VansAirForceForums  
Home > VansAirForceForums

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

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-14
Register FAQ Members List Calendar Today's Posts

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 12-12-2014, 08:21 PM
HiPlanesDrifter HiPlanesDrifter is offline
 
Join Date: Feb 2014
Location: Huntsville, AL
Posts: 30
Default Machine Countersinking .032?

So this has me a bit baffled. Horizontal elevator plans, Page 09-10, step 4 has you to countersink the rear spar on the holes which are common to the trim tab hinge.

http://www.vansaircraft.com/pdf/revisions/RV-14/09.pdf

The rear spar is only .032 thick. I have not proceeded yet, but under very careful examination, it appears the countersink would be very slightly too deep, causing a knife edge around the inside of the hole.

I do realize that section 5.5 does say you can countersink .032 thickness material as shown here:

"For AD3 rivets, a total material thickness between .016 [.4 mm] and .032 [.8 mm] must be dimpled. Material thickness between .032 [.8 mm] and .040 [1.0 mm],should be dimpled, but a countersink may be used if necessary. Finally, for a thickness of .050 [1.3 mm] and above the material must be countersunk."

So .032 is on the very low end.

I am very new at all this, and the only other time I have encountered needing to recess holes associated with hinges was on the tool box practice kit. Interesting, the lid is also .032 thick, and it had you to dimple it and the hinge for the flush rivets.

I hate the thought of going against the plans, but have any other builders entertained dimpling the .032 spar at the hinge rivet holes rather than countersinking, thus avoiding any potential knife edge? Perhaps they don't want us dimpling the hinge causing weakness or misalignment of some kind???

Thanks!
Chuck
__________________
Chuck Robertson
Amarillo, TX - River Falls Airport (H81)
And
Westcliffe, CO

RV-14a / Builder #140137
Empennage/Aft Fuselage built / Wings arrived / Build on hold until approx Summer 2016 - can't wait to get restarted!

Last edited by HiPlanesDrifter : 12-12-2014 at 08:33 PM.
Reply With Quote
  #2  
Old 12-12-2014, 08:51 PM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
Thumbs up Special case

Special case here. Like the other RV kits the softer aluminum of the hinge does not dimple well - it buckles a bit and deforms.

Countersinking the spar lets you use simple holes in the hinge for a much better job.

The plans are correct even if you do make a bit of a knife edge in this case.
__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
Reply With Quote
  #3  
Old 12-12-2014, 08:58 PM
rvbuilder2002's Avatar
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
Default

+1 Gil's comment, and the knife edged spar flange is sandwiched between the hinge and the skin.

This is one of the few places that the plans will specify to not follow the recommendation listed in chapter 5
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
Reply With Quote
  #4  
Old 12-12-2014, 09:21 PM
HiPlanesDrifter HiPlanesDrifter is offline
 
Join Date: Feb 2014
Location: Huntsville, AL
Posts: 30
Default The Plans are correct - once again!!!

Excellent info gentlemen! I appreciate it. Countersinking I shall do. Precisely per the plans.
Thank again!
Chuck
__________________
Chuck Robertson
Amarillo, TX - River Falls Airport (H81)
And
Westcliffe, CO

RV-14a / Builder #140137
Empennage/Aft Fuselage built / Wings arrived / Build on hold until approx Summer 2016 - can't wait to get restarted!
Reply With Quote
  #5  
Old 12-12-2014, 09:27 PM
fl-mike's Avatar
fl-mike fl-mike is offline
 
Join Date: Jul 2005
Posts: 1,346
Default

But!, make sure you have the hinge or other material behind the 0.032 you are countersinking, or the countersink will chatter or wallow in the hole!

Practice on some scrap first.
__________________
Mike W
Venice, FL
RV-6A. Mattituck TMX O-360, FP, GRT Sport EFIS, L3 Lynx NGT-9000
N164WM
N184WM reserved (RV-8)....finishing kit in progress. Titan IOX-370
Reply With Quote
  #6  
Old 12-13-2014, 12:11 AM
HiPlanesDrifter HiPlanesDrifter is offline
 
Join Date: Feb 2014
Location: Huntsville, AL
Posts: 30
Default

Mike,
Fortunately I followed the plans to a T, and it called for having the hinge clecoed in place while countersinking. I wasnt sure exactly why, but you just explained it. It went great without a hitch.
Thank you!
Chuck
__________________
Chuck Robertson
Amarillo, TX - River Falls Airport (H81)
And
Westcliffe, CO

RV-14a / Builder #140137
Empennage/Aft Fuselage built / Wings arrived / Build on hold until approx Summer 2016 - can't wait to get restarted!
Reply With Quote
  #7  
Old 12-13-2014, 09:08 AM
JonJay's Avatar
JonJay JonJay is offline
 
Join Date: Jan 2007
Location: Battleground
Posts: 4,348
Default

Entire wings,HS, and VS have been skinned and countersunk instead of dimpling. If you own an Art Chard built machine, you probably have one. The wing was skinned entirely 032 which also got away from the .025 to .032 transition. However, it requires one to attain a high level of skill to master the technique.
Properly set up an experienced builder could skin a wing much faster as there are fewer operations to perform.
Sadly, rules changed and those builders quit producing airplanes.

Point being, don't be afraid to countersink .032. Practice, back your material, and make sure you have good tools.
__________________
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
  #8  
Old 12-13-2014, 09:11 AM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
Smile

Quote:
Originally Posted by HiPlanesDrifter View Post
Mike,
Fortunately I followed the plans to a T, and it called for having the hinge clecoed in place while countersinking. I wasnt sure exactly why, but you just explained it. It went great without a hitch.
Thank you!
Chuck
This one job where you don't want to follow the advice of Tim Allen...

Real men don't use instructions, son. Besides, this is just the manufacturer's opinion on how to put this together.

TIM ALLEN, Home Improvement
__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
Reply With Quote
  #9  
Old 12-13-2014, 11:30 AM
rvbuilder2002's Avatar
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
Default

Quote:
Originally Posted by JonJay View Post
Sadly, rules changed and those builders quit producing airplanes.

Point being, don't be afraid to countersink .032. Practice, back your material, and make sure you have good tools.
Actually it is not a rule John, just a recommendation based on service experience.
Builders can still mach. C.S. .032 if they choose, but it has been found to not be as durable over the long term.

Couple Examples -
The red RV-6B prototype built largely by Art had the emp. stabilizer skins mach. C.S. After quite a few years there were smoking rivets in the rear spar that had to be repair numerous times until it was retired.
The fwd bottom skins on RV-6's used to be called for M.C'ing because it was .040. Even that thickness would develope smoking rivets over time.

Many times over, a dimpled rivet joint has proven to be more durable than a machine countersunk one (at least on RV's with the light skin thicknesses we use).

So from a static strength perspective mach. C.S. .032 is acceptable (other than small localized applications of a few rivets when necessary), but from a longevity standpoint it is not a good idea.
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
Reply With Quote
  #10  
Old 12-13-2014, 12:25 PM
Tom Martin Tom Martin is offline
 
Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,544
Default

I just went through this in another thread. If you were doing a repair to an aircraft you would need 1.44% more rivets using countersunk rivets to maintain the same strength as a dimpled joint. This information came from one of the older AN repair tech sheets. It makes sense as the two dimples "lock" together. I have also seen more smoking rivets with countersunk surfaces.
__________________
Tom Martin RV1 pilot 4.6hours!
CPL & IFR rated
EVO F1 Rocket 1000 hours,
2010 SARL Rocket 100 race, average speed of 238.6 knots/274.6mph
RV4, RV7, RV10, two HRIIs and five F1 Rockets
RV14 Tail dragger

Fairlea Field
St.Thomas, Ontario Canada, CYQS
fairleafield@gmail.com
Reply With Quote
Reply



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 01:48 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.