September 19th 17, 07:11 PM
On Monday, February 13, 1995 at 11:58:24 AM UTC-5, Stephen Eldredge wrote:
> In article > (Kurt da' Squirt) writes:
> >From: (Kurt da' Squirt)
> >Subject: Douglas fir vs sitka spruce
> >Date: 13 Feb 1995 01:47:49 -0700
> >Keywords: wood
> > I have been thinking a bit about wood planes. And have often
> >heard that douglas fir can be used in place of spruce in certain areas of
> >a plane in order to reduce costs. Just what areas?
> >Spars?
> >fuselage?
>
> According to the FAR's if fir is up to spec it can be used in any area that
> spruce is used.
>
> >Wing ribs?
> >From what I remember, (if that is right) douglas fir of the same
> >dimentions, is heavier, and slightly stornger than spruce.
>
> Fir is about 25% heavier and about 21% stronger than Sitka Spruce.
>
> >I am just wondering in which areas of construction douglas fir could be
> >used, whithout violating some reasonable conventions of safety. And also
> >just how much you would save in money and gain in weight, if you used as
> >much douglas fir as would be resonable. Its just that spruce seems so
>
> Cost savings varies, but if you can find a good deal on fir it can save you
> up to 80%.
>
> Gordon Nichol
> Steve Eldredge
Some years ago, I built a Corben Jr. Ace. Open cockpit, fabric covered sport plane from 1929. I read everything the EAA had on wood and wood substitutions. In the end, I found my local lumber yard had some terrific Doug Fir in long lengths with tight, straight running grain.
I used it for the spars, I ripped it into the 1/4" x 1/4" strips I needed to build the ribs and everything else where Sitka was called for.
The FAA inspector told me it was way better than almost all the Sitka he's seeing these days.
Go ahead and use it.
Brian
Michigan
> In article > (Kurt da' Squirt) writes:
> >From: (Kurt da' Squirt)
> >Subject: Douglas fir vs sitka spruce
> >Date: 13 Feb 1995 01:47:49 -0700
> >Keywords: wood
> > I have been thinking a bit about wood planes. And have often
> >heard that douglas fir can be used in place of spruce in certain areas of
> >a plane in order to reduce costs. Just what areas?
> >Spars?
> >fuselage?
>
> According to the FAR's if fir is up to spec it can be used in any area that
> spruce is used.
>
> >Wing ribs?
> >From what I remember, (if that is right) douglas fir of the same
> >dimentions, is heavier, and slightly stornger than spruce.
>
> Fir is about 25% heavier and about 21% stronger than Sitka Spruce.
>
> >I am just wondering in which areas of construction douglas fir could be
> >used, whithout violating some reasonable conventions of safety. And also
> >just how much you would save in money and gain in weight, if you used as
> >much douglas fir as would be resonable. Its just that spruce seems so
>
> Cost savings varies, but if you can find a good deal on fir it can save you
> up to 80%.
>
> Gordon Nichol
> Steve Eldredge
Some years ago, I built a Corben Jr. Ace. Open cockpit, fabric covered sport plane from 1929. I read everything the EAA had on wood and wood substitutions. In the end, I found my local lumber yard had some terrific Doug Fir in long lengths with tight, straight running grain.
I used it for the spars, I ripped it into the 1/4" x 1/4" strips I needed to build the ribs and everything else where Sitka was called for.
The FAA inspector told me it was way better than almost all the Sitka he's seeing these days.
Go ahead and use it.
Brian
Michigan