Carf-Models Ultra Flash Instruction Manual page 43

Now the plumbed tanks can get glued in the fuselage with silicone permanently. The silicone
shown here is Kerosene proof and high quality.
It is much better to glue in the tanks with silicone instead of epoxy because the silicone is flexible
and can be cut out with a steel cable in case you have to take out a tank for any reason without
damaging the fuselage.
After the silicon cured (may take up to 16 hrs. depending on temperature and humidity) you can
start to install the engine duct and engine (or put it back in)
Attention: due to the tight fit of the saddle tanks you might need to shorten the M4x45 wing
mounting screws so they don't hit the tanks. Be careful and make sure they are still long
enough for a safe mounting of your wings.