Jim Clark was nice enough to gift me a 1/43 scale (7-1/2”) Casper shovelnose hydro hull. If you do a search for Casper hydroplanes, you will find some links where these hulls are “raced” on a track with special turning vanes to keep the “free flight” boats going in a circle. I haven’t been able to find much more information on them; specifically motor/prop/battery details, availability, and build details. From the videos I’ve seen, these boats are more displacement hulls plowing through the water than hydroplanes and they do not appear to ever get on step. Since I am the de-facto micro enthusiast here, I thought I’d try to make this little hull actually work as an RC race boat. To that end, I have two goals: Get it to run on step and get it to be fully controllable
I'll be extensively modifying it for RC. Ride pads are definitely a consideration as the vacuum-formed polystyrene hull no doubt has high drag rounded corners. Looking at the vacuum-formed bottom, it may get some re-shaping of the aft bottom, maybe get a lot of air trap. I’ll know more when it actually arrives. Also planned is a homemade rudder, a homemade micro strut, a 1/32 wire drive, and a homemade motor/shaft coupler. Maybe a straight shaft would save some weight and complexity, but I like the adjustability of a strut; we shall see. The BIG problem will be a prop. As of this writing, I see a couple of options: I could modify a 20mm Raboesch prop (see: https://www.ebay.com/itm/Brass-3-Bla...19.m1438.l2649), or I could modify a 20mm micro Eco prop (see: http://doctorprops.torgg.com/collect...mm-doctorprops).
The Raboesch prop has an M2 threaded hub which means I would have to bore a 1/32" hole through an M2 threaded brass rod (cut the head off a brass screw). I have a mini lathe so this is not impossible, but it does not leave much meat on the threaded rod. The 3mm hub of the mini Eco prop would make this machining process a whole lot easier to accomplish as I can simply ream one of the 1.5X3 prop adapters to 1/16" I.D. and I'm done. It may even be possible to reduce the prop diameter a bit to more closely resemble (and behave like) a surface prop.
I’ve ordered the following motor, servo, and battery for it:
Motor: https://hobbyking.com/en_us/turnigy-...or-4500kv.html
ESC: https://hobbyking.com/en_us/hobbykin...c-1a-ubec.html
Servo: https://hobbyking.com/en_us/hobbykin...cro-servo.html
Battery: https://hobbyking.com/en_us/turnigy-...lb3002s35.html
At this moment, I only have the photo provided by Jim Clark. The paper photo of the Bardahl hides a lot of the sponson and hull detail. I kinda wonder what those rectangular “bumps” are on the aft portion of the bottom and located on either side of the driveshaft. It also appears the prop was designed to run inside of a “tunnel”. I assume this was for geometric and safety reasons. I plan to have the prop behind the transom as is normal for most RC hydros and I'll be closing off this prop tunnel.
This project will have to take a back seat to my newest project (The 1/20 scale Atlas Van Lines) when the wood I've ordered for it arrives. Be sure to follow the build thread I’ve created for it too.
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