Doing some research/planning and starting to fab doubler for AV-520/CI-159C to be mounted on VS-1006 (not intended to be a debate on archer wingtip antenna). Couple questions/considerations (would like your input):
1) FAA AC 43.13-1B Section 4 calls for 1.5x thickness for reinforcement/repairs for cracks (see Figures 4-21&22, for example). Assume would use similar for antenna doublers? In this case, V-1006 is .025", so .040" should be adequate? Or should I go to .063? Want adequate structural support, but minimal weight or impact to potential flutter characteristics.
2) AC 43.13-2B 309(b)(2) and (b)(4) on antenna installation state: (2) structural backing plate highly recommended (duh) and if they do not attach to load carrying structure, do not provide structural load support. (4) Sandwich the aircraft skin between the antenna base plate and the internally mounted backing plate. With this in mind, I see three potential configurations:
a) Doubler & antenna sandwich VS-1006 (per 2B(309)(b)(4) above).
b) Doubler and antenna atop VS-1006.
c) Doubler and antenna atop VS-1006 with doubler tied into front spar.
For this application, have not seen anyone bend up and tie into flanges as shown in Figure 4-21. Have seen it only on fuse & wing skin antenna doublers.
Here are some examples of each configuration: