Who wants to build a semi-scale all-wood micro hydro?

[JimClark]

Is Jim Stevens doing the DLP printing? That is looking very good. How durable is it in a wet enviroment?

[Dr. Jet]

Jim Stevens does FDM printing and did those motors for me shown in post #139. The DLP motor in post #180 was actually done by laser guy #2. While his laser has some shortcomings, his 3D printer more than makes up for it. 100% waterproof and lighter than FDM because they can be made hollow. With really cool 1:20 engines available, the basic Atlas hull will do at least a dozen other boats (mostly exposed engine) from 1972 through 1983.

Now, I have to convince him to do an Allison.....

[old guy]

30 more days lol till we can order

[Dr. Jet]

30 more days lol till we can order

That's what happens when you have to depend on others....

Actually, you can order one today,......... It just won't ship until 30 days.

Atlas kits are ready to go!

[Dr. Jet]

Here's the layout. Note small bends in the rudder pushrod.

[Dr. Jet]

This is what it looks like before trimming off the supports.

[Dr. Jet]

https://www.turbosquid.com/3d-models...-engine/370280

It wouldn't be difficult to edit the file such that the exhaust was going the other way. While not as precise as the Merlin, at 1:20 scale it would look just fine in one of my little hulls. As you can see, the file is not cheap, so it would have to be worthwhile to buy it.

That said with the two hulls I've done, a person could build dozens of different boats. The secret one I have in the works was a large boat at 32' so it may only do the one hull. Instead, I may do a Karelson hull which would open up countless more options.

[Dr. Jet]

OK, here's the completed 1/32" wire drive. The majority of the driveshaft is actually 1/16" stainless steel tube, but the 1/32" wire runs full length from the stubshaft to the motor coupler. It is only where the driveshaft exits the hull to the nosecone on the strut that the 1/32" wire is exposed to allow a gentle curve in the driveshaft.

[Dr. Jet]

A bit more modern, but it will work with most 1:20 scale boats with some tweaking.

[Dr. Jet]

Well, all the design work for Short Circuit kits is done. Boxes are being populated with parts and all that remains to add to them are the laser cut wood and copying the instructions to a CD. The laser guy is on vacation but I should have it all cut by April 15th at the latest. Burning the CDs is a matter of 20 minutes. I have an idea I thought I would throw out there. I now have the ability to 3D print a Rolls Royce Merlin, an Allison V-1710 and a couple of different driver figures in 1:20 scale. That opens these two kits into making dozens of different hulls. Making the kits 100% complete was a bit of a PITA, and I don’t think I will do it again. Furthermore, I don’t think it was necessary to cut and supply all the balsa parts; most builders should be more than capable of cutting out those parts from sheet stock. It is the intricate and precise-fitting plywood parts that really benefit from laser-cutting.

So here’s my plan from here on out: I’m going to produce “Short Kits” ONLY, and only on demand. They will be just the laser-cut plywood and paper templates for the balsa bits. No information will be provided for the cowls since there are so many variants. I will be able to include scale engines and driver figures by special order. Everything else will be up to the builder.

I could do a 1:20 scale Karelson hull that would do at least a dozen other boats as well, provided there were enough interest.

[Dr. Jet]

Here they are.......

[Dr. Jet]

Well, I have the 3D printed Merlin and driver figure in hand and they look great. The only problem is they're too big. I'm going to reduce the driver to 85% of his current self and will work out a reduction figure for the Merlin when necessary. Mike printed the driver as one piece, but the files were separate arms, head, body. and steering wheel. I'm going to have him printed in parts so he can be posed better. I always like the head tilting a little left or right and looking off to the side. I think it just looks better like that.

[Dr. Jet]

This is what I mean about posing the driver figure.

[JimClark]

Looks great very good detail. What about weight?

[Dr. Jet]

Looks great very good detail. What about weight?

They're hollow on the inside so weight is minimized, but they're still a bit hefty. I'll give you an exact weight later.

UPDATE: My electronic digital .01 gram scale died. I guess I can use the triple-beam and get .1 gram accuracy. Please Stand By.........

[Dr. Jet]

And carefully video recorded everything on my spy glasses. I got home, pulled out the card and......

NOTHING!

Other than that, here's the report:

I don't like the curved turn fin in the Atlas. If it's not perfectly oriented. it will either lift up or dig in the right sponson. I'm going to take the bend out of it for the next trials. I need to toy with CG and strut angle/depth, but it's really close. The atlas hauls buns on 2S with the Y531 plastic prop, and even does OK with the 27mm plastic prop (thinned and sharpened) in the kit. The motor was a bit warm at 125° with the Y531. I think the optimum prop would be a de-tongued X432 reduced in diameter to 30mm, Motor temps with the 27mm prop were slightly warm to the touch.

It gets up on plane instantly with either prop I tested and corners like a dream, but it does bleed off some speed too. The 1/32 wire drive worked flawlessly and there wasn't a drop of water in the hull after running.

All in all a success I would say.

[old guy]

any up dates on the round nose

[Dr. Jet]

any up dates on the round nose

I will contact the laser guy tomorrow, Monday. I suspect he should be back and can get to it rather quickly. The kits are ready to go (except for the wood and instructions). I'll let everyone here know.

[old guy]

hows your prototype coming along

[Dr. Jet]

hows your prototype coming along

I'm at a standstill because I need the sponson bottoms to proceed. I'll get them when the new stack of wood is cut. I've run the 1:16 scale roundnose and it drives great. The 1:16 and 1:20 Atlas drive virtually the same, so I expect the smaller roundnose to be pretty much the same as the larger version.

Do you want to do yours up as the '58 Short Circuit or do you plan a different livery?

[old guy]

i know it will not be 100% scale but was thinking one of the such crust boats but not sure yet

[Dr. Jet]

None of these are really 100% scale. They're more "Stand-Off Scale".

This would do a convincing model of any of the single-engine Such Crust boats.

Note sent to laser guy, waiting for response.

[Dr. Jet]

Just heard from the laser guy. He can start cutting the Roundnose and the rigger on Thursday; I may have stuff ready to go out on Friday!

UPDATE: The laser guy has the wood as of today, April 2, 2019.

[Dr. Jet]

Looks great very good detail. What about weight?

The DLP Merlin is a bit large and probably needs to be reduced by 15%. Furthermore, it is the entire engine, you will no doubt grind off the lower half (or more) to get it to fit in a hull. As such, it is 54 grams right now. The FDM one (and only the upper 50% of the engine) is 21 grams. My guess that a proper-sized DLP engine, cut down to the the visible components would be an ounce (28 grams) or less.

[Dr. Jet]

I have four roundnose kits boxed up and ready to go.

I have four Atlas kits boxed up and ready to go.

[Dr. Jet]

This project has languished for some time while I worked on other projects. As a result of my last outing on the pond, I decided to update my decades-old and slightly shrunken Jay Turner Pool Racer (JTPR), mainly because it was just too much fun. The new and improved Mini Pool Racer (MPR) #1 is complete and ready to go using the drive train salvaged from the original JTPR. MPR #2 is on hold waiting for parts to ship on a slow boat from China. See separate build thread here in "Mini and Micro Boats".

The shovelnose hull only needs the sponson non-trips, the flotation foam, and the decking to be complete enough to start sanding and painting. The Atlas needs a paint touch-up (I screwed up doing some sanding ), some final clear coating, and final assembly/detailing to be completed. The Atlas Prototype #1 has already run with a couple of cheap plastic props and while it was more than satisfactory with those, I think I've narrowed the final choices to an Octura X430 de-tongued, or an X632 reduced to 30mm and de-tongued. I may start with an X431P (plastic) that is de-tongued and reduced in diameter.

Due to operator error, my attempts to video it at the last outing failed . I plan to go to the pond on Saturday, May 11th and hopefully will video it with all of the aforementioned props.

[Dr. Jet]

....

[Dr. Jet]

I received some questions about the making of the cowl. It's made from layers of 1/4" balsa stacked together. The cowl and the headrest (glued to the plywood fin) get sanded to shape before the fin/headrest assembly are glued to the cowl. Then, the headrest gets faired into the aft cowl with some putty/Spackle. After everything looks good, the bottom gets sanded to fit the deck.

[Dr. Jet]

.... And nowhere to go....

[old guy]

well the round nose made it to my sisters thanks I might see it by summers end lol so waiting for you to finish up yours so I can see what hardware is in the box and a video of it running lol