Russian Alfa Class
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I have another question?
Does it make any difference if the water inlet is in the center of piston tank or if it is located near the bottom of the tank! I have seen some tanks where the water inlet/outlet is located nearer the bottom of the tank! Just don't know if it would draw in more water from the bottom or if it does not make any difference!? Any thoughts would be appreciated!
Rob
"Firemen can stand the heat"Last edited by rwtdiver; 09-16-2021, 02:22 AM.Comment
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For drawing in water, I do not think it makes a difference. I place my inlet near the bottom to allow draining on the bench, but it depends on if that makes the most sense with all the other devices. Sometimes in the center just is easier for piping. The thing that is important is the inlet needs to be large enough to move the water the piston pushes. In other words, if it ia too small the piston will push, but there will be a lot of resistance because the water cannot get out quick enough.This will cause the motor to work harder than it needs to.If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.Comment
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For drawing in water, I do not think it makes a difference. I place my inlet near the bottom to allow draining on the bench, but it depends on if that makes the most sense with all the other devices. Sometimes in the center just is easier for piping. The thing that is important is the inlet needs to be large enough to move the water the piston pushes. In other words, if it ia too small the piston will push, but there will be a lot of resistance because the water cannot get out quick enough.This will cause the motor to work harder than it needs to.
I think I will leave the opening where it is located (center of tank) at this point. I will install a fitting that will give me at least a full 1/4" ID for water movement!
Thanks Tom, I appreciate your expertise!
Rob
"Firemen can stand the heat"Comment
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Most common rule is propeller diameter = brushed motor can diameter.Make it simple, make strong, make it work!Comment
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The can size can be misleading, you need to also look at the RPM and torque characteristics of the motor.
You ought to be looking at a shaft speed of about 4-5000RPM for decent performance for a 1/96 Alfa.
Direct drive
555 for direct drive. High turn crawler 500's are another alternative .e.g. https://www.componentshop.co.uk/mabu...-dc-motor.html
Geared
A speed 385 geared down about 2.5:1 for reduction.
Brushless alternative-.
28-35mm outrunner, 400-500kv, direct drive.Comment
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The can size can be misleading, you need to also look at the RPM and torque characteristics of the motor.
You ought to be looking at a shaft speed of about 4-5000RPM for decent performance for a 1/96 Alfa.
Direct drive
555 for direct drive. High turn crawler 500's are another alternative .e.g. https://www.componentshop.co.uk/mabu...-dc-motor.html
Geared
A speed 385 geared down about 2.5:1 for reduction.
Brushless alternative-.
28-35mm outrunner, 400-500kv, direct drive.
Thank you VERY much for the great information! I do appreciate you taking the time to post it up! I was able to locate the Mabuchi 555 motors 12V 4500 RPM on ebay, and I purchased three off them for possible new boats and for back-up! Thanks again for you help!!
Rob
"Firemen can stand the heat"Last edited by rwtdiver; 09-17-2021, 08:25 PM.Comment
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I am making some more progress on my scratch built WTC! I have printed out some cylinder bridging and also two end caps! I am using some colored PLA instead of the old plain white, not sure on colors yet!
This shot just show a total overview of the preliminary cylinder layout! It is going to be tight for sure!
These two last shots are showing the piston gearing set-up and the piston shut down (full ballast tank position) micro switch! There will another micro switch on the other end of the cylinder that will shut the piston down when the cylinder is empty! Still have more design and building to do to get everything needed inside the WTC for full system operation!
Rob
"Firemen can stand the heat"Comment
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I have a Battery question?
I found a NMHB 12 volt 2000mAh rechargeable battery! It's made up of 10 AA batteries.
This battery is a great fit for my Alfa 1:96 scale sub build. Without going into a lot of detail (which I understand you need for an accurate answer) this battery will be operating the following: 1-550 12v DC drive motor, 1- 12v geared piston tank drive motor, and 2- 12g mini drive servos.
With my current situation, this boat would be in the water 10 to 15 min in between battery charges! My question, based on the information I have given you, will this battery do the job?
Rob
"Firemen can stand the heat"Comment
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Cant you use a lipo instead? I assume your machinary will deplete them rather quick. Also the cables look very thin. I had the problem on my early models that such small cells were drained quickly when you had everything running at once.
Besides, great work with your ALFA. Am curious how your cylinder will perform!
JörgComment
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My 1/72 Skipjack runs on them and I get an long amount of time (never depleted them completely) - ran over an hour. If running all your electronics draws 1 amp, you will get 2 hours on that battery.If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.Comment
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Thank you Jorg and Tom!
I appreciate the information and advice! I may just give it a run and see what happens. When the ballast tank piston is in operation it is pulling almost 6 amp's, (approximately 45 seconds) The wires seem a little undersized to me as well, may just step them up a GA. or two! Thank you very much for the help you guys!!
Rob
"Firemen can stand the heat"Comment
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Rob,
Yes, if I used my piston like crazy and ran my sub at full speed, it wouldn't last 10 minutes....but I don't. I really look forward to seeing you get this one working.If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.Comment
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