Today's Message Index:
----------------------
1. 03:54 AM - Re: Properly setting rivets with dimpled surfaces (wskimike)
2. 07:11 AM - Re: Properly setting rivets with dimpled surfaces (Michael D Crowe)
3. 07:53 AM - Re: Properly setting rivets with dimpled surfaces (Scott Bilinski)
4. 07:59 AM - Re: Wing tip com antenna (Bob J)
5. 08:06 AM - Re: Properly setting rivets with dimpled surfaces (Bob Collins)
6. 08:56 AM - Re: Properly setting rivets with dimpled surfaces (Dave Bristol)
7. 09:46 AM - Re: Properly setting rivets with dimpled surfaces (Skylor Piper)
8. 09:46 AM - Re: Properly setting rivets with dimpled surfaces (Bill Cary)
9. 09:48 AM - Re: Properly setting rivets with dimpled surfaces (Jamie Painter)
10. 10:36 AM - Las Cruces/Santa Teresa (don522@webtv.net (Don McCallister))
11. 10:58 AM - Re: Properly setting rivets with dimpled surfaces (MLWynn@aol.com)
12. 11:07 AM - Re: Properly setting rivets with dimpled surfaces (Smitty)
13. 11:35 AM - Re: Properly setting rivets with dimpled surfaces (David Burton)
14. 11:40 AM - Re: Properly setting rivets with dimpled surfaces (Matt Johnson)
15. 12:30 PM - Re: Countersinking tips was Properly setting rivets with ()
16. 12:38 PM - Re: Properly setting rivets with dimpled surfaces (PJ Seipel)
17. 01:12 PM - Re: Properly setting rivets with dimpled surfaces (Darrell Reiley)
18. 01:35 PM - Re: Wing tip com antenna (sportav8r@aol.com)
19. 03:09 PM - Re: Wing tip com antenna (Bob J)
20. 05:32 PM - Re: Firewall ?????????? (Frank Stringham)
21. 05:43 PM - Re: Properly setting rivets with dimpled surfaces (Frank Stringham)
22. 06:11 PM - Re: Las Cruces/Santa Teresa (Ron Lee)
23. 07:06 PM - Re: Properly setting rivets with dimpled surfaces (not processed: me... (Fiveonepw@aol.com)
24. 07:17 PM - Re: Las Cruces/Santa Teresa (Fiveonepw@aol.com)
25. 08:23 PM - Re: Wing tip com antenna (sportav8r@aol.com)
26. 08:57 PM - Re: Wing tip com antenna (Richard E. Tasker)
27. 11:38 PM - Re: Properly setting rivets with dimpled surfaces (Dan Checkoway)
Message 1
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: "wskimike" <wskimike@mchsi.com>
Just "slightly" sand the bottom portion of the dimpled skin and it will
solve your problem. An old trick from a long time sheet metal man. The metal
will sit flush and you won't have to worry about swelling the rivet between
the two surfaces.
Mike
----- Original Message -----
From: "Dan Checkoway" <dan@rvproject.com>
Subject: Re: RV-List: Properly setting rivets with dimpled surfaces
> --> RV-List message posted by: "Dan Checkoway" <dan@rvproject.com>
>
> Remind me tomorrow to put an AN426AD3-x rivet in my female dimple die. I
> honestly haven't even tried that yet...but I intend to! I wonder if the
> rivet will sit flush or sit low. My $.02 bet is that it will sit low.
>
> I'll try to remember to check it out tomorrow...
>
> Also, there is a distinction between "spring back" dimple dies and the
> regular flavor. The end result is supposed to be the same but it may not
> be.
>
> do not archive
> )_( Dan
> RV-7 N714D
> http://www.rvproject.com
>
> ----- Original Message -----
> From: "Rob Prior (rv7)" <rv7@b4.ca>
> To: <rv-list@matronics.com>
> Subject: Re: RV-List: Properly setting rivets with dimpled surfaces
>
>
>> --> RV-List message posted by: "Rob Prior (rv7)" <rv7@b4.ca>
>>
>> On 18:57:18 2005-10-06 "D.Bristol" <dbris200@sbcglobal.net> wrote:
>>> --> RV-List message posted by: "D.Bristol" <dbris200@sbcglobal.net>
>>> Be careful here. With a quality dimpling die, the under side of a
>>> dimpled hole is the same size as the top. You can see this when you
>>> put 2 dimpled sheets together - they fit just fine. However, when
>>> fitting the dimpled sheet into a countersunk piece you can have a
>>> problem with fit because the edge of the countersunk hole is sharp
>>> and the corresponding point on the bottom of the dimple is not,
>>> (quality "spring back" dies may give a sharper transition than cheap
>>> dies) especially if you didn't use enough force when forming the
>>> dimple.
>>
>> The engineer in me must speak up: A countersunk hole will always have a
>> sharp transition at the top corner, unless you remove it. A dimpled
>> piece
>> of aluminum will always have a rounded (or filleted) corner in the
>> corresponding location. This means you will end up with one of two
>> situations:
>>
>> One, you can countersink until the skin sits flat, in which case there
>> will
>> be an air gap under the dimpled skin in the "cone" of the countersink.
>> You
>> don't want this. It's not as strong a joint, and can lead to corrosion
>> in
>> the cavities, well beyond where you can see it happening.
>>
>> Two, you can countersink to fit the rivet, in which case the skin will
>> *not* sit flat in the countersink. This is not a problem, if your dimple
>> is good. When you drive the rivet it will drive that rounded corner into
>> a
>> sharp one and it will all become flush. This is what you want.
>>
>> So: Countersink only far enough to fit the head of the rivet. There's no
>> reason to go further
>>
>> As for drilling a smaller hole so everything is "tighter", the engineer
>> in
>> me says you will end up with a smaller diameter of "meat" in the hole
>> once
>> the rivet is driven. This means that every rivet joint will be slightly
>> less strong than it was designed to be. Which means your airplane is
>> slightly less strong than it was designed to be. Why would you want
>> that?
>>
>> Stop second-guessing the designer.
>>
>> -Rob
>>
>>
>>
>
>
>
Message 2
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| Subject: | Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: "Michael D Crowe" <rv8a@bellsouth.net>
Hi everyone. I'm just getting started on an RV-10 project and
practiced riveting a bit on scrap material first last night. And
I've run into a couple of problems/questions that I'm sure at least
some of you have had, but I couldn't find anything in a search of the
archives.
And lastly, I've read in the archives that some people prefer to
drill a hole slightly smaller than required when dimpling a skin
(using a #41 instead of #40, for example), since the hole will expand
slightly while dimpling. Is this just being overzealous, or is there
a good case to be made for this? I'm thinking that if the hole were
slightly smaller, the rivet would expand a bit less while filling the
hole, leaving a bit more material for the shop head, making the
tolerances for setting it just the right amount a bit less fine.
Any advice that anyone can provide to a beginner like myself?
Thanks! Dan
--
Syzygy Research & Technology
Box 83, Legal, AB T0G 1L0 Canada
Phone: 780-961-2213
Dan,
I have been researching this subject myself. I would suggest you look at
this link.
http://www.tech.purdue.edu/at/courses/at308/Technical_Links/MMPDS/OptionsMen
u.pdf
Look at the introduction to see the approval for use. Chapter 8 covers solid
rivets. Look at Table 8.1.2(a) page 8-12 It shows a 41 bit as the standard
rivet-drill size for a 3/32 rivet.
Mike Crowe
Message 3
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: Scott Bilinski <bilinski@kyocera-wireless.com>
From another E-mail list....
Two days ago I got around to doing something that I had planned last
year -- actual pull tests on riveted aluminum coupons to see how
critical it is to drive rivets to the correct height. All of us
building or with completed RVs (as will those those planning on it in
the future) have had to wonder which imperfect rivets to drill out and
which are OK. The answer is obvious when there is a severe cosmetic
problem, but when strength is at issue, how much does a slightly under
or overdriven rivet affect strength? How much does a grossly under or
overdriven rivet affect it? Frankly, I had made the decision that the
risk of damage from drilling out a flush rivet is greater than the
benefit of doing so, unless an obvious cosmetic defect or really bad
rivet is at issue. Now I have some hard data to go by.
What I did was to make up 10 test coupons. Each of these consisted of
two pieces of .032 2024-T3 sheet 1.5 inches wide and 4 inches long.
These two pieces were overlapped by 1.5 inches and riveted together with
two parallel rows of 3 rivets each. Of the 10 total coupons, five
involved the use of universal head AN 470 AD3 rivets and the other 5
used AN 426 AD3 flush rivets. In the latter case, both pieces of
aluminum were dimpled at each rivet location, as is routinely done in
Van's airplanes. In fact, the coupon construction is similar to the
double rivet line where the lower outboard wing skin overlaps the lower
inboard wing skin. This joint is loaded in tension normally for
positive G flight and gave me the idea to mimic it for the pull tests.
Before getting into the results, let me ask you a question. Please
think about the answer before proceeding. Just how many pounds of force
do you think it would take to destroy one of the sheets used in making
up the coupons? Remember this is .032, 2024-T3 sheet 4 inches long and
1.5 inches wide with no holes or rivets in it. Think about grabbing and
suspending it at one end with some sort of clamp across the entire 1.5
inch width and then hanging weights on the other end from another clamp.
How much weight would it take to break this .032 inch thick sheet?
Would a 100 pound set of barbells do it? A 500 pound set? A 1200 pound
small car? A gross weight RV8 at 1800 pounds? A gross weight Grumman
Tiger at 2400 pounds? More than that? Come up with some sort of gut
feel before proceeding. I was surprised by the answer. You may or may
not be, depending on your knowledge in this area.
Since some of you will cheat and read on, I'll hold the answer for a
moment! Each of the 5 test coupons, both with the universal head rivets
and the flush head rivets, was riveted to a different degree. One was
grossly under driven, one was slightly under driven, one was correct per
the rivet gauge, one was slightly over driven and the last was grossly
over driven. The slightly under driven and slightly over driven rivets
were such that you would probably need a rivet gauge to detect them -- I
did this because I suspect that most of the rivets in our planes fall
into this category. The grossly over and under driven rivets were
really gross. The over driven were squashed nearly flat and the under
driven were barely set at all. I did this to see just how poorly a
joint make of this sort of gross error would hold up. You would easily
see these and know there was a problem immediately. You'll find the
results interesting.........
The idea was to put each coupon in a pull test machine and expose the
riveted joint to a slowly increasing force until it yielded. This was
done at a structural test lab in Paramount (Southern CA city) that works
mostly with civil engineering construction materials. A stress/strain
graph was running and we monitored it to see the first indication of
joint failure as indicated by a decrease in force required as the coupon
stretched, cracked, broke in two, sheared or tipped rivets, etc. I was
interested in the force required to cause the initial failure, as well
as the nature and appearance of that initial failure; ie, what actually
happened first. We agreed to stop the machine at the incipient
indication of failure, thus preserving the coupon in its early failure
state without destroying the joint completely. I was very curious as to
how things would fail and really had no idea other than the thought that
the dimpled, flush riveted joint would probably be stronger than the
undimpled one with the 470 universal head rivets. In contrast, one of
the owners of the lab came in to watch and thought the opposite would be
true. In his 50 years in the business, he had never seen this test
done. What do you think would hold best?
That said, here is the answer to my prior question. A force of 2300
pounds was required to break the test material with no rivets or holes
in it. It failed catastrophically shortly after some initial stretching
was noted. I had no idea that a cross section of this 2024 T3 sheet,
.032 inches thick and 1.5 inches wide, would sustain anywhere near that
load. Frankly, I was surprised when it passed 1000 pounds and still
going strong.
Before showing you the numbers, I will give a brief summary of them:
1. The dimpled, flush riveted construction was stronger, but not by as
much as I had thought. However, and this is really important, initial
failure of the dimpled construction was generally not catastrophic and
occurred as rivet tipping and rivet head distortion. In contrast,
initial failure of the AN 470 undimpled construction was generally
catastrophic by rivet shear. I am really happy Van uses the flush
riveted, double dimpled joints throughout most of the airplane!
2. Slightly under driving or slightly over driving a rivet makes an
observable and thus measurable difference in the joint strength.
3. Slightly over driving is stronger than slightly under driving and
results (in my opinion) in an insignificant difference in strength as
compared to properly driven rivets.
4. In the one test of slightly over driven AN 470 rivets, the joint was
actually stronger than with properly driven rivets. This may have just
been the luck of the draw for this single sample, so I wouldn't put any
real faith in it.
5. A joint made of grossly over driven rivets is stronger joint than a
joint make of grossly under driven ones.
6. A grossly under driven AN 470 joint is much weaker than a grossly
under driven AN 426 joint.
7. No joint was as strong as the parent material itself.
To summarize the summary, try for properly driven rivets but realize
that minor over driving is preferable to minor under driving and results
in nearly the same strength as does the condition of properly driven
rivets.
AN 426 AD 3 Table
Condition Force at failure Nature of failure
Gross under 1650 Rivet tipping, head distortion
Slight under 1775 Same
Correct 2025 Same
Slight over 1975 Same
Gross over 1825 Sheet tear at rivet line
AN 470 AD 3 Table
Gross under 1100 Rivet tip plus one sheared rivet
Slight under 1600 5 sheared rivets!
Correct 1625 6 sheared rivets!
Slight over 1750 6 sheared rivets!
Gross over 1500 Rivet tip plus sheet tear at
rivet line
Anyway, those are some real numbers for an area we have undoubtedly
thought about at one time or another. My opinions, FWIW: I think an
occasional rivet that is slightly under driven or slightly over driven
is utterly no big deal and can safely be ignored. We all have some of
these flying in formation in our airplanes. A line of them would be
another matter. Even an occasional grossly over driven rivet is
probably OK, especially if getting rid of it could cause damage. And if
underdriven too much, just whack it again. Hope you learned something
from this. I certainly did.
Scott Bilinski
Eng dept 305
Phone (858) 657-2536
Pager (858) 502-5190
Message 4
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| Subject: | Re: Wing tip com antenna |
--> RV-List message posted by: Bob J <rocketbob@gmail.com>
For those who have not had good experiences with the wingtip comm antennas,
please describe how you had the antenna mounted in the wingtip. I have had
people who have had these antennas tell me they work great, of those that
did they had the radiating element attached to the top surface of the
wingtip to maximize the vertical component of the antenna. In other words
the ground portion was attached to the bottom of the wingtip and the antenna
was bent so that the radiating element was glassed to the top surface of the
wingtip along its edge.
With that said...
I have a belly mounted antenna that works well on my -6, and I have borrowed
a MFJ antenna analyzer to check it. VSWR of the belly mounted antenna was
typically 1.2-1.8 best as I can remember across the frequency range. The
problem with a good antenna is that you pick up everybody and their mother
transmitting within a three state radius so sometimes the chatter can get
overwhelming especially if you only care about the aircraft that are within
a few miles of you. So to have a 50 mile radius of communications is
acceptable to me, the only time you really ever use that sort of range or
beyond is to chit-chat with your buddies on the other side of the state.
There is one RV-8 that I occasionnally fly with that whenever I get up
close, we can't talk to each other. If I back out 20 ft then everything is
fine. I suspect it has to do with the geometry in which the signals radiate
between our two airplanes. My point being is there is no perfect location
for an antenna on an RV for all circumstances.
Regards,
Bob Japundza
RV-6 flying, F1 under const.
Message 5
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| Subject: | Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: "Bob Collins" <bcollinsrv7a@comcast.net>
I'd like to see some analysis of in-flight break-up of planes to see how
many occurred along a rivet line.
Do not archive
Message 6
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: Dave Bristol <dbris200@sbcglobal.net>
Very good report Scott! This answers some good questions that I never
had answers for before. Thanks!
Dave
Scott Bilinski wrote:
>--> RV-List message posted by: Scott Bilinski <bilinski@kyocera-wireless.com>
>
> From another E-mail list....
>
>
>Two days ago I got around to doing something that I had planned last
>year -- actual pull tests on riveted aluminum coupons to see how
>critical it is to drive rivets to the correct height. All of us
>building or with completed RVs (as will those those planning on it in
>the future) have had to wonder which imperfect rivets to drill out and
>which are OK. The answer is obvious when there is a severe cosmetic
>problem, but when strength is at issue, how much does a slightly under
>or overdriven rivet affect strength? How much does a grossly under or
>overdriven rivet affect it? Frankly, I had made the decision that the
>risk of damage from drilling out a flush rivet is greater than the
>benefit of doing so, unless an obvious cosmetic defect or really bad
>rivet is at issue. Now I have some hard data to go by.
>
>
>What I did was to make up 10 test coupons. Each of these consisted of
>two pieces of .032 2024-T3 sheet 1.5 inches wide and 4 inches long.
>These two pieces were overlapped by 1.5 inches and riveted together with
>two parallel rows of 3 rivets each. Of the 10 total coupons, five
>involved the use of universal head AN 470 AD3 rivets and the other 5
>used AN 426 AD3 flush rivets. In the latter case, both pieces of
>aluminum were dimpled at each rivet location, as is routinely done in
>Van's airplanes. In fact, the coupon construction is similar to the
>double rivet line where the lower outboard wing skin overlaps the lower
>inboard wing skin. This joint is loaded in tension normally for
>positive G flight and gave me the idea to mimic it for the pull tests.
>
>
>Before getting into the results, let me ask you a question. Please
>think about the answer before proceeding. Just how many pounds of force
>do you think it would take to destroy one of the sheets used in making
>up the coupons? Remember this is .032, 2024-T3 sheet 4 inches long and
>1.5 inches wide with no holes or rivets in it. Think about grabbing and
>suspending it at one end with some sort of clamp across the entire 1.5
>inch width and then hanging weights on the other end from another clamp.
>How much weight would it take to break this .032 inch thick sheet?
>Would a 100 pound set of barbells do it? A 500 pound set? A 1200 pound
>small car? A gross weight RV8 at 1800 pounds? A gross weight Grumman
>Tiger at 2400 pounds? More than that? Come up with some sort of gut
>feel before proceeding. I was surprised by the answer. You may or may
>not be, depending on your knowledge in this area.
>
>
>Since some of you will cheat and read on, I'll hold the answer for a
>moment! Each of the 5 test coupons, both with the universal head rivets
>and the flush head rivets, was riveted to a different degree. One was
>grossly under driven, one was slightly under driven, one was correct per
>the rivet gauge, one was slightly over driven and the last was grossly
>over driven. The slightly under driven and slightly over driven rivets
>were such that you would probably need a rivet gauge to detect them -- I
>did this because I suspect that most of the rivets in our planes fall
>into this category. The grossly over and under driven rivets were
>really gross. The over driven were squashed nearly flat and the under
>driven were barely set at all. I did this to see just how poorly a
>joint make of this sort of gross error would hold up. You would easily
>see these and know there was a problem immediately. You'll find the
>results interesting.........
>
>
>The idea was to put each coupon in a pull test machine and expose the
>riveted joint to a slowly increasing force until it yielded. This was
>done at a structural test lab in Paramount (Southern CA city) that works
>mostly with civil engineering construction materials. A stress/strain
>graph was running and we monitored it to see the first indication of
>joint failure as indicated by a decrease in force required as the coupon
>stretched, cracked, broke in two, sheared or tipped rivets, etc. I was
>interested in the force required to cause the initial failure, as well
>as the nature and appearance of that initial failure; ie, what actually
>happened first. We agreed to stop the machine at the incipient
>indication of failure, thus preserving the coupon in its early failure
>state without destroying the joint completely. I was very curious as to
>how things would fail and really had no idea other than the thought that
>the dimpled, flush riveted joint would probably be stronger than the
>undimpled one with the 470 universal head rivets. In contrast, one of
>the owners of the lab came in to watch and thought the opposite would be
>true. In his 50 years in the business, he had never seen this test
>done. What do you think would hold best?
>
>
>That said, here is the answer to my prior question. A force of 2300
>pounds was required to break the test material with no rivets or holes
>in it. It failed catastrophically shortly after some initial stretching
>was noted. I had no idea that a cross section of this 2024 T3 sheet,
>.032 inches thick and 1.5 inches wide, would sustain anywhere near that
>load. Frankly, I was surprised when it passed 1000 pounds and still
>going strong.
>
>
>Before showing you the numbers, I will give a brief summary of them:
>
>
>1. The dimpled, flush riveted construction was stronger, but not by as
>much as I had thought. However, and this is really important, initial
>failure of the dimpled construction was generally not catastrophic and
>occurred as rivet tipping and rivet head distortion. In contrast,
>initial failure of the AN 470 undimpled construction was generally
>catastrophic by rivet shear. I am really happy Van uses the flush
>riveted, double dimpled joints throughout most of the airplane!
>
>
>2. Slightly under driving or slightly over driving a rivet makes an
>observable and thus measurable difference in the joint strength.
>
>
>3. Slightly over driving is stronger than slightly under driving and
>results (in my opinion) in an insignificant difference in strength as
>compared to properly driven rivets.
>
>
>4. In the one test of slightly over driven AN 470 rivets, the joint was
>actually stronger than with properly driven rivets. This may have just
>been the luck of the draw for this single sample, so I wouldn't put any
>real faith in it.
>
>
>5. A joint made of grossly over driven rivets is stronger joint than a
>joint make of grossly under driven ones.
>
>
>6. A grossly under driven AN 470 joint is much weaker than a grossly
>under driven AN 426 joint.
>
>
>7. No joint was as strong as the parent material itself.
>
>
>To summarize the summary, try for properly driven rivets but realize
>that minor over driving is preferable to minor under driving and results
>in nearly the same strength as does the condition of properly driven
>rivets.
>
>
>AN 426 AD 3 Table
>
>
>Condition Force at failure Nature of failure
>
>
>Gross under 1650 Rivet tipping, head distortion
>
>Slight under 1775 Same
>
>Correct 2025 Same
>
>Slight over 1975 Same
>
>Gross over 1825 Sheet tear at rivet line
>
>
>AN 470 AD 3 Table
>
>
>Gross under 1100 Rivet tip plus one sheared rivet
>
>Slight under 1600 5 sheared rivets!
>
>Correct 1625 6 sheared rivets!
>
>Slight over 1750 6 sheared rivets!
>
>Gross over 1500 Rivet tip plus sheet tear at
>
>rivet line
>
>
>Anyway, those are some real numbers for an area we have undoubtedly
>thought about at one time or another. My opinions, FWIW: I think an
>occasional rivet that is slightly under driven or slightly over driven
>is utterly no big deal and can safely be ignored. We all have some of
>these flying in formation in our airplanes. A line of them would be
>another matter. Even an occasional grossly over driven rivet is
>probably OK, especially if getting rid of it could cause damage. And if
>underdriven too much, just whack it again. Hope you learned something
>from this. I certainly did.
>
>
>Scott Bilinski
>Eng dept 305
>Phone (858) 657-2536
>Pager (858) 502-5190
>
>
>
>
Message 7
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: Skylor Piper <skylor4@yahoo.com>
Here's a link to the article, as it's posted on Kevin
Horton's website. It includes pictures:
http://www.kilohotel.com/rv8/rvlinks/marvelrivets.html
Do Not Archive
--- Scott Bilinski <bilinski@kyocera-wireless.com>
wrote:
> --> RV-List message posted by: Scott Bilinski
> <bilinski@kyocera-wireless.com>
>
> From another E-mail list....
>
>
> Two days ago I got around to doing something that I
> had planned last
> year -- actual pull tests on riveted aluminum
> coupons to see how
> critical it is to drive rivets to the correct
> height. All of us
> building or with completed RVs (as will those those
> planning on it in
> the future) have had to wonder which imperfect
> rivets to drill out and
> which are OK. The answer is obvious when there is a
> severe cosmetic
> problem, but when strength is at issue, how much
> does a slightly under
> or overdriven rivet affect strength? How much does
> a grossly under or
> overdriven rivet affect it? Frankly, I had made the
> decision that the
> risk of damage from drilling out a flush rivet is
> greater than the
> benefit of doing so, unless an obvious cosmetic
> defect or really bad
> rivet is at issue. Now I have some hard data to go
> by.
>
>
> What I did was to make up 10 test coupons. Each of
> these consisted of
> two pieces of .032 2024-T3 sheet 1.5 inches wide
> and 4 inches long.
> These two pieces were overlapped by 1.5 inches and
> riveted together with
> two parallel rows of 3 rivets each. Of the 10 total
> coupons, five
> involved the use of universal head AN 470 AD3 rivets
> and the other 5
> used AN 426 AD3 flush rivets. In the latter case,
> both pieces of
> aluminum were dimpled at each rivet location, as is
> routinely done in
> Van's airplanes. In fact, the coupon construction
> is similar to the
> double rivet line where the lower outboard wing skin
> overlaps the lower
> inboard wing skin. This joint is loaded in tension
> normally for
> positive G flight and gave me the idea to mimic it
> for the pull tests.
>
>
> Before getting into the results, let me ask you a
> question. Please
> think about the answer before proceeding. Just how
> many pounds of force
> do you think it would take to destroy one of the
> sheets used in making
> up the coupons? Remember this is .032, 2024-T3
> sheet 4 inches long and
> 1.5 inches wide with no holes or rivets in it.
> Think about grabbing and
> suspending it at one end with some sort of clamp
> across the entire 1.5
> inch width and then hanging weights on the other end
> from another clamp.
> How much weight would it take to break this .032
> inch thick sheet?
> Would a 100 pound set of barbells do it? A 500
> pound set? A 1200 pound
> small car? A gross weight RV8 at 1800 pounds? A
> gross weight Grumman
> Tiger at 2400 pounds? More than that? Come up with
> some sort of gut
> feel before proceeding. I was surprised by the
> answer. You may or may
> not be, depending on your knowledge in this area.
>
>
> Since some of you will cheat and read on, I'll hold
> the answer for a
> moment! Each of the 5 test coupons, both with the
> universal head rivets
> and the flush head rivets, was riveted to a
> different degree. One was
> grossly under driven, one was slightly under driven,
> one was correct per
> the rivet gauge, one was slightly over driven and
> the last was grossly
> over driven. The slightly under driven and slightly
> over driven rivets
> were such that you would probably need a rivet gauge
> to detect them -- I
> did this because I suspect that most of the rivets
> in our planes fall
> into this category. The grossly over and under
> driven rivets were
> really gross. The over driven were squashed nearly
> flat and the under
> driven were barely set at all. I did this to see
> just how poorly a
> joint make of this sort of gross error would hold
> up. You would easily
> see these and know there was a problem immediately.
> You'll find the
> results interesting.........
>
>
> The idea was to put each coupon in a pull test
> machine and expose the
> riveted joint to a slowly increasing force until it
> yielded. This was
> done at a structural test lab in Paramount (Southern
> CA city) that works
> mostly with civil engineering construction
> materials. A stress/strain
> graph was running and we monitored it to see the
> first indication of
> joint failure as indicated by a decrease in force
> required as the coupon
> stretched, cracked, broke in two, sheared or tipped
> rivets, etc. I was
> interested in the force required to cause the
> initial failure, as well
> as the nature and appearance of that initial
> failure; ie, what actually
> happened first. We agreed to stop the machine at
> the incipient
> indication of failure, thus preserving the coupon in
> its early failure
> state without destroying the joint completely. I
> was very curious as to
> how things would fail and really had no idea other
> than the thought that
> the dimpled, flush riveted joint would probably be
> stronger than the
> undimpled one with the 470 universal head rivets.
> In contrast, one of
> the owners of the lab came in to watch and thought
> the opposite would be
> true. In his 50 years in the business, he had never
> seen this test
> done. What do you think would hold best?
>
>
> That said, here is the answer to my prior question.
> A force of 2300
> pounds was required to break the test material with
> no rivets or holes
> in it. It failed catastrophically shortly after
> some initial stretching
> was noted. I had no idea that a cross section of
> this 2024 T3 sheet,
> .032 inches thick and 1.5 inches wide, would sustain
> anywhere near that
> load. Frankly, I was surprised when it passed 1000
> pounds and still
> going strong.
>
>
> Before showing you the numbers, I will give a brief
> summary of them:
>
>
> 1. The dimpled, flush riveted construction was
> stronger, but not by as
> much as I had thought. However, and this is really
> important, initial
> failure of the dimpled construction was generally
> not catastrophic and
> occurred as rivet tipping and rivet head distortion.
> In contrast,
> initial failure of the AN 470 undimpled construction
> was generally
> catastrophic by rivet shear. I am really happy Van
> uses the flush
> riveted, double dimpled joints throughout most of
> the airplane!
>
>
> 2. Slightly under driving or slightly over driving
> a rivet makes an
> observable and thus measurable difference in the
> joint strength.
>
>
> 3. Slightly over driving is stronger than slightly
> under driving and
> results (in my opinion) in an insignificant
> difference in strength as
> compared to properly driven rivets.
>
>
> 4. In the one test of slightly over driven AN 470
> rivets, the joint was
> actually stronger than with properly driven rivets.
> This may have just
>
=== message truncated ===
__________________________________
Message 8
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| Subject: | Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: "Bill Cary" <williamc@rv9builder.com>
Great INFO Scott !!
Now I won't feel so bad about the few rivets I left in place that weren't
just right. Sometimes one has to weigh the potential for making things worse
against leaving the non-perfect rivet there. This info just confirms my
building decisions.
Thanks Again
Bill
Message 9
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: Jamie Painter <jamie@jpainter.org>
I know that we all want to build our airplanes as best as possible, but
shouldn't we worry about things that matter with building? I am not an
expert but I can tell you that I've read every single NTSB accident
report on RV's and none of them crashed because someone drilled with a
#40 instead of a #41. In fact, none of them crashed because someone
riveted incorrectly. The one exception is an accident in which an RV-4
had about 1/5 of the required rivets in the spar that led to wing
separation during a low pass and high G pull-up (how's THAT for
strength??). There have been others to suffer structural problems
(insufficient edge-distance on the rear spar attach bolt, for example),
but the overwhelming majority of accidents have been obvious pilot error
(controlled flight into terrain) or firewall forward/fuel system issues.
Let's concentrate on the things that matter. Let the engineers at Van's
design the airplane.
By the way: Does anyone else see the irony in trusting Van's design but
not trusting his instructions for building it (obvious plans errors
aside)? If you can't trust him when he says to use a #40, how can you
trust that his wing spar design is sound?
do not archive
Jamie Painter
http://rv.jpainter.org
Message 10
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| Subject: | Las Cruces/Santa Teresa |
--> RV-List message posted by: don522@webtv.net (Don McCallister)
Any RV-6A's going Oct. 14th--16th???
Do not archive.
Message 11
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: MLWynn@aol.com
Hi Rob,
I am nearly done with my empennage and am about to countersink the trim
spar. I have been struggling with this concept for some time. What you say here
makes really good sense. I think I have countersunk excessively in the
past--trying to get the dimpled skin to lay flat on the countersunk section.
I
had looked at the profiles and clearly noticed the difference in the shape
between the dimple and countersink. I wondered if it wouldn't press out. I
asked Van's about this and they told me to fit the countersink to a rivet and
then go two clicks more on the countersink guide and that will be it.
I had also had trouble with the machined countersinks being ragged looking
and occasionally making the hole excessively big. I told myself (at least on
the left elevator side of the trim support spar) that having the hinge as a
backing should take care of any movement due to excessive hole size. Hope
that is really true.
The list made the suggestions of going to a single flute countersink. I got
one from Cleveland Tools. It works beautifully, especially in a low speed
driver drill. I did discover that it is pretty delicate. I broke it after
about four holes. I contacted Cleveland and they were generous enough to send
me a replacement. Can't say enough good about their quality or service.
At any rate, this is a challenging part for us newbies. After this spar, my
next countersinking project is the wing spar. Definitely do not want to
foul that up. So, thank you for this erudite explanation of a frustrating
subject.
Regards,
Michael Wynn
RV 8 (Still on the) Empennage
San Ramon, CA
Do Not Archive
Message 12
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: "Smitty" <smitty@smittysrv.com>
I have to agree with Jamie. I'm with what Van's instructions say and will
not deviate from it.
Smitty
http://SmittysRV.com
> --> RV-List message posted by: Jamie Painter <jamie@jpainter.org>
>
> I know that we all want to build our airplanes as best as possible, but
> shouldn't we worry about things that matter with building? I am not an
> expert but I can tell you that I've read every single NTSB accident
> report on RV's and none of them crashed because someone drilled with a
> #40 instead of a #41. In fact, none of them crashed because someone
> riveted incorrectly. The one exception is an accident in which an RV-4
> had about 1/5 of the required rivets in the spar that led to wing
> separation during a low pass and high G pull-up (how's THAT for
> strength??). There have been others to suffer structural problems
> (insufficient edge-distance on the rear spar attach bolt, for example),
> but the overwhelming majority of accidents have been obvious pilot error
> (controlled flight into terrain) or firewall forward/fuel system issues.
>
> Let's concentrate on the things that matter. Let the engineers at Van's
> design the airplane.
>
> By the way: Does anyone else see the irony in trusting Van's design but
> not trusting his instructions for building it (obvious plans errors
> aside)? If you can't trust him when he says to use a #40, how can you
> trust that his wing spar design is sound?
>
> do not archive
>
> Jamie Painter
> http://rv.jpainter.org
>
>
Message 13
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: "David Burton" <dburton@nwlink.com>
> Remind me tomorrow to put an AN426AD3-x rivet in my female dimple die. I
> honestly haven't even tried that yet...but I intend to! I wonder if the
> rivet will sit flush or sit low. My $.02 bet is that it will sit low.
The rivet sets low in a regular die. Now the question is how to get the
rivet back out of the die... :-)
Message 14
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
(not processed: message from valid local sender)
--> RV-List message posted by: "Matt Johnson" <matt@n559rv.com>
The jagged countersinks had me confused to. As soon as I started using a cordless
electric instead of the air drill they looked much nicer.
Turning it at lower speeds is definitly the solution to this for anyone experiencing
it.
- Matt
-----Original Message-----
From: MLWynn@aol.com
Subject: Re: RV-List: Properly setting rivets with dimpled surfaces
> --> RV-List message posted by: MLWynn@aol.com
>
> Hi Rob,
>
> I am nearly done with my empennage and am about to countersink the trim
>
> spar. I have been struggling with this concept for some time. What
> you say here
> makes really good sense. I think I have countersunk excessively in
> the
> past--trying to get the dimpled skin to lay flat on the countersunk
> section. I
> had looked at the profiles and clearly noticed the difference in the
> shape
> between the dimple and countersink. I wondered if it wouldn't press
> out. I
> asked Van's about this and they told me to fit the countersink to a
> rivet and
> then go two clicks more on the countersink guide and that will be it.
>
>
> I had also had trouble with the machined countersinks being ragged
> looking
> and occasionally making the hole excessively big. I told myself (at
> least on
> the left elevator side of the trim support spar) that having the hinge
> as a
> backing should take care of any movement due to excessive hole size.
> Hope
> that is really true.
>
> The list made the suggestions of going to a single flute countersink.
> I got
> one from Cleveland Tools. It works beautifully, especially in a low
> speed
> driver drill. I did discover that it is pretty delicate. I broke it
> after
> about four holes. I contacted Cleveland and they were generous enough
> to send
> me a replacement. Can't say enough good about their quality or
> service.
>
> At any rate, this is a challenging part for us newbies. After this
> spar, my
> next countersinking project is the wing spar. Definitely do not want
> to
> foul that up. So, thank you for this erudite explanation of a
> frustrating
> subject.
>
> Regards,
>
>
> Michael Wynn
> RV 8 (Still on the) Empennage
> San Ramon, CA
>
> Do Not Archive
>
>
>
>
>
>
Message 15
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|
| Subject: | Re: Countersinking tips was Properly setting rivets with |
dimpled surfaces
--> RV-List message posted by: <chaztuna@adelphia.net>
Listers,
I'll second Matt's experience. I'll even go one better. I bought into all the
hype about Avery's "one hole" countersinks. They do not "chatter" at the high
speeds used on air drills. However, that single hole often clogs up with metal
chips. This occasionally leads to a nice round circular scratch on the aluminium
hole surrounding the countersink. It happens when the sharp edge of a chip
curls over and contacts the skin.
Once you switch to either a battery powered or slower electric cord drill, the
standard 3 flute countersinks work great. They don't chip bind and they don't
chatter at the lower speeds. I used to waste a lot of time cleaning out the single
flute on my Avery countersinks. Now they just sit in my countersink holder.
I love the standard 3 flute countersinks mounted on a cordless electric drill.
:-)
Charlie Kuss
---- Matt Johnson <matt@n559rv.com> wrote:
> --> RV-List message posted by: "Matt Johnson" <matt@n559rv.com>
>
> The jagged countersinks had me confused to. As soon as I started using a cordless
electric instead of the air drill they looked much nicer.
> Turning it at lower speeds is definitly the solution to this for anyone experiencing
it.
>
> - Matt
>
> -----Original Message-----
> From: MLWynn@aol.com
> To: rv-list@matronics.com
> Date: Fri, 7 Oct 2005 13:57:41 EDT
> Subject: Re: RV-List: Properly setting rivets with dimpled surfaces
>
> > --> RV-List message posted by: MLWynn@aol.com
> >
> > Hi Rob,
> >
> > I am nearly done with my empennage and am about to countersink the trim
> >
> > spar. I have been struggling with this concept for some time. What
> > you say here
> > makes really good sense. I think I have countersunk excessively in
> > the
> > past--trying to get the dimpled skin to lay flat on the countersunk
> > section. I
> > had looked at the profiles and clearly noticed the difference in the
> > shape
> > between the dimple and countersink. I wondered if it wouldn't press
> > out. I
> > asked Van's about this and they told me to fit the countersink to a
> > rivet and
> > then go two clicks more on the countersink guide and that will be it.
> >
> >
> > I had also had trouble with the machined countersinks being ragged
> > looking
> > and occasionally making the hole excessively big. I told myself (at
> > least on
> > the left elevator side of the trim support spar) that having the hinge
> > as a
> > backing should take care of any movement due to excessive hole size.
> > Hope
> > that is really true.
> >
> > The list made the suggestions of going to a single flute countersink.
> > I got
> > one from Cleveland Tools. It works beautifully, especially in a low
> > speed
> > driver drill. I did discover that it is pretty delicate. I broke it
> > after
> > about four holes. I contacted Cleveland and they were generous enough
> > to send
> > me a replacement. Can't say enough good about their quality or
> > service.
> >
> > At any rate, this is a challenging part for us newbies. After this
> > spar, my
> > next countersinking project is the wing spar. Definitely do not want
> > to
> > foul that up. So, thank you for this erudite explanation of a
> > frustrating
> > subject.
> >
> > Regards,
> >
> >
> > Michael Wynn
> > RV 8 (Still on the) Empennage
> > San Ramon, CA
> >
> > Do Not Archive
> >
> >
> >
> >
> >
> >
>
>
>
>
>
>
Message 16
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: PJ Seipel <seipel@seznam.cz>
Ha! At least you didn't make my mistake: I used a female die and a
rivet in order to dimple an area I couldn't fit the male die into (can't
remember where it was right now). The rivet was too long for the hole
in the female die and when I hit it, the rivet expanded in the die and
got stuck. Getting it out was not much fun.
PJ
40032
David Burton wrote:
>--> RV-List message posted by: "David Burton" <dburton@nwlink.com>
>
>
>
>>Remind me tomorrow to put an AN426AD3-x rivet in my female dimple die. I
>>honestly haven't even tried that yet...but I intend to! I wonder if the
>>rivet will sit flush or sit low. My $.02 bet is that it will sit low.
>>
>>
>
>
>The rivet sets low in a regular die. Now the question is how to get the
>rivet back out of the die... :-)
>
>
>
>
Message 17
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: Darrell Reiley <lifeofreiley2003@yahoo.com>
This will be the somewhat the same for countersinking. You want a very slight...
ever so slight recess of the rivet head on the 426 rivet. You should just see
a faint shiny hair thin part of the countersink and the rivet should be basically
flush.
Darrell
David Burton <dburton@nwlink.com> wrote:
--> RV-List message posted by: "David Burton"
> Remind me tomorrow to put an AN426AD3-x rivet in my female dimple die. I
> honestly haven't even tried that yet...but I intend to! I wonder if the
> rivet will sit flush or sit low. My $.02 bet is that it will sit low.
The rivet sets low in a regular die. Now the question is how to get the
rivet back out of the die... :-)
---------------------------------
Click here to donate to the Hurricane Katrina relief effort.
Message 18
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|
| Subject: | Re: Wing tip com antenna |
--> RV-List message posted by: sportav8r@aol.com
You'll want more than 50 miles of range if you ever call flight service for wx
at your destination.
In close formation, you are experiencing receiver front-end overload, which has
everything to do with near-field signal strength and little to do with exact
antenna location, save for its distance from the other ship's antenna.
If you want just 50 miles' range, try lopping the antenna off at 6 or 8 inches.
The high swr will fold back your radio's power output, and you'll reduce aerodynamic
drag to boot. Kidding, of course.
-Stormy
-----Original Message-----
From: Bob J <rocketbob@gmail.com>
Subject: Re: RV-List: Wing tip com antenna
--> RV-List message posted by: Bob J <rocketbob@gmail.com>
For those who have not had good experiences with the wingtip comm antennas,
please describe how you had the antenna mounted in the wingtip. I have had
people who have had these antennas tell me they work great, of those that
did they had the radiating element attached to the top surface of the
wingtip to maximize the vertical component of the antenna. In other words
the ground portion was attached to the bottom of the wingtip and the antenna
was bent so that the radiating element was glassed to the top surface of the
wingtip along its edge.
With that said...
I have a belly mounted antenna that works well on my -6, and I have borrowed
a MFJ antenna analyzer to check it. VSWR of the belly mounted antenna was
typically 1.2-1.8 best as I can remember across the frequency range. The
problem with a good antenna is that you pick up everybody and their mother
transmitting within a three state radius so sometimes the chatter can get
overwhelming especially if you only care about the aircraft that are within
a few miles of you. So to have a 50 mile radius of communications is
acceptable to me, the only time you really ever use that sort of range or
beyond is to chit-chat with your buddies on the other side of the state.
There is one RV-8 that I occasionnally fly with that whenever I get up
close, we can't talk to each other. If I back out 20 ft then everything is
fine. I suspect it has to do with the geometry in which the signals radiate
between our two airplanes. My point being is there is no perfect location
for an antenna on an RV for all circumstances.
Regards,
Bob Japundza
RV-6 flying, F1 under const.
Message 19
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| Subject: | Re: Wing tip com antenna |
--> RV-List message posted by: Bob J <rocketbob@gmail.com>
On 10/7/05, sportav8r@aol.com <sportav8r@aol.com> wrote:
>
> --> RV-List message posted by: sportav8r@aol.com
>
> You'll want more than 50 miles of range if you ever call flight service
> for wx at your destination.
I've had mixed luck getting FSS or flightwatch even with a good antenna.
If you want just 50 miles' range, try lopping the antenna off at 6 or 8
> inches. The high swr will fold back your radio's power output, and you'll
> reduce aerodynamic drag to boot. Kidding, of course.
>
I just turn the dang radio off! :)
So...how was your antenna installed; was it on the bottom surface only?
Regards,
Bob
Message 20
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|
| Subject: | Re: Firewall ?????????? |
--> RV-List message posted by: "Frank Stringham" <fstringham@hotmail.com>
Hi to all
I am at that stage in the project where I need to start formulating plans
for fire wall info. Things to contemplate, gotches to watch out for, and the
equipment needs. I will be hanging an IO 360 fuel injected, Pmags, CS
prop......................I am also considering (99% for sure) dual oil
coolers, horizontal sump........it is real out in SW Utah Desert Country.
Also the need for a gascolater considering I will have fuel
injection???????? Your help and info will be greatly appreciated.
TIA
Frank @ SGU and SLC 7A Fuse about to be rolled.....Finish kit will arrive
next week
Message 21
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|
| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: "Frank Stringham" <fstringham@hotmail.com>
Scott
Thanks for the valuable info. I would be interested in the clinched rivet
senerio. Also I would think that a head that was round and to spec but
slightly tiped would pretty much mimic your results. At any rate
thanks.....I can now breath a little more easy about some of my more
interesting buck / shot / driven RIVETS. Plus I belive that this airplane is
way over enginneered and probably has 25% more rivets than really needed .
JUST a GUESS
Frank @ SGU and SLC
>From: Dave Bristol <dbris200@sbcglobal.net>
>Reply-To: rv-list@matronics.com
>To: rv-list@matronics.com
>Subject: Re: RV-List: Properly setting rivets with dimpled surfaces
>Date: Fri, 07 Oct 2005 08:56:04 -0700
>
>--> RV-List message posted by: Dave Bristol <dbris200@sbcglobal.net>
>
>Very good report Scott! This answers some good questions that I never
>had answers for before. Thanks!
>
>Dave
>
>Scott Bilinski wrote:
>
> >--> RV-List message posted by: Scott Bilinski
><bilinski@kyocera-wireless.com>
> >
> > From another E-mail list....
> >
> >
> >Two days ago I got around to doing something that I had planned last
> >year -- actual pull tests on riveted aluminum coupons to see how
> >critical it is to drive rivets to the correct height. All of us
> >building or with completed RVs (as will those those planning on it in
> >the future) have had to wonder which imperfect rivets to drill out and
> >which are OK. The answer is obvious when there is a severe cosmetic
> >problem, but when strength is at issue, how much does a slightly under
> >or overdriven rivet affect strength? How much does a grossly under or
> >overdriven rivet affect it? Frankly, I had made the decision that the
> >risk of damage from drilling out a flush rivet is greater than the
> >benefit of doing so, unless an obvious cosmetic defect or really bad
> >rivet is at issue. Now I have some hard data to go by.
> >
> >
> >What I did was to make up 10 test coupons. Each of these consisted of
> >two pieces of .032 2024-T3 sheet 1.5 inches wide and 4 inches long.
> >These two pieces were overlapped by 1.5 inches and riveted together with
> >two parallel rows of 3 rivets each. Of the 10 total coupons, five
> >involved the use of universal head AN 470 AD3 rivets and the other 5
> >used AN 426 AD3 flush rivets. In the latter case, both pieces of
> >aluminum were dimpled at each rivet location, as is routinely done in
> >Van's airplanes. In fact, the coupon construction is similar to the
> >double rivet line where the lower outboard wing skin overlaps the lower
> >inboard wing skin. This joint is loaded in tension normally for
> >positive G flight and gave me the idea to mimic it for the pull tests.
> >
> >
> >Before getting into the results, let me ask you a question. Please
> >think about the answer before proceeding. Just how many pounds of force
> >do you think it would take to destroy one of the sheets used in making
> >up the coupons? Remember this is .032, 2024-T3 sheet 4 inches long and
> >1.5 inches wide with no holes or rivets in it. Think about grabbing and
> >suspending it at one end with some sort of clamp across the entire 1.5
> >inch width and then hanging weights on the other end from another clamp.
> >How much weight would it take to break this .032 inch thick sheet?
> >Would a 100 pound set of barbells do it? A 500 pound set? A 1200 pound
> >small car? A gross weight RV8 at 1800 pounds? A gross weight Grumman
> >Tiger at 2400 pounds? More than that? Come up with some sort of gut
> >feel before proceeding. I was surprised by the answer. You may or may
> >not be, depending on your knowledge in this area.
> >
> >
> >Since some of you will cheat and read on, I'll hold the answer for a
> >moment! Each of the 5 test coupons, both with the universal head rivets
> >and the flush head rivets, was riveted to a different degree. One was
> >grossly under driven, one was slightly under driven, one was correct per
> >the rivet gauge, one was slightly over driven and the last was grossly
> >over driven. The slightly under driven and slightly over driven rivets
> >were such that you would probably need a rivet gauge to detect them -- I
> >did this because I suspect that most of the rivets in our planes fall
> >into this category. The grossly over and under driven rivets were
> >really gross. The over driven were squashed nearly flat and the under
> >driven were barely set at all. I did this to see just how poorly a
> >joint make of this sort of gross error would hold up. You would easily
> >see these and know there was a problem immediately. You'll find the
> >results interesting.........
> >
> >
> >The idea was to put each coupon in a pull test machine and expose the
> >riveted joint to a slowly increasing force until it yielded. This was
> >done at a structural test lab in Paramount (Southern CA city) that works
> >mostly with civil engineering construction materials. A stress/strain
> >graph was running and we monitored it to see the first indication of
> >joint failure as indicated by a decrease in force required as the coupon
> >stretched, cracked, broke in two, sheared or tipped rivets, etc. I was
> >interested in the force required to cause the initial failure, as well
> >as the nature and appearance of that initial failure; ie, what actually
> >happened first. We agreed to stop the machine at the incipient
> >indication of failure, thus preserving the coupon in its early failure
> >state without destroying the joint completely. I was very curious as to
> >how things would fail and really had no idea other than the thought that
> >the dimpled, flush riveted joint would probably be stronger than the
> >undimpled one with the 470 universal head rivets. In contrast, one of
> >the owners of the lab came in to watch and thought the opposite would be
> >true. In his 50 years in the business, he had never seen this test
> >done. What do you think would hold best?
> >
> >
> >That said, here is the answer to my prior question. A force of 2300
> >pounds was required to break the test material with no rivets or holes
> >in it. It failed catastrophically shortly after some initial stretching
> >was noted. I had no idea that a cross section of this 2024 T3 sheet,
> >.032 inches thick and 1.5 inches wide, would sustain anywhere near that
> >load. Frankly, I was surprised when it passed 1000 pounds and still
> >going strong.
> >
> >
> >Before showing you the numbers, I will give a brief summary of them:
> >
> >
> >1. The dimpled, flush riveted construction was stronger, but not by as
> >much as I had thought. However, and this is really important, initial
> >failure of the dimpled construction was generally not catastrophic and
> >occurred as rivet tipping and rivet head distortion. In contrast,
> >initial failure of the AN 470 undimpled construction was generally
> >catastrophic by rivet shear. I am really happy Van uses the flush
> >riveted, double dimpled joints throughout most of the airplane!
> >
> >
> >2. Slightly under driving or slightly over driving a rivet makes an
> >observable and thus measurable difference in the joint strength.
> >
> >
> >3. Slightly over driving is stronger than slightly under driving and
> >results (in my opinion) in an insignificant difference in strength as
> >compared to properly driven rivets.
> >
> >
> >4. In the one test of slightly over driven AN 470 rivets, the joint was
> >actually stronger than with properly driven rivets. This may have just
> >been the luck of the draw for this single sample, so I wouldn't put any
> >real faith in it.
> >
> >
> >5. A joint made of grossly over driven rivets is stronger joint than a
> >joint make of grossly under driven ones.
> >
> >
> >6. A grossly under driven AN 470 joint is much weaker than a grossly
> >under driven AN 426 joint.
> >
> >
> >7. No joint was as strong as the parent material itself.
> >
> >
> >To summarize the summary, try for properly driven rivets but realize
> >that minor over driving is preferable to minor under driving and results
> >in nearly the same strength as does the condition of properly driven
> >rivets.
> >
> >
> >AN 426 AD 3 Table
> >
> >
> >Condition Force at failure Nature of failure
> >
> >
> >Gross under 1650 Rivet tipping, head distortion
> >
> >Slight under 1775 Same
> >
> >Correct 2025 Same
> >
> >Slight over 1975 Same
> >
> >Gross over 1825 Sheet tear at rivet line
> >
> >
> >AN 470 AD 3 Table
> >
> >
> >Gross under 1100 Rivet tip plus one sheared rivet
> >
> >Slight under 1600 5 sheared rivets!
> >
> >Correct 1625 6 sheared rivets!
> >
> >Slight over 1750 6 sheared rivets!
> >
> >Gross over 1500 Rivet tip plus sheet tear at
> >
> >rivet line
> >
> >
> >Anyway, those are some real numbers for an area we have undoubtedly
> >thought about at one time or another. My opinions, FWIW: I think an
> >occasional rivet that is slightly under driven or slightly over driven
> >is utterly no big deal and can safely be ignored. We all have some of
> >these flying in formation in our airplanes. A line of them would be
> >another matter. Even an occasional grossly over driven rivet is
> >probably OK, especially if getting rid of it could cause damage. And if
> >underdriven too much, just whack it again. Hope you learned something
> >from this. I certainly did.
> >
> >
> >Scott Bilinski
> >Eng dept 305
> >Phone (858) 657-2536
> >Pager (858) 502-5190
> >
> >
> >
> >
>
>
Message 22
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| Subject: | Re: Las Cruces/Santa Teresa |
--> RV-List message posted by: Ron Lee <ronlee@pcisys.net>
>Any RV-6A's going Oct. 14th--16th???
Most likely multiple 6As. Are you looking for a ride or just
want to get ideas? If you want a ride you should try to
arrange that beforehand since I seldom see people go up
once they land.
Are you close to AEG?
Ron Lee
Do not archive
Message 23
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| Subject: | Re: Properly setting rivets with dimpled surfaces (not processed: |
me...
--> RV-List message posted by: Fiveonepw@aol.com
In a message dated 10/07/2005 12:42:28 PM Central Standard Time,
matt@n559rv.com writes:
As soon as I started using a cordless electric instead of the air drill they
looked much nicer.
>>>
Ditto here- (still don't know why I bought an air drill!) See:
http://websites.expercraft.com/n51pw/?q=tools
and scroll to very bottom of page...
Mark - do not archive
Message 24
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| Subject: | Re: Las Cruces/Santa Teresa |
--> RV-List message posted by: Fiveonepw@aol.com
>Any RV-6A's going Oct. 14th--16th???
>>>>
I'd love to go but at $4/gal ga$, I'd need someone else to buy every other
tank- any takers? Contact off-list...
Mark Phillips - near Nashville (SYI)
RV-6A N51PW, 240 hours & do not archive
FMI: http://websites.expercraft.com/n51pw/
Message 25
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| Subject: | Re: Wing tip com antenna |
--> RV-List message posted by: sportav8r@aol.com
Yes, bottom surface only, curving most of the way up to the outermost edge
-----Original Message-----
From: Bob J <rocketbob@gmail.com>
Subject: Re: RV-List: Wing tip com antenna
--> RV-List message posted by: Bob J <rocketbob@gmail.com>
On 10/7/05, sportav8r@aol.com <sportav8r@aol.com> wrote:
>
> --> RV-List message posted by: sportav8r@aol.com
>
> You'll want more than 50 miles of range if you ever call flight service
> for wx at your destination.
I've had mixed luck getting FSS or flightwatch even with a good antenna.
If you want just 50 miles' range, try lopping the antenna off at 6 or 8
> inches. The high swr will fold back your radio's power output, and you'll
> reduce aerodynamic drag to boot. Kidding, of course.
>
I just turn the dang radio off! :)
So...how was your antenna installed; was it on the bottom surface only?
Regards,
Bob
Message 26
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| Subject: | Re: Wing tip com antenna |
--> RV-List message posted by: "Richard E. Tasker" <retasker@optonline.net>
Shouldn't be installed on the bottom surface (or the top surface for
that matter). It should be installed to get the maximum vertical
orientation. This means that it does not touch the internal surface of
the wingtip (at least on the 9 tips) except at the bottom of the antenna
and at the top of the antenna. Support it with fiberglass.
Dick Tasker
sportav8r@aol.com wrote:
>--> RV-List message posted by: sportav8r@aol.com
>
>Yes, bottom surface only, curving most of the way up to the outermost edge
>
>-----Original Message-----
>From: Bob J <rocketbob@gmail.com>
>To: rv-list@matronics.com
>Subject: Re: RV-List: Wing tip com antenna
>
>
>--> RV-List message posted by: Bob J <rocketbob@gmail.com>
>
>On 10/7/05, sportav8r@aol.com <sportav8r@aol.com> wrote:
>
>
>>--> RV-List message posted by: sportav8r@aol.com
>>
>>You'll want more than 50 miles of range if you ever call flight service
>>for wx at your destination.
>>
>>
>
>
>I've had mixed luck getting FSS or flightwatch even with a good antenna.
>
>If you want just 50 miles' range, try lopping the antenna off at 6 or 8
>
>
>>inches. The high swr will fold back your radio's power output, and you'll
>>reduce aerodynamic drag to boot. Kidding, of course.
>>
>>
>>
>
>I just turn the dang radio off! :)
>
>So...how was your antenna installed; was it on the bottom surface only?
>
>Regards,
>Bob
>
>
>
>
--
----
Please Note:
No trees were destroyed in the sending of this message. We do concede, however,
that a significant number of electrons may have been temporarily inconvenienced.
----
Message 27
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| Subject: | Re: Properly setting rivets with dimpled surfaces |
--> RV-List message posted by: "Dan Checkoway" <dan@rvproject.com>
http://rvproject.com/images/2005/20051007_rivet_in_dimple_die.jpg
That's a standard AN426AD3-3 rivet sitting in the female 3/32" dimple die.
According to Avery, where I bought it, it's a "springback" dimple die. As
you can see, the rivet sits WAY lower than flush. It's a fuzzy photo
(sorry), but you can still see it. It's more than just the acceptable
"halo" that has been mentioned.
The rivet is definitely sitting considerably below the face of the die. I'm
not saying this is a problem, it's just representative of the possibilities.
I can only surmise that it's the "springback" nature of this die set that
allows the aluminum to be bent *past* the point of rivet-size, because (as
the theory goes) the metal is supposed to spring back to the proper bend.
Or does it... ;-)
Anyway, my point is that it's at least _conceivable_ that the convex side of
a dimple may not be the EXACT same size as a rivet head.
)_( Dan
RV-7 N714D
http://www.rvproject.com
----- Original Message -----
From: "Dan Checkoway" <dan@rvproject.com>
Subject: Re: RV-List: Properly setting rivets with dimpled surfaces
> Remind me tomorrow to put an AN426AD3-x rivet in my female dimple die. I
> honestly haven't even tried that yet...but I intend to! I wonder if the
> rivet will sit flush or sit low. My $.02 bet is that it will sit low.
>
> I'll try to remember to check it out tomorrow...
>
> Also, there is a distinction between "spring back" dimple dies and the
> regular flavor. The end result is supposed to be the same but it may not
> be.
>
> do not archive
> )_( Dan
> RV-7 N714D
> http://www.rvproject.com
>
> ----- Original Message -----
> From: "Rob Prior (rv7)" <rv7@b4.ca>
> To: <rv-list@matronics.com>
> Sent: Thursday, October 06, 2005 9:53 PM
> Subject: Re: RV-List: Properly setting rivets with dimpled surfaces
>
>
>> --> RV-List message posted by: "Rob Prior (rv7)" <rv7@b4.ca>
>>
>> On 18:57:18 2005-10-06 "D.Bristol" <dbris200@sbcglobal.net> wrote:
>>> --> RV-List message posted by: "D.Bristol" <dbris200@sbcglobal.net>
>>> Be careful here. With a quality dimpling die, the under side of a
>>> dimpled hole is the same size as the top. You can see this when you
>>> put 2 dimpled sheets together - they fit just fine. However, when
>>> fitting the dimpled sheet into a countersunk piece you can have a
>>> problem with fit because the edge of the countersunk hole is sharp
>>> and the corresponding point on the bottom of the dimple is not,
>>> (quality "spring back" dies may give a sharper transition than cheap
>>> dies) especially if you didn't use enough force when forming the
>>> dimple.
>>
>> The engineer in me must speak up: A countersunk hole will always have a
>> sharp transition at the top corner, unless you remove it. A dimpled
>> piece
>> of aluminum will always have a rounded (or filleted) corner in the
>> corresponding location. This means you will end up with one of two
>> situations:
>>
>> One, you can countersink until the skin sits flat, in which case there
>> will
>> be an air gap under the dimpled skin in the "cone" of the countersink.
>> You
>> don't want this. It's not as strong a joint, and can lead to corrosion
>> in
>> the cavities, well beyond where you can see it happening.
>>
>> Two, you can countersink to fit the rivet, in which case the skin will
>> *not* sit flat in the countersink. This is not a problem, if your dimple
>> is good. When you drive the rivet it will drive that rounded corner into
>> a
>> sharp one and it will all become flush. This is what you want.
>>
>> So: Countersink only far enough to fit the head of the rivet. There's no
>> reason to go further
>>
>> As for drilling a smaller hole so everything is "tighter", the engineer
>> in
>> me says you will end up with a smaller diameter of "meat" in the hole
>> once
>> the rivet is driven. This means that every rivet joint will be slightly
>> less strong than it was designed to be. Which means your airplane is
>> slightly less strong than it was designed to be. Why would you want
>> that?
>>
>> Stop second-guessing the designer.
>>
>> -Rob
>>
>>
>>
>>
>>
>>
>
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