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Sometimes, you just have to sit back and enjoy the hilarity...

N546RV

Well Known Member
So for several work sessions, over the past couple weeks, I've been agonizing over my pitot tube position. Inboard of the bellcrank? Just outboard? Further outboard? Out at the wingtip?

I spent literal hours clamping the mast here and there, envisioning line routing, thinking of what I'd need to fabricate to secure things, considering what it'd be like to have to remove the pitot down the road for maintenance, etc etc etc. I even went so far as to test how the hard lines heated up to get an idea of how much I might be able to trim them.

After all of this, I finally settled. It was going to go one bay out from the bellcrank, against the outboard rib. So tonight was the night to make the cut and commit. Despite my agonizing, I was comfortable with my choice and didn't second-guess myself at all. It didn't even feel that odd making a hole in the skin.

Maybe it should have felt odd, because I put the hole in the wrong *** place, one bay outboard from my intended location.

I'm not even upset about it, just thoroughly amused at the irony of it all. This location is perfectly workable, I'll just need to lengthen the wiring harness between the tube and heat controller a bit.

Maybe that's the funniest part, how completely at peace I am with it not being in my carefully-chosen location. Almost amusingly anticlimactic.

Just gotta build on...

Ow6YFEjl.jpg
 
Haha that?s a great story! I do the same things.. overthinking sometimes but feel better when I actually just do it! Question, do you need any access to behind the pitot tube ever? Maybe a good idea at fabricate a doubler and access panel? I see the benefits of it being on the factory panel that accesses the bell crank, but I also see the desire to pick an empty bay.
 
Haha that?s a great story! I do the same things.. overthinking sometimes but feel better when I actually just do it! Question, do you need any access to behind the pitot tube ever? Maybe a good idea at fabricate a doubler and access panel? I see the benefits of it being on the factory panel that accesses the bell crank, but I also see the desire to pick an empty bay.

Access shouldn't be necessary. I'm going to trim the hard lines from the pitot down to about 6" or so, and have service loops in the wing bay for both the pitot/AOA lines and the wires from the heat controller. If I need to service the tube, I can just pull the tube out and detach the lines and wires outside the wing.
 
Access shouldn't be necessary. I'm going to trim the hard lines from the pitot down to about 6" or so, and have service loops in the wing bay for both the pitot/AOA lines and the wires from the heat controller. If I need to service the tube, I can just pull the tube out and detach the lines and wires outside the wing.

Do yourself a favor now and put a piece of masking tape on each plastic tube on the aircraft side AND the pitot side of the connection, and label it for static/AOA. Or at least clearly delineate in some manner that THIS tube belongs on that THAT side, so you can reconnect them correctly. Your memory will not be sufficient years later....

I had to go retrace my lines once to remind myself that I should have done it while building.
 
Colored tubing

Do yourself a favor now and put a piece of masking tape on each plastic tube on the aircraft side AND the pitot side of the connection, and label it for static/AOA. Or at least clearly delineate in some manner that THIS tube belongs on that THAT side, so you can reconnect them correctly. Your memory will not be sufficient years later....
Or buy some nicely colored tube from Stein. :D

https://www.steinair.com/product-category/pitot-static/

P-PITOT-L-DSC09452.jpg
 
So for several work sessions, over the past couple weeks, I've been agonizing over my pitot tube position. Inboard of the bellcrank? Just outboard? Further outboard? Out at the wingtip?

I spent literal hours clamping the mast here and there, envisioning line routing, thinking of what I'd need to fabricate to secure things, considering what it'd be like to have to remove the pitot down the road for maintenance, etc etc etc. I even went so far as to test how the hard lines heated up to get an idea of how much I might be able to trim them.

After all of this, I finally settled. It was going to go one bay out from the bellcrank, against the outboard rib. So tonight was the night to make the cut and commit. Despite my agonizing, I was comfortable with my choice and didn't second-guess myself at all. It didn't even feel that odd making a hole in the skin.

Maybe it should have felt odd, because I put the hole in the wrong *** place, one bay outboard from my intended location.

I'm not even upset about it, just thoroughly amused at the irony of it all. This location is perfectly workable, I'll just need to lengthen the wiring harness between the tube and heat controller a bit.

Maybe that's the funniest part, how completely at peace I am with it not being in my carefully-chosen location. Almost amusingly anticlimactic.

Just gotta build on...


You realize this means you're going to have to build another identical airplane with the mast in your intended location and perform a complete flight test regime to get experimental data confirming whether the location matters, right?
 
Or buy some nicely colored tube from Stein. :D

The SafeAir1 kit I have has color-coded lines already, so I'm there. I'm still going to label the tubing out at the wing end, because to Greg's point, when I pull this back out in however-many-years, I can already see myself thinking "wait, is blue pitot and green AOA or vice versa?"
 
Congratulations! Your RV is already unique and you haven't gotten to the canopy yet!
 
Phillip,
You will thank yourself later, AOA/pitot lines access not withstanding, for this outboard location. When you tie down your airplane, the pitot tube won?t be in the way. And - you won?t need to bring as much rope, because airport tie downs are for long winged Cessnas, not short winged RV?s, so you will always need to bring your own tie down ropes/straps. If your access to plumbing/wiring isn?t adequate, just add another inspection opening. Nobody will see it, unless they are buying it, and they will appreciate your thoughtful consideration of your design. I think you have found the perfect spot for your pitot tube.
 
We cut this hole in our skin about a week ago. It's terrifying to make a cut like that in the skin. Glad your okay with where it ended up.
 
Doh!

Colored lines alone don't help. I used blue and white to tell AOA and pitot ports apart. A year later I hooked them up backwards anyway! No airspeed on first flight attempt! Need to label them too.
 
Do yourself and / or the next owner a favor and put an access panel there. Having just changed out a pitot tube (heater failure), I assure you that one is entirely necessary.
 
Check

Colored lines alone don't help. I used blue and white to tell AOA and pitot ports apart. A year later I hooked them up backwards anyway! No airspeed on first flight attempt! Need to label them too.

Cant one point a hair dryer at the pitot tube and check to make sure the “needle” moves to verify correct hookup? I know not to blow in it, but I figure a hair dryer would be ok. I guess you could even point the plane into the wind during engine first start.
 
I don't know about the hair dryer, but you can slip a length of surgical tubing over the end of the pitot, then roll it up like a toothpaste tube to create some reference pressure in small, easily controlled increments.
 
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