[PSUBS-MAILIST] Dry Ambient Sub

[Alan via Personal_Submersibles]

Hi Tarek,
no diagrams came out in my email.
I would do a full size model of what you intend & get in &
make sure the space works. Especially if you intend to have a
diver exit in the bottom. Can you get out comfortably with scuba 
tanks! Also as you go out the diver exit the sub becomes lighter
to the extent of the weight of yourself & your dive gear.
Tim's ambient sports sub has a system for adjusting this loss of 
weight by letting in more water. I am not sure how this works but
if you adopted it you would need to allow for a volume of water to
come in to the bottom hatchway of the sub. And of course the oposite
is true when you re-enter.
If you have problems with stability when diving you could always add
syntactic foam up high & more lead down low to counteract it.
Have you had a look at Cliff's R300 on the projects page, as the hull
seems a similar size.
Cheers Alan


Sent from my iPad

> On 17/02/2018, at 11:41 PM, Tarek Harb via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Dear guys,
> I would like to share with you my initial plan for the Dry Ambient sub I am building.  I would love to hear any suggestions or comments about my calculations.
>  
> The Dimensions of the Dry Cock pit is: width = 0.7 m, Length = 1.6 m, and Height = 0.85 m.
> This will give a total volume of: 0.952 m3.  The Cock pit will produce an upward Buoyant force of about 950 kg (I do understand that kg is not a unit of force, but I do this for sake of clarity).  
>  
> The total Mass of the Sub is around 850 Kg.  So in order to make sure that the sub dive, its weight (or mass) has to be heavier than the Buoyant force produced by the
> Cock pit, so I will add about 100 kg of Lead to compensate.
>  
> I did the calculations of the Center of Gravity and the Center of Buoyancy, from which I obtained the MetaCentric height. 
> this calculations indicated that the design will keep the sub at a stable condition on surface and while descending, which is very important and critical.
> I can provide this calculations later on if anyone interested.
>  
> Here is a rough diagram indicating the thoughts so far
>  
> On surface
>  
> <image005.png>
> <image006.png>
>  
> 
>           
>  
> <image011.png><image012.png><image018.png> 
>       FB                           FB                          Water level
> <image021.png>
> <image024.png>
> <image025.png>
>  
>  
>  
>  
>  
> 
>                         Weight of all sub = 950 Kg
>  
> 1= Cock Pit. Volume is 0.95 m3.
> 2= Main Ballast Tanks.  Volume is 0.95 m3, this will give an upward force of 950 kg assuming that the density of water is 1000 Kg/m3.
> 3. Trim Ballast Tanks
> FB= Buoyant force = both forces will add up to cancel the weight of the sub.
> At this stage all the Ballast tanks are empty and full of air.
> <image026.png>Descending
>                              FB = Buoy Force from Cock Pit                         
> <image027.png>
> <image028.png>
>  
> 
> <image021.png><image030.png><image032.png><image034.png>                                                                   Water level
>           
>  
> <image018.png> 
>                                                
> <image037.png>
> <image038.png>
>  
>  
>  
>  
>  
> 
>                        Weight = 950 Kg
>  
> At this stage, the Buoyant Force from the Pit + the Buoyant force from the Trim Tanks will equate the downward weight of the sub.
> The Main Ballast Tanks are full as the blue color indicates.  Since they are full, they will not contribute to give upward force.
>  
>  
> <image039.png>UnderWater
> FB = Buoy Force from Cock Pit     
>  
> <image040.png>                                                Water level                  
>                             
> <image042.png><image044.png><image046.png>                                                                  
>           
>  
> <image018.png> 
>                                                
> <image037.png>
> <image038.png>
>  
>  
>  
>  
>  
> 
>                        Weight = 950 Kg
>  
> Underwater, the Buoyant Force from the pit will equate the downward weight of the sub, and it will maneuver using the Motors.
>  
> At a final note, the cockpit will have an exit hole at the bottom.
>  
> regards
>  
>  
>  
>  
>  
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