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Pitot tube slightly plugged...

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nuckolls.bob(at)aeroelect
Guest

Posted: Fri Sep 21, 2012 9:13 am Post subject: Pitot tube slightly plugged...

At 06:21 PM 9/20/2012, you wrote:




<snip>



Called the factory in OH, and related a new-to-them technique of 

removing the obstacle. Good feeling to re-invent the wheel, a bit. 

BTW, the manufacturing process and subsequent internal road map 

knowledge IS proprietary... short of destroying the $600 p-tube.



    It would be really interesting to know the

    makeup of the obstruction.



    The interior passages for a pitot tube are

    a maze of holes, turns, drains and baffles

    designed to strip high velocity moisture

    (wet or frozen) from the air sample, keep

    it warm enough remain liquid, and allow

    a real sample of dynamic pressure to be

    impressed upon ship's instruments.



http://aeroelectric.com/Pictures/Pitot_Tube/Pitot_Tube_Heater.jpg



    The fact that you were unable to physically

    dislodge it suggests it was buried around

    a sharp turn or hiding behind a baffle. I'm

    thinking that it was probably a spider nest

    where adult but tiny creatures carried a succession

    of materials inside and built an obstructing

    volume. Pitot tube covers are a GOOD thing

    and it wouldn't hurt if they were TIGHT. Perhaps

    a piece of slip-fit hose or tubing.



    I got to work with the folks at Aero Instruments

    when HBC was wrestling with what appeared to

    be 'clear air' blocking of one and sometimes

    both pitot tubes on airplanes cruising a

    high altitude. The instruments always recovered

    at lower altitude/warmer atmosphere.



    It had to be ice accumulating in a poorly

    deiced volume within the tube. The problem

    was to figure out exactly where and how.

    Not all spaces within the dynamic pressure

    vessel are held above freezing when the

    OAT is -50C or so.



    Interesting story . . . and I'm please to

    hear that you were able to salvage an otherwise

    useless piece of expensive hardware!



   Bob . . .

wynaire(at)citlink.net
Guest

Posted: Fri Sep 21, 2012 8:45 pm Post subject: Pitot tube slightly plugged...

Thanks for the illustrative cutaways and info Bob. These PT's are much more

sophisticated than at a 2nd glance. And your pix do indicate the same 

pathway my safety wire probe was trying to navigate. The "remains" are 

stored for photo-micro graphing later on in the slightly "green" depleted 

battery acid. However, the heater elements still perform per  Aero 

Instruments test-for-certification specs on element amp draw and resistance. 

So, despite a little brightening of the copper and identical air-flow based 

on a non-plugged same model p-tube, all is well. Life is interesting.

Heater element test specs on Aero Instruments' Pitot Tube model PH502 

series: 12 vdc pitot element should draw 6.34 to 8 amps after 2 minutes 

operation.

A 24 vdc pitot element [same model] should draw 3.17 to 4 amps after 2 

minutes operation.

Resistance in ohms should range from 0.1 to 400. This info is also available 

as a .pdf at their web site: www.aero-inst.com/products/aeroph502.php.

Mike

**********

---

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Sep 22, 2012 10:20 am Post subject: Pitot tube slightly plugged...

. . the heater elements still perform per  Aero Instruments test-for-certification specs on element amp draw and resistance. So, despite a little brightening of the copper and identical air-flow based on a non-plugged same model p-tube, all is well. Life is interesting.



   Those heater elements are pretty complex. They appear to be

   semi-rigid, linear, tube heaters not unlike those one might buy

   from Cal-Rod . . . 



   In fact, there heater wire is wound around a core but with

   variable spacing such that x watts are dissipated in one

   segment, y watts in another, and z watts elsewhere. The 

   probability for ice accretion and risk therefrom varies

   throughout the geometry of the assembly. The hammer-n-tongs

   approach is to simply put enough heater in to warm the whole

   thing up so that adequate calories are always delivered to

   the worst case location. This would probably double the

   current draw and make for a very hot tube.



   On the ground and zero air flow, a heated pitot will achieve

   cherry red emissions temperatures. In clear air, 300kts,

   41K feet and -40C . . . the tube merely heats up to

   100C or so.  See:



  http://tinyurl.com/74yr5q8



   At 41K, we can see the effect of increase velocity.

   At 200Kts, certain parts of this particular device

   rose to about 90 and 110C . . . but as IAS went up

   sharply in descent they quickly dropped before there

   was much. Ram Air Temp rise sharply during that maneuver

   too. 



   Now, pile some super cooled water on or in the tube

   that becomes hard ice on impact and the tube temperature

   drops WAaayy down and quickly. At the same time, the

   heater-resistance goes down causing the tube to draw

   much more current. That 4 amp current on the bench goes

   to 10A under heavy icing conditions. Here's some data

   I gathered on about a half dozen, exemplar 28v tubes.



  http://tinyurl.com/cnndlub



   even thought the surface of the tube is firmly

   locked at 0C in stirred ice, the heater inside

   was still running about 140C . . . due to limits

   on how low the thermal resistance could be for

   an electrically insulating medium around the

   heater wires.



   Getting a pitot tube to perform well in the icing

   tunnel is an almost frenetic hat-dance around limits

   and goals. There is more to those devices than meets

   the eye.



   After being tasked with participating in one

   such a hat-dance, I took a hint from Weller

   soldering guns, HV supplies in CRT/vacuum

   tube TV, and modern microwave magnetron

   power supplies and proffered this idea:



 [img]cid:.0[/img]



   Suppose you made a pitot tube out of concentric

   stainless steel tubes like this and excited

   the assembly with very low voltage, high

   current energy from a switchmode power supply

   built into the base of the tube. I hypothesized

   that one could distribute heating energy between

   inside and outside tubes by controlling wall

   thickness.



   The tube WAS also the heater. No temperature drop

   across heater/tube insulation. Plenty of heat

   thoughout such that tailored distribution

   issues might go away. No independent heater to

   fabricate, no heater-tube insulation issues . . .

   or LOSSES.



   I proposed that to my boss who was willing

   to take it up the ladder . . . but the immediate

   response was, "We get our pitot tubes from Aero

   Instruments. They build pitot tubes, we build

   airplanes."



   There was a time when I worked my first projects

   with Beech that somebody would have taken this

   ball down-court to at least see if it bounced.



   I hear the Russian space program is turning blue

   with loss of grey-mater. See:



  http://tinyurl.com/blzjvu3



   Some connectors-of-dots in the world wide

   aerospace industry have noted that the glow

   is off the rose for working on 'rockets and

   airplanes'. Young bucks fresh out of school

   know they can make more money in information

   technologies and consumer materials . . . the

   lure that brought many of us to aviation years

   ago doesn't work the magic it did back then.

   Hot hangars, grease, JP, hydraulic oil and

   gouges all over your body have been replaced

   with brightly lit, air conditioned, keyboards

   and tech benches . . . and low risk of

   discomfort.

  

   Russia, like the US, is losing it's intellectual

   horsepower and as the grey-beards retire, the

   effects are showing.



   So, perhaps there's an opportunity for somebody

   out there with some metal working skills and

   a curious nature. I'd be willing to stroke

   the electronics if some one of you could acquire,

   bend and weld alloys of steel that might make

   good heaters cum pitot tube.



   It would be interesting to see if this ball

   would at least bounce. Could we learn to "build

   the better pitot tube" for MUCH less than

   $600?



   Bob . . .



 



 



 



 

 

   Bob . . .

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Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Sat Sep 22, 2012 3:48 pm Post subject: Re: Pitot tube slightly plugged...

I flew one of those flights where you just KNEW we already had two strikes. And gosh I learned a lot.



I took off from Furnace Creek into a rapidly approaching (astonishing!) black sandstorm. But the sandstorm quickly outran and engulfed us. Made a 180 out of the sandstorm to find I had no airspeed indicator. The winds were ferocious and making Santa Monica with fuel onboard was dicey, KWJF Fox Field (our normal fuel stop) was closed due to winds. So we stopped in Aqua Dulce...using the stall warning.



We tried to clear the pitot tube with a coat-hangar wire but no dice. We had inadequate tools. Next day the mechanic cleared it. Analysis--Mud dauber wasp.



Jeeeze....the thing you learn and shouldn't do again.



But three points: Cover the pitot tube when parked--always. Unless you have one of those airspeed-operated flapper valves.



A way of ram-rodding the tube would be a step forward in design. But the problem is usually only discovered after getting airborne. So glancing at the ASI during the takeoff run will be in my scan, even if Cessnas easily fly themselves off the ground. 



Some bug biologist-psychologist should invent a neat way to keep out dauber wasps. It would make a good science project. Mud daubers bring down heavy iron too.

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

rparigoris

Joined: 24 Nov 2009
Posts: 796

Posted: Sat Sep 22, 2012 4:13 pm Post subject: Pitot tube slightly plugged...

Hi Eric 

 	Thx. for sharing your experience. 

 	You mentioned "Unless you have one of those airspeed-operated flapper valves". 

 	I owned a 1948 Cessna 170 ragwing for 19 years. Twice I got mud dapper nest in the Pitot tube. 

 	The second time it happened, the wind was howling and I noticed right after take off, so landed and cleared it. When putting tools away and a little worried the plane may roll in a pretty big gust (even though I had wheel chocks in place), I just happened to notice that the airspeed actuated flapper Pitot cover was fully opened, hmm. Then a few seconds later I observed a dapper wasp somehow manage in this wicked gusty wind to land on and crawl inside! 

 	I replaced flapper with a cover and never had another problem. 

 	Ron Parigoris 

 	     [quote][b]

raymondj(at)frontiernet.n
Guest

Posted: Sat Sep 22, 2012 4:43 pm Post subject: Pitot tube slightly plugged...

We have a bad problem with the mud daubers around here.  If I leave an 

air tool outside for a day, they find it, and build in the inlet.  Got 

me to thinking,  Has anyone had problems with them building in static 

intake ports, fuel vents on gas caps, or the drains on collators.  

Starting to think my preflight should include all the above.



Raymond Julian

Kettle River, MN.



"And you know that I could have me a million more friends,

and all I'd have to lose is my point of view." - John Prine



On 09/22/2012 07:13 PM, rparigor(at)suffolk.lib.ny.us wrote:

 	  Quote: 	
		  

 Hi Eric



 Thx. for sharing your experience.



 You mentioned "Unless you have one of those airspeed-operated flapper 

 valves".



 I owned a 1948 Cessna 170 ragwing for 19 years. Twice I got mud dapper 

 nest in the Pitot tube.



 The second time it happened, the wind was howling and I noticed right 

 after take off, so landed and cleared it. When putting tools away and 

 a little worried the plane may roll in a pretty big gust (even though 

 I had wheel chocks in place), I just happened to notice that the 

 airspeed actuated flapper Pitot cover was fully opened, hmm. Then a 

 few seconds later I observed a dapper wasp somehow manage in this 

 wicked gusty wind to land on and crawl inside!



 I replaced flapper with a cover and never had another problem.



 Ron Parigoris

deej(at)deej.net
Guest

Posted: Sat Sep 22, 2012 4:55 pm Post subject: Pitot tube slightly plugged...

On 9/22/2012 8:42 PM, rayj wrote:

 	  Quote: 	
		   Has anyone had problems with them building in static intake ports, 

 fuel vents on gas caps, or the drains on collators. 


	


     Yes, multiple times I've had bugs build a nest in my fuel drains 

and vents.  My cheap solution:



Go to Walmart and buy a 100 pack of bright orange "fuzzy sticks" for 

$0.99.  Used to be commonly known as "pipe cleaners".  You can find them 

in the fabric and crafts section.



http://www.walmart.com/ip/Kids-Craft-100pk-Fuzzy-Sticks-Neon/19525338



Cut off a 4 inch section.  Fold in half, then on each leg halfway up 

fold outward.



You end up with something shaped like this:  _/\_



Stick the "V" end up in the hole in the fuel drain, gascolator, fuel 

vent, etc, with the legs sticking out to the side.



Remove before flight, but in theory air would be able to pass if you 

accidentally left them in the fuel vent.



Been doing this for a few years now and no more bug problem in the fuel 

drains.



-Dj



-- 

Dj Merrill - N1JOV

Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Glastar Flyer N866RH - http://deej.net/glastar/

raymondj(at)frontiernet.n
Guest

Posted: Sat Sep 22, 2012 5:19 pm Post subject: Pitot tube slightly plugged...

Great idea!!  I was starting to think about covers for everything and 

imagining a whole bag full.

I'll definitely be doing this.

THANKS!!

do not archive

-- 

Raymond Julian

Kettle River, MN.

"And you know that I could have me a million more friends,

and all I'd have to lose is my point of view." - John Prine

On 09/22/2012 07:55 PM, Dj Merrill wrote:

 	  Quote: 	

 On 9/22/2012 8:42 PM, rayj wrote:

> Has anyone had problems with them building in static intake ports, 

> fuel vents on gas caps, or the drains on collators. 

     Yes, multiple times I've had bugs build a nest in my fuel drains 

 and vents.  My cheap solution:

 Go to Walmart and buy a 100 pack of bright orange "fuzzy sticks" for 

 $0.99.  Used to be commonly known as "pipe cleaners".  You can find 

 them in the fabric and crafts section.

 http://www.walmart.com/ip/Kids-Craft-100pk-Fuzzy-Sticks-Neon/19525338

 Cut off a 4 inch section.  Fold in half, then on each leg halfway up 

 fold outward.

 You end up with something shaped like this:  _/\_

 Stick the "V" end up in the hole in the fuel drain, gascolator, fuel 

 vent, etc, with the legs sticking out to the side.

 Remove before flight, but in theory air would be able to pass if you 

 accidentally left them in the fuel vent.

 Been doing this for a few years now and no more bug problem in the 

 fuel drains.

 -Dj

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Sep 23, 2012 10:10 am Post subject: Pitot tube slightly plugged...

 	  Quote: 	
		  

Stick the "V" end up in the hole in the fuel drain, gascolator, fuel 

vent, etc, with the legs sticking out to the side.



Remove before flight, but in theory air would be able to pass if you 

accidentally left them in the fuel vent.



Been doing this for a few years now and no more bug problem in the 

fuel drains.


	


   An elegant solution Dj . . . how about some photos

   of these critters in place. Let's do a little one-pager

   for the AEC website archives.



   Bob . . .

deej(at)deej.net
Guest

Posted: Sun Sep 23, 2012 4:10 pm Post subject: Pitot tube slightly plugged...

On 9/23/2012 2:07 PM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		  

   An elegant solution Dj . . . how about some photos

   of these critters in place. Let's do a little one-pager

   for the AEC website archives.




	


Hi Bob,

     I did a quick little write-up on my website at:



http://deej.net/aviation/bug-plug/



     Feel free to use the pictures and info on that page if you want to 

put something up on the AEC site.



-Dj



-- 

Dj Merrill - N1JOV

Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Glastar Flyer N866RH - http://deej.net/glastar/

N20DG

Joined: 02 Jan 2008
Posts: 61
Location: lancaster, texas

Posted: Sun Sep 23, 2012 4:41 pm Post subject: Pitot tube slightly plugged...

Can you convert the document to PDF format so it can be easily saved

 Thanks,

 Dick

  

  

  In a message dated 9/23/2012 7:11:01 P.M. Central Daylight Time,  deej(at)deej.net writes:

  	  Quote: 	
		  -->    AeroElectric-List message posted by: Dj Merrill    <deej(at)deej.net>



On 9/23/2012 2:07 PM, Robert L. Nuckolls, III    wrote:

 	  Quote: 	
		  

   An elegant solution Dj . . . how about some    photos

   of these critters in place. Let's do a little    one-pager

   for the AEC website archives.




	


Hi    Bob,

     I did a quick little write-up on my website    at:



http://deej.net/aviation/bug-plug/



     Feel    free to use the pictures and info on that page if you want to 

put    something up on the AEC site.



-Dj



-- 

Dj Merrill -    N1JOV

Sportsman 2+2 Builder #7118 N421DJ -    http://deej.net/sportsman/

Glastar Flyer N866RH -     = Use  ilities  ay                 - MATRONICS WEB FORUMS               - List Contribution Web Site  p;                             



	


 [quote][b]

harley(at)AgelessWings.co
Guest

Posted: Mon Sep 24, 2012 4:42 am Post subject: Pitot tube slightly plugged...

I have Firefox, and am not sure how to do it with other browsers,     but it allows me to download and save the page directly as it is in     two steps.  

     

     First, when on the page, select "File" then "Save Page As...", and     select the location where you want to put it.  It will sutomatically     save the text and html code as an htm file.  

     

     Second step, go back to the online page, select ANY image, RIGHT     click on it and select "Download All Images".  Firefox will pick the     folder that you last saved to by default, which is probably the one     where you put the htm file, and download all the images there as     well. 

     

     To view it, simply click on the htm file on your computer and it     will load offline in your browser just as the original page did.

     

     Harley

      

     On 9/23/2012 8:40 PM, RGent1224(at)aol.com (RGent1224(at)aol.com)       wrote:

     

     [quote]                              Can you convert the document to PDF format so it can be           easily saved

         Thanks,

         Dick

          

          

                    In a message dated 9/23/2012 7:11:01 P.M. Central             Daylight Time, deej(at)deej.net (deej(at)deej.net) writes:

            	  Quote: 	
		  -->               AeroElectric-List message posted by: Dj Merrill               <deej(at)deej.net> (deej(at)deej.net)

               

               On 9/23/2012 2:07 PM, Robert L. Nuckolls, III wrote:

               >

               >   An elegant solution Dj . . . how about some photos

               >   of these critters in place. Let's do a little               one-pager

               >   for the AEC website archives.

               >

               

               Hi Bob,

                    I did a quick little write-up on my website at:

               

               http://deej.net/aviation/bug-plug/

               

                    Feel free to use the pictures and info on that page               if you want to 

               put something up on the AEC site.

               

               -Dj

               

               -- 

               Dj Merrill - N1JOV

               Sportsman 2+2 Builder #7118 N421DJ -               http://deej.net/sportsman/

               Glastar Flyer N866RH -   = Use ilities ay              -               MATRONICS WEB FORUMS            - List Contribution Web               Site p;                         

               

               

               

             	
         

               	  Quote: 	
		  

	
       

No virus         found in this message.

         Checked by AVG - www.avg.com

         09/23/12     [b]

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Mon Sep 24, 2012 5:23 am Post subject: Re: Pitot tube slightly plugged...

Mud dauber wasps are the bane of small holes everywhere. I want to suggest that an enterprising individual do the following long-term experiment (Actually, you might try searching the USPTO first):



Let's see what attracts mud dauber wasps. Do many experiments with enough time to allow the wasps to build nests (and taking the weather into account.):



1) Drill a grid of different size holes in a board. Mount the board in a location know for having a known problem with the wasps. Do the WMDs (Wasps, Mud Dauber) prefer a hole size? Log the result.

2) Repeat with a spectrum of different colors. Do the WMDs prefer a color? How about in the UV? Log the result.

3) Repeat with various contrasting patterns around the holes (e.g. starburst, concentric circles, snowflake, spirals, flower petals, angry jagged shapes...whatever you can think of). Log the result.

4) Put a colored LED behind a series of the same size holes. Log the result.

5) Put a blinking LED behind a series of the same size holes. Try various colors. Log the result. 

6) Keep going until you find a solution.

7) Patent it. "Method of Preventing Aircraft Pitot Tube Obstruction by Mud Dauber Wasp." 

 Pick up your Nobel prize in Stockholm.

9) Your MacArthur Genius Prize will be waiting when you return home.



Okay, perhaps that is going too far. But the airlines and pitot tube makers would be very happy to pay for any workable results. Remember, every jet engine you see has that curly snake on the nose cone. This reliably prevents birds from nesting in the inlet. A bird will never come near anything that (in its tiny bird brain) might possibly be a snake. I put a rubber snake on my rear deck which absolutely keeps bird and their mess away.



The goal is to find something in the WMDs brain that works similarly. There are myriad odd insect habits. Perhaps they won't ever come near a yellow pitot probe, or one with UV-bright flower petals or a blinking LED...nobody knows. Several solutions might be possible.



This would be a great science project, even for a whole classroom.



Good luck, and tell us what happens.



Addendum: See my website for a pitot tube of interest:

http://www.periheliondesign.com/downloads/thermopitot.pdf

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

harley(at)AgelessWings.co
Guest

Posted: Mon Sep 24, 2012 5:34 am Post subject: Pitot tube slightly plugged...

Very interesting idea, Eric! As a start to whoever wants to attempt     this, I had several two foot long pieces of 3/16 inch shrink tubing     hanging from a shelf in my garage.  The daubers plugged up the black     tubing, but NOT the yellow, white or red!  Not very definitive, but     all the openings were hanging in the same location, bunched     together.  The black looked like it had several years of nests in     it, going a couple of inches up the tubing on both ends, but the     others were absolutely clear. 

     

     Harley

          On 9/24/2012 9:23 AM, Eric M. Jones       wrote:

     

     [quote]        	  Quote: 	
		  --> AeroElectric-List message posted by: "Eric M. Jones" <emjones(at)charter.net> (emjones(at)charter.net)



Mud dauber wasps are the bane of small holes everywhere. I want to suggest that an enterprising individual do the following long-term experiment (Actually, you might try searching the USPTO first):



Let's see what attracts mud dauber wasps. Do many experiments with enough time to allow the wasps to build nests (and taking the weather into account.):



1) Drill a grid of different size holes in a board. Mount the board in a location know for having a known problem with the wasps. Do the WMDs (Wasps, Mud Dauber) prefer a hole size? Log the result.

2) Repeat with a spectrum of different colors. Do the WMDs prefer a color? How about in the UV? Log the result.

3) Repeat with various contrasting patterns around the holes (e.g. starburst, concentric circles, snowflake, spirals, flower petals, angry jagged shapes...whatever you can think of). Log the result.

4) Put a colored LED behind a series of the same size holes. Log the result.

5) Put a blinking LED behind a series of the same size holes. Try various colors. Log the result. 

6) Keep going until you find a solution.

7) Patent it. "Method of Preventing Aircraft Pitot Tube Obstruction by Mud Dauber Wasp." 

 Pick up your Nobel prize in Stockholm.

9) Your MacArthur Genius Prize will be waiting when you return home.



Okay, perhaps that is going too far. But the airlines and pitot tube makers would be very happy to pay for any workable results. Remember, every jet engine you see has that curly snake on the nose cone. This reliably prevents birds from nesting in the inlet. A bird will never come near anything that (in its tiny bird brain) might possibly be a snake. I put a rubber snake on my rear deck which absolutely keeps bird and their mess away.



The goal is to find something in the WMDs brain that works similarly. There are myriad odd insect habits. Perhaps they won't ever come near a yellow pitot probe, or one with UV-bright flower petals or a blinking LED...nobody knows. Several solutions might be possible.



This would be a great science project, even for a whole classroom.



Good luck, and tell us what happens.



Addendum: See my website for a pitot tube of interest:

http://www.periheliondesign.com/downloads/thermopitot.pdf



--------

Eric M. Jones

www.PerihelionDesign.com

113 Brentwood Drive

Southbridge, MA 01550

(508) 764-2072

emjones(at)charter.net





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=383883#383883







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     [b]

klehman(at)albedo.net
Guest

Posted: Mon Sep 24, 2012 5:56 am Post subject: Pitot tube slightly plugged...

Similar here. They like the black but not the clear transparent tubing.

Ken



On 24/09/2012 9:33 AM, Harley wrote:

 	  Quote: 	
		   Very interesting idea, Eric! As a start to whoever wants to attempt

 this, I had several two foot long pieces of 3/16 inch shrink tubing

 hanging from a shelf in my garage. The daubers plugged up the black

 tubing, but NOT the yellow, white or red! Not very definitive, but all

 the openings were hanging in the same location, bunched together. The

 black looked like it had several years of nests in it, going a couple of

 inches up the tubing on both ends, but the others were absolutely clear.



 Harley

 ------------------------------------------------------------------------

 On 9/24/2012 9:23 AM, Eric M. Jones wrote:

> 

>

> Mud dauber wasps are the bane of small holes everywhere. I want to suggest that an enterprising individual do the following long-term experiment (Actually, you might try searching the USPTO first):

>

> Let's see what attracts mud dauber wasps. Do many experiments with enough time to allow the wasps to build nests (and taking the weather into account.):

>

> 1) Drill a grid of different size holes in a board. Mount the board in a location know for having a known problem with the wasps. Do the WMDs (Wasps, Mud Dauber) prefer a hole size? Log the result.

> 2) Repeat with a spectrum of different colors. Do the WMDs prefer a color? How about in the UV? Log the result.

> 3) Repeat with various contrasting patterns around the holes (e.g. starburst, concentric circles, snowflake, spirals, flower petals, angry jagged shapes...whatever you can think of). Log the result.

> 4) Put a colored LED behind a series of the same size holes. Log the result.

> 5) Put a blinking LED behind a series of the same size holes. Try various colors. Log the result.

> 6) Keep going until you find a solution.

> 7) Patent it. "Method of Preventing Aircraft Pitot Tube Obstruction by Mud Dauber Wasp."

>  Pick up your Nobel prize in Stockholm.

> 9) Your MacArthur Genius Prize will be waiting when you return home.

>

> Okay, perhaps that is going too far. But the airlines and pitot tube makers would be very happy to pay for any workable results. Remember, every jet engine you see has that curly snake on the nose cone. This reliably prevents birds from nesting in the inlet. A bird will never come near anything that (in its tiny bird brain) might possibly be a snake. I put a rubber snake on my rear deck which absolutely keeps bird and their mess away.

>

> The goal is to find something in the WMDs brain that works similarly. There are myriad odd insect habits. Perhaps they won't ever come near a yellow pitot probe, or one with UV-bright flower petals or a blinking LED...nobody knows. Several solutions might be possible.

>

> This would be a great science project, even for a whole classroom.

>

> Good luck, and tell us what happens.

>

> Addendum: See my website for a pitot tube of interest:

> http://www.periheliondesign.com/downloads/thermopitot.pdf

>

> --------

> Eric M. Jones

> www.PerihelionDesign.com

> 113 Brentwood Drive

> Southbridge, MA 01550

> (508) 764-2072

> emjones(at)charter.net

>

millner(at)me.com
Guest

Posted: Wed Sep 26, 2012 12:05 pm Post subject: Pitot tube slightly plugged...

>> I'm please to hear that you were able to salvage an otherwise 

useless piece of expensive hardware!



Let me warn that there appears to be an error in the repair 

description.  The OP wrote battery acid, HCl.  But of course, battery 

acid is H2SO4.



I can believe a weak (3 molar?) solution of HCl, as is often used as 

swimming pool acid or brick cleaning acid might dislodge organic 

material from a pitot tube without dissolving the pitot tube itself.  I 

would be very surprised (would not likely believe) that battery acid, 

full strength, undiluted sulfuric acid was able to do anything but 

significantly dissolve a pitot tube...



Hopefully the OP can clarify what he meant, since his acid description 

was internally inconsistent.



Paul

wynaire(at)citlink.net
Guest

Posted: Wed Sep 26, 2012 12:46 pm Post subject: Pitot tube slightly plugged...

Thanks, Paul. I stand corrected. The acid used was obtained directly from a 

surplus supply left over from filling a new dry lead-acid car battery. The 

container had been capped, but was at least one year old. I do not know the 

strength of the solution. FWIW: The vinegar actually brightened the visible 

copper more than the battery acid.

And thanks to all who contributed their improvised techniques to thwarting 

insects from creating homes in small holes. Especially interesting was the 

comment about using different colored tubing. With a bug-plugged 

scupper-ring at the fuel fill port on a C337, the rain-water level will rise 

above the lip of the fuel cap neck. Until the owner [me] realizes that he 

has a plugged scupper vent line, the appearance of water in the fuel 

tank/test is an interesting and humbling mystery. My fix in 2001 was to add 

2 inches of clear Tygon tubing to each vent outlet. I figured that if the 

bugs were there, I'd at least see them the next time. However, they never 

returned. Now I know why. Thanks guys.

Mike

---

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