Don,
Great work... You convinced me that this line is for blowing MBT 3! It seems like such a small air line to blow such a huge ballast tank (MBT 3). Comparing the size of the blowing line to the size of the venting valves (2) for MBT 3 in the venting trunks...
The diameters of the blowing lines: internal 17 mm, external 20 mm.
As a point of interest, the regulating tanks and Q-tanks blowing lines diameters are: internal 22 mm, external 26 mm.
Since the blowing line is such a small diameter have you ever read as to how long it took to blow MBT 3 (even partially blow)?
No, as I recall, I have never met such data. But knowing the flooding holes cross-area and blowing air pressure and amount, the time could be possible to estimate.
If I remember correctly, Mark has made such calculations.
With the differential in vent and blowing diameters, then diving time would be faster, and surfacing time would be much slower...
I'm not sure if flooding cross-area did not have greater influence on blowing and flooding time than vent and blowing lines diamater.
I see there are two blowing valves for MBT 3 Port and Starboard...
Yes, you are right. I was not able to locate stb valve. If both valves were located symmetrical, the stb one should be located near the aft diving plane operating station. But there are oxygen bottles on the deck. So I guess, that the stb valve is located near (under) the blowing distributor.
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Regards
Maciek