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lacofdfireman

Member
I am sure this is a dumb question and the fact that why would you even want to build an RV with a pop or Pulled rivet will be mentioned but I am curious as to if it can be done... Downsides besides looks and aerodynamics? Is there issues with structual integrity also? I am years away from being able to build but I like to lurk and ask dumb questions... Someday though I will have me a tungsten bar and be bucking rivets on my own RV7A... It's a dream at this time in my life but one day it will happen...
 
I don't know about structural issues but the resale value would probably be close to zero.
 
There is a local Mustang II built with 'round head' rivets.
That, plus it's sitting on tricycle gear. It took me a while to realize it is a Mustang!
I did not meet the owner to get his comments on performance. I know I went thru a lot of hassle dimpling and all, but seeing is believing in this (close enough) case.
 
Pulled rivet structures can be just as strong as driven-rivet structures, so there's no issues there. The number of rivets may need to be adjusted to match the strengths. Aerodynamically? Well, you could always use countersunk pulled rivets (in dimpled holes) and then fill in the holes, but it would be almost as much work as just using solid ones in the first place.
 
Why would you want to?

...not a dumb question. Pop rivets generally have less structural integrity, poorer aerodynamic properties, higher weight, and/or higher cost. The RV-12 can pull this off because of its lower airspeed and performance requirements with "lower quality" pop rivets. But why would you want to consider pop rivets for a higher performance aircraft? The pop rivets generally included with RV kits do not have the same structural integrity as the prescribed driven rivets. You would need to use Cherry rivets or equivalent structural rivets to achieve the same or similar structural strength. This would require much higher additional cost and weight to achieve the same or similar performance, with absolutely no advantage over driven rivets. Driven rivets are the most aerodynamic, lightweight, cost-effective solution available, and that is why Van's specifies them. In my RV-7 I only use pop rivets where I absolutely cannot use driven rivets.

By the way, I built my entire "standard build" RV-7 without a tungsten bucking bar. While it may be easier, it's not totally necessary (although I wish I had purchased one when I started my project).
 
However...

...Vans early RV-6 instructions say that it is permissible to rivet the entire lower wing skins with countersunk CS-4-4 or MK-319-BS rivets - so they are structural enough for wing skins.

But, as said above, it would look ugly....:(
 
Sparky said:
The RV-12 can pull this off because of its lower airspeed and performance requirements with "lower quality" pop rivets. But why would you want to consider pop rivets for a higher performance aircraft?
Click to expand...

Actually the RV-12 being lower performance has very little to do with an industrial grade blind rivet being acceptable as a rivet fastener.
It is primarily related to the structure being designed to use a rivet fastener with a given strength rating. If a replacement rivet of a strength equal to the ones it is replacing is used, then blind rivets could be substituted for most of the rivets in an RV (but it wouldn't be very practical for all of the reasons already mentioned).
 
No, Really! Why would you want to???

The only reason (that I could think of) for a lurker to ask this question, is that he may think that it's simpler to pull pop rivets than it is to buck rivets. If someone thought that they were going to spend a lot of time with little or no help, they may think that they couldn't shoot rivets by themselves.

If that's the reason for this question, then the real question should be "Can I shoot and buck rivets without assistance?"

The answer (for about 95% of the rivets on an RV) is YES! Very few of us had an assistant standing by with a bucking bar, just waiting for us to match-drill, deburr, countersink, and then buck a rivet. Most of us simply prepared the area, loaded the rivets in the prepared holes, picked up a 3X rivet gun in one hand and an bucking bar in the other, and pounded rivets. After bucking a handful of rivets, you'll get pretty good at bucking/shooting your own rivets. Much easier than pulling pop rivets, and more pleasing to the eye!

There are a few areas where assistance is required. For example, when you're closing out the wing skins, you're going to need help. Also, when you're closing out the skins on the fuselage. By the time you get to that stage of the construction, you'll probably have met a few RVers who would be happy to stop by, buck a couple of rivets, and drink your beer.
 
lacofdfireman said:
I am sure this is a dumb question and the fact that why would you even want to build an RV with a pop or Pulled rivet will be mentioned but I am curious as to if it can be done... Downsides besides looks and aerodynamics? Is there issues with structual integrity also? I am years away from being able to build but I like to lurk and ask dumb questions... Someday though I will have me a tungsten bar and be bucking rivets on my own RV7A... It's a dream at this time in my life but one day it will happen...
Click to expand...

It is most certianly not a dumb question! In fact, almost the same question like this came up some months ago, and the answer was except for the wing spars, then the answer was a "yes" provided that the correct type of pop rivets are used.

However, these type of rivets are a good bit heavier than the solid rivets so there will be a weight penalty. Also, they will not be quite as aerodymanic and using them so extensively may hurt the resale value.

But, if you are looking for a more authoritative answer, then I suggest that you ask Vans.

I hope this helps!
 
I actually do know of an older gentleman building an 8 with strictly pop-rivets. However, I believe he is in his late 80's and the plane will realistically never fly, its more of a hobby and just giving him something to do.
 
Gentleman.... one word of advice as an A&P with lots of technical experience under my belt....In my eyes, our hobby/our passion is way to fragile as it is in the public opinion forum to take unnecessary risk when working your own aircraft.

Use FAA AC43.13 as the Acceptable Methods, Techniques and Practices on how to build an aircraft. Take the guessing factor out of the equation. Good reading for those with no experience, little experience, some experience and lots of experience. This is the bible on whats accptable when working in your aircraft....Certified, experimental or hangar queen.....

I have found myself reviewing this same data over and over for the last 25 years both as an A&P and aircraft owner performing my own maintenance.

I make it easy for you....

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/ccfe0d58d41d2c8086256a55006c6b67/$FILE/AC43.13-1b.pdf

Section 4-120 starts talking about the different rivets...


As to the direct answer to your question:

Blind rivets are used when there is access to only one
side of the structure. Typically, the locking
characteristics of a blind rivet is not as good as a driven
rivet. Therefore, blind rivets are usually not used when
driven rivets can be installed.

Self plugging rivet may be installed when there is
access to only one side of the structure. The
blind head is formed by pulling the tapered
stem into the hollow shank. This swells the
shank and clamps the skins tightly together.
When the shank is fully upset, the stem pulls
in two. The stem does not fracture flush with
the rivet head and must be trimmed and filed
flush for the installation to be complete.
Because of the friction-locking stem, these
rivets are very sensitive to vibrations.



read the last sentence...hope this answers your questions
 
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That said, I believe there are a number of successful designs that use blind rivets as the primary fastener -- the Zenith and Murphy lines come to mind. However, they were designed from the get go to use those types of fasteners. My point is I think blind rivets can be used if the engineering supports it, but I wouldn't think you'd want to substitute blind rivets for solid rivets wholesale without some sort of analysis. YMMV...
 
Of course, the smart-aleck response to the original question is "of course!" The RV-12 is completely built with pop rivets....:)
 
Ironflight said:
Of course, the smart-aleck response to the original question is "of course!" The RV-12 is completely built with pop rivets....:)
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I think this is kinda where I was going with this question because I have a neighbor that is building a Sonex with pop rivets... So it just made me wonder if the Van's aircraft was able to be built like that... I had no idea the RV12 was built like that... Also I would have no intentions of building an RV with pop rivets based on looks alone... A sexy airplane such as the RV 7 would just not look right with them... JMHO...
 
az_gila said:
...Vans early RV-6 instructions say that it is permissible to rivet the entire lower wing skins with countersunk CS-4-4 or MK-319-BS rivets - so they are structural enough for wing skins.
Click to expand...

I believe the rivets commonly suplied in the Vans kits are not Cherrymax. I assume they are considered "friction lock"?

In the AC 43 book, I do not see these described in terms of their strength or relative strength (to standard driven rivets). So how does one know if they are a strong enough substitute for driven rivets?

Bevan
 
I used several hundred MK-319-BS rivets to close out my QB wings.

The strength of these rivets is 258Lbs in shear and 292Lbs in tension.

Your average 426AD3 rivet has a shear strength of 180Lbs and a tensile strength of 262Lbs.
 
Bevan said:
I believe the rivets commonly suplied in the Vans kits are not Cherrymax. I assume they are considered "friction lock"?

In the AC 43 book, I do not see these described in terms of their strength or relative strength (to standard driven rivets). So how does one know if they are a strong enough substitute for driven rivets?

Bevan
Click to expand...

The manufacturers data usually over-rides any general FAA data.

Vans early written instuctions for the RV-6 (and probably the RV-4) says specifically that the rivet substitution is acceptable and gives the type of rivets.
 
Pulled Rivet Strength

Many pulled rivets are stronger than solid -AD rivets. They're also many times more expensive. The CCC-32 cherry rivet is stronger than an AN426AD3- rivet, BUT costs $246 for 3000 (ACS gives discounts when you buy lots). The AN426AD3-3.5 costs $23.23 for the same quantity.

I also wonder what's going to happen to all these pulled rivets in 1000hrs. Are they going to slowly vibrate loose? They sure aren't set with the same force as a solid rivet. I've heard of CherryMax rivets vibrating loose, and they're set with a lot more force than the pulled rivets in RV kits.

Disclaimer: Price examples are in CAD.
 
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The Thorp T-18 (NOT referring to the T-211 light sport) was designed for construction with pulled rivets, and many of them are very close to the same performance as RV's with the same engine. 180-190 mph cruise speeds are common with higher HP models. While they don't look as 'slick' as a flush riveted RV, they still look good and fly very well. And they were also designed to be built from scratch, at home, using matched hole tooling, long before the 1st RV-1 was conceived.

So yes, pulled rivet construction can work very well.

Charlie
 
DakotaHawk said:
There are a few areas where assistance is required. For example, when you're closing out the wing skins, you're going to need help.
Click to expand...

Actually on the RV-4 I built I bucked all the wing rivets solo. Wing was placed in horizontal position and from either leading or trailing edge I was able to reach as required. Now my arms are fairly long (35" inseam) but in no case was I straining to reach. In fact the only rivets I required assistance in bucking were those on the top of the fuselage. Only way to get those is somebody crawling into the tunnel.

Riveting seems to be a huge psychological barrier in that it seems like it must be very difficult, physically demanding, or both. Personally before I jumped in and did it I thought it was going to be a "big deal". After watching a few videos and practicing on some scrap a bit I dived in and got good at it in short order. Sure I had a few "dings" and "smileys" along the way but nothing all that bad and I considered it part of the learning process. The one skill it took a bit longer to get good at was drilling out bad rivets. That took me awhile to do and made me reluctant to drill out marginal rivets lest I make the situation worse. Now I can drill out a rivet in noting flat. The lesson: the only way to learn is to do it and you will make mistakes. None of them will likely be fatal in the sense you will destroy a part and almost all can be "repaired" so that none will be detected. OK if you plan to polish your airplane and go for an award maybe you should build one for practice first that you won't mind having a bit of filler covering the few mistakes. And on that vein - always rivet the bottom parts first. :)

Making pulled rivets look as good as driven rivets is way more work and cost more money. The costs of tooling is a tiny fraction of what you need to spend in any event. If tool costs are holding you back consider I built the RV-4 with a small air compressor and rivet gun as the only power tools. Later added a small drill press because in those days you had to cut your won lightening holes in the ribs. I can't believe it but I cut all the reinforcement angles for the ribs with a hack saw and filed the ends by hand. Yes having the power sander, chop saw, drill press, bandsaw, etc. makes things go faster it really isn't required to have to build an RV. But a rivet gun and air drill...pretty much table stakes.
 
POP RIVETS

John Thorp approved the use of monel pop rivets in the assembly of the T-18. They are stronger than AN in schear but not as strong in tension. Rivets are not intended to be used in tension anyway. That is not to say that they would be good for an RV. The T-18 uses 1/8 inch rivets where most on the RV are 3/32.
 
Not quite.

Wally said:
Rivets are not intended to be used in tension anyway. .
Click to expand...

....er, All the rivets that hold the top skin on, where lift is created, are in tension. You can easily see that in flight, because the skin bulges upward between the ribs.

Best,
 
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