[TowerTalk] (no subject)

Bill Coleman AA4LR aa4lr@radio.org
Mon, 20 Mar 2000 13:29:06 -0500

On 3/17/00 11:25 PM, K7GCO@aol.com at K7GCO@aol.com wrote:

> >In a message dated 16.03.00 14:51:40 Pacific Standard Time, 
> >writes:

>> You did not say "pop rivets." You most clearly said "aluminum rivets." 
>******Bill  Antenna element rivets that were failing left and right appeard 
>in TT many times.  Everyone one else but you knew they were pop rivets.

According to Force 12, they use structural blind rivets. They do not use 
the tubular pulled rivets (which we inappropriately call "pop" rivets).

>You can't use an aircraft rivet on tubing.


Structural blind rivets can and often are used on tubing. Indeed, I'm 
starting an aircraft project very soon that is built out of aluminum 
tubing and gussets held together entirely with these blind fasteners.

>I assumed everyone would know what I 
>was takling about and I was wrong.  I even thought about that after I had 
>sent it.

That was a poor assumption.

>>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.
>******Bill  I said in my E-mail I worked on all kinds of rivets at Boeing so 
>you are preaching ot the Quire.   As I said in my last E mail I've taken a 
>couple thousand pictures of them.  Did you read that?

Yes, I did. Which is why I can't possibly fathom why you'd write that 
aluminum rivets would not be suitable for this service.

>> I was not defending "pop" rivets. 
>*****Bill  You defended the rivets used in the antennas and they are pop 

According to Force 12, they do not use "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)
>****Bill  They have not done the job.  Why can't you get the straight?
>They have failed elsewhere in the beam also.

Is this a failure of the rivet, the rivet installation, or the design? 
None of that is clear.

>> Further, it has not been established that rivets have insufficient 
>> electrical conductivity. 
>***Bill  The rivet doesn't carry any RF itself.  The joint it pinches 
>together does just at the diameter change

Again, this has not been established. I would argue that the weight of 
the elements will tend to make contact all around an oblong oval-shaped 
path as the smaller tube levers in the larger one.

>If you have been reading you have read of all the Penatrox failures.

Well, I've been practically a charter subscriber to TowerTalk, and I try 
to read everything. All I've read are instances of where the Penetrox 
"dried out" over many years, and is easily removed with a solvent. I have 
yet to read of an instance where Penetrox either caused corrosion in a 
joint, or cause a lack of electrical conductivity.
>> The Murphy Aircraft Co, as well as other aircraft designs do not use 
>> hollow blind fasteners. 
>******Yes  Bill  I konw I know I know.

Well, if you know, then why the wise-crack about "cramming for finals on 
the way down"?

>>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.  
>****Bill  I agree and I won't even ue them on an antenna.  Even Force 12 is 
>removing them---that's how bad they are.

Force 12 doesn't use tubular blind fasteners -- they only use the 
structural variety.

>***Bill  Rivets have no place in antennas and even Force 12 knows that now.

This is pure baloney. An antenna environment is no more harsh than 
aircraft. (Indeed, there are many similarities between the two) If 
structural blind fasteners can be used successfully in aircraft, there's 
no reason they couldn't be used in antennas.

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

FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm