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

[Dr. Jet]

Thanks Jim! PM sent.

[Dr. Jet]

Thanks Jim!!

Here all along, I thought I did the 1957 version. Actually, it was the 1958 version that only ran one race. This will be the subject of the upcoming 1/20 scale shovelnose Prototype I.

[Dr. Jet]

Well, I've ordered some materials to cut four Atlas kits. The first run will include a strut, a rudder, a turn fin, and the materials to build the wire drive. You will need to supply your own prop stub shaft (an Octura 1/8" x 1/16" or the same from Jeff Wholt - http://www.rcraceboat.com/Storewiredrive.html), a drive dog, prop, and prop nut, and some 3/32" brass tubing. You will also need to supply a motor coupler to fit the particular motor you choose. Again, Jeff Wholt is the man to contact for one of those. If you use a motor with a 3mm shaft, I may be able to include a modified Aquacraft one from the now discontinued GP-1s.

I don't have a quote for the laser-cutting so I'm searching the deep, dark crevices of my fertile mind to recall what the prior costs were. I'm thinking I could produce the kits for $130, which is a screaming deal considering it includes the strut/rudder/turn fin/wire drive.

[Dr. Jet]

Motor Selection

We originally ran the MHZ and H&M Micro Shovelnose hulls on the 2620 Mystery 3000 motor spinning a Graupner S-29 prop (29mm x 1.6P) using 6 NiMh cells. This was enough power to occasionally blow the little hulls off the water, but remember: These hulls are smaller at slightly over 15" (about 1/24 scale). We ran the same power system in the MHZ Gecko, and again, it was almost to much power. In the heavier 15" BBY Micro Turbine Hydro, I used a 2620 Chinese 3850 Kv motor. This arrangement, spinning a Graupner S-31 was simply too much power, resulting in more air time than water time; but reducing the prop to an S-29 made a stupid fast, great handling boat. I have two of those same Chinese 2620 motors in my BBY Micro Scat Cat spinning de-tongued X430s and it hauls a$$. I have some 2822 TubroRix motors that I might try in one of these hulls as well (I don't recall the Kv). All the aforementioned motors have 2.3mm shafts.

Based on these prior data, I have picked a number of motors to try. First of all, these boats are bigger, but not a whole lot heavier. I believe a motor with a similar Kv but more torque will be necessary; and as such have chosen the 28 series motors and with longer cans. Atlas Prototype I has a 3550 Kv 2822 motor installed and I will first test it with an Octura X431 (plastic), cut down to 28mm and de-tongued (1.55 effective pitch). I will incrementally push the prop sizes up to an X632, but that will most likely be overkill. I have other motors in that size and up to 3800 Kv, but I expect similar results from them. I do have a pair of 4000 Kv 2818 motors that might be interesting. With a higher Kv and a lower torque (shorter can), they might do well with an X427 (de-tongued of course )

One of the members here has expressed interest in two of the first 4 kits produced. Since he will essentially be a "Beta Tester", I'll include motors with his kits with the caveat that he photo-document the build.

[Norwest]

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[Dr. Jet]

Atlas Prototype Updates

I'm getting REALLY close to being done. The hull is ready for the final coat of primer and wet sanding prior to the final color coat. The cowl has gone for another belt-sander ride and needs a bit more filling and sanding. The wing and fins are done and ready for sealing, filling, and priming.

[Dr. Jet]

Atlas Kit Update

I have everything necessary to make 4 Atlas Kits being shipped to me as of this writing. I have a quote for the laser-cutting. I have a victi....... er volunteer to build the first two production kits.

I have the ability to make the kits virtually 100% complete, with motor, ESC, and all the hardware. You would just need supply pieces of brass/aluminum/styrene tubing, wood dowels, or whatever for the exhaust stacks, a receiver, a battery, the electrical connectors of your choice, and a propeller. Should be about $220 including shipping. That's less than just an ESC for a "BIG" boat.... Or, I could do it without the motor, ESC, coupler, stub shaft, drive dog, and prop nut for about $145 including shipping. Jeff Wholt can supply the stub shaft, drive dog, prop nut, and coupler to fit your choice of motor.

The drawback? If there are more folks that want one than the two I'll have in stock (rather optimistic, I know... ), there could be a fairly long wait as a lot of the parts I need come on a slow boat from China.

I need to test the motor/prop/ESC combo I have before anything happens though, so I can confirm assumptions and make recommendations.

[Dr. Jet]

1:20 Scale Shovelnose Update

Parts for two prototypes are being laser cut as of this writing. This is a simpler hull with a lower parts count so cutting costs will be less. It is a slightly longer boat at almost 19", mainly due to the bow overhang ahead of the sponsons. This hull has the slightly pointed nose, which is why I use the term "shovelnose" in lieu of "roundnose".

Assembly should be a snap, especially in light of the many lessons learned in developing the Atlas. Jim Stephens of Scale-3d.com is shipping a 3-D printed Allison engine for this kit, although I'll be building the hooded version of the '68 Short Circuit. I may carve out the underside of the balsa cowl and fit this engine in it, just to look uber-cool.

Full build photos to follow after the Atlas is done.

[Norwest]

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[Dr. Jet]

On the Atlas, the motor mount locks into position on the bulkhead; on the shovelnose, it gets its own bulkhead. The turn fin I'm using on the prototypes and including in the kits is this one: https://www.ebay.com/itm/CNC-Machine...72.m2749.l2649 I will start with the strut at a 4° angle with the prop 1/2" below the transom. The stuffing tube ends at the bottom of the hull and the 1/32 wire is the only thing below the hull. The front edge of the drive dog is 1-1/4"+ behind the transom.

All of this is a no-brainer, since everything is pre-drilled for the included hardware and I'm providing nut plates to hold the nuts in position on the inside of the hull.

[NativePaul]

While vintage hydros can't be made to be self righting with the traditional roll over, modern ones when fitted with with salt water intakes do, in a similar size I have seen a number of Mhz Miss Madisons that had roll over self righting.

Tail sinking self righting is growing increasingly common here allowing self righting in platforms that have too much lateral stability, and while it is not often as fast or as reliable as rolling self righting, I think that it may be possible for that hull shape as long as the wing is pretty buoyant. It would take some testing with an empty hull and weights to see for sure though.

[Norwest]

!!!!!!!!!!!!!!!!!

[Norwest]

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[Norwest]

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[Norwest]

addressed title DR JET subject next I gave subject matter.