VansAirForceForums  
Home > VansAirForceForums

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

- Today's Posts | Insert Pics

  #1  
Old 06-26-2020, 12:09 AM
EdRv7 EdRv7 is offline
 
Join Date: Mar 2020
Location: Saratoga CA
Posts: 5
Default ELT antenna top skin stiffness

I am building an RV-7 slider and am planning on mounting my ACK ELT antenna on the top skin just aft of the F-707 bulkhead (i.e. a few inches aft of the end of the canopy slide track). The ACK antenna instructions say to install a 2 inch diameter doubler plate. I am worried that the skin there isn't very stiff, even with a doubler plate. The instructions say "13 lbs test force applied at base of antenna should cause no appreciable distortion of skin". My question is: what is the definition of "appreciable"? Anybody else mount their ELT antenna there and later have cracking or other issues?

Thanks for any advice!
Reply With Quote
  #2  
Old 06-26-2020, 10:17 AM
Ralph Inkster Ralph Inkster is offline
 
Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 857
Default

I usually put in about a 5x5" .032 doubler and never had issues.
I've inspected other planes with no doubler, although I'd consider it being a bit light, didn't show any cracking.
My vote would be to install the doubler, to insure that 40 years from now, after avgas is a memory, there still would be no cracking there.
__________________
Ralph
It's time to work on just my own planes, not everybody else's...
Reply With Quote
  #3  
Old 06-26-2020, 03:53 PM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 1,007
Default Just me

I installed a doubler there for my elt. The curvature makes it very strong. I chose to tie the doubler in to the bulkhead, but not sure if I needed to.
__________________
John S

WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2020, worth every penny

RV9A- Status:
Tail 98% done
Wings 98% done
Fuselage Kit 98% done
Finishing Kit 10% working canopy
Electrical 5%
Engine In Stock
www.pilotjohnsrv9.blogspot.com
Reply With Quote
  #4  
Old 06-26-2020, 05:57 PM
gmcjetpilot's Avatar
gmcjetpilot gmcjetpilot is offline
 
Join Date: Jan 2005
Posts: 4,265
Default

Quote:
Originally Posted by EdRv7 View Post
I am building an RV-7 slider and am planning on mounting my ACK ELT antenna on the top skin just aft of the F-707 bulkhead (i.e. a few inches aft of the end of the canopy slide track). The ACK antenna instructions say to install a 2 inch diameter doubler plate. I am worried that the skin there isn't very stiff, even with a doubler plate. The instructions say "13 lbs test force applied at base of antenna should cause no appreciable distortion of skin". My question is what is the definition of "appreciable"? Anybody else mount their ELT antenna there and later have cracking or other issues? Thanks for any advice!
I like how you think... Larger douber would be good as suggested. ELT does not have too much drag. If you push on it with a few lbs of force near base. It should not move and skin should not have significant deflection.

Not sure what bay you will be in, how close you will be to a frame, but you will be adequate with a larger doubler. Try and screw closer to one of the frames than mid bay...
__________________
George
Raleigh, NC Area
RV-4, RV-7, ATP, CFII, MEI, 737/757/767

2020 Dues Paid
Reply With Quote
  #5  
Old 06-26-2020, 08:04 PM
EdRv7 EdRv7 is offline
 
Join Date: Mar 2020
Location: Saratoga CA
Posts: 5
Default

I am putting in the doubler. But I noticed that the skin still deflects some even with the doubler. Maybe I'll put in a larger one as you suggest.
Reply With Quote
  #6  
Old 06-26-2020, 08:34 PM
jliltd jliltd is offline
 
Join Date: Sep 2013
Location: Rancho San Lorenzo
Posts: 798
Default

Are you riveting the doubler onto the original skin or is it loose and captivated by the antenna mounting like a big washer?
__________________
RV-8
RV-3B
Reply With Quote
  #7  
Old 06-26-2020, 08:51 PM
EdRv7 EdRv7 is offline
 
Join Date: Mar 2020
Location: Saratoga CA
Posts: 5
Default

Quote:
Originally Posted by jliltd View Post
Are you riveting the doubler onto the original skin or is it loose and captivated by the antenna mounting like a big washer?
The doubler has 6 rivets. But it does seem small, just 2 inches diameter (per the mounting instructions from ACK).
Reply With Quote
  #8  
Old 06-26-2020, 09:09 PM
jliltd jliltd is offline
 
Join Date: Sep 2013
Location: Rancho San Lorenzo
Posts: 798
Default

I believe I would go with it.
__________________
RV-8
RV-3B
Reply With Quote
  #9  
Old 06-26-2020, 11:48 PM
Draker's Avatar
Draker Draker is offline
 
Join Date: Jun 2016
Location: Livermore, CA
Posts: 354
Default

This is what I did (Artec antenna). It seems very solid, and Iím not concerned about the doublerís strength.





Disclaimer: Airplane not flying yet.
__________________
Ryan Drake
Livermore, CA
https://stiletto.smugmug.com/RV7
Donated 12/16/2019
RV-7A (N12VD): Empennage and wing kits complete minus fiberglass, fuselage 90% complete. Canopy in progress. Engine and prop ordered.
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 02:26 PM.


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.