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Flush mounted static port

PrescottB787

Active Member
Can anyone point me in the right direction for a flush mounted static port. Chose not to go with Vans static port. Seem to me that with a flush mounted port there is less error.

Thanks
 
It has been shown time after time that Van's "rivet" static port is the most accurate.

Doesn't have to be the "pop rivet" as such, but the same basic configuration. i.e. Not "flush".
 
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Data?

I would like to see substantiated data on that statement versus other machined options such as the safe air 1 ports or any of the other machined ports.

Not trying to be difficult but I am a numbers guy (engineer) and am partial to substantiated data. Searching these boards I find a bunch of anecdotal evidence supporting every different opinion. Usually the guys that use the pop rivet say it works great and the same can be said of the guys using machined products.

Though I am not flying yet, I chose a machined product that has the same exterior profile as the pop rivet. There should, therefore, be no discenable difference in accuracy between the two...we will see.

Just seems like a really hokey way to put a static port on a $160k plane...pop rivet with stem removed and a blob of proseal...whatever works, I guess...
 
Flush Static

Hi Ken,

I used some beautiful flush mounted static ports that included some really neat "O" Ring sealed connectors on my last RV9a build. If memory serves, they were from a company out of the Dallas-Ft. Worth area. It was a mistake! The airspeed was way off using these and, after much trial and error, I found that moving the port out from the skin about .040 gave me the accuracy that I needed---and not coincidentally .040 is about the height of the Vans pop rivet system. Just my experience and consistent with the experience of many other folks-- as Mel points out!

Cheers,

db
 
So you want three quotes, and a background check?

I would like to see substantiated data on that statement versus other machined options such as the safe air 1 ports or any of the other machined ports.

Not trying to be difficult but I am a numbers guy (engineer) and am partial to substantiated data. Searching these boards I find a bunch of anecdotal evidence supporting every different opinion. Usually the guys that use the pop rivet say it works great and the same can be said of the guys using machined products.

Though I am not flying yet, I chose a machined product that has the same exterior profile as the pop rivet. There should, therefore, be no discenable difference in accuracy between the two...we will see.

Just seems like a really hokey way to put a static port on a $160k plane...pop rivet with stem removed and a blob of proseal...whatever works, I guess...

The information is here within VAF -

After many hours of research and gathering - I used the SafeAir one, but cut off the tip in a lathe and used the Vans (baffle) rivet (lots of proseal) to attach it to the skin. So got the external profile and internal 1/4 NPT attach. There is a rivet profile copy now- Cleaveland I think.
 
Wow, that didn?t take long...

A guy asks for substantiated data between the two and gets attacked immediately. Glad I didn?t ask about priming!
 
Not an engineer

But I was also not quite happy to live with the pop rivet head as per Vans instructions.
However, there was no need for me to see numbers to believe that the shape of a protruded rivet head was in fact the most accurate static port known to RVs.
I used one of the flush versions after market static ports attached with 4 rivets and a proper female 1/8 NPT
on the inside.
I Enlarged the static port to accept a solid AN470 rivet head with the center of the rivet drilled for the static port. Glued in with Pro seal or JB weld.
Looks beautiful and I can't detect a static error.
 
A guy asks for substantiated data between the two and gets attacked immediately. Glad I didn?t ask about priming!

I don't think anyone is "attacking" you. They're simply pointing out that there is much substantiated data to be found by searching past posts.
 
But I was also not quite happy to live with the pop rivet head as per Vans instructions.
However, there was no need for me to see numbers to believe that the shape of a protruded rivet head was in fact the most accurate static port known to RVs.
I used one of the flush versions after market static ports attached with 4 rivets and a proper female 1/8 NPT
on the inside.
I Enlarged the static port to accept a solid AN470 rivet head with the center of the rivet drilled for the static port. Glued in with Pro seal or JB weld.
Looks beautiful and I can't detect a static error.

Exactly what I did with an old Cleavland (?) flush static port, except mine had a metal barbed attachment on the inside.

I used a 3/16 AN470 rivet and kept sanding it down until I got within 1 kt of error. I ended up at about 0.050" protrusion above the skin.
 
Yes

Yeah, attacked was not the right word. What I was after was someone who had actually tested the two and documented the resulting differences. Like I said, I?m kind of a numbers guy...
 
Yeah, attacked was not the right word. What I was after was someone who had actually tested the two and documented the resulting differences. Like I said, I’m kind of a numbers guy...

The "crude" Vans static ports have been a point of discussion since I first started participating on RV forums twenty years ago. Numbers or no numbers, a host of builders have found out after dealing with airspeed errors that flush ports just don't work as well in our aircraft as those that have a profile similar to a rivet head. This question was settled many years ago by actual field experience, guess that is a form of testing.

By the way, my RV-6 has been flying with the pop rivet ports since 1999....I never notice them and they have never required any maintenance. :)
 
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Another example of where "per plans" is easiest, cheapest, safest, and offers the best performance. The only reason I have ever heard not too is some feel the pop rivet approach isn't sturdy, or appears "hokey". However, time has proven otherwise.
 
And...

Some here are content with the ?That?s the way it has always been done, so it?s the best, cheapest, and safest way? mentality. That is great and it is your opinion, however, consider this: If Van himself subscribed to that mentality, would there even be an RV-anything.?

You will certainly not get into any ?hot water? building strictly to the plans but that doesn?t necessarily mean there aren?t better ways to accomplish things...

I chose to use a machined static port with the same surface profile as the rivet, while providing a more refined way of attaching the corresponding lines. From an engineering standpoint, there should be no discernible difference between the two. That remains to be seen and thus the question for DATA was posed. I will not argue that the rivet works; as has been stated, it does. I am looking for quantifiable data between the two...

I don?t suppose anyone here has modeled the -10 in a CFD program, have they? If so, I would be interest in the theoretical pressure distributions on the fuselage and fuse/wing intersection...
 
It's not an opinion. It is a simple fact, proven over thousands of installs and tens of thousands of hours in practical use.
However, the beauty of experimental aviation is you are free to do what you will. You don't need a reason. If you don't like how it is engineered, you certainly can re-engineer it to your liking.
I have a better tail wheel and fork, and other not per plans stuff in my build, but the static port just didn't seem to be an area I wanted to mess with. The archives contain many threads on this subject.
 
Don't go flat

Flat static ports on the RV-10 will cause excessive inaccuracy. I didn't want to use the rivet method either, so I bought some nice Cleavland flat ports. After flying a while I found them to be horribly inaccurate. At that time they also started selling domed ones, so I had to pull mine out and install new ones. The domed ones are much more accurate. I found that you could make them even more accurate by adding dams in front of them but I don't use them anymore.

Just don't go with flat ports. You need them to protrude.
 
Sheesh

I think some out there need to READ the post before jumping into the fray.

I never said I disagreed with the field results, I only asked for quantifiable data on the difference.

I also am using a protruding head machined port that matches the rivet head but allows for a pipe fitting on the back side.

I am just looking for data from an engineering perspective. My ports are already installed...
 
Anecdotal evidence is still valid evidence. Perhaps one might look at it as the basis for a statistical comparison.

I'd trade flight test any day for CFD modeling. This reminds me of the old question, what is the difference between theory and practice? In theory, there isn't any difference - but in practice, there is.

Dave
 
Some here are content with the “That’s the way it has always been done, so it’s the best, cheapest, and safest way” mentality. That is great and it is your opinion, however, consider this: If Van himself subscribed to that mentality, would there even be an RV-anything.?

You will certainly not get into any “hot water” building strictly to the plans but that doesn’t necessarily mean there aren’t better ways to accomplish things...

Valid point.

But the flip side of that is that right now there are probably 100's (yes that is plural) of RV's flying with airspeed indicator error because the original builder thought that because a different manufacturer/vendor made and sold a static port that looked less hokey to them, that it would be better.

A lot of those airplanes wont ever get fixed until the builder or a future discriminating owner is annoyed by it enough to research how to fix the problem. The forums are full of threads started by people doing just that.

I imagine your response will now be that that is what you are doing. Researching.

Another valid point.

And the responses from a number of very experienced RV builders to your info inquiry should be enough to decide that your static ports should at least mimic the shape of the hokey ones.
Nothing wrong with wanting actual data, but even if some one had it, how do you know data from one single person is more valid than the consensus of the combined experience of an entire online forum?
 
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I succumbed to my engineer's desire to "improve" the static ports on my RV-9A several years ago. However, by that time I had already read dozens of posts regarding the shape, size and location of the static ports. So I carefully measured the shape of the standard pop rivet and duplicated that shape outside of the skin. On the inside of the skin I machined a flange which I riveted to the skin and on the inside of the flange I machined a 1/8" NPT female thread to attach screw type pneumatic fittings. I'm very satisfied with the results (not flying yet), but I have to say whenever I make one of these improvements, I find it's heavier and way more work (and usually more expensive) than the solution in the plans. Luckily I have a lathe, mill and drill press.

There is a great article "Static Port Location and Altitude Calibration" in the October 2017 Kitplanes magazine that is well worth reading. It used CFD and experimentation. Way too much work to do this when we know the shape and location of the static ports in the plans works.

Which reminds me of a CFD joke:
Theory is when you know everything but nothing works
Practice is when everything works but no one knows why
In CFD theory and practice are combined: nothing works and no one knows why.

OK a little harsh, and CFD is much better now than the last time I ran any in the 1980s, better, faster computers and much better code. But there's still some black magic.
 
Again

As simple as I can say it:

1. I am not disputing the field data that the pop rivet works, it does.

2. I am using a machined static port WITH THE SAME PROFILE as the rivet.

3. I am using the machined part to take advantage of the NPT fitting inside.

4. I wondered if anyone had documented data for differences between the two.

5. I am curious, from an engineer's perspective, what the difference is, that's all.

To your point about researching, no, I did that before I decided on the ports that I have already installed (several years ago). That research is the reason that the ports I selected have the same 3D profile as the rivet they replace. There should be no discernible difference between these ports and the rivets.

I do appreciate the advice and knowledge available on this forum and it has saved me many, many hours of build time and an unknown amount of dollars saved...

Hopefully, I will soon join the ranks of flying RVs...
 
Yeah, attacked was not the right word. What I was after was someone who had actually tested the two and documented the resulting differences. Like I said, I?m kind of a numbers guy...


I am the ultimate numbers guy :D Data has no opinion.

There is no doubt a post of mine going back to about 2009 when I went down this road. We fitted the machined ports (probably from A/spruce) as the SafeAir may not have been on the market then.

The story goes like this.....flew the plane, it had a VERY slow TAS, 9 knots slow. Did a GPS box to verify it. Static error also meant a large altimetry error too, I think about 140 feet I calculated at the time.

I thought glue a vans rivet head on, see what happens. WOW...now I had the fastest RV10 in the world, but the GPS box proved the error swung the other way. I thought lets try a file and see if I can change them.....it worked a bit. Out of frustration I thought lets try a "fence" like some certified aircraft have. I had some aluminium welding rod handy, which I made into an arc and some epoxy glue. This was only temporary right!

https://encrypted-tbn0.gstatic.com/...AlgzfFLeR2uuzRSvnYz2eqGBCxt-KD9XKDiv02FUfjzGV

Well that worked..... with less than 2 knots error at any test, it was a wash. Now ask me what I did with those temporary additions? :roll eyes: Yes still there.

Use whatever you like but a GPS box is the only way to test/correct for error. And yes I have had to help correct many others since with various methods.
 
I have responded in red and caps.....not because I am SHOUTING at you, but for clarity or who wrote what. Hope this helps you understand they why's and where's. ;):)

As simple as I can say it:

1. I am not disputing the field data that the pop rivet works, it does. NOT ALWAYS - YOU MUST TEST

2. I am using a machined static port WITH THE SAME PROFILE as the rivet. MEANS NOTHING - YOU MUST TEST

3. I am using the machined part to take advantage of the NPT fitting inside. GREAT - THAT IS WHAT WE THOUGHT AND DID

4. I wondered if anyone had documented data for differences between the two. DATA FROM ANYONE, I HAVE A SPREADSHEET, BUT IT JUST PROVES WHAT I EXPLAINED IN THE PREVIOUS POST. THE NUMBERS WERE ONLY USEFUL TO ME ON MY PLANE, MAY NOT APPLY TO YOURS.

5. I am curious, from an engineer's perspective, what the difference is, that's all. UNLESS YOU WIND TUNNEL TEST IT IS HARD TO SAY

To your point about researching, no, I did that before I decided on the ports that I have already installed (several years ago). That research is the reason that the ports I selected have the same 3D profile as the rivet they replace. There should be no discernible difference between these ports and the rivets. SAME SIZE, SHAPE AND UNDETECTABLE TO THE HUMAN EYE THE SAME?

I do appreciate the advice and knowledge available on this forum and it has saved me many, many hours of build time and an unknown amount of dollars saved...

Hopefully, I will soon join the ranks of flying RVs... YOU WILL BUT THE TEST FLIGHT PERIOD IS WHERE YOU IRON OUT THE BUGS. BOEING AND AIRBUS DO THE SAME.
 
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