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  #41  
Old 01-25-2012, 05:37 AM
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Geico266 Geico266 is offline
 
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Quote:
Originally Posted by DonFromTX View Post
Great idea, I was about to post the same thing. At least we will feel we are making some sort of progress rather than just stalling.
Not a bad time to figerglass the wing tip close out also. There is a lot you can do to improve the looks and performance of the -12.

Keep us posted of your progress guys!
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  #42  
Old 01-25-2012, 02:33 PM
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Default Flush Rivets

Quote:
Originally Posted by RudiGreyling View Post
Joe what methods have you been using on your flush RV12? Rudi
My web site shows each time I time made an alteration from the plans.
I have an engineering back ground and very comfortable with all my deviations.
This is not an endorsement to follow my alterations; this should only be preformed if you know what all the loads applied to each occurrence of the deviations.
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  #43  
Old 01-27-2012, 08:55 AM
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Larry I have a couple of questions:
Did you have trouble putting rivet hole filler on the sides and underbelly, did the stuff want to run back out?
I have lost my information on wing tip finishing, can you give me a link or hint as to where to go for this information?

Quote:
Originally Posted by Geico266 View Post
Not a bad time to figerglass the wing tip close out also. There is a lot you can do to improve the looks and performance of the -12.

Keep us posted of your progress guys!
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  #44  
Old 01-28-2012, 02:45 PM
aerofurb aerofurb is offline
 
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Quote:
Originally Posted by Bill_H View Post
Lets do a little simple arithmetic.
For a 400nm trip, "flushing" saves about 6 minutes. (say 110kt vs 113 kt).
Now, for some reason the term 'flushing' amuses me and should be the term used in future for this subject.

We decided in the end to leave the rivets au naturel but would have filled them if we had time before painting, purely for the aethetics.

Flushing through the use of countersunk rivets on an RV-12 is really not worth the effort (in my humble opinion) for an aircraft in this speed range.
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  #45  
Old 01-29-2012, 11:16 AM
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Default Flush Rivets Re-think

One more Thing
3500 Hrs x 3 mph = Free 10500 miles @ 20 MPG = 525 Gallons @ $4.00 = $2100 for 100 Hrs Work = $21 Dollars per hour of work + or -. Times the number of times the 12 add's 3500 hrs to it's total time.

Pluss
Aesthetics and ease of waxing.
And I think 100 hours may be a little high but close.

Re-think

Quote:
Originally Posted by Bill_H View Post
Lets do a little simple arithmetic.
Say it takes 100 hours of extra build time for the flush riveting. This is probably low.
Lets say the result is a 3 kt speed increase (probably WAY high).
For a 400nm trip, "flushing" saves about 6 minutes. (say 110kt vs 113 kt).
One must therefore make one thousand such trips to break even on time saved when flying vs. extra time spent in building.
That means breakeven does not occur until the plane reaches more than 3500 hrs total time.

Aesthetics might be a reason and justification, but not speed unless we are kidding ourselves! But hey, I've spent a lot of time on aesthetics on my plane, and part of the great thing about building is that we can have the result that we want and be proud of our workmanship! There was a -12 at OSH in 2010 that had all of the rivets filled before painting. Took lots of time and effort to do that, looked beautiful.
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  #46  
Old 01-29-2012, 12:08 PM
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Flyfalcons Flyfalcons is offline
 
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Lots of figuring going on here when the undisputed correct answer of why someone would want to flush rivet the 12 is simply "...because I want to".
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  #47  
Old 01-29-2012, 12:16 PM
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gblwy gblwy is offline
 
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Default Your calc, my numbers

Hey Joe, I like the way you are thinking. For me the numbers are different:

1000 hours (I don't care if someone else gets the benefit after that)
$9 per gallon here in the UK
30 hours effort expended using Superfil - I excluded having to do one wing twice (that's another story) ;-)
For me that comes to ?10 or $15 per hour, which isn't bad for a hobby.

And my real purpose was for polishing. This is the second black pop-rivet plane I have owned. I don't polish too often, but you only need to do it once or twice to fill the rivet holes with white polish - which looks daft on a black plane ;-)

Cheers...Keith
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  #48  
Old 01-29-2012, 01:12 PM
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Bill_H Bill_H is offline
 
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Ryan is exactly point on. Do it if you want to, but don't expect any economic benefits. 3 Kts difference simply won't happen - I really doubt if it would even be measurable. (I think Vans wrote about this in an RVATOR). The calculation was to just show how, if everything is outrageously optimistic, that the benefits are still nil. And, filling the rivets is not the same as using flush rivets. Don't confuse the two, the time investments will be very different.
BTW to get really nitpicky about it, you might want to do a Net Present Value calculation. You are doing 100 hours of work "now" for a stream of money to be paid back over many years, and the value of that future money is less.
But Ryan has the correct answer - bragging rights! We all want a plane that is slightly different and gets some oohs and ahs...
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  #49  
Old 01-29-2012, 03:38 PM
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joedallas joedallas is offline
 
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Default Fulsh Rivets Re-Think for Speed

Bill with all due respect
2.60 knots is not 3 knots and at 120 Knots --138mph I think 3 mph is a real number.

And not to mention the color difference

Black is faster by keeping the air near the surface warmer; it reduces the viscosity of the air in the boundary layer. This reduces drag, ....but then again it depends on the type of paint , carbon based paints are faster than metallic , lead based paints..

It’s all to do with thermodynamics and metallurgy...


I am not Building Lsa

I'm a Old dragracer and I do mean old.

I may be wrong but I am doing this because I think I'm right.
and I have more time then money.

Quote:
Originally Posted by Bill_H View Post
Ryan is exactly point on. Do it if you want to, but don't expect any economic benefits. 3 Kts difference simply won't happen - I really doubt if it would even be measurable. But Ryan has the correct answer - bragging rights! We all want a plane that is slightly different and gets some oohs and ahs...
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Last edited by joedallas : 01-30-2012 at 05:55 AM. Reason: Typing
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  #50  
Old 01-29-2012, 08:15 PM
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My education for the day Joe, I did not know that. Very interesting.
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