[TowerTalk] (no subject)

Bill Coleman AA4LR aa4lr@radio.org
Fri, 17 Mar 2000 10:04:46 -0500

On 3/16/00 7:55 PM, K7GCO@aol.com at K7GCO@aol.com wrote:

>In a message dated 16.03.00 14:51:40 Pacific Standard Time, aa4lr@radio.org 
><< On 3/16/00 4:51 PM, K7GCO@aol.com wrote:
> >The above illustrates that aluminum rivets just do not have the 
> >strength to support the stresses of aluminum tubing in the wind 24 hrs a 
> >day. 
> Yeah, right! That's why they've been used almost exclusively on aircraft 
> since the DC-1!
>  >>
>The home use hollow "pop rivets" of soft aluminum are not the same as 
>aircraft rivets which I've inspected thousands of.

You did not say "pop rivets." You most clearly said "aluminum rivets." 
The vast majority of driven rivets as used in production aircraft are 
aluminum. Such rivets are certainly plenty strong to deal with the 
stresses of the wind, temperature, moisture and age of aircraft.

>The evidence is "POP 
>RIVETS" are coming lose in antenna elements--NOT "AIRCRAFT RIVETS" which use 
>a bucking bar.

Not all aircraft rivets are of the driven variety. There are sound, 
structural fasteners of the pulled variety. They are known as "blind" 
rivets. These have been used in aviation quite effectively for many years.

>Why are you defending the "Pop Rivets" 
>that have been widely discussed in many many posts when they are not holding 
>or maintaining low RF resistance?

I was not defending "pop" rivets. If you read my other posts, you'll find 
that I make a clear distinction between "pop" rivets and other blind 
rivets. However, given proper use, a "pop" rivet may actually be strong 
enough to be used in an antenna. (Certainly not in a boom to mast, or 
element to boom junction -- but to hold telescoped elements in position 
they can work well)

Further, it has not been established that rivets have insufficient 
electrical conductivity. In an element joint, most of the electrical 
conductivity should take place between the closely nested portions of the 
elements. This conductivity is significantly enhanced using a compound 
such as NoAlOx or Penetrox. This compound also impedes the introduction 
of moisture which can cause corrosion of the joint.

>Would you believe they are putting Gidean Bibles on the "Eagle Hardware 
>Hollow Soft Aluminum 1/8" Pop Rivet Planes" you mentioned (I really believe 
>they have the right rivets).

The Murphy Aircraft Co, as well as other aircraft designs do not use 
hollow blind fasteners. As I have said in my other posts, these designs 
call for structural pulled rivets, which leave a solid steel shank in the 
fastener. The hardware store variety "pop" rivets have no place on any 
man-carrying aircraft.

I won't dignify your impuning the safety record of homebuilt aircraft 
with an answer.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@radio.org
Quote: "Boot, you transistorized tormentor! Boot!"
            -- Archibald Asparagus, VeggieTales

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