DUKW Scratch Builds

[Ecam]

The length of the motors are about even. Adding a reduction unit to a 540 doesn't look likely if I try to keep it "under" decks. Qundry time.....

[Ecam]

Still working out a drivetrain for the 16th scale. I built a 9 cell to try with the 12v motor. It did run better, but not what I want.

I put some effort in the 9th ish scale chassis. First attempt with a 13 turn 540 (an on hand motor) with a 3 to 1 gear reduction, resulted in a duck that would rival many 10th scale cars for speed. Switched to a "truck puller 2" (unknown turns) and came up with a much more reasonable top speed.

Now I am working on finding a motor/gear combo for the 16th DUKW. There is room for a 540 up front but not two. The 380 is the same diameter and some are shorter. I haven't found a gear reduction for the smaller 280.

I may attempt to kit bash a couple motors and see if I can get additional turns on the 12v 380. It is fairly easy to stall the motor after the gear reduction with fingers on the bare output shaft.

[Ecam]

Still fiddling around with motors and gear boxes. I've got a worst case worked out. Using the other transfer case that was ordered for this project, installed in front.... One 540 with a 4 to 1 reduction can run wheels and prop together. But am still working on a second motor/ESC to run prop.

Did do a float test this morning. Twelve cells, (4 three packs) 3 each side just in front of rear fenders, and 3 each. in the rear corners. Motor, gearbox, motor mount, 1 esc and both transfer cases on board. The model is relatively heavy and I had doubts it would float, however it rode quite high in the water and a bit nose down. It looks as that would float at twice the weight. Did have a small leak, and am working on that now. Soon I will get some pictures up. Just not much to show yet.

[Ecam]

Pictue time.

If you've been following along you know I have been struggling with separate power for wheels and prop (and to keep it below deck). I may have finally come up with a solution.

These little motors showed up as a five pack. One was sacrificed trying to figure out if the shaft could be driven backwards to allow a motor to be coupled behind it. The upper pair, the front motor was trimmed at the rear plastic bell to allow just enough shaft to epoxy a brass tube to it. After building a couple jigs and working slowly I was able to drive the shaft on the motor in the foreground enough to have about 5mm of shaft on both ends of it.



Then I made a collar to couple the two together, I did end up trimming down the rear motor to 5mm.



Length is good but most important the diameter allows it to fit below the cargo deck.



I am going to cut the prop shaft shorter to allow for a couple u joints ( arriving in a couple days).



Getting crowded, but most of the equipment is on board.



Steering and rudder parts should be in soon as well. This thing is getting heavy, I sure hope the HL axles can cope with it.



I did some testing on the coupled motors. Powered separately, they both turn the assembly with ease. Not sure if it will make a difference or help at all but I have them phased a few degrees off. Turning the main shaft you can feel 12 magnet pulls per rotation instead of six like normal. The battery packs are joined so my input volts to the ESC's are still 7.2v just twice the amps. These will not be the cells eventually used on Duck 1. These were very old Ni Cad packs from yester year. Once testing is complete new packs will be assembled.

[Ecam]

Monster Duck:

These were the too short driveshafts from earlier in the thread.



That tubing I mentioned earlier showed up. I cut the driveshafts and extended them. I ground some lengthwise grooves on the out side of the driveshafts and filed some grooves on the inside of the tubing. Two part epoxy has made a great bond.



Temporary motor placement for testing. Input shaft on the transfer case is easily reversible.



Max travel on rear suspention before short driveshaft between tandem axles pulls apart. I did make a stop for the rear axle (same travel) to prevent problems.

[HERMAN BIX]

Epic amount of work going in here Mr Ecam, very innovative use of components to gEt a fantastic result.
Watching in

[Ecam]

Coming soon the first swim of the 1/16th DUKW. Been waiting on a neighbor's knee to heal up so he can help me. I don't want to attempt to drive and photog at the same time.

[sassgrunt]

Here it is that we don't hear from you for weeks at a time, ad then you roar back and flood us with several posts! I like your "coupled" motor arrangement. Reminds me of the He-177 setup (which was prone to catching fire) or the TV Tommy Ivo's dragster with four V8 engines. -Mike

[Ecam]

I'm prone to getting sidetracked....... you should know that!

[tankme]

I'm prone to getting sidetracked....... you should know that!

Aren't we all? I think it's a prerequisite for getting into the hobby.