Standard Pitot or Other?

pilot28906 · #1 06-11-2010, 03:58 PM

I am trying to decide if I should go with the standard tube for the Pitot tube or use another one like the Dynon. I will probably be basic VFR but might use a Dynon which would make sense to use the Dynon Pitot for the AOA.

For those of you who use the standard tube; do you another type of AOA or the stalll warning switch that Van's sales?

Thanks

Mel · #2 06-11-2010, 04:17 PM

I've used the standard RV pitot for over 17 years with absolutely no ill effects.
Recently I added another "tube" to the aft side of the stock one for AOA. I simply "nested" the second tube against the stock one and bent the inlet down 60 degrees. I attached it with J-B Weld and calibrated the Dynon. Works great.
I don't know what it weighs because I don't have scales that will measure that "light".

elippse · #3 06-11-2010, 07:27 PM

You might also want to check out the pitot-static tube that used to be available form ACS for about $120. It's used on the Pitts and is installed in the leading edge of the wing. In testing I have done with Pitts biplanes, their IAS errors were always very small; not so with the testing I've done with many other planes that had errors of 10-18 mph, three of them RVs.

pilot28906 · #4 06-11-2010, 07:58 PM

Thanks for the info. Anyone using the stall indicator instead of the AOA? If not using the Dynon AOA which one are you using?

Thanks

Ironflight · #5 06-11-2010, 08:12 PM

Quote:

Originally Posted by elippse

In testing I have done with Pitts biplanes, their IAS errors were always very small; not so with the testing I've done with many other planes that had errors of 10-18 mph, three of them RVs.

Hey Paul, I'd suggets that the error you saw on the RV's was probably due more to static port position/design than pitot placement or type. The pitot is much less sensitive to where it is located than the static system is to port location and design. Lots of folks try to "improve" on Van's static ports, and end up with less accurate systems. We've found that for pitot, you can use just about anything headed generally into the wind and a minimum distance below the wing.

Paul

elippse · #6 06-12-2010, 09:59 AM

Quote:

Originally Posted by Ironflight

Hey Paul, I'd suggets that the error you saw on the RV's was probably due more to static port position/design than pitot placement or type. The pitot is much less sensitive to where it is located than the static system is to port location and design. Lots of folks try to "improve" on Van's static ports, and end up with less accurate systems. We've found that for pitot, you can use just about anything headed generally into the wind and a minimum distance below the wing.

Paul

You're absolutely right, Paul (Lovely name, what?). We corrected the errors by putting layers of cellophane tape behind the static port until we got rid of the error at cruise. The reason I recommended the Pitts pitot-static probe is that it is all combined in one tube sticking out the LE and has little or no static error, unlike a lot of fuselage static ports that are location sensitive. On my plane I had to put four layers of tape ahead of the port as the IAS error was -4mph.

pilot28906 · #7 06-20-2010, 01:56 PM

Mel,
I really like the idea of your AOA/Pitot setup (low cost). Do you have some photos and description of how you made this?

Thanks

paul330 · #8 06-20-2010, 02:35 PM

Although I have spent my entire career as a pilot I studied design mechanical engineering at university - OK, a looooong time ago.

I simply could NOT use a piece of bent aluminium tube and a pulled rivet with a plastic tube RTVed to the back as my pitot/static system

I am still building but the Dynon pitot and SafeAir static ports are on my aeroplane. Can't vouch for their accuracy yet but their design at least does not offend me. From what I understand the static inaccuracies are due to not ensuring that the port protrudes far enough from the fuselage to keep it clear of the boundary layer.

AirbusPilot · #9 06-20-2010, 03:08 PM

I have intalled dynon pitot tube and safeAir static port on my 8 and speed accuracy has a max error of 2 kts. Altitud accuracy has a max. Error of 10 feet.
Never tried Van's pitot or static port.

Mel · #10 06-20-2010, 04:13 PM

Quote:

Originally Posted by paul330

I simply could NOT use a piece of bent aluminum tube and a pulled rivet with a plastic tube RTVed to the back as my pitot/static system

That's why these aircraft are called experimental. You are free to experiment. It's just pointed out here that that's the way Van designed the system and it's worked great for thousands of RVs for almost 4 decades.