If someone is looking for STRONG fiberglass booms .. try your local High
School track coach .. ask him if he has any old or broken pole-vaulting
poles that he would like to get rid of ... tell him you'll make a modest
donation toward his program. If he has pieces, they are usually in 6 to
8-foot lengths .. sometimes 10-foot long. You will have to clean-cut
the ends and check the poles for linear splitting. They make GREAT
tower stand-offs for holding wire antennas away from the tower.
He might even have some old 'Swedish steel' pole-vault poles from the
'pre-fiberglass' era .. those are fantastic ! .. usually available in
12, 13, 14, and 15-foot lengths!!!
Randy Williamson wrote:
> Solid is not stronger than hollow as it was explained to me its about
> surface area. What would be interesting is carbon fiber and epoxy resin
> over a round mold.
> -----Original Message-----
> From: firstname.lastname@example.org
> [mailto:email@example.com] On Behalf Of Don Havlicek
> Sent: Thursday, February 28, 2002 6:50 AM
> To: WB9UWA Jim Shaffer
> Cc: firstname.lastname@example.org
> Subject: Re: [Towertalk] Strength of fiberglass.
> Solid fiberglass rod is HEAVY .. much heavier than the same
> length/diameter of aluminum.
> WB9UWA Jim Shaffer wrote:
> > Hi All,
> > I am designing a VHF yagi array and strongly considering using
> > for the booms. Does anyone have a strength rating for fiberglass that
> > useful
> > to the layman? For example, if 10 feet of 1/2" solid rod fiberglass
> is held
> > horizontal,
> > how many pounds of weight would cause the end of the rod to deflect 1
> > (stiffness rating)?
> > Also, and probably of greater importance, because even PVC can be
> > if done properly, how much weight at the end of this pole does it take
> > cause
> > catastropic failure of the fiberglass (yeild strength)? I have heard
> > of fiberglass antennas
> > bending way over in the wind and recovering fully. This is the sort of
> > windload
> > design I have in mind. I have some industry standard numbers for
> > but they
> > are not something that I can make sense of. The strength rating is
> > like 30,000 PSI.
> > 73, Jim Shaffer, WB9UWA.
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