Today is official Global James Bond Day, an annual celebration of the 007 franchise held on October 5th. This date marks the release of the first James Bond film DR. NO, in 1962.
Required to use up annual leave but still in hard lockdown here in Melbourne and unable to travel
SO, in celebration of the official James Bond Day I decided to recreate that iconic twin cylinder breathing device featured in Thunderball... it always gets mentioned in any Bond film discussion by divers.
Watched Thunderball again, and working off some screengrabs I found online plus known dimensions (for example, the Romeo Y Julietta aluminium cigar tube is 19.6mm ID) I was able to construct a fairly accurate 3D CAD model.
Hat tip to the original props department at Eon Productions... it is very difficult to get all parts to fit inside the cigar tube, there must have been multiple prototypes in the days before 3D CAD!
I designed a rudimentary rotary on/off valve that fits the package constraints… sadly, laws of physics get in the way regarding a working LP regulator which fits inside a cigar tube!
The model makers obviously based the twin cylinders on 8g CO2 Sparklet bulbs which would have been a common item in 1960's Britain, rather than externally threaded 12g C02 inflator cylinders. So in order to get clearance around the mouthpiece and still fit into the cigar tube they added an extender piece. Standard 12g threaded cylinders will fit into the cigar case using a different adaptor.
And what about cylinder capacity I hear you ask?
I found the CO2 cylinder MSDS, and they are surprisingly strong... fill pressure 57 BAR, test pressure 235 BAR burst pressure >500 BAR.
100 BAR could be considered a 'Cave Fill' or more accurately an 'Evil Genius Grotto Fill'
So I calculated the tiny cylinder’s capacity at different fill pressures at surface and at 5m (omitting gas temperature/Compressibility Z factor for simplicity).
Happy to stand corrected, but my calculations based on Atmospheric Pressure of 1.01325 BAR at the surface and 1.51847 BAR at 5m:
Nominal_Capacity (L) = Water_Volume (L) × Working_Pressure (BAR) ÷ Atmospheric_Pressure
The original Studio model filled to 100 BAR would have held 4.8 breaths at the surface, 3.2 breaths at 5m using a resting tidal volume of 0.5L per breath.
At a working tidal volume of 1.1L per breath, our hero would have 2.2 breaths at the surface or only 1.5 breaths at 5m!
Not very useful…
I’m sure Q would have made an Extended Range MKII version based on the 12g cylinder.
In that case at 100 BAR fill Bond has 7.2 resting breaths or 3.3 working breaths at the surface.
At 5m 4.8 resting breaths or 2.2 working breaths… getting better.
Q would not have to suffer tiresome budget constraints on his Black Projects, so maybe a MKIII device could use high performance custom Titanium cylinders and reach 235 BAR or even 300 BAR fills!
For a 12g cylinder with a 300 BAR fill Bond gets a leisurely 21.6 resting breaths or 9.8 working breaths at the surface. At 5m he gets 14.4 breaths resting and 6.5 working breaths… sufficient to avoid rampaging Tiger sharks or aquatic Spectre goons with admittedly cool black double hose rigs!
Clearly I have W-A-Y too much time on my hands, but at least its kept me busy and one step away from going crazy in the end room after months of WFH in CV-19 isolation… with actual diving still a distant dream.
Enjoy
