Cigarette/AMG Offshore Powerboat - Page 5 - RC Groups
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Aug 22, 2017, 08:00 PM
Grumpa Tom
Kmot's Avatar
Put it in the pool and checked how it sits. The water line is just over the output driveshafts where I had to make seals. The seals keep most of the water out, but not all of it. Am going to have to think about this for a bit, how to mitigate that.
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Aug 22, 2017, 08:11 PM
Registered User
Gravman's Avatar
Wow! That is one fine looking boat! It looks fast just sitting still. I like the colors on the out drives. Great job. I am glad you got an old project done at last. I got too many of those myself.
Aug 23, 2017, 10:50 AM
Registered User
Tim B.'s Avatar
Killer !
Aug 24, 2017, 01:42 PM
Grumpa Tom
Kmot's Avatar

Greaser!


The "seals" I made from the Ionomer foam sheet had to have X-slits cut in them to allow the drive shafts to poke through. Turned out the boat sits in the water with those seals under the water line. So water got inside the boat when I put it into my pool to see how it sat in the water and to see if there was any water ingress.

I am assuming that the water that got inside came through those seals. To try to mitigate this I packed the area with synthetic grease. I am hoping this will slow down the process of water ingress.
Aug 24, 2017, 01:49 PM
Grumpa Tom
Kmot's Avatar

Final Adjustment?


The next to last thing I had to do was make the final adjustment to the steering linkage, tighten and Loctite all lock nuts, and lube the balls in the Heim joints.

There is one last detail I want to attend to. I ordered some thin foam strip with adhesive on one side. I will run that around the inside of the hatch so that the hatch cover will rest on it when it is put into place. The foam strip is scheduled to arrive tomorrow.
Aug 26, 2017, 09:17 PM
Grumpa Tom
Kmot's Avatar

Maiden Voyage


Had the maiden voyage today. Ran it on 4S and all was good. Probably around 13-15 mph. Looked good out on the water. The grease worked well as very little water was inside. I'm very happy how it went.

Cigarette AMG Maiden (3 min 57 sec)
Aug 27, 2017, 06:17 AM
Boat Modeller
Lewist's Avatar
Looks great on the water - top job. How do you feel about the speed and power that those motors provide?
Aug 27, 2017, 10:39 AM
Registered User
Tim B.'s Avatar

Scale Speed


Well produced vid ( as usual ), Great scale speed appearance, nice to see brushed motors at work in this fine model ~

Aug 27, 2017, 11:02 AM
Grumpa Tom
Kmot's Avatar
Quote:
Originally Posted by Lewist
Looks great on the water - top job. How do you feel about the speed and power that those motors provide?
Thanks Lewis! Regarding the motors, they are designed as 20 volt motors and I was running (4S) 15 volts. So they were not being supplied what they wanted. However, I felt the speed looked "scale" for a cruising type situation. I ran for approximately 3 minutes, and the batteries had hardly been consumed, so this could be a good setup for a run-float-run type of deal. I did next run on (6S) 25 volts, and the performance was quite a bit more spirited. Unfortunately, due to a Quality Control issue by the manufacturer (metal debris left inside the motor) the run was short with some damage.

Quote:
Originally Posted by Tim B.
Well produced vid ( as usual ), Great scale speed appearance, nice to see brushed motors at work in this fine model ~

Thanks Tim!
Aug 27, 2017, 11:45 AM
Grumpa Tom
Kmot's Avatar

Quality Control Issues


[RANT] Well, I guess this is going to be a "bitch session"....

I have had quality control issues with all of the components in the power train of this model. The ESC's were bad on arrival and had to be repaired. The stern drives are not equal in machined measurements, one is slightly longer than the other, and the drilled holes were not done properly in several spots and had to be re-worked. The prop shafts are not equal, and the drive dogs are not the same length. Lastly, one of the motors locked up on the workbench when testing. I freed it by turning it backwards, It locked again. I freed it again. Then it started spinning like normal and did not seem to have a problem. I had ASSumed I had gotten a sliver of wood from the transom inside the motor while working on it, and that it caused the stoppage, but got broken up by the back and forth motion I did on the armature. I also ran it with a vacuum hose over it. All seemed good again, and I took it to the pond for its maiden voyage.

The maiden voyage went without a hitch. Ran it on 4S batteries. I was happy.

Later that day I ran it a second time, using 6S batteries. It ran very nice, looked great. I stopped the boat in the water to look at my telemetry and check the motor temp. 106F, not bad. I then added power and was going to come back to the dock but within a second or two, the sound changed. I knew instinctively that something had failed. Only one motor was running. It sort of sounded like one motor had lost a prop. I drove it back to the dock at reduced power. By the time it got back to the dock, smoke was coming out of the hatch area.

Thanks to the fella's at the lake (Rick, Ray, Dennis) they got the hatch screws undone and lifted off the hatch. An enormous cloud of toxic lithium smoke and stench rose out of the boat. Dennis quickly unplugged the puffed, melting, lithium spitting lipo battery. I then yanked the battery out of the boat and tossed it on the ground.

The motor was scalding hot, impossible to touch. I got my electronic temp gauge and measaured 196F at some spots on the motor. It was locked up solid.

My initial thought was that it was all my fault, for using inferior batteries. They were only 20C rated. (This is, of course, way higher than the C rating for the NiCd batteries it was designed for back in the day). I ASSumed that the low C rating caused the motor's current draw to be excessive and make the motor overheat, the battery overheat, and lock up the motor by expanding the armature and magnets against each other.

The other motor, and other battery, were fine. And the temperatures nominal.

When I got back home, I took the motor out of the boat and tore it down. That is when I discovered the REAL reason for the carnage. QUALITY CONTROL! Or to be more precise, LACK OF QUALITY CONTROL!

This motor was NIB when I purchased it. The shaft had never been ground for a grub screw. The power leads had the factory solder tinning on the ends. The commutator was clean. But what I found inside was shocking, and made me very angry. A diamond piece of metal had been left inside the motor. It was what caused the motor to lock up that first time on the workbench, and later out on the lake. It was hanging onto the magnet, and I hypothesize that when the motor stopped turning from letting off the power, it could have twisted very slightly, making the point of the metal piece jam into one of the slots on the armature. This locked up the motor.

Out on the water, when I was bringing the boat back under the one operating motor, this motor was stalled. This caused a massive current draw, massive buildup of heat, and damaging the lipo battery and causing it to puff and nearly catch fire. I could have lost the boat if it had happened a few yards further out.

This metal, arrow shaped piece, appears to have broken at what might be the "arm" it was part of. It sort of looks like a watch hand to me. Or from a tiny instrument of some sort. In any case, it is ferrous and very strong metal.

So the second run nearly ended up in a disaster, nearly caught the boat on fire, and I am thankful to my Hansen Dam Violator buddies for helping me save the day!

{/RANT]
Aug 27, 2017, 12:45 PM
WooHoo!
woodybob's Avatar
Whew...
Aug 27, 2017, 01:18 PM
Registered User
Tim B.'s Avatar

No fires please


Quote:
Originally Posted by Kmot
So the second run nearly ended up in a disaster, nearly caught the boat on fire, and I am thankful to my Hansen Dam Violator buddies for helping me save the day!
Great Luck no fire !
Aug 27, 2017, 03:06 PM
Grumpa Tom
Kmot's Avatar
Quote:
Originally Posted by Tim B.
Great Luck no fire !
Seriously!

Here is the second run on 6S batteries.


Cigarette AMG 2nd Run (2 min 52 sec)
Aug 27, 2017, 03:18 PM
Registered User
Tim B.'s Avatar

Good scale speed


'Attsa cool lookin' boat ~

Aug 27, 2017, 04:08 PM
Boat Modeller
Lewist's Avatar
Major downer on the motor issue! I have to say it runs much better on 6s. It jams along nicely with that power and looks great. Is the motor ok or is it now cooked?


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