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Postby Carcharadon » Wed Jan 31, 2007 8:45 pm

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Postby Carcharadon » Fri Aug 31, 2007 3:45 am

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Postby Scott T » Fri Aug 31, 2007 1:20 pm

Good job!
Any pictures of pump installation?

Scott
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Postby Carcharadon » Fri Aug 31, 2007 3:49 pm

Scott, thanks.

Working on it now.

4 pumps are in, 2 to go.

Batteries are from a cordless drill.

I want to use 4 but not sure how things will fit

I'll take photos if I can get it all in
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Postby Carcharadon » Mon Sep 03, 2007 1:54 pm

Scott pictures last pdf


This is background on what I’m trying to accomplish


http://home.comcast.net/~gustofur/TESTS.pdf



I've installed four pumps and their associated plumbing. Because of the configuration I want to achieve with the port and starboard ex-current nozzles as close to the tail as possible necessitates that the two forward pumps excurrent nozzles had to be placed higher than in the previous 4 ft jet nautilus model. This should not change forward performance. It's still possible to lower the port and starboard excurrent nozzles but this would mean more plumbing external of the shell. So for the time being I'm trying to keep things internal as possible.

Although I have a lot of experience and it took me long time to workout all the variables on the first 4 ft there's no guarantee that I'll get it right the first time on the second version.

As I was anxious to try out the pump with the higher voltage battery I temporarily connected the 14.4 V cordless drill battery to one of the forward pumps. To keep a supply of water I simply filled the bottom hull section using a garden hose. To my surprise I found that the pump would empty the hull (in about one or two seconds) even with the garden hose fully opened, the discharge pump exceeded the capacity of the garden hose at full open.

I wanted to install four cordless drill batteries. These battery packs with their awkward shape and size would be hard to fit in the shell even if I could waterproof them. So I took out the Ni Cad batteries and encased them in fiberglass to insure waterproofing. The other 4 foot used sealed batteries so there was no need to waterproof. There are 48-1000 milli-amp cells that I took out of the four cordless drill battery packs. This should give me decent runtimes. Also unique to Ni Cads is that their discharge voltage remains high to the very end. The sealed batteries drop voltage proportionate to the level of charge. So that cuts into your runtime.

I had to take apart a charger and rewire it since the original battery packs are no longer. Since the charger was designed to charge only one battery pack at a time a total of four at once may generate too much heat. In that case charging may be a two or three stage process, leaving time for the new pack to cool or I may need some type of water cooling.

If too much heat is generated the fiberglass used to encase the cells would crack exposing the cells to water and corrosion.

I'm not worried about discharge heat in the sub since it will be in contact with a constant flow of cooling water while the sub is operating.

What remains to be installed now are the down and reverse pumps and the RC electronics. Then the RAM needs to be completed, the bottom rakers and a rear stabilizing fin. This bottom rear fin serves two purposes. Since the sub hull is full of water with a lot of inertia, the sub tends to turn underwater when brought to a stop. The stabilizing fin resists this turning and keeps the sub in a straight orientation when the forward pumps stop. Also the sub may veer to the right or left when under full forward power at the surface. Since there is no rudder control, the rudder itself can be repositioned slightly by heating the fiberglass and making a best guess correction. This can't be tested unless the sub is actually in use at the Pond. However the stabilizing fin made of aluminum can be bent slightly while at the Pond in real-time mode. Slight adjustments are usually enough to keep the sub straight.

http://home.comcast.net/~gustofur/shell2.pdf



Some more info on progress to date with pictures



I was anxious to test the system to try and get an idea if the concept will work. I'm trying to get better turning performance at full speed by relocating the turning Jets to the rear of the sub where they will deflect one of the foward Jets. This is illustrated in the PDF file linked below. The bilge pumps themselves are not yet sealed as I wanted to get an idea if it would work before I committed to further development.

And while it seems like it might work I won't really know until I actually take it to the pond.

Also found out that charging the equivalent of 4 cordless drill batteries at once does not increase the heat but just takes four times longer.

http://home.comcast.net/~gustofur/Jets1.pdf
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Postby Carcharadon » Thu Sep 13, 2007 8:45 am

The original RC electronic system used a combination of solid-state devices and automotive relays to power the bilge pumps. Eventually I was able to eliminate the automotive relays. This was on a system using 12 Volt standard sealed batteries. Sealed batteries drop voltage continuously during use.

The new NiCad batteries (cordless drill batteries 14.4 volt) charge up to 16 V and maintain slightly above 15 during use.

Apparently this was too much for the MOSFETs to handle (the two forward bilge pumps) and while conducting additional test tank runs they cooked.

But then that's the nature of an experiment, you change one thing in a proven tested system and something else fails.

I took the solid-state device apart removed the burnt component and installed a part I obtain from a computer power supply. Since this MOSFET was about three times larger I actually had to make electrical extensions using paperclip sections. Although it was obvious from its size that the new MOSFET could handle the power because of space limitations a heat sink was not used and of course it burnt out too.

However I have a solution as yet untested but I think it'll work if I can fit it all in. When working with the solid-state devices extreme caution is required because even if a loose wire grounds only momentarily everything can short. So far I've gone through two radio receivers and one Opto isolated E switch.

I have a CRYDOM solid-state relay which should handle all the power the bilge pumps require at 15 V or more. I've learned from past experience that the solid state relay input will short out an Opto isolated E switch because of the low resistance. A load resistor in series with the input is required to keep the Opto isolated E switch from blowing.

All this tests out on the bench but I'll just have to see under real-time test tank conditions and maybe then it's off to the pond?

http://home.comcast.net/~gustofur/eswitch.pdf
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Postby Scott T » Thu Sep 13, 2007 1:31 pm

I looked at your pictures of piping the water. What do you think of using
hose (wheres that garden hose) instead of a rigid pipe. It might make it easier to pack everything in.
Hoses could curve around objects but still be held in position for aiming jets of water.

Keep up the good work.

Scott
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Postby Carcharadon » Thu Sep 13, 2007 3:08 pm

Thanks Scott,

Scott, hose works great and I have used it. Even in the new 4 foot there is a short piece of hose. The solid pipe is fixed to the hull and provides support to the bilge pumps and is less flexible than hose. The PVC pipe can be heated and bent but sometimes a hose serves the same purpose. The only negative aspect of a hose is that in bending it may go out of round depending on the type of hose. Since I'm after all the power I can get fixed pipe is the choice over hose, but hose works well too.
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