Primarily for general aviation discussion, but other aviation topics are also welcome.
By Rupert S
#8350
Does anyone know what gismos they put into the inlets of the pitot system to stop it getting clogged with water? Presumabely, if you were to go flying in the rain, along with air being rammed into the pitot tube (or even venturi tubes on older a/c), some water would also get in. I would imagine this would damage the system. Anyone got any ideas?
By poetpilot
#8351
Not only water. Over a long period, more solid gunk can accumulate. Friend of mine suffered ASI failure in the states in a Cessna (172 I think). They found the pitot bunged up with all sorts of grot. And (according to him) there was nothing in the maintenance schedule that said "take pitot off & examine for grot".
By Rupert S
#8352
I still can't imagine there isn't a filter of some sort. If the a/c was in moderate rain, the pitot system would be filled with water in no time.
By Neil Gascoigne
#8353
Cover the tube with a filter? How's the air going to get in properly? ;)

There's pitots and pitots. Not all are tube shaped. You've probably just answered why the PA28's is a different design.
By James R
#8354
I guess in most cases you are only testing for pressure rather than airflow. The air (and water and grot etc.) will go into the pitot tube and not get much further as it hasn't got anywhere to go. It will just move backwards and forwards as you go up or down and the pressure changes.

Just a thought
By Jane
#8355
Consider the size of the pitot tube and the space between the rain drops. What is more likely to go up the pitot tube water or air?
By Chief Engineer
#8357
There are baffle or cintered plates which prevent ingress of water etc.
You will notice the the tube is normally tapered at the pointy end and there is a deflection effect with high speed airflow.
Dont forget to always test the heating element in pre-flights or one day that ice will give you a zero airspeed - Ok so you fly off the Rev. counter - have you practiced that on your sims.
By Steve Morley
#8358
Talking of Jane's post, They used to say about me (when I was svelt and young) "he has to run around in the shower just to get wet"
I know what they meant now.
By poetpilot
#8359
ah, an embittered engineer :-)

"..the diletheum crystals 'll no take it cap'n....."

I find it better to practice in a real aircraft funnily enough. That way I can feel how the aircraft is flying...
By Tailwheeler
#8360
I think there is more risk of things nesting in the pitot when parked up.

My, imported, Piper has a flap over the end on the pitot which lifts off as the airspeed builds up, simple but it seems to work.
By Jane
#8361
Thought the pitot was meant to have a pitot cover when on the ground. Not that I ever see one.
By Mark A
#8363
Remember that there is no flow of air through the pitot system.
The air stagnates at the front of the pitot head and the ASI measures the pressure rise (pitot minus static - pressure difference) and converts it to IAS.

Water and bugs are much more likely to enter when the aircraft is static, hence the value of pitot covers.
By Richard B.
#8364
.. and where does the name come from. Sounds French.

pee-toe?
pie-toe?
pee-tot?
pie-tot?
pointie-tube?
silver-thingy-that looks-like-a-gun-on-some-aircraft?
eh?

-R