clam

clam

Well Known Member
fellow aviators,
anyone ever run the pitot lines (1 for pitot, 1 for aoa for dynon) in front of the wing spar? thinking of mounting pitot mast 1 bay outboard from plans, and running the lines through the spar web to the front side. then run the lines in front of the spar just below the bottom end of the tank spacer extrusions. this will allow fuse entry near the -8 gear towers. anyone think of any disadvantages?
thanks for inputs.
-clam
 
clam said:
anyone think of any disadvantages?
thanks for inputs.
-clam
Click to expand...

Interesting idea, and solves the problem of how to bring them through the spar. The only things I'd caution you on is think far ahead as to how you are going to mount and connect the pitot - once you get the forward skin on, you won't have any kind of easy access to make connections. I really doubt the pitot line would ever go bad, but if it is forward, it might be hard to replace. Just things to think about.

Paul
 
Per plans on early models...

clam said:
fellow aviators,
anyone ever run the pitot lines (1 for pitot, 1 for aoa for dynon) in front of the wing spar? thinking of mounting pitot mast 1 bay outboard from plans, and running the lines through the spar web to the front side. then run the lines in front of the spar just below the bottom end of the tank spacer extrusions. this will allow fuse entry near the -8 gear towers. anyone think of any disadvantages?
thanks for inputs.
-clam
Click to expand...

Clam, This was the plans method for the RV-6s

...and the old kits did not have the Z-brackets, so there was much less room between the tank and the spar. The plans called for small attach clips to be made and pop riveted to the spar web.

Should be OK on the -8 and other models....

gil A
 
thru or around z-brackets

gil & paul,
thanks. i'm planning on the heated dynon probe with aoa (navy guy and thus can't land a plane without aoa or make any right hand turns). thinking of running the tubing lines forward through the spar web via an fittings or snap bushings right there at the access hole.

do you think there is room under the z-brackets for the two tubing runs? i'm out of the country currently and only have a couple of plans dwgs with me.

was thinking of either securing them to the z-brackets with adel clamps or even passing them through the z-brackets with snap bushings. the z-brackets not structural as i understand it.

-clam
 
Brackets...

clam said:
gil & paul,
thanks. i'm planning on the heated dynon probe with aoa (navy guy and thus can't land a plane without aoa or make any right hand turns). thinking of running the tubing lines forward through the spar web via an fittings or snap bushings right there at the access hole.

do you think there is room under the z-brackets for the two tubing runs? i'm out of the country currently and only have a couple of plans dwgs with me.

was thinking of either securing them to the z-brackets with adel clamps or even passing them through the z-brackets with snap bushings. the z-brackets not structural as i understand it.

-clam
Click to expand...

Clam... can't say exactly since I only have RV-6 plans....:)

However, on the RV-8 tank baffle I helped assemble/proseal this week it seemed like there is enough room for two tubes under the Z brackets.

However, I would assume that these brackets are structural, they support the weight of a full fuel tank under high Gs.

A call to Vans would verify if grommet holes can be put in the brackets.... if the answer is yes, that would be the cleanest way to go.

In the -6 there are lightening holes in the spar web that allow the tubes to come forward of the spar.... does the -7 have any spar web holes out by where you plan to fit the pitot?

gil A
 
i shot an email off to vans about drilling through the z-brackets. they wouldn't say either way, and went with the standard "best method is to stick to the plans". but i just don't see how the best method is to drill through the center section for pitot lines. running them in front of the tank does make the prospect of removing a tank a bit more complicated.
have to think some more on this...
-jeff
 
Conduit?

clam said:
i shot an email off to vans about drilling through the z-brackets. they wouldn't say either way, and went with the standard "best method is to stick to the plans". but i just don't see how the best method is to drill through the center section for pitot lines. running them in front of the tank does make the prospect of removing a tank a bit more complicated.
have to think some more on this...
-jeff
Click to expand...

Jeff,

Will a length of Vans corrugated electrical conduit fit between the Z-brackets and the bottom skin of the tank?

If so, you could bond the conduit to the spar with RTV and use flexible nylon type lines for the AOA and pitot, just sliding them in the conduit.

I plan on this approach (but aft of the spar) to add a Dynon AOA pitot to an already built -6A wing that has the conduit installed. I'll mount the pitot by the next to last rib in the wing, getting access through the tip.

gil A
 
Pitot location on 9 wings

Watch out for interference with tie down ropes snagging pitot tubes if you mount them 1 bay outward on the 9 wings. I have 2 tubes on my 9, and mounted one in the next bay outboard from where the plans called it out. Wished I hadn't done that!

HTH...Chris
 
Good call Chris!

I was about to mention the same thing. This was a problem on the very early -6s. The pitot was just outboard of the tie-down. I moved my pitot inboard to avoid this interference.
 
gil- good idea. the conduit is .810" od and all of the passages under the z-brackets are wider than that except the innermost bracket. this one has about .750+" clearance, and the conduit could be press-fit through this one space. bonding to spar would prevent any troubles removing the tanks.

the -8's pitot tube is located just 2-7/16" inboard of the tiedown per plans. i'm moving the pitot tube outboard one bay to more clearance, and will probably enlarge the tooling holes nearby to pass the pitot line and aoa line through the spar. will use safeair kit 90 elbows once on the front side and continue with safeair's flex tubing through conduit.
 
Mel said:
I moved my pitot inboard to avoid this interference.
Click to expand...

Question: If you move the pitot location, do you take a chance at altering the accuracy of the indicated airspeed on the gauge?

Just wondering.................
 
PCHunt said:
Question: If you move the pitot location, do you take a chance at altering the accuracy of the indicated airspeed on the gauge?
Click to expand...
No, there is no risk of a problem, as long as the new location is far enough from the wing skin to be out of the boundary layer, not in the prop wash, not in the wake of some protrubence, and the pitot tube is aligned with the airflow within about 15 degrees or better.

Pitot tubes are very tolerant of a wide variety of mounting locations, as the laws of physics are working in our favour. They measure total pressure, and that remains the same all around the airframe. Static ports, on the other hand, are much more difficult. They measure static pressure, and that varies significantly in different places on the airframe. It is a real trick to find a static port location that has a pressure that remains close to the far stream ambient pressure throughout the whole flight envelope.
 
What Kevin said! On my Moni, the pitot was actually on the stabilizer tip. (The Moni used a VERY short prop.)
 
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