Flanged Pitot

Assembly indications

Check this article, BAD probe was tested within a wind tunnel

After a prolonged use of the classical 8 mm pitot tube some installation problems have been reconsidered and solved, so now the classical model can be suited with a fixation flange. To speed up your work you can find here a 3D .stl file of the assembled probe, here below an animation of the model. Use of the two brass pipes as impulse lines is simple but they can't be trimmed near the pitot body, if they are shortened or bended around likely they will leak or break away, overall dimensions are considerable. A workaround for this issue is to build a flange that can route the pressure lines to a standard barbed port, so a new design was put under test. In Figure 1 the finished pitot flange, you download a 3D model for the pitot flange here
Figure 1: Pitot flange with barbed ports
Figure 2: Assembled pitot with flange, carbon fiber 8 mm tube
Finished pitot will look like those of Figure 2. And a short video of preliminary assembly process, you can download the label template here

Referring to the Video 1, also a new 3d printed head is used, you can download the 3D model here.
Other parts still the same of classic probe, static pressure pipe is not needed any more and is to note that the length of pitot 8 mm pipe and total pressure 3 mm pipe should be adapted to the desired finished pitot length as follow. Given L as the total assembled length the 8 mm pipe finished length should be then L-27mm and the 3 mm pipe length equal to L-12mm, in the Figure 2 L=200 mm so 8 mm pipe is 173mm and 3 mm pipe is 188mm. All the required parts are depicted in Figure 3.

I publish some pictures of the main assembly process steps, for the assembly you will need:
Epoxy bicomponent resin, 5 minutes fast curing;

Warm space to work, epoxy resin have some problem to cure below 20°C;
Scissors;
Electrical tape;
Sandpaper 600-800 grit;
Paper sheets;
Some toothstick or other similar disposable object to apply the resin;

Figure 3: All the parts needed for the pitot

Assembly process can start once you have all the parts clean and you have check the assembly as per Video 1. You should use the sand paper to prepare the surfaces that will be joined with the resin.
So prepare the pitot head to be glued with the 3 mm tube, sand at least 10mm on the pipe and clean the part, sand also the flat at the top of the pitot head. Carefully seal the head part that not will be glued with the Electrical paper, your pitot head should look like Figure 4.

Test the cure position, that should be head down, like the picture 5.

Cover your working plane with white paper, mix few grams of epoxy resin and with a toothstick lay a generous amount of resin at about 4 mm from the pipe tip, just like the picture below. The resin should not enter the pipe (Figure 6).

As the resin have a medium viscosity keep turning the pipe until you finally put in into the pitot head and then leave it to cure (Figure 7).

After the resin is cured remove the electrical tape and you should get the result in Figure 8.

After that this crucial part is completed test the if the joint is airtight, ahead with the assembly will be impossible to correct any defect.
If the head is airtight you can proceed to the final assembly phases, every time you make a new glued joint it's a good practice to check the airtightness.

Refer to the video Video FP 2.

Video 1: Instruction to assembly flanged pitot

After the assembly only two operations are left, they are the pressure taps drilling.
With a pillar drilling machine and a 1mm dia bit make the total pressure hole, the farthest from the pitot head, with a deep of 13mm the other hole should be drilled 10.5mm deep.

A figure of drilling is reported in Figure 9.

During the drilling process check if the drill has to break trough the pipe wall blowing into the total or static ports.
Now your probe is ready to be fitted with the sensors.

Proceed to the integration section for a hardware interface description.

Figure 4: Pitot head ready to be glued
Figure 5: Position to be held to cure the resin
Figure 6: 3 mm pipe with resin
Figure 7: Total pressure pipe glued
Video 2: Instruction to assembly flanged pitot
Figure 9: Drilling of the pressure taps

After the assembly only two operations are left, they are the pressure taps drilling.
With a pillar drilling machine and a 1mm dia bit make the total pressure hole, the farthest from the pitot head, with a deep of 13mm the other hole should be drilled 10.5mm deep.

A figure of drilling is reported in Figure 9.

During the drilling process check if the drill have break trough the pipe wall blowing into the total or static ports.
Now your probe is ready to be fitted with the sensors.

Proceed to the integration section for an hardware interface description.

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