Can anyone tell me what it says on this Swordfish lighting switch panel?

[pogotc]

The image below is taken from a Swordfish walkaround video
(
View: https://youtu.be/Bx-ysOGUicI?t=1562),

but frustratingly bits of the text are out of focus. The bits I'm trying to decipher are:

1. The long message at the top, it looks like it says "the pressure head switch must be off when ....... pressure head" but I can't make out the bits in between.
2. The set of options to the right of the first switch, it looks like they say off / morse / form, does that sound right?
3. The label on the right most switch, I think based on the long message at the top it says "press head"?

I've tried going frame by frame on the video but those bits are always just out of focus, if anyone could tell me what it says it'd be much appreciated.

 

[Wurger]

Ad.1 ... THE PRESSURE HEAD SWITCH MUST BE OFF WHEN MOD 318 IS IN USE
and the label below ... PRESSURE HEAD
the label with the arrow at the box top ... SWITCH ON BEFORE TAKING OFF
Ad.2 ... OFF / MORSE / FORMTn ... the FORMTn is and abbreviation of the word FORMATION.
Ad.3 ... the label pointed by the arrow for the right most switch ... PRESS HEAD

 

[pogotc]

Thank you so much, I would never have got that.

As a follow up question, do you know what "mod 318" refers to and what the pressure head switch does?

 

[Wurger]

The inscription PRESSURE HEAD is a part of the inscription SWITCH ON BEFORE TAKING OFF and refers to the right most switch ... PRESS HEAD. IIRC the switch was also called the Pitot Head. So it seems to be a pressure system that worked with the speedometer. Regarding the Mod 318 ... I'm not sure but it looks like it had in common with the aircraft configuration. But I may be wrong.

 

[SaparotRob]

.. But I may be wrong.

Maybe, but I doubt it.

 

[pogotc]

Huh, I didn't think pitot tubes needed any kind of pressurisation system to power the speedometer, which it sounds like might be what's going on here if I've understood you correctly.

I can't find anything on Google about mod 318, this plane is managed by an organisation called NavyWings so I wonder if it's something specific to them and not on all Sworfish

 

[Wurger]

Huh, I didn't think pitot tubes needed any kind of pressurisation system to power the speedometer, which it sounds like might be what's going on here if I've understood you correctly.

As memo serves the Brits used two kinds of the Pitot Head. The early MK.I used a one with two pipes seen while the later Mk.I and the next variants used the Pitot of one head. These were attached on the port front wing strut. Because the Stringbag had the wings folded it is possible the line form the air pressure sensor to the speed indicator had to be closed for some reason. The Mod 318 may mean "Modification 318" what may suggest that there was a "correction' introduced that required the switch being off.

 

[ThomasP]

I think I remember reading that the early production Swordfish Mk I had an unheated Pressure Head (ie Pitot Tube). Later production received a Mod that introduced Pressure Head (Pitot Tube) heating. The Mod number I read about was a lower (I think) number than 318, but there may have been more than one Mod number for the same thing depending on the Swordfish Mark and the already existing equipment and/or other Mods.

I have read other instructions where there is mention of an aircraft's Pitot Head heater being turned on before take-off.

Maybe?

 

[Wurger]

I think I remember reading that the early production Swordfish Mk I had an unheated Pressure Head (ie Pitot Tube). Later production received a Mod that introduced Pressure Head (Pitot Tube) heating. The Mod number I read about was a lower (I think) number than 318, but there may have been more than one Mod number for the same thing depending on the Swordfish Mark and the already existing equipment and/or other Mods.

I have read other instructions where mention of an aircraft's Pitot Head heater being turned on before take-off.

Maybe?

I agree. That also sounds very likely.

 

[pogotc]

I think that all sounds quite likely as well, thanks both for the responses and explanations!

 

[MIflyer]

It says, "Too much sex is bad for your eyes."

 

[Crimea_River]

Yeah, I'm thinking the label for the right-most switch would read "Pitot Head", not pressure head. Mosquito B.35:

 

[Wurger]

Yeah, I'm thinking the label for the right-most switch would read "Pitot Head", not pressure head. Mosquito B.35:

View attachment 771377

Andy, the Press Head is the abbreviation for the Pressure Head applied on the box as the label of the switch. It is the same what the Pitot Head.

the source: Swordfish C-GEVS

 

[special ed]

Maybe the Swordfish flew so slowly that there wasn't enough air pressure into the pitot to work the instrument, so additional pressure was needed. -- just guessing.

 

[Wurger]

Maybe the Swordfish flew so slowly that there wasn't enough air pressure into the pitot to work the instrument, so additional pressure was needed. -- just guessing.

Ooh .. they would make it with a spring then .
However it should be kept in mind that the Pitot Head there wasn't use for the speedometer only but also for an altimeter and a variometer. As ThomasP has mentioned that above, the Pressure Head Mk.IVA/VA/VII/VIIA ( two pressure tubes seen ) were non-heated types while the Mk.VIII was the heated one.

 

[pogotc]

Wurger - thanks so much for posting those photos and the link to the website where they came from, there are some fantastic photos there from lots of angles I haven't seen before.

 

[Wurger]

My pleasure.

 

[dasstuka]

this might help some as I opened the photo in Gimp photo editor inverted the color image and adjusted brightness and contrast