Hi Pawel,
Sorry for the delayed response, I was at the Seattle IPMS show yesterday. I took 2nd and 3rd place, ironically not the Cobras, but they did get Honorable Commendation. The CH-47D took 2nd and H-21 took 3rd.
That blade antenna mounted at the 7 O'clockish position on the tailboom behind the aft skid cross tube is the UHF-VHF Antenna AT-1108/ARC. It’s also just aft of ADF Sense Antenna which is that black bottom panel on all Cobras. The UHF-VHF antenna was installed in that position on certain G, Q and all S(Mod) Cobras below via Maintenance Work Order MWO 55-1520-221-30/17. The P, E and F Cobras had a different UHF-VHF antenna and location which looked like a boomerang.
AH-1G Config. D, s/n 68-15000 through 68-17113 and 69-16410 through 69-16447.
AH-1G Config. E, s/n 70-15936 through 70-16105.
If you see a G model cobra that doesn't have the UH-VHF antenna on the lower tailboom, then it's located in the upper rotor pylon behind the pilot's canopy. Those are config A,B and C AH-1G Cobras which are;
AH-1G Config. A, s/n 66-15249 through 66-15257
AH-1G Config. B, s/n 66-15258 through 66-15357
AH-1G Config. C s/n 67-15450 through 67-15869
If you have the 1/72 SH722283 kit its piece 125 and SH72076 (M35 gun) its piece 129. Look in the plastic bag before you scratch build one. I usually find tiny parts still in the bag that fell off the sprue. Wait, how funny is this?, I was looking for it myself to measure for you on the 1/72 kit and couldn't find mine either. The sprue illustrations don't even show Part 129 but there is a note that says "*) in initial batches part no.129 is loose, not in frame A." Look for it on sprue A where the right fuselage half was on the sprue. It’s in the same location on sprue A (no.125) for the SH722283 kit.
If you still can't find it and need to scratch build one, use the 1/48 scale dimensions and scale down to 1/72. The 1/48 should be more accurate to and please check my math conversions to.
The 1/48 kit antenna is (0.30in/7.62mm) long, (0.22in/5.6mm) wide at the tailboom side and (0.15in/3.81mm) wide at the tip and is (0.025in/0.635mm) thick. The tip tapers less on the foward side like a wing. I estimate it only tapers back at the tip (0.02in/0.51mm) on the forward side and (0.05in/1.27mm) on the rear side of the antenna tip.
1/72 conversion: If the 1/48 scale was (0.30in/7.62mm) long, the real one was (0.30in/7.62mm) x 48 = (14.4in/365.76mm) long in full scale.
1/72 scale =
Length (0.2in/5.08mm).
Width @ tailboom mount (0.146in/3.92mm)
Width @ antenna tip (0.1in/2.54mm)
Thickness (0.0167in/0.423mm)
At tip taper Leading edge (0.013in/0.34mm)
At tip taper Trailing edge (0.03in/0.85mm)
I hope that was correct....
Thanks,
Tom