[PSUBS-MAILIST] thruster sizing etc

Sun Sep 28 09:14:22 EDT 2014

Alan,
In an effort to keep things simple and cost under control, I would agree with Alec.  Fixed motors are much less complicated, and given the low cost of motors, it is cheaper to install extra motors rather than fabricate rotating mechanisms.  
Hank --------------------------------------------
On Sun, 9/28/14, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] thruster sizing etc
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Sunday, September 28, 2014, 5:40 AM

 Thanks
 Alec that was helpful.Is that the normal mode of
 operation, having the side thrusters
 lockedvertical? Were you putting them in reverse
 or just relying on positive buoyancy.I was
 planning on having side thrusters that are rotated by
 electric motors, so my hands are just on a
 couple of joy sticks controlling all the motor
 functions.I liked the idea of using rotating side
 thrusters so that I could have double the power
 travellinghorizontally if need be. Also there
 would be no need to ramp the motors down to
 change from forward to reverse.Any
 thoughts on the pros or cons of this
 anyone?Alan

 Sent from my iPad
 On
 28/09/2014, at 4:55 pm, Alec Smyth via Personal_Submersibles
 <personal_submersibles at psubs.org>
 wrote:

 Hi Alan,
 On the stern, snoopy has a 55 lb
 Minnkota. The side thrusters are actually of unknown thrust,
 they came with Snoopy and are Motorguides but I'm not
 exactly sure which model. My estimate would be about 40 lbs
 (each). What you saw in Florida would have been forward
 motion based on the stern thruster alone, as I was using the
 side thrusters just for depth keeping, locked vertical. The
 K250 has very limited battery capacity, carrying three
 batteries in the standard design and four in Snoopy. I find
 the thrusters well proportioned to the limited battery
 capacity. The bottom line is that a K250 has perfectly
 adequate thrusters and batteries for diving, but not enough
 for surface runs. Something in the league of Minnkota 101s
 is great, but only on subs with battery pods.
 Best,
 Alec 
 On Sat, Sep 27, 2014 at
 8:17 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:
 Alec,

 what size motors do you have on Snoopy?

 I remember watching you disappear into the blue surprisingly
 quickly in Florida.

 Were you using the stern & side thrusters
 simultaneously?

 Are you happy with the speed?

 I have spent a LOT of time Googling brushless motors &
 haven't come up with

 an easy solution.

 I was looking particularly at inrunner motors, as they have
 a couple of advantages

 over outrunners, however outrunners have lower revs.
 Whatever, they are both going

 to need gearing down majorly & matching up with a
 planetary gear isn't looking easy.

 Most of the motors that are available are found at Hobby
 King & are lightweight & made

 mainly for model planes. So their strength & ability to
 sustain several hours of

 continual operation are in question.

 Must be a solution out there because 9 out of 10 thruster
 manufacturers are using brushless motors & I doubt they
 would be making there own.

 Alan

 Sent from my iPad

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