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Thread: Micro Scat Cat Twin

  1. #1
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    Default Micro Scat Cat Twin

    Someone asked me about this. Although it is on RRR, this person had problems registering. Here are some photos for you, as requested:
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    And a couple more:
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  3. #3
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    cool i am going to run the same drive set up as you do in the hydro we are going to run a micro class like you guys do . would i use the same rudder assy from ose for a single motor set up?

  4. #4
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    Yes, that will work. Also, look at using the Octura aluminum "Strudder" for 1/8" propshaft (I think it is part number OC4STRA). I think Steve carries them on OSE. You can use the 0.098" cable, but a coupler to the 2.3 mm motor shaft may be hard to come by. Maybe using a 1/16" wire drive with one of Jeff Wholt's couplers would be the ticket. Maybe the complete MiniCat hardware system will work with 2.3 mm motors, I do not know, as I have never used it.

  5. #5
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    what is it that you have layed in the bottom and the sides of the boat?

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    That is carbon fiber mat with a layer of 3/4 oz. glass over everything. I did not pay much attention to the typical "Jet" neatness; rather I just stood back a few feet and threw carbon, fiberglass, epoxy, and Cab-O-Sil at it until it looked like a hull.

    The hull is stiff as a board. All the floatation foam is structural, and glued in with expanding polyurethane glue. I could use the hull for a battering ram if necessary.

  7. #7
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    cool did you make the carbon rudder mount? and should it be mounted this way?

  8. #8
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    Quote Originally Posted by waynedawg View Post
    cool did you make the carbon rudder mount?
    Yes, it also doubles as the servo mount. Very rigid assembly.

    Quote Originally Posted by waynedawg View Post
    and should it be mounted this way?
    I did it that way to get the rudder behind the props. The stock mount would have set the rudder in front of the props with the way my drive is set up.

    By the way, I'm using a larger 3400 rpm/V outrunner than I am using in the hydros, and turning counter-rotating x430s on a single 2S1P 2500 mah 25C. It's not the fastest thing in my fleet, but it is dependable, stays dry inside, it's almost impossible to flip, and it sounds cool. I get long runtimes and cool temperatures. It is a great fun little boat.

    One note: If you look at the profile photo, you may notice that I "chopped" it by about 3/8". I did this by trimming that amount off the top edge of the bottom hull prior to assembly. With the twin arrangement, I did not need as much space under the deck for a motor. I think it looks better than the stock "highboy" version.

  9. #9
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    Way Way kewl!! Did Randy redesign this hull? I dont remember it looking like that.

  10. #10
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    Quote Originally Posted by SJFE View Post
    Way Way kewl!! Did Randy redesign this hull? I dont remember it looking like that.

    I "chopped" it by 3/8" to improve the look.

  11. #11
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    We need vids!!!!!!!!!!!
    MMGMMarine
    RobertsonRacing

  12. #12
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    Quote Originally Posted by Spot Me 2 View Post
    We need vids!!!!!!!!!!!
    It's been a while since I've run this. It is waiting in the building queue for hull finishing and paint. Maybe I'll take it out again for grins and vids. At full speed, it turns left and right on a dime. At lower speeds, I can do figure 8s at full power in an area about 4' x 8' .

    It accelerates to full speed quickly, but just just seems to hit the governor. It will not go faster. Motor temps are cold, so I think I'm just running out of prop (X430 L&R). I may try a higher Kv motor. Other people see it, and they think it's fast, but I know that hull is capable of going MUCH faster than the (estimated) low-mid 30s my setup sees.

    That said, it's one of the most fun boats I have and it will be a sad day if I ever sell it.
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  13. #13
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    Envy! Looks awsome!! I can't wait to finish my mini cat. Can't wait to see some vids!
    Twin power =

  14. #14
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    subscribing
    The Manx has been sitting dormant, but I think I finally have my motivation back. I hope to see it float soon.

  15. #15
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    Any updates DR. Jet?
    Twin power =

  16. #16
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    please tell me their are updates

  17. #17
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    Quote Originally Posted by screwball View Post
    please tell me their are updates
    Yes, after nearly a decade of doing other things, I am finishing this cat. Stay tuned for details!
    A nation of sheep breeds a government of wolves

  18. #18
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    Quote Originally Posted by Dr. Jet View Post
    Yes, after nearly a decade of doing other things, I am finishing this cat. Stay tuned for details!
    Nothing like get back to a project, haha. I have a scratch built jet boat like that, rofl

    Look forward to seeing it run

  19. #19
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    I've built new 1/32" wire drives for this boat (lost one due to a loose setscrew) and have obtained WAY HUGE L&R props. It's in the paint shop now and will be a few weeks before I'll post photos. The fixed stingers that I built into the hull had the props rather high compared to the waterline which is why I opted to go with aforementioned WAY HUGE (32mm) props. It originally ran out of gas with the Octura X430 L&R props I initially had on it, but modern suppliers have bigger L&R props that may work well with it.

    Stay tuned for photos.

    BTW, I ordered longer motors (more torque) of a similar Kv to install if the current motors don't like the bigger props. They are on backorder, so we shall see........
    A nation of sheep breeds a government of wolves

  20. #20
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    While the micros have their advantages, one big disadvantage is working room. It's not real easy to reach the motor mounting screws and I need a 90° screwdriver to mount the servo, but that's the price you pay with micros.

    Here's a few photos of the MSC. The hatch cover is still in the paint shop so I'll post more photos in a couple of days.
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    A nation of sheep breeds a government of wolves

  21. #21
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    I complain about the room in my 36" twin cat. Banana hands means no micro building for me!
    Vac-U-Tug Jr (13mph)

  22. #22
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    More photos. I just need to mount the receiver and install the antenna. That's maybe 10 minutes on the bench at most.
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    A nation of sheep breeds a government of wolves

  23. #23
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    Well, I finally got to run this boat today. The last time I ran it, it had our "spec" 3000Kv motor, and 6 NiMh cells. In its current form, it has 3850Kv Fan-cooled helicopter motors, 2S LiPos, counter-rotating and de-tongued X430s, and re-designed 1/32" wire drives.

    This thing hauls a$$!! And, it corners like it's on rails!! On the first run, it was a bit too loose due to the lower weight of the batteries (they're forward of the CG). On the subsequent runs, I added some weight to the bow. It was still plenty loose, but my fear of a blow-over was significantly reduced. The 1/32 wire drives worked flawlessly and not a drop of water entered the hull.

    Another keeper from Randy!
    A nation of sheep breeds a government of wolves

  24. #24
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    Default I Made Some Graphics

    I made some graphics for the MSC. I ordered some extra-thin water-slide decal paper and will add the graphics as soon as I print them on the paper. Only the folks my age will get the double-entendre of the graphics.

    Stay tuned for videos.....
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    Last edited by Dr. Jet; 01-27-2018 at 08:58 PM.
    A nation of sheep breeds a government of wolves

  25. #25
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    I bet 3s on the spec 3000kv motors would have been a hoot too, I run that kv on a lot of minis with 27-32mm props.

    I have never thought of painting a cockpit blue, I've always gone for black or silver, but it really works and looks great with the gold.
    Paul "tug Killer" Upton-Taylor, Cat lover.
    FastElectricBoats.co.uk

  26. #26
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    I can barely keep this thing on the water with 2S. I've upgraded the 3000 Kv motors to something around 3850 Kv (give or take - I don't recall). 3S would be insane with this setup. Stay tuned for videos. As for the graphics, all I have to say is....
    https://www.youtube.com/watch?v=7qICIi0TZWA
    Last edited by Dr. Jet; 01-28-2018 at 03:38 AM. Reason: Post better music link
    A nation of sheep breeds a government of wolves

  27. #27
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    Well, after a number of delays and sidetracks, I finally put some graphics on the MSC. As an added bonus, I now have a way to video record it while I'm driving it. Stay tuned for videos the next time I take it out!
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    A nation of sheep breeds a government of wolves

  28. #28
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    Time to resurrect this old thread. I can't believe it's been two years since I last posted on it. I can't believe I started this project 12 years ago!

    So here's the latest update: Suitable props for the minis are few and far between when compared to the bigger ones. Add the need for counter-rotating sets and the available options almost vanish. For years, the only option was the Octura X430 L and R. Now, with the influx of cheap Chinese RC boats, there is a bit more to select. TFL now makes a CNC 430 prop in counter-rotating pairs. Steve sells them here at his shop.

    These props have the same "tongues" as the Octura X-Series props, so I promptly cut them off, balanced and sharpened them and stuck them on the MSC. It was noticeably faster than with the Octura props, but now I suffered a different, but easily remedied problem: My current setup has both motors running off of one rather large (2.25 mah) battery. I'm getting inconsistent motor start-ups. When testing the motors before putting it in the water, one motor will start, and the other would shudder. Once in the water with some load on the props, they would both eventually run, but one would often start before the other.

    Once both motors were running, this thing hauled a$$. It had a perfect flight attitude with none of the porpoising some cats have. There was a lot of "Nothin' but prop" on the straight, high speed runs. I did have the single battery as far forward as I could to move the CG forward. It cornered like it was on rails.

    What was happening with the startup issues was no doubt a voltage drop when one ESC started a millisecond before the other, and the other ESC seeing that voltage drop and subsequently freaking out over it. The solution is simple: Just use a separate battery for each ESC. I need a bit more weight forward anyway, so this is a win-win. I'll solder new connectors to everything, hog out a bit more flotation foam and I can call this project "DONE". And it only took 12 years.......

    I have a new place to run and there are often people there to take videos. I'll see if I can post some the next time I take it out.
    A nation of sheep breeds a government of wolves

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