How many pitot's do you need?

stevengrasley · #1 11-27-2011, 09:51 PM

When configuring a -7A for IFR with a glass cockpit is seems the wisdom out there dictates to also install some steam gauge backups. If so, then can a single pitot work for the EFIS ADAHRS and the steam gauge? May sound like a dumb question but I have asked several folks... including AP's...and the range of answers is somewhat astounding. What is the input from the VAF crowd?

Steve

AltonD · #2 11-27-2011, 10:00 PM

I have one pitot feeding an autopilot, steam airspeed, and an AFS3500. There is no flow in the pitot line.

pierre smith · #3 11-28-2011, 06:05 AM

Since there really isn't any "flow" but rather pressure, you can use one pitot for multiple points.

My -10 has it to a D-100, a standby AS and the TruTrak autopilot.

Best,

Ironflight · #4 11-28-2011, 08:09 AM

For my IFR aircraft, I use a single Pitot (been flying that way for decades in spam cans...). Pitot heat should take care of ice (although I flight plan to avoid evene the potential of icing, or I don't go!) - you are susceptable to a perfectly aimed bug of course. I personally consider that a low risk.

JoeM · #5 11-28-2011, 08:35 AM

Just my opinion as a not yet pilot or aircraft owner but it seems the most likely item to cause a failure of the airspeed/altimeter indications would be leaks or clogging of the pitot/static probes and lines. I would see nothing wrong with separate systems.

Sid Lambert · #6 11-28-2011, 08:57 AM

One for each pilot on-board.

Mark12A · #7 11-28-2011, 09:12 AM

I quickly read through the thread title and I though it said, "How many pilots do you need?"

That sounds like the entry line for any number of crude jokes. Especially around fighter pilots.

krw5927 · #8 11-28-2011, 09:32 AM

Put 2 pitots in and you'll always wonder which one's right. Small chance they'll both read exactly the same.

Kind of like asking a guy with 2 watches what time it is.

David Paule · #9 11-28-2011, 09:57 AM

Quote:

Originally Posted by Ironflight

....you are susceptable to a perfectly aimed bug of course. I personally consider that a low risk.

If you don't use a pitot cover on the ground, there's a much higher chance for a clogged pitot due to a bug. Happened to me once.

Now I use one of those flip-up-in-the-wind covers, test it on preflight, and in the next 1,400 hours of mostly rural airports, have had no problems and no cover malfunctions.

Here's a link to one:
http://www.aircraftspruce.com/catalo...eprotector.php

The only issue with these is that they pop open during the take-off roll and the airspeed needle swings wildly for a second right when you'd like to have it work. As a result my take-offs are by feel. And before lift-off everything's fine. The gadget is recommended.

Dave

Don · #10 11-28-2011, 02:05 PM

Quote:

Originally Posted by Sid Lambert

One for each pilot on-board.

I read it correctly but my first thought was, 'It depends on how many airplanes you own.' I prefer having one pitot for every plane I own. Right now I have two pitot tubes but I might need a third on soon<g>...but the wife doesn't share my opinion...yet.