I fancied a change of task today so decided to fabricate a mount for the pitot tube. I had a pitot left over from a Cessna I had owned that the CAA decided was not the correct part number for that plane so had to be replaced. The standard Wittman pitot is a tube through the leading edge and whilst this is light and simple it has a couple of drawbacks. At high angles of attack it is reported to significantly under read and it is vunerable sticking out from the front of the wing (and also possibly dangerous to eyes whilst the aircraft is on the ground). The conventional pitot should be more accurate as the underside of the wing will channel air past it even at high angles of attack and is certainly less vunerable. The starting point for the mount was purchasing a length of streamlined steel tubing 2.023" x 0.857" x 0.049" which is a standardly available size and fits perfectly around the stem of the pitot - I presume this is deliberate. Then a plate of 0.063" steel sheet was cut to fit round the streamline tubing and a second plate drilled to attach to the rear of the wing main spar. These were then jigged against the spar using some scrap timber and the joint tack welded to get exactly the correct angle (don't try this if you are gas welding!). Then the plates were removed from the wing and the streamline tube welded into position and the joint between the plates final welded. The pitot then screws into the bottom of the streamline tubing.The cable safes have arrived from ACS so I also mounted the cable support bracket between the sump and the carburettor and clamped the cable outers into place. The controls cables were cut to length and the controls adjusted so that full throttle and full-rich mixture both were achieved with the controls almost, but not quite, fully forward.
