[PSUBS-MAILIST] "Torpedo"-build

[Stephen Fordyce via Personal_Submersibles]

Hi Lasse,
I made a rig to run a cheap air drill off a SCUBA tank a while ago. It
worked, but used a frightening amount of air on the surface, and increasing
amounts at depth (ie. Theoretically twice as much at 10m). While drilling a
couple of sample holes in steel, the 12L (80c.f.) SCUBA tank lasted about 5
min!

A quick Google indicates maybe I was doing something wrong (or asking too
much of it) and that typical flow rates of 5cfm would give run time of
16min.

I would compare that to a diver propulsion vehicle (DPV)/"scooter" - I
recently did a 7km/4hr cave dive with one of these.  With a custom lithium
ion battery I designed, it weighed the same amount as a SCUBA tank. With
lead acid batteries it's probably still good for more than twice the SCUBA
tank.

Cheers,
Steve

On 13 Sep 2016 7:48 am, "JimToddPsub via Personal_Submersibles" <
personal_submersibles at psubs.org> wrote:

> Using a battery powered drill motor might be more prudent and referring to
> it as an ROV.  Sure it changes the design somewhat, but an air trail on the
> surface might scare the heck out of people.  Where would you be testing it
> and at what depth?
> Jim
>
>
> Sent from my iPhone
>
> On Sep 12, 2016, at 1:25 PM, Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Lasse,
>
> You're very well regarded here, we all know you and have for a long time.
> But may I suggest that in today's world someone who did not know you and
> came across such a project (for instance a Youtube video of it) might not
> react the same way? There are people whose full time job is spotting
> security threats, and what is really a completely innocent initiative might
> cause them concern. They can be expected to err on the side of caution with
> regulations or prohibitions of some sort. In short, I would suggest for the
> sake of everyone, this idea although fun is probably not advisable given
> the current state of affairs. It pains me to say so, because I used to
> build canons and bombs for fun when I was a 12 year old, but times have
> changed.
>
>
> Cheers,
>
> Alec
>
> On Mon, Sep 12, 2016 at 7:44 AM, Lasse Schmidt Westrén via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>> Hey guys,
>>
>> My crew friends at submarine Malen are planning to build a torpedo-ish
>> machine to fool around with in the evenings.
>> We are thinking of taking a scuba-tank, connecting a simple motor from an
>> air drill and connecting a propeller to it. We are planning to use RC for
>> steering and heading hold via a gyro.
>> Have anyone tried and have input on this?
>>
>> Cheers, Lasse
>>
>>
>>
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>>
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