[PSUBS-MAILIST] Vertical thrusters

[David Colombo via Personal_Submersibles]

Hi Alan, Im thinking the same thing. The collar should be 2-3 long below
the flush grill with the top of the wing. Aesthetically I think the flush
grill will look better.
David

On Sat, Jul 4, 2020, 1:33 PM Alan via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> David,
> I would put it down lower so you have more propeller in the collar area
> to get a bit of the kort nozzle effect & for visual streamlined look as it
> will
> protrude more with a proppeller guard on it.
> You will get some power loss with the wash hitting the sides of the
> horizontal
> Tunnel, but maybe you could make the uncut hole much larger to eliminate
> a bit of that effect.
> Alan
>
> On 5/07/2020, at 7:55 AM, David Colombo via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Alec, the 12" hole will be in the bottom as well. I just hadn't cut it
> out yet.  I'm thinking that that the prop will sit just below the grill
> which will be flush with the surface. Even with that placement the nose of
> the thruster may just peek out the bottom just a bit, so entanglement
> issues.
> David
>
> On Sat, Jul 4, 2020, 12:00 PM Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> Hi Dave,
>>
>> Looking good! Surely there is a 11" diameter hole coming in the bottom of
>> that tunnel? You wouldn't want to draw water in horizontally and expel it
>> vertically - you'd want it to come in directly from the bottom and go out
>> the top. And once you had that hole, the thruster maybe could also go a
>> little lower, so that the prop was just below grade on the top skin. But
>> the latter suggestion seems to me much less important than the first.
>>
>> Best,
>> Alec
>>
>> On Sat, Jul 4, 2020 at 1:47 PM David Colombo via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Ok guys, looking for comments on potential issues with vertical
>>> thrusters. This morning I laid in the first vert thruster in the wing to
>>> mock up the attaching bracket to the hull. The twelve inch hole will go
>>> thru the wing. The questions are:
>>> 1) hold the prop flush with top surface or raised  slightly. I will be
>>> fabbing a grill cover.
>>> 2) as the prop can draw water from the bottom as well as thru the
>>> thruster tube, any concerns with prop wash being pushed out more laterally
>>> vs vertically. Wondering if i need to have a collar at least as deep as the
>>> prop?
>>>  You might be also wondering why I have 101 lb vertical thrusters. Never
>>> know when you might need to do a barrel roll maneuver.
>>> I appreciate the feedback
>>> David
>>> _______________________________________________
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>>>
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