAA chapter.

(Hey, I do a bit of non-aviation carpentry. I *love* working with oak!)

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

Ron Wanttaja

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

In article ,
Ron Wanttaja wrote:

[[.. munch ..[[

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....

Obviously, then, the new box is a son of a beech.

On Tue, 04 Nov 2003 15:49:01 GMT, ()
wrote:

In article ,
Ron Wanttaja wrote:

[[.. munch ..[[

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....

Obviously, then, the new box is a son of a beech.


his old one was a beechcraft battery box :-)
Stealth Pilot

"Ron Wanttaja" wrote in message
...
snippage
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

So is the new box "Son of the beech"?

Tim Ward

From: Ed Wischmeyer
Date: 11/4/2003 6:57 AM Central Standard Time

snip

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

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

Ed Wischmeyer

Ed, you know a bunch of people are going to birch about your comment.

Dan, U. S. Air Force, retired