The lower air exit was fitted partly as a scale detail but mainly to try to relieve the pressure build up in the fuselage which was blowing off the belly hatch on the first few flights.
All built up from balsa, with a 1/64in ply reinforcing plate to the rear aperture, the finished blister was film covered on the inside before being fitted to the fuselage.
To ensure that the vent was fully functional, I cut out the largest aperture I could manage in the fuselage underside. The lower keel was left intact though.
The dummy engine and four bladed prop more or less balanced out the cg shift achieved by moving the batteries further back so the need for a bit of tailweight remains. Initially the lead was just taped onto the underside of the fuselage so a box was built to fit into the fuselage.
The box is glued to the rear face of a former but I was still haunted by the vision of the lead-filled box breaking free and wreaking havoc with the elevator linkage so a couple of cocktail sticks were used to reinforce the joint. The balsa 'lid' is just pushed in place and a film patch applied so that it should be relatively easy to open the box up if the amount of ballast needs to be changed.
So, by the end of the month, with eight flights under its belt, the P47 is beginning to look like the finished article.
