Tamjets Tips and Instructions



Text Box:  A-4 Skyhawk Drop Tank/Pylons

Text Box: Before beginning any finish work, wash all the parts with warm soapy water and dry off.

Text Box: 1. Sand seams on each tank. When the center seam has been flattened out in preparation for filler and primer, locate the two phenolic tubes that will be visible thru the glass on the bottom of each tank. Refer to photo #1 below for the approx. location of the tubes. Using a small conical dremel bit, open holes as shown in the photo until the hole is the same diameter as the inside of the tube. These are the pilot tubes to prevent the tank bolts from being lost inside the tank when installing and removing the tanks form the pylons.

Text Box: 2.  Prepare an 1/8” diameter extension drill bit by wrapping it with tape as shown in photo #2. The tape should be just slightly smaller than the inside of the phenolic tube. The tape will insure the drill  holes are centered in the phenolic tubes. Be sure to drill slowly, as the tape will get hot a shred off the drill bit making a mess inside the tubes.

Text Box: 3. Using  a small length of double sided tape, position the tank pylons onto the top of each  tank with the front edge of each pylon aligned with the scribe line on the top of each tank just forward of the 2nd panel line. See photo #4 below
Text Box: Pylon anti-sway bracket installation:

Text Box: 7. Refer to the photos below for sway brace locations for each pylon. The front bracket is 7/8” back from the L.E. of each pylon and the brackets are approx. 1/2” wide. The rear brace is located 2-7/8” from the rear of the front bracket. These placements are not crucial, but need to be close. Use a dremel cut off wheel to make the cross cuts and a straight carbide bit to remove most of the material to create the slot. Finish the slot edges using a file. Here’s where Perma grit tools are worth the money.

Text Box: The slots should be as neat as possible so that the bottom edge of each brace is flush with the bottom of the pylon.
8. The location of the mounting holes for the pylons to mount  to the wings are located on the top of each pylon. Place each pylon on a drill press and drill through the top of each pylon using a 9/64” drill bit. Be careful that the holes remain vertical thru the pylons. Relieve bolt head clearance holes as necessary to clear the 6-32X1-1/2” cap screws. Locate each pylon onto the wing at the appropriate location and mark the pylon bolt hole locations onto the bottom of each wing. 
9. There are no hard points in the A-4 wings, so you will have to make something for yourself here. Be certain that whatever is used, that it will be very strong  and go from skin to skin inside the wings. The tanks will have a lot of drag on them and could easily rip out of a weak installation. 
10. Fill all seams, prime and paint. Install all 2-56 x1/4" adjustment jack screws after finishing.
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Text Box: The mark is located 1/2” forward of the 2nd panel line on the top of each tank where denoted above by the small black line perpendicular to the center molded seam. This is the tank pylon’s front location.

Text Box: 4. Once the pylons have been taped in place on the top of each tank, drill the holes thru the internally mounted tank blocks (approx. 3/4” thick each) until the bit just comes thru the top of each tank, marking the hole location onto each pylon.  Repeat for each hole and both tanks. Remove the pylons from the tanks and remove the tape as necessary. Using a 9/64” drill bit, drill a clearance hole thru the top block of each tank. 
5. Using a 3/32” drill bit, drill thru each hole location, now marked on the bottom of each tank pylon. After drilling holes, tap each hole using a 6-32 tap. Apply thin CA to each hole, allow to cure fully and re-tap each hole. Use the supplied 6-32X1-1/2” socket head cap screws to fasten the tanks to the pylons.  After testing the fit, remove pylons from tanks and set tanks aside. 
6. Refer to the scale line drawing below for the approx. location of each wing pylon.