You should have the following parts:
Probe with mounting bolt
Bracket (no mounting hardware for bracket included, on the S6 and 7
an existing strut bolt is used)
Length of tubing
In box with gauge:
U mounting bracket
2 threaded rods and nuts
2 - ¼ x 3/16 x 1.5” tubes
Gauge instruction sheet.
This illustrates how the instrument is connected but note that in the picture the gauge is actually upside down. When in the panel, the outer barb is at the bottom.
The hose barbs on the gauge are marked for high and low pressure (low is at the centre of the gauge, high at the outside edge). Looking at the side of the probe with the point facing forward, there is an upper hole and a lower hole. The upper hole goes to the high pressure inlet barb on the perimeter of the gauge; lower goes to low pressure inlet barb near the centre of the gauge.
After you push the short lengths of ¼” tube onto the instrument barbs, the 3/16” tubes from the probe can simply be pushed inside these ¼” tubes on the gauge. There is enough friction to keep them there. Some lubrication may be helpful to get the tubes pushed in an adequate distance (> ½”).
If you draw a line on the side of the L bracket between the two lower holes and a line on the probe from the point through the center of the mounting hole, an initial mounting position is with these two lines parallel to each other. This was the case on my Rans S7; other aircraft may vary. On the Rans this was approximately 30 degrees nose down form the aircraft centre line.
The holes on the back of the probe accept the 3/16” tubing with a snug fit and take a little effort to ensure the tubes get pushed in as far as they will go (the holes are drilled to #20 drill size). Lubrication may help here as well. Two small plastic ties, one around the two tubes and the other through the first tie and through the hole aft of the probe should be enough to prevent the tubes from pulling out. Careful not to tighten the ties so much that they distort or squeeze the lines.
The probe can be mounted anywhere outside of the prop blast in smooth air and, more than about six inches below the lower wing surface. While the bracket was designed for the Rans S7 and S6 wing strut position, you could decide to mount anywhere that is secure and convenient. My guess is that shorter tube runs could be better so consider the jury strut position or equivalent and if you have a pusher a good place would be right up front.
If you have a straight bracket that you need to bend, clamp it in a vice and tap it with a plastic mallet near the vice jaws. Be sure to pad the vice jaws with a piece of aluminum with a 90 degree bend to provide a radius for the probe bracket bend or you could crack the aluminum.
Start with the centre line of the probe positioned as mentioned above (about 30 degrees nose down). Take a flight and stall the plane. As the nose goes up and speed drops the needle should come off the right hand stop and move towards the red area. Note the position of the needle when the stall occurs. You want the needle to be near the left side of the red arc at stall. If the needle gets to the left side before the stall then the nose of the probe is too high so rotate it down before the next flight.
Conversely, if the needle is still in the yellow at stall, then the nose of the probe is too low so raise it some before the next flight. When you have it set where you want it, tighten the mounting bolt and put a mark on the mounting shaft so you can see that it hasn’t been moved later.
Thus, the method is: needle reading lower than you want: lower the nose of the probe; needle reading higher than you want: raise the tip of the probe.
If you want a different face on the gauge, instructions for removing the gauge bezel are on the insert with the gauge. Also see more details at: “Completing the unfinished kit”
Please let me know how you like it.
pcowan41 at sympatico.ca