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Pitot Tubes Question


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Bit of a silly question perhaps but just wondering why most/many WW2 fighter aircraft always seem to have their pitot tubes on the port wing. It may just be coincidence as there are only two wings to chose from anyway but the Spitfire, Bf109, A6M Zero and P-40 all have them on the port wing so just wondered if there is any particular reason for this?

 

Regards

Colin.

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P-51s and Fw 190s have them on the starboard wing ūüėõ¬† Lavochkin designs have them on the starboard wing as well (but Yaks have them on the port side). That's some pretty big counter-examples there (but can't find any British ones interestingly). There's probably no real rhyme or reason to it other than manufacturer preference (like the supercharger intake position on Damiler-Benz vs JuMo engines).

Edited by Vlad
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As above, I don't think there is any convention.  Fw190A & D and Ta152 series all had theirs on the starboard wing, as did the La-5 & 7.  Probably others too.  There's only two wings to choose from.. ;) 

 

My biggest concern over pitot tubes is generally what colour to paint them - camo colour, or something else.  The tips usually appear to be NMF, but as for the body colour..

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Port or starboard side could have something to do with the prop turn direction and the torque airflow (at least for the tubes on the wing leading edge)?

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Thanks for clarifying, as you say they only have two to chose from although the thought about prop rotation and subsequent airflow over the wings is something I hadn't thought about

 

Re' the painting I've always painted the final section aluminium as applying paint to this part it real life could end up gumming up the works but also never been entirely sure what colour to paint the first section as did they really very neatly apply the top camo colour to the top and then carefully mask off to apply the lower camo colour to the underside? I must say I'm not convinced about this so more often than not I paint all of the tube in aluminium. This way I can always claim that the paint, if any, has flaked off.

 

Thanks again for the replies and sorry if it was a bit of a daft question.

 

Regards

Colin.

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My only other speculation is that pilots might like to do a final inspection of the pitot before getting into the cockpit, and it seems they mostly get in from the port side, which is pretty consistent across designs and nations.

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Pilots should do a complete walk-around, checking both ailerons for example.  So that's not a reason.

Pitot probes have to be placed as much as possible clear of any air disturbed by the aircraft's passage, so any prop effects will be inboard of their positioning.  Which is why there are positioned near the tip.  Note that the Spitfire's stayed in position despite the Griffon turning in the opposite direction to the Merlin.

The tips are indeed bare metal and very smooth in order not to upset/change the flow.  But they do not need to be like that all the way.  I don't see any reason why painting top and bottom different colours would be particularly difficult as it would only require them being delivered in one colour and a bit of tape adding when painting the other.  OK, plus some protection for the hole(s).

 

I don't know of any reason why designers (or indeed nations) should prefer one wing over the other, and it does seem to be fairly random.  But there is a lot of aerodynamics that I don't understand now, if I ever did.  

 

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Just now, Graham Boak said:

Pilots should do a complete walk-around, checking both ailerons for example.  So that's not a reason.

Pitot probes have to be placed as much as possible clear of any air disturbed by the aircraft's passage, so any prop effects will be inboard of their positioning.  Which is why there are positioned near the tip.  Note that the Spitfire's stayed in position despite the Griffon turning in the opposite direction to the Merlin.

The tips are indeed bare metal and very smooth in order not to upset/change the flow.  But they do not need to be like that all the way.  I don't see any reason why painting top and bottom different colours would be particularly difficult as it would only require them being delivered in one colour and a bit of tape adding when painting the other.  OK, plus some protection for the hole(s).

 

I don't know of any reason why designers (or indeed nations) should prefer one wing over the other, and it does seem to be fairly random.  But there is a lot of aerodynamics that I don't understand now, if I ever did.  

 

Pitots are generally heated so they don’t ice up. They can get hot enough to burn the cover off if you neglect to remove it before flight, which is why the forward portion at least is unpainted...

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Very interesting and informative discussion! I learned something new today, and I keep forgetting that @Graham Boak has an aeronautical engineering background. BTW, some pitot tubes have the ends in what looks like a brass/bronze color and the tubes in aluminum or camouflage paint. (Maybe because there is pitot tube heat on many designs and paint would not remain on the heated end?)

Mike

 

Whoa! @Tailspin Turtle just now answered my question as I was asking it- is that guy good or what?  :giggle:

Edited by 72modeler
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And you're only talking single-engined aircraft. Multi-engined aircraft had pitots all over the place. Mosquitos had it on top of the vertical fin. Stirlings had two behind the bombaimer's window. Sunderlands had it on the mast behind the cockpit. It goes on.

 

 

 

Chris

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Just looking at my collection, for those with wing tip mounted pitots I'd say 70% on the left wing 30% on the right (ignoring a few where the pitot seems to have gone walkabout). But as regards consistency - my Ju-87 has it on the right, my Ju-88 on the left.

 

Cheers

 

Colin

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Some Italian WW2 aircraft had one on each wing.

 

 

 

Chris

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Just me but I've read that they were heated so I paint my tips with Tamiya Dark Iron or Gunze Burnt Iron

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For "heated" read "warmed": enough to melt any ice affecting the size of the hole but not enough to burn iron- or aluminium.  Heating the air coming in would affect the pressure being measured.  Nothing like exhaust pipes.

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3 hours ago, Graham Boak said:

Pitot probes have to be placed as much as possible clear of any air disturbed by the aircraft's passage, so any prop effects will be inboard of their positioning.  Which is why there are positioned near the tip.  Note that the Spitfire's stayed in position despite the Griffon turning in the opposite direction to the Merlin.

 

I don't want to challenge your wisdom because I'm not an aerodynamics specialist, but as it so happens, while I checked all the modells currently in my cabinet, I found no exception to the following discovery: prop turning clockwise (pilot's view) = pitot tube port, prop turning anti-clockwise = pitot tube on the starboard wing. The Spitfire has an underwing tube as far as I remember, like the P-51. My observation is only fit for wing leading edge tubes. May be coincidence, though. Happy to hear of any exceptions.

 

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Hard to find a photo online that isn't from a model: Spitfire...

 

https://thumbs.worthpoint.com/zoom/images2/360/0914/28/ww2-raf-spitfire-pitot-head_360_8b8186ad741feddc8193ebba54a6caa8.jpg

 

 

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54 minutes ago, Toryu said:

 

I don't want to challenge your wisdom because I'm not an aerodynamics specialist, but as it so happens, while I checked all the modells currently in my cabinet, I found no exception to the following discovery: prop turning clockwise (pilot's view) = pitot tube port, prop turning anti-clockwise = pitot tube on the starboard wing. The Spitfire has an underwing tube as far as I remember, like the P-51. My observation is only fit for wing leading edge tubes. May be coincidence, though. Happy to hear of any exceptions.

 

I just checked my Tamiya 1/72 FW190A. It has an engine turning the prop clockwise and the pitot on the leading edge of the starboard wing.

 

/Finn

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On TBM, F6F, F4F the Pitot tube was painted in red lacquer,

On F4F & F6F it was stencilled on Pitot tube :

"DO NOT USE AS A HANDLE" in mat black

 

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2 hours ago, Toryu said:

 

I don't want to challenge your wisdom because I'm not an aerodynamics specialist, but as it so happens, while I checked all the models currently in my cabinet, I found no exception to the following discovery: prop turning clockwise (pilot's view) = pitot tube port, prop turning anti-clockwise = pitot tube on the starboard wing. The Spitfire has an underwing tube as far as I remember, like the P-51. My observation is only fit for wing leading edge tubes. May be coincidence, though. Happy to hear of any exceptions.

 

See above: Ju.87 and Ju.88 with pitots on the opposite side yet the same engines.

 

I can't immediately think of any reason why underwing or leading edge pitots should differ.

Edited by Graham Boak
DB/Jumo props go the same way round... methinks
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I`ve only been up close and personal with  the pitots on a row of Vampires when I got " lent " by my boss , the Signals Officer to the

squadron Tech Officer of 612 Sqd . My job , blow down the end while an instrument "basher " checked the ASI and sucked on the

side slots while he checked the Altimeter ,( yes really ! ) . On one Vamp. after he climbed in and turned on the electric master switch

I got a nasty " surprise ", the pitot head became very hot ! , after shouting something unmentionable the bod said he was sorry , the

pilot had left the pitot head heater on and he hadn`t noticed , grrrr ! .I`ll bet they don`t do it that way now ! .

The actual " head " on a Vampire , and they were the only ones I met on a personal level were unpainted gunmetal colour , mounted

on the top of the port fin , I could just reach them to do the job . Happy days , and all because my boss caught me sloping off for an

early tea . 

               Don .

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