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Thread: Another Hare-Brained Idea

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    Default Another Hare-Brained Idea

    So I have a new pond to run my boats where I don't have to deal with a lot of floating reeds. Most of the people are there to fly RC float planes, but boats are welcome, and smaller boats are even more welcome. One of the club members approached me the other day when I was running my 1:20 Short Circuit and asked about a good hull candidate for club members to race and stir up boating interest in general. The requirements were that they be reasonably quick, but not insanely so, easy to get on the water, small, and cheap. I have all sorts of hulls that fit those requirements and the 1:20 scale hydros would be perfect; BUT WAIT!........ There was one more requirement.... They had to handle rough water when the wind came up.

    That got me to thinking (uh oh! ). What do I have in my inventory that fits all of those requirements? All the hydros are out. The twin cats are out due to the complexity. The single cat is a possibility, but when flipped, that's it. A self-righting, V-hull boat is what's needed. I have the Geckos, but the self-righting feature is kinda iffy with them now that they run the lighter weight LiPos. What is really needed is something with a flood chamber for positive self-righting. I suppose I could put a flood chamber in the Geckos, but that's a lot of ex post facto work.

    Pre-molded composite hulls would be the best option for simplicity's sake. They are easy to get on the water with a minimum of work, and even more so when the manufacturer has a package deal with much of the hardware included or sometimes already installed (my Geckos and other MHZ hulls came that way at the time). The Germans have some hulls that will meet those aforementioned needs, but shipping is expensive. What to do?? How about yet another wood build? Now, I realize I already have a lot of irons in the fire that I need to finish up first. But both of the 1:20 scale hydro designs are complete with just some final tweaks needed to the running models. The same applies to the single-step hydro. I wanted to build a final prototype of the twin cat, but I really should do more hull tuning work on the single version before I finalize the plans for the twin. I already have the Micro Scat Cat Twin running, and propeller tweaking is in the works. The rigger project will be next on the bench; THEN, I can think about building another wood project from the ground up.

    I can still do a lot of the preliminary design work on the new project as time allows. I don't need workbench space; my computer has plenty of room for all the ongoing projects. This new project should be something really easy to build, with a low parts count. I should do it such that there is no part longer than 12" in order to make it easy to find building materials. And it will get a flood chamber! An added benefit is that the diminutive size will accommodate the lengths of special "homemade" strakes that I can produce. I always like doing something a bit on the "different" side, and this should be no exception. I think I will design something that employs the well-tested power system of the little stepped hydro with the 2030 inrunner (3100 Kv), a straight shaft, and a de-tongued 26 mm CNC aluminum prop. I think I'll be able to have enough room for a 2040 motor, but that would no doubt be overkill in a 12" hull.

    Hmmmm... I have an idea!!

    Oliver Seiss (Hydro & Marine) has been making and selling essentially the same list of hulls for decades now. I have some of his cat and hydro hulls in my inventory and the construction quality is quite good. On his site he has listed the perfect hull for my proposed project. It has the ability to install a flood chamber, it is a stepped V-hull, so it should do well in rough water, and it is a bit quirky in appearance. At well under 500 mm, it already fits the definition of "Mini".

    My plan? I've ordered one, and I will install running gear using stuff I already have in my parts inventory. I have an assortment of 2040 motors with water jackets that should work in a hull designed around a Speed 400 brushed motor. Yeah, shipping was a little pricey, but I ordered a bunch of other parts to amortize the shipping over a greater number of items. I'll build it "quick and dirty" to see IF I like it. If I do, I'll scale it down to make a 12" version out of wood. I'll forgo a lot of the sexy compound curves and simplify some things, but the heritage will be obvious.


    Stay tuned....
    Last edited by Dr. Jet; 03-09-2020 at 01:32 PM. Reason: Cut-and-paste doesn't keep all the punctuation...
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    Length for length a decent rigger will maintain at least the same speed in rough water as a decent mono will.
    Paul "tug Killer" Upton-Taylor, Cat lover.
    FastElectricBoats.co.uk

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    How about a Sonicwake ??

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    Quote Originally Posted by NativePaul View Post
    Length for length a decent rigger will maintain at least the same speed in rough water as a decent mono will.
    Yeah, but it still looks like a 'rigger. It's not always about going fast, sometimes it's how you look attempting it.
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    Quote Originally Posted by willy43 View Post
    How about a Sonicwake ??


    WAY too big, WAY too fast....
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    A bit away from the topic of this thread, but I didn't want to start a new one for just a short note. I'm completing a lot of projects that have been languishing for a while and this is one that I've had in the works for 12 years. It is the BBY Micro Scat Cat Twin. It's gone through several upgrades and revisions over the years, but was never 100% perfect. Now it is; it looks good and goes like stink. If I get some good vids of it, I'll post links to them here.

    Just another thing finished up so I can work on the new project.
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    Default Back on Topic.....

    You've all heard me bellyaching about the limited supply of little props.

    Native Paul from the UK has come up with many great suggestions in the past, and in one thread where I was bellyaching about little props, he mentioned a 26mm Graupner prop that was pretty decent. It was unusual in that it fits a M2 threaded shaft, but I can deal with that.

    This was a year or so ago and I searched all around at the time and finally found a few in Germany. Shipping was prohibitive.

    Low and behold, I was wandering around the OSE Store, and what do you think I found??

    You guessed it. Steve has those 26mm props. I have some unhardened 304 stainless steel shaft. I might be able to cut some M2 threads on them.

    Or, there's always this option: https://www.ebay.com/itm/Model-Boat-...Bq4_b8wvhhJjeg

    It's entirely possible I could do this Hare-Brained project using all over-the-shelf hardware.
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    Well, I bought Steve's entire inventory of 26mm Graupner props. I hope he can still keep a few in stock for future needs. My plan is to use a water-cooled Hacker B20 18L (3080Kv) and a 30A ESC with added water cooling in this Hare-Brained 12" stepped mono. I hope the 26mm will be enough for this setup on 2S. I'll be able to swap the 2mm shaft with M2 threads for a 2mm shaft with M4 threads in seconds, so I can always prop up if necessary, but I'm thinking the small prop is a good start.

    Stay tuned.......
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    A 1/16th scale hydro would be perfect run on 2s lipo. you could get Mike L to laser cut kits
    "Our society strives to avoid any possibility of offending anyone – except God.”
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    Quote Originally Posted by JimClark View Post
    A 1/16th scale hydro would be perfect run on 2s lipo. you could get Mike L to laser cut kits
    I have a 1/16 scale 2S boat in my inventory. In fact, it was THE HULL that got me into the whole 1958 Short Circuit fascination. I liked the double-entendre (triple-entendre) of that name. I thought the color scheme was rather striking and I could do all the decals on a black and white printer.

    I powered it with an 11-Series NeuMotor (don't recall which one at the moment) to keep it light, as it was built for scale looks and not racing. I never finished it though. I still need to make the exhaust stacks, mount the steering wheel, paint and mount the driver, and make the removable cowl attachment points.

    It's on my list of things to do....
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    Last edited by Dr. Jet; 03-26-2020 at 04:33 PM.
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    Quote Originally Posted by JimClark View Post
    A 1/16th scale hydro would be perfect run on 2s lipo. you could get Mike L to laser cut kits
    Does Mike L make 1/16 scale kits? I thought he was making 1/10 and larger.
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    No but I bet he could rework one down to !/16th. Doug campbell has a couple of 1/16th scale kits and there are always Gary Findlay plans still out there
    "Our society strives to avoid any possibility of offending anyone – except God.”
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    The 1:16 Short Circuit above was from Garry Finlay's Plans. Some build photos are attached.

    I don't know how well the hydros would do when it gets windy though. That's why I'm planning a V-hull for my Hare-Brained idea.
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    Well, the hull I ordered from Germany has arrived and I'm re-thinking my power options. For this project, I want to use a water-cooled inrunner. The air-cooled boats are fine for sport running, but if you want to push things, water-cooling is a must.

    In my inventory, I have a Hacker B20 12L (basically a 2040 motor) that I'm thinking is too small for this hull, but would be the perfect candidate for the shrunken 12" version I'm planning. I have an old Aveox 1005 1.5Y but with a Kv of 5500 rpm/V, it may be too hot for a V-hull. I need something more in the low 3000s with enough torque to spin a 29~31mm prop. I have an 1112/1.5D NeuMotor, but that's a 1200-Watt motor and belongs in a pylon racer or a big rigger.

    What to do?

    Pick a common 28mm inrunner with a Kv around 3200~3300. They're cheap and plentiful. Is that the solution for an "All-out" racer? No, but it will get you pretty close. I can always swap out for the appropriate 11-Series NeuMotor at a later date.
    Last edited by Dr. Jet; 04-02-2020 at 06:01 PM.
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    I added an uber-thin sheet of carbon fiber to make the inner wall of the flood chamber, and sealed it with an epoxy and Cab-O-Sil mix. After that cured, I cut out that portion of the transom to allow water in and out and tested it for leaks. Finally, I provided a vent hole at the forward end of the chamber.

    At last! A hull with positive self-righting.

    I added a thicker sheet of carbon fiber plate to make a transom doubler for the rudder attachment hard point.

    I used a bit of that G-10 I have on hand to make a super-sanitary looking mount for the turn fin. Monos have to have turn fins, right?

    My experience with H&M hatch covers is they tend to warp a bit over time. Since my hatch was thinner than the recesses in the hull for it, I thickened the edges of the hatch with some stranded carbon fiber.

    I'm going to use the factory-recommended 2mm straight shaft, but I have the ability to replace the small diameter stuffing tube that carries a brass bushing for the shaft with a larger diameter stuffing tube that will accommodate supporting the shaft with ball bearings instead.
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    While Oliver does have molds that are decades old, he does also make a new boat every year, so while they are mostly the same, his list is slowly growing.

    Your such a tease, he has 4x <500mm stepped monos, which one did you get? I am guessing Mini King Cobra.
    Paul "tug Killer" Upton-Taylor, Cat lover.
    FastElectricBoats.co.uk

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    Quote Originally Posted by NativePaul View Post
    ...

    You're such a tease, .....
    Who me??
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    One issue I faced was finding the proper rudder for a mini. There is this one that I've used countless times (https://www.offshoreelectrics.com/pr...prod=ose-80048), but its short length would require mounting it rather low on the transom. Additionally, I don't like where the pushrod connects; it's not in the plane of the pivot and as such has some "differential" throw built in. Another option is this one (https://www.offshoreelectrics.com/pr...prod=ose-80047). The pushrod end is in the plane of the pivot, AND its longer length allows it to be placed higher on the transom, but wait!....... That bracket is WAY too long and has internal attachments that just won't work.

    What to do?

    Swap mounting brackets of course!!

    Oliver included a piece of Delrin with the hull that was machined to the proper angle to match the sloping transom. I machined this Delrin block down to fit the bracket dimensions and all is good now.
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    I'm using one of Oliver's straight shaft assemblies. I have these on my Geckos and they work extremely well; shaft alignment issues are non-existent. He has ball bearing models as well, but this particular one has a 4mm brass tube with a short 2mm I.D. brass bushing at the propeller end. I have a bunch of 2mm x 5mm ball bearings that I use in the Geckos, so I'm thinking of reaming the motor mount out to fit a 6mm brass tube and use a couple of ball bearings to support the shaft. I like the idea of a center bearing support as well, but I make sure it's not EXACTLY in the middle as it would fall on a vibrational node if I did. They seem to run much smoother if the center bearing is a bit off-center, if you get my drift. .
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    I've mounted the rudder to the transom and have made an opening for the pushrod. In this build, I'm going to use the conventional pushrod and bellows arrangement for the rudder linkage. Now I have to figure out where and how I'm going to mount the servo.
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    Made the servo mount from a scrap of carbon fiber sheet. The epoxy is cooking off now, I'll check it in the morning.....
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    Snap. I also found the 50mm rudders to be insufficient for Minis, while the 62mm are goldilocks in blade size, but too long in the mount.

    This is on my current Mini Hydro oval boat.
    20200405_131908.jpg
    Paul "tug Killer" Upton-Taylor, Cat lover.
    FastElectricBoats.co.uk

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    Great minds think alike.....
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    I've mounted the servo and constructed the rudder linkage. I had to put a slight bend in the pushrod to make it all work, but that's OK, that's just one of the benefits of working with minis. With a 1/8 scale boat, finding a spot for the ESC is a no-brainer. On a boat with a working area that is only slightly larger than the palm of your hand, it becomes a bit more problematic.
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    Default The Secret Revealed!!

    I've been pulling Native Paul's chain with this project by not revealing what it is. I thought I may have given enough clues already to determine which of Oliver's hulls I am bashing into submission:

    1. Whimsical appearance (that's a dead give-away).
    2. Under 500mm.
    3. Stepped mono.
    4. Sloping transom.
    5. Flood chamber.

    So for those of you still wondering, here are some photos with more to come in following posts.
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    Default More Revelations

    More progress photos. Flood chamber details and hatch stiffening.
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    Default Even More

    Even more progress photos.
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    One of the thoughts rambling around in my head is the cooling system. As you can see, there's not a whole lot of room in this hull for miles of hoses and tubing, so I have to plan things as I go. The hull inlet tube will be somewhere near the turn fin. Then, the hose will go in the "wing" behind the servo and curve into the starboard side of the aluminum cooling block I've attached to one of those cheap 30A ESCs (see previous photo). From there it will go to the motor jacket, but then what?

    I don't want/need a bunch of extra length in the system, and since the motor is so close to the front end of the flood chamber; why not vent the cooling water INTO the chamber?

    It shortens the hose/tubing run, and leaves a cleaner exterior.
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    Driveshaft/motor mount installed, cooling inlet tube installed. I put a bevel on the inlet tube inside the hull to make it easier to slide the hose onto it in those cramped quarters.
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    That would have been the last one I would have guessed, you said you didn't want a rigger as they are too ugly, then you got a Redbird!
    Paul "tug Killer" Upton-Taylor, Cat lover.
    FastElectricBoats.co.uk

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