VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-10
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 10-01-2017, 11:26 AM
Sam Buchanan's Avatar
Sam Buchanan Sam Buchanan is online now
hall monitor
 
Join Date: Dec 2004
Location: North Alabama
Posts: 3,473
Default

Quote:
Originally Posted by rocketman1988 View Post
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.
__________________
Sam Buchanan
1999 RV-6
1918 Fokker D.VII replica

Last edited by Sam Buchanan : 10-01-2017 at 11:32 AM.
Reply With Quote
  #12  
Old 10-01-2017, 11:39 AM
JonJay's Avatar
JonJay JonJay is offline
 
Join Date: Jan 2007
Location: Battleground
Posts: 3,586
Default

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.
__________________
Smart People do Stupid things all the time. I know, I've seen me do'em.

RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
Reply With Quote
  #13  
Old 10-01-2017, 12:04 PM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 690
Default 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...
__________________
Bob
Aerospace Engineer '88

RV-10
Structure - 90% Done
Cabin Top - Aaarrghhh...
Doors - Done
On Gear
290 HP Barrett Hung
ShowPlanes Cowl with Skybolts Fitted - Beautiful

Dues Paid 2016,...Thanks DR+
Reply With Quote
  #14  
Old 10-01-2017, 01:20 PM
JonJay's Avatar
JonJay JonJay is offline
 
Join Date: Jan 2007
Location: Battleground
Posts: 3,586
Default

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.
__________________
Smart People do Stupid things all the time. I know, I've seen me do'em.

RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
Reply With Quote
  #15  
Old 10-01-2017, 02:01 PM
TimO TimO is offline
 
Join Date: Feb 2005
Location: Wisconsin
Posts: 330
Default 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.
__________________
Tim Olson - CFI
RV-10 N104CD - Flying 2/2006 - 1200+ hours http://www.MyRV10.com
RV-14 N14YT - Flying 6/2016 - 150+ hours http://www.MyRV14.com
RV-10/14 Transition Training: http://www.RVCFI.com
Reply With Quote
  #16  
Old 10-01-2017, 04:04 PM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 690
Default 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...
__________________
Bob
Aerospace Engineer '88

RV-10
Structure - 90% Done
Cabin Top - Aaarrghhh...
Doors - Done
On Gear
290 HP Barrett Hung
ShowPlanes Cowl with Skybolts Fitted - Beautiful

Dues Paid 2016,...Thanks DR+
Reply With Quote
  #17  
Old 10-01-2017, 04:20 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 3,196
Default

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
Reply With Quote
  #18  
Old 10-01-2017, 06:31 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 6,856
Default

Quote:
Originally Posted by rocketman1988 View Post
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?
__________________
Any opinions expressed in this message are my own and not necessarily those of my employer.

Scott McDaniels
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")

Last edited by rvbuilder2002 : 10-01-2017 at 06:34 PM.
Reply With Quote
  #19  
Old 10-01-2017, 06:59 PM
terrye terrye is offline
 
Join Date: Feb 2010
Location: Vancouver, BC, Canada
Posts: 636
Default Flush mounted static port

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.
__________________
Terry Edwards
RV-9A (Fuselage)
Reply With Quote
  #20  
Old 10-01-2017, 09:51 PM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 690
Default 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...
__________________
Bob
Aerospace Engineer '88

RV-10
Structure - 90% Done
Cabin Top - Aaarrghhh...
Doors - Done
On Gear
290 HP Barrett Hung
ShowPlanes Cowl with Skybolts Fitted - Beautiful

Dues Paid 2016,...Thanks DR+
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 08:44 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.