INSTALLATION
(2009/08/07)
click for
instructions to finish the kit version
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.
Setup:
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.
Peter.
pcowan41 at sympatico.ca