Pitot Tubes - 1 vs 2

Steam Gauges, Glass Cockpit, IFR Navigators, VOR Antennas,etc.
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StingerEquip
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Location: Louisville, KY

Pitot Tubes - 1 vs 2

Post by StingerEquip »

When designing your setup will you use 1 or 2 pitot tubes for redundancy? I'm planning on 2 unless I hear a good reason otherwise.

I have not seen this discussed before and wonder why? Seems like one of those things you can't afford to loose. You can do pretty much anything else on a iPhone or iPad....but not indicated air speed.

ebrunye
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Re: Pitot Tubes - 1 vs 2

Post by ebrunye »

You have GPS for backup if your pitot tube is clogged or something. It's only going to give you ground speed but loss of your pitot tube/ias is not a life threatening situation.

Here's the problem. You would have one pitot tube installed that must never be used except in the event of failure of the primary. If they both feed the ahars units, it's possible there will be an average pressure reading between the two, but it's also possible it creates an open loop system where the air flows in one and out the other and gives a false reading or none at all to your instruments. Therefore, you must have a switch installed somewhere for your alternate pitot tube, which would be unused 99.99% of the time, in the very unlikely event of a pitot tube clog. Not to mention the amount of extra work required to install a second pitot tube, presumably in the other wing, which requires cutting of skins and building mounting brackets.

Alternately, if your pitot tube becomes clogged or you're having trouble with your ias, use a combination of GPS speed/known throttle or rpm settings to land at the nearest airport to unclog the tube.

That being said, I installed 3 pitot tubes on my TSi, considering adding a 4th.

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PhilipRueker
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Re: Pitot Tubes - 1 vs 2

Post by PhilipRueker »

While redundancy is nice, a second pitot tube would require a lot of additional consideration.

Like Evan mention, first of all you'll have to cut the skins and fit another mounting bracket on the other wing. And then you have to figure out either a switch over system, or have a separate sensor powered by the other pitot tube, which adds more cost.

While you would be losing the indicated speed, you'll still have GPS speed and should have known throttle settings that should hopefully be able to get you to the ground safely.

So rather, I will use the heated pitot tube, the automatically regulated one, so that way you can turn it on as part of your standard operating procedures and don't have to remember to turn it on based on temperature.
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StingerEquip
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Joined: Sun Nov 24, 2019 10:13 am
Location: Louisville, KY

Re: Pitot Tubes - 1 vs 2

Post by StingerEquip »

The known throttle position makes sense to be “Good Enough” to land safely. A known thrust will give a safe airspeed for landing.

MTJ
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Re: Pitot Tubes - 1 vs 2

Post by MTJ »

For me, knowing the basic pitch/power for the the desired phase of flight is usually a close enough WAG for any airspeed problems.

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