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  #1  
Old 01-16-2021, 03:56 PM
MIKE JG MIKE JG is offline
 
Join Date: Sep 2016
Location: NE Ohio
Posts: 132
Default RV-8/8A Plans Gotchas

Those cool guys over on the RV-7 forum have their own stickied thread with gotchas for that airframe. Many of those for the empennage are applicable to building the RV-8 empennage but we don't have a similar thread for the 8 that I can find.

Is there one anywhere or has anyone kept a log anywhere? Or does anyone want to start populating one for the RV-8??
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  #2  
Old 01-16-2021, 05:14 PM
scsmith scsmith is offline
 
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Default

I know of two that I would add if someone wants to start such a permanent thread.
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  #3  
Old 01-16-2021, 06:48 PM
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N804RV N804RV is offline
 
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Location: Mount Vernon, Wa
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Not so much as "gotcha's" as little nit-noids that get overlooked. ...Like, leaving certain pre-punched holes open for nut plates to attach the empennage fairings. And, the order of operations for riveting the skins onto the skeleton for the Vert and Horiz stabs. If you don't have a plan to set every rivet before you start riveting, its really easy to "paint-yourself-into-a-corner" so to speak.
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  #4  
Old 01-16-2021, 10:26 PM
David Z David Z is offline
 
Join Date: Aug 2010
Location: Thunder Bay Ontario
Posts: 473
Default Firewall

Quote:
Originally Posted by N804RV View Post
And, the order of operations for riveting the skins onto the skeleton for the Vert and Horiz stabs. If you don't have a plan to set every rivet before you start riveting, its really easy to "paint-yourself-into-a-corner" so to speak.
Haha, I've "riveted myself into a corner" before too, recently actually. There's some nut plates on the firewall that just didn't make sense to rivet in that order, but I dutifully followed the instructions. Later on, I was unable to buck 3 rivets because nut plates were in the way. Ended up drilling out some nut plates, bucked the firewall rivets and re-riveted the nut plates. One firewall rivet I was far enough into, that I just stuck in a c/s Cherry Max and called it a day.
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  #5  
Old 01-16-2021, 10:29 PM
Anon455 Anon455 is offline
 
Join Date: Dec 2020
Posts: 51
Default Tips and Tricks

1. Minimum Edge Distance for rivets. 470 rivets are 2 x the diameter and 426 rivets are 2.5 x the diameter.

2. Machine countersink only when material thickness is greater than rivet head. This doesn't mean the total thickness it means the sheet of material directly under the rivet head.

3. #3 Rivet hole is 3/32. When dimpling - drill the 3/32" hole, dimple and then if necessary ream to a #40. If you final drill to a #40 your holes will be sloppy when you dimple and they'll be too big for the rivet.

4. Cutting / Trimming. Always 2nd guess Van's on their cutting dimensions. When cutting something cut it long and then trim or file to fit. Otherwise you won't have the minimum edge distance for riveting. Especially see #1 and #5

5. R-710. Don't trim to Van's specs. If you do, you'll not have the edge distance along the edge you just trimmed. Go to the Search Box and simply type in R-710 - you'll see

6. R-802. There are punched holes in R-606 and R-405PD that line-up with each other, but no corresponding holes in the R-802 spar. The holes in 606 and 405 are holes used for alignment of the part during manufacturing. Don't use the holes and don't drill into the spar.

7. Circled Xs. Look on plan Drawing 3-8 of the horizontal stabilizer. On the inside edge of the left and right horizontal stabilizer you'll see circled x's over rivet holes and there's a corresponding note and arrow that reads leave Open on top side only for empennage fairing attach, 10 places. Well, don't dimple the skin or the understructure where these are depicted.

8. "Information acceptable to the administrator" Is Free. That means it's information promulgated by the FAA. Let's face it. We ask questions and opinions on an open forum because were curious, we like short cuts, we don't have any idea where to find the information or we're just too lazy to do our own homework. Van's publishes a lot of information in the beginning of the builder's manuals and that also includes some "tricks". But every bit of information on building aircraft, wood, fabric, metal, helicopter, balloon, their components, and the rules, regulations, minimum criteria etc. is free from the FAA. Especially useful are mechanic's handbooks. https://www.faa.gov/regulations_poli...uals/aircraft/

9. Drilling a hole. Drilling a hole is apparently an art. Different materials and different thicknesses require different speeds. Pushing too hard leads to a bent, malformed triangle. Drill bits are like dresses, there's a lot of differences. There are fractional, numbered, and lettered, angles are 90°, 110°, and 118° 140°. There's 0° rake angle, single cutting edge, double cutting edge. There's HSS, Titanium, Black Oxide, Cobalt, Carbon. They come in different lengths, some are double margin. Theres different speed drills. Then there's IPS. Drilling in Acrylic or Lexan or other plastic there's single cutting edge vs. 2 cutting edge Unibits. Then there's Rotabroach....Then there's about 50 different kinds of reamers.

10. Hole prep. Improper hole preparation facilitates cracks. Prior to dimpling or squeezing rivets the hole has to be clean, the correct size and round. When shooting or squeezing a rivet, the rivet expands into the hole with enormous force. Any inclusion in the hole is potentially a crack later on.

11. Bending Metal Just like there's a minimum edge distance for riveting, bending metal has a minimum bend angle. That depends on the material, the hardness, and the thickness. The overwhelming majority of A&Ps and I/As even when given the formula and charts can't tell you the minimum bend angle of a piece of metal - and of the 5% of those who can I'll bet 2% of them can't give you the set back. Take a scrap piece of aluminum and squeeze the daylights out of it and then put it under a 10x or better magnifying glass. You'll see where the clad plating starts separating from "work hardening" the material from excessive pressure. (I'm sure, I'm in the 95%)

12. Work Hardening Dimpling and bending metal and hammering on it via riveting work hardens the metal. Use as light a blow and as few blows as you can from a rivet gun.

13. Scrubbing the aluminum coating off AlClad. The Aluminum is there for corrosion protection but some people use Scothcbrite to scrub the protective surface off the AlClad so they can apply a protective surface (alodine). The pure aluminum coating is only 2%-5% of the material thickness so on a piece of .020" the pure aluminum coating can be as little as .0004" thick. Scrubbing the corrosion protection off to apply another corrosion protection never made much sense to me.

Last edited by Anon455 : 01-16-2021 at 11:39 PM.
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  #6  
Old 01-19-2021, 11:02 PM
jls32 jls32 is offline
 
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Location: Denver, CO
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"3. #3 Rivet hole is 3/32. When dimpling - drill the 3/32" hole, dimple and then if necessary ream to a #40. If you final drill to a #40 your holes will be sloppy when you dimple and they'll be too big for the rivet."

Is this true? They didn't teach this at Synergy, Van's doesn't say to do this, and wouldn't it be awful hard to debur the reamed, dimpled hole? If so, then I guess I'll ordering a new vertical stab.....
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  #7  
Old 01-20-2021, 01:30 AM
Jonnyb Jonnyb is offline
 
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Location: UK
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Strictly speaking it’s correct. Dimpling does stretch the hole slightly, so if you final drill before you dimple then the hole will be over size. Also if you use a reamer then the need for deburring is reduced.
However, doing it this way is not what Vans says is required and is not taught in the building classes here in the U.K. And loads of aircraft have been safely flying for years with out this level of accuracy.
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  #8  
Old 01-20-2021, 06:20 AM
Taltruda Taltruda is offline
 
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I don’t think this is correct.. looking forward to the smarter guys on here to speak up. I feel if you drill 3/32 then dimple, you risk stretching the metal to the point you’ll get micro cracks around the hole. Sometimes I do drill #41 though before I dimple..
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  #9  
Old 01-20-2021, 07:54 AM
Jonnyb Jonnyb is offline
 
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Location: UK
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According to Vans instructions you fit the parts, match drill to final size, debur, dimple, prime. And that's the way it's taught here in the UK at our equivalent of the Sport Air Workshops.

Quite a long thread about it here:
https://vansairforce.net/community/s...ad.php?t=49478
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Last edited by Jonnyb : 01-20-2021 at 08:02 AM.
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  #10  
Old 01-20-2021, 08:04 AM
PhatRV PhatRV is offline
 
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Location: Buena Park, California
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Quote:
Originally Posted by Taltruda View Post
I don’t think this is correct.. looking forward to the smarter guys on here to speak up. I feel if you drill 3/32 then dimple, you risk stretching the metal to the point you’ll get micro cracks around the hole. Sometimes I do drill #41 though before I dimple..
I know some build centers will just dimple the holes without additional drilling. The dimple tool die acts as the reamer. If anything, this action slightly compresses the metal around the holes because the holes in the pre-punch RV8 sheetmetal are almost full size. You still have to fit the metal parts and to drill holes in the parts that are not perfectly aligned .
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