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Re: [PSUBS-MAILIST] Bilg pump
Doug,
Whew, for the moment I thought you might of thought I was crazy
bringing up bowling balls. Just being descriptive about
weight/balance/trim.
Good to know I'm only partially nuts.
Also, I was thinking about the power overhead needed to operate bilge
pumps vs just human power needed to manipulate a mechanical ballast
system. But, I assume both would be desireable.
Off topic:
As for the "blocks", it wasn't just the blocks, but the blocks and the
weight of our
bodies [ mine mashed up against the yoke face pressed on windshield ]
that offset the COG so that it was forward heavy. Kind of like tipping a
seesaw.
Also, all it took was a slight pitch down so the prop could chew some air
and
thrust to add forward momentum so it just wasn't the weight offset.
The other amazing thing is since we were mashed up like that you couldn't
see
the airspeed indicator. I read and was taught not to trust your instincts
[ ie.,
"Stick 'n Rudder" the classic ]. But I've come to realize [ and after
flying for
a while ] that pilots develop a whole "new" set of instincts otherwise
how did my
instructor know when to pull back on the yoke when minimum airspeed
before
stall was reached? He was hugging the console , too. Well, it worked and
I'm
still here ! I'm sure the physics could be worked out to demonstrate
this. After
that episode I asked him for all the emergency training I could get. Try
spin
recovery under the hood : -o don't eat before doing this.
--Steve
On Tue, 16 Mar 2004 09:50:22 EST DJACKSON99@aol.com writes:
> Hello Steve
>
> The bilge pump in my sub will clear the engine snorkel and keep the
> hull dry
> while surfaced, not much different from a normal installation. All
> of my
> ballast weight is mechanical so its more like 50 bowling balls. See
>
> http://jackson.parcabul.com/sub/Sub_H8_files/Sub_H8.htm
>
> I do think that a bilge pumps are a good idea for wet and ambient
> subs that
> want to obtain greater freeboard or stability once on the surface.
> They can be
> used to empty flooded portions of the hull or pontoons. No air
> lines are
> required and no vent must remain sealed so the risk are reduced.
>
> Off-Topic: I have done neg-g's in a small plane just for fun, and
> once we
> were floating around the cabin along with everything else that was
> not strapped
> down our movements had no noticeable effect on the attitude. What
> did you do
> with the brick and what effect would moving it have?
>
> Thanks
> Doug J
>
>
>
> In a message dated 3/15/2004 3:50:56 PM Central Standard Time,
> cirtemoeg@juno.com writes:
> Pierre and Doug,
>
> I didn't think the idea was far fetched. If I may use an
> illustration I
> experienced during pilot training [again]. My instructor kept two
> cinder
> blocks just behind the forward seats. I thought this was odd and
> asked him about this and was told it was for emergencies in case
> the aircraft went into a flat spin or loss of control. He also
> stated
> that
> we probably would never have to use them. Hmmm, well, we DID in
> one cross-country trip over the Sierras. We hit a wind shear going
> over
> a mountain ridge and dropped 500 ft in a split second. Also, there
> was
> no airflow over wing and control surfaces, so we were in a flat
> drop.
> First time I experienced zero Gs. The cinder blocks floated past us
> and
> my instructor said, quick, grab one and pushed me against the yoke
> and my face mashed-up against the window. [ his also ]. We
> gradually
> pitched forward and we got enough air flow for control and
> ever-so-gently
> eased her back up. Good thing, the ground was coming up awfully
> fast!!!
>
> My thought is why not just a mechanical ballast mechanism. Two
> bowling
> balls on a short rail forward and aft of COG made adjustable by hand
> lever or foot pedal?
>
> Feasible ?
>
> --Steve
>
>
> On Mon, 15 Mar 2004 16:10:25 EST DJACKSON99@aol.com writes:
> > Greetings Pierre
> >
> > I use bilge pumps on my home built ROV, and unfortunately they
> > barely do the
> > job and my ROV only weighs about 8 pounds. See
> > http://jackson.parcabul.com/rov/index.html I am in the process of
> > upgrading my ROV and converting the bilge
> > pumps to use impellers but even then I don't think they would
> stand
> > a chance
> > of pushing your sub around. I am going to test a bilge pump to
> 150
> > feet
> > because I need one on my sub when it is surfaced. You might be
> > interested in that.
> > It could be used to give a wet or ambient more freeboard by
> pumping
> > a ballast
> > tank dry once surfaced, consuming battery instead of compressed
> air.
> > Here is
> > the pump I am going to test:
> > http://jackson.parcabul.com/sub/shurflow_bilge_pump.htm
> >
> > How are you coming on your sub?
> >
> > Kindest Regards
> > Doug Jackson
> > http://jackson.parcabul.com/sub/
> >
> >
> >
> > In a message dated 3/15/2004 1:44:06 PM Central Standard Time,
> > pipo305@hotmail.com writes:
> > Hello all!
> >
> > A long time ago I saw a R/C sub that used small water pumps for
> > movement. (I
> > saw that on psubs).
> >
> > I was wandering, could we use that on our psubs for small position
>
> > movements? We could use boat's pump (12V) and steer the output in
> > the
> > direction we want.
> >
> > What do you thing about that? It could be a good (read cheap) idea
>
> > instead
> > of minn-kota motors...
> >
> > Pierre Poulin
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