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Length of RV 12 pitot tube

Dvalcik

Well Known Member
Sponsor
Anyone close to their RV12 today, would you please measure the distance from the spinner grommet to the end of the pitot tube.

Thanks in advance
 
Last edited:
Length of Pitot Tube

About 15/16" or 23.5mm, probably 1" nominal
By grommet, I assume that you mean the bearing.

Joe, as one of our inquiring minds, have you given any thought to what would be the effect of making that length shorter, say, 5/16".

From time to time I brush against mine on the way to unlatch the hangar door on the far side.

Shorter would make the contacts less likely with less stress on the tube.
 
I had that problem too, until I started using my pitot cover.

IMG_1416-400x300.jpg
 
Be Careful.....

Joe, as one of our inquiring minds, have you given any thought to what would be the effect of making that length shorter, say, 5/16".
From time to time I brush against mine on the way to unlatch the hangar door on the far side.
Shorter would make the contacts less likely with less stress on the tube.

You might try experimenting, but if you get it too short you may start picking up the boundary layer around the spinner.
 
I do not know the affect of making the pitot tube shorter. I do not think that shorter will prevent injuries. It is just a matter of time and becoming complacent. You could move the pitot tube to the wing. While still potentially dangerous on the wing, that area gets a lot less foot traffic.
 
Mel,

I think you are wrong about the relationship between boundary layer (BL) thickness and speed. Many years ago I took a boundary layer course at Ohio State and we used Schlitching's text for our study. Boundary layer is a function of Reynolds Number (Re). In the Re equation "free stream" air velocity (outside the BL) is in the numerator. The boundary layer thickness is computed in an equation where the answer is dependent upon 1 over the square root of the Re. That would put the velocity in the denominator. You following me? For this reason computed BL is thinner on a faster moving object. Conversely, BL at lower speeds (most GA prop planes) is much thicker, in relative terms. The boom you see in the picture is for collecting air data in undisturbed air forward off the fuselage. This is to eliminate or minimize any airframe induced compressibility effects (affects?) as you approach Mach 1 and beyond . . . or so it seems to me.

George
 
Well, according to http://www.hochwarth.com/misc/AviationCalculator.html I was pulling about 0.19491 MACH on my way to breakfast on Saturday in my RV-12. Clearly those thousands of raised pulled rivets reduced my speed by at least 0.00805 MACH. Takes a big man to admit that his pitot tube might be a little short....will be sure to keep the cover on it when I'm on the ground now on, as I wouldn't want to embarrass myself in front of those other RVs with longer tubes...:p
 
The stall vane and pitot tube are sharks waiting to bite. Early on I left my pound of flesh on both, but I figured it out pretty fast -- a beat dog is a wiser dog! I wouldn't experiment with cutting it shorter as it would be a real PITA to replace a pitot tube!
 
Well, according to http://www.hochwarth.com/misc/AviationCalculator.html I was pulling about 0.19491 MACH on my way to breakfast on Saturday in my RV-12. Clearly those thousands of raised pulled rivets reduced my speed by at least 0.00805 MACH. Takes a big man to admit that his pitot tube might be a little short....will be sure to keep the cover on it when I'm on the ground now on, as I wouldn't want to embarrass myself in front of those other RVs with longer tubes...:p

It did seem to take you a long time to get to smoketown. Regarding the governor's tube, he has boasted about his being the longest in the fleet, but he is not boasting now that it has sheared off:eek:
 
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