Hi Patrick,
No I don't think that I misunderstood your meaning but maybe you
misunderstood mine. :>)
The old rumor about aerodynamic engineers claiming that the bumble bee
shouldn't be able to fly, is just that- a rumor. No aerodynamic engineer
with any credibility ever made that claim that I know of. But I don't doubt
that some not so well informed people many years ago started that rumor and
it has persisted to this day and some people still hang their hat on that as
an indication that "science is not always right".
As far as no towers falling down because of aluminum imbedded into concrete,
I don't know about that.
But I can tell you that I don't have any elephant repellant around my house
and I have never been attacked by one so it must be working.
"Fact trumps theory" is another good one. The answer to that is if fact and
theory do not agree then one of them is wrong.
I don't know of any aluminum towers with their legs planted in concrete but
then I haven't necessarily seen everything.
I did work for Motorola for a few years issuing sub contracts for tower
installations for new systems. Never did I see aluminum in concrete.
If you talk to any concrete engineer I am sure that they would tell you all
about concrete and aluminum.
No, you are not poking pins into my balloon as I don't have one. :>)
Yes I understand what you are saying about some of these tubes holding up
18HT's for a long time.
All I am saying is I wouldn't put anything aluminum into concrete.
If you or others feel comfortable doing so it's ok with me.
I am interested in how well the hytower works on the metal roof. I have one
laying around that I was thinking about trying, mounting it on another tower
section on the ground and the base of the hytower at roof level connected to
it as a ground plane.
73
Gary K4FMX
> -----Original Message-----
> From: Patrick Greenlee [mailto:patrick_g@windstream.net]
> Sent: Friday, December 19, 2014 2:56 PM
> To: Gary Schafer; towertalk@contesting.com
> Subject: Re: [TowerTalk] A couple of 18HT questions
>
> Gary, You misunderstand my meaning. Another try... Hy-Gain has sold
> Hy-Towers since the 50's and I know of no failures due to corrosion of
> those tubes. Has there been one? Anyway, those telling us of the the
> dangers caused by "chemistry" are like the aerodynamics types claiming
> the bumble bee couldn't fly. The bee flies and the tower doesn't fall
> down due to corrosion of the aluminum due to concrete contact. Ground
> truth trumps speculation however informed.
>
> Oh, by the way, I did take that physics class and a bunch of others and
> was a physicist before finding true religion (computers) and getting a
> BSCS and MS softwarre engineering.
>
> I'm the guy who pokes pins in others balloons, recommending
> (allegorically) that rather than pontificate and guestimate at the
> number of angels dancing on the head of a pin, get a lens and count the
> little buggers! Fact trumps theory. I don't deny that the concrete
> corrodes the aluminum but given the facts related to the number of
> towers failing, apparently the corrosion isn't significant. There are
> towers out there with aluminum legs in concrete for over 60 years. If
> corrosion was a significant issue you'd think there would be eHam
> postings mentioning that.
>
> Patrick NJ5G
>
>
>
>
> On 12/17/2014 9:13 PM, Gary Schafer wrote:
> > You should have taken the physics course too. :>) The old "bumble bee
> > shouldn't be able to fly" is an old wives tale that has been around
> for
> > ages.
> >
> > 73
> > Gary K4FMX
> >
> >> -----Original Message-----
> >> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf
> Of
> >> Patrick Greenlee
> >> Sent: Wednesday, December 17, 2014 8:00 PM
> >> To: towertalk@contesting.com
> >> Subject: Re: [TowerTalk] A couple of 18HT questions
> >>
> >> Yeah, I had the requisite year of freshman chemistry too but lets get
> >> real. Hy-Gain has been making these antennas for how long? They have
> >> been putting aluminum into concrete for how long? Anyone ever here
> of a
> >> failure due to corrosion of the aluminum? I don't have a dog in this
> >> fight as I replaced the thick walled aluminum tubes with solid steel
> >> bars as in mounting on the roof of my barn I wanted to weld the three
> >> "posts" to some of my custom base components (steel) and I'm not good
> at
> >> welding steel to aluminum. I still have the aluminum tubes awaiting
> a
> >> use to present itself.
> >>
> >> Somehow I am reminded of the old story of the bumble bee and the
> >> aerodynamicists. :-) ;-) :-D
> >>
> >> Patrick NJ5G
> >>
> >>
> >> On 12/17/2014 3:36 PM, L L bahr wrote:
> >>> I have had my 18HT up for 30 years with aluminum tubes in the
> >> concrete. I see no signs of deterioration. That's good enough for
> me.
> >>> Lee, w0vt
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> > You do not want concrete in contact with aluminum! It will eat
> up
> >> the
> >>>> aluminum. Even aluminum windows come with a warning to not let the
> >> brick
> >>>> mortar come in contact with the aluminum frame when installing.
> >>>> After the concrete is set and dried it may be ok then, not sure.
> >>>>
> >>>> 73
> >>> Yes indeed.. Aluminum is readily attacked by most acids and bases:
> the
> >>> surface oxide helps a lot, and, of course, a chemical conversion
> >> coating
> >>> (anodize, alodine) would too. BUT, a scratch in the coating provides
> a
> >>> nice surface to be attacked.
> >>>
> >>> ALuminum is attacked by most basic hydroxides (e.g. sodium
> hydroxide,
> >>> lye, is used to etch aluminum panels).. It is a way to make hydrogen
> >>> gas, in fact.
> >>>
> >>> Mortar is a mixture of quicklime (CaO) and sand, for the most part,
> >> and
> >>> when you add water to it (slaking the lime) it forms Calcium
> Hydroxide
> >>> (Ca (OH)2).
> >>>
> >>> Concrete has similar chemistry.
> >>>
> >>> So, yes.. keep your aluminum out of the concrete footing.
> >>>
> >>> _______________________________________________
> >>>
> >>>
> >>>
> >>> _______________________________________________
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> >>> TowerTalk@contesting.com
> >>> http://lists.contesting.com/mailman/listinfo/towertalk
> >>> _______________________________________________
> >>>
> >>>
> >>>
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> >>>
> >> _______________________________________________
> >>
> >>
> >>
> >> _______________________________________________
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> >> http://lists.contesting.com/mailman/listinfo/towertalk
> >
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