How to make a positive and a mold for a cross tail for Trinitus
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This is the story of how I make a cross tail modification of the Trinitus - i.e. positives and a molds for a cross tail for Trinitus. At the same time I'm making a positive for the fin to the Catch 22.

This cross tail modification includes the making of five four mold sets:

  1. Fin mold with added length (+50mm)
  2. All moving tailplane in vacuum bagging technique at first (colors with colored tissue) - a mold will follow.
  3. Longer nose cone (+40mm)
  4. New rear fuselage with collar to adapt the fin part
  5. New servo platine with added length (+40mm)

a + b has first priority due to the time of the season. The longer front (c + e) and new rear fuselage (d) must have to wait if time isn't up to it.

20th of May 2004. The first thing I did was to take a crashed fuselage and cut the back of it. The principle of the cross tail will be that it shall be made in a negative mold in vacuum like a wing or a V-tail, put together and then glued onto the fuselage. This means that the last part of the original fuselage has to be sawn off to mount the cross tail. I then cut a small foam core and covered it in one layer of 49 grams glass, one layer of 108 grams glass and small patches of 49 grams glass at the base. It was cured in a vacuum bag of course.

21st of May 2004. I then took it out, sanded it nice and smooth and I did also sand through the leading edge at the top so I had to repair the leading edge with two layers of 49 grams glass cloth.

22nd of May 2004. Then the leading edge was sanded smooth again and epoxied to the sawn of rear Trinitus fuselage.

 trinitus cross tail-1.jpg (17694 byte)

 

trinitus cross tail-2.jpg (43731 byte)

 

 
25th of May 2004. The holes at the fin base was filled and the nosecone was modified +40mm and the rear fuselage was sanded and filled.  trinitus cross tail-3.jpg (9412 byte)  trinitus cross tail-4.jpg (9895 byte)

trinitus nose cone-1.jpg (22356 byte)  trinitus nose cone-2.jpg (23982 byte)  
26th of May 2004. The nose cone and the rear fuselage was sanded and filled and sanded and painted  gray primer. The fin was filled some more.

I just got an email from Don Berry, Australia, telling me that 2 layers 25 grams glass on the bias (or 1 layer 49 grams) + carbon caps - just as a DLG wing - should be adequately strong and light for a vacuum bagged all moving tail plane.

 trinitus nose cone-3.jpg (8676 byte) trinitus rear fuse-1.jpg (8109 byte) 
27th of May 2004. The fuselage and nose cone is sanded, filled, sanded and painted red trinitus nose cone-4.jpg (9884 byte)  trinitus rear fuse-3.jpg (12885 byte)
28th of May 2004. The fuselage and nosecone is sanded back to the grey, filled, sanded and painted red again. trinitus nose cone-5.jpg (6305 byte)  trinitus rear fuse-4.jpg (11330 byte)

trinitus nose cone-4.jpg (9884 byte)  trinitus rear fuse-3.jpg (12885 byte)
29th of May 2004. The fuselage and nosecone is sanded back to the grey, filled, sanded and painted red again trinitus nose cone-5.jpg (6305 byte)  trinitus rear fuse-4.jpg (11330 byte)

trinitus nose cone-4.jpg (9884 byte)  trinitus rear fuse-3.jpg (12885 byte)

 
30. of May 2004. The fuselage is wet sanded and painted red. The curve in front of the fin is made with a piece of scrap balsa and likewise is the bottom of the fin. Filling is started. trinitus nose cone-4.jpg (9884 byte)  trinitus rear fuse-3.jpg (12885 byte)
31st of May 2004. Nothing is done on the fuse and nose cone. The paint has to cure totally and then it shall be polished. I did happily discover that my molds for the Trinitus servo platine is long enough for the enlarged nosecone. Great! One two part mold less to make. More filling to the fin. trinitus cross tail-5.jpg (10762 byte)  trinitus cross tail-6.jpg (11314 byte)
1st of June 2004. No real work done since my wife has gone to instruct some people into Nordic Walking. Pictures added from the last couple of days.