Hi Erik,
> that people are just not inclined to share that level of
> information
Probably more like, they really don't know. It works well enough. Why
bother? The work to populate the data base will be a pain, for the
sub owner.
For instance if a sub moves forward. Do they care to know if its top
speed is 3 knots or 4 knots. Just guessing isn't good enough for the
database. As a results they would have to figure out a method to get a
reasonable number, take a trip out to a body of water, and run the
test just to get this one data point.
How about figuring out prop RPM? To be valid the test has to be in the
water over various hull speeds. Some have the expertise to figure out
a method to figure that. How about those who don't? What methods do
they use? Who will help them? Again the owner would bear the brunt of
the data collection hassles.
Personally I think this project will take a lot more then just saying,
hey, please fill out my cool database. There need to be some bounds
and controls around the parameters. For instance:
1. Pointers to the database. Where it was?
2. Instructions on how to use the database.
3. For each paramter in the database a definition of what that value
is. The units used.
4. A short discription on how to come up with, figure out, or measure
a value. Take the above forward speed question. Someone may say hey, I
know the distance from this dock to that jetty over there is 3 miles
(Well that is what he heard, it is really 3.2 statute miles.). Using
his wrist watch for elasped time and it was close to 3:30PM (Really
3:30:45PM).
Better would be:
a. Use a GPS, take a fix and write down.
b. Either use a wrist watch and write down hours, minutes and seconds.
Or use a stopwatch.
c. Power to distant point for at least 30 minutes in as straight a
line as possible.
d. Take GPS fix, write down, calculate elasped distance.
e. Stop stopwatch and write down elasped time. Or if used wrist watch
then record hours, minutes, seconds and calculate elasped time.
f. Calculate speed:
speed = elasped distance (in nautical miles) / elasped time (in hours)
g. Repeat steps a-f by going in opposite direction.
h. Average both numbers to average out drift by currents.
Regards,
Ray
Erik Muller wrote:
Hi Folks,
I think this is question is a validation for an on-site page which
can disseminate information about the various parameters of peoples
currently operating subs.
I tried to implement such a thing a while ago, and the information
page was designed by warrens brother. It works very well, though
no-one seems particularly interested in contributing to it. I'm not
sure if this means that absolutely noone has operating subs (which I
know is not true), or that people are just not inclined to share that
level of information.
I personally would LOVE to know about the physical parameters of
operating machines, though I suppose I am in a minority. Is this the
case? Is there anyone else who is interested in discovering some
empirical correlations with parameters like displacement, resistive
cross section, thrust, velocity, power.. etc etc etc.?
If so, is there space to make such an information page more
immediately visible on psubs?
EM.
Brian Cox wrote:
Hi, I have a question for Gary Boucher if he is listening! On
your sub "Vindicator" I was wondering what RPM your propeller motor
runs at? I can't remember if you go direct electric propeller or if
you said that it is a hydrolic motor? Thanks
Brian Cox
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