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Thread: Has anyone build one of these?

  1. Default Has anyone build one of these?

    Looking into building one of Doug Campbells 1/10th scale laser cut kits has anyone built the Thriftway version

    http://classichydros.com/#!/1-10th-S...tegory=4581162

    http://classichydros.com/10thScale3-viewdrawing.pdf

    6670
    "Our society strives to avoid any possibility of offending anyone – except God.”
    Billy Graham

  2. #2

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    Jim,

    I have built this exact kit, see my post below. I am currently in the process of rebuilding the hull due to a run in with a floating pier. I had been working on trimming it out running 6S with a Leopard 1250KV motor using an X447 prop.

    At full speed the hull would hop off the water, and land, and continue to hop. The biggest change I had made was to cut out the air traps. I started out cutting off about 25% of the air trap to get the hull to settle down, which showed promos. I ended up completely cutting them off after several tests slowly cutting off a little at a time. The hull finely settled down.

    Once I get everything back together I hope to experiment with some prop selections and do a little racing here in District 12 this summer.

    https://forums.offshoreelectrics.com/...ished-now-what

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    If I build one it will run on 4S and maybe have a little extra weight in the nose

    Sent from my Moto G (4) using Tapatalk
    "Our society strives to avoid any possibility of offending anyone – except God.”
    Billy Graham

  4. #4

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    That PDF that the OP posted really shows the nature of sponson troubles in hydros. I was involved in full size hydros when I was young. My brother, Scott Pierce, drove. We did 5 Litre hydros and then Unlimiteds, Executone, O Boy Oberto, Budweiser... We had modelers around us all the time, they had some of the neatest boats! But they always complained of aero instability and blow overs. FE boats, by scale, run MUCH faster than full sized hydros! Sponson design is critical, in both arenas. I always recommended the same modifications, sponsons parallel at the back with the water surface, flat up 2/3 of the sponson with no more than 2.5 -3 degree rise. Front part of sponson can have some curve, but it works better to shingle the front into the rear, providing a step down to the back 2/3's surface. I've seen a UL-1 mod on this forum by a senior guy. That's the way you do it! I'm new to OSE, just getting back into r/c boats. I had a 36" nitro boat about 20 years ago that I designed and built from aircraft plywood. I'm building a DF Vortex 34 Hydro right now, and the sponsons are totally jacked up like this PDF. I recommend before making air flow adjustments, that the sponsons be blue printed for proper water dynamics, then CG and strut, lastly air dams... many of these hulls have bad sponsons as purchased. If you set your boat on a flat table and pick up the stern to the proper ride height, and your sponsons don't touch the table across the back and the angle takes off for the moon, then they are wrong!

  5. #5

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    Quote Originally Posted by CraigP View Post
    That PDF that the OP posted really shows the nature of sponson troubles in hydros. I was involved in full size hydros when I was young. My brother, Scott Pierce, drove. We did 5 Litre hydros and then Unlimiteds, Executone, O Boy Oberto, Budweiser... We had modelers around us all the time, they had some of the neatest boats! But they always complained of aero instability and blow overs. FE boats, by scale, run MUCH faster than full sized hydros! Sponson design is critical, in both arenas. I always recommended the same modifications, sponsons parallel at the back with the water surface, flat up 2/3 of the sponson with no more than 2.5 -3 degree rise. Front part of sponson can have some curve, but it works better to shingle the front into the rear, providing a step down to the back 2/3's surface. I've seen a UL-1 mod on this forum by a senior guy. That's the way you do it! I'm new to OSE, just getting back into r/c boats. I had a 36" nitro boat about 20 years ago that I designed and built from aircraft plywood. I'm building a DF Vortex 34 Hydro right now, and the sponsons are totally jacked up like this PDF. I recommend before making air flow adjustments, that the sponsons be blue printed for proper water dynamics, then CG and strut, lastly air dams... many of these hulls have bad sponsons as purchased. If you set your boat on a flat table and pick up the stern to the proper ride height, and your sponsons don't touch the table across the back and the angle takes off for the moon, then they are wrong!
    Good stuff. I agree 100%.

    Exactly : " sponsons parallel at the back with the water surface, flat up 2/3 of the sponson with no more than 2.5 -3 degree rise. Front part of sponson can have some curve, but it works better to shingle the front into the rear, providing a step down to the back 2/3's surface...."

    I'm still working on getting my ridiculously overpowered Vortex34 settled down. Haven't done any surgery yet as my intention is to offer it up for sale unmolested. Will keep an eye out on your build thread..
    2008 NAMBA P-Mono & P-Offshore Nat'l 2-Lap Record Holder; '15 P-Cat, P-Ltd Cat 2-Lap
    2009/2010 NAMBA P-Sport Hydro Nat'l 2-Lap Record Holder, '13 SCSTA P-Ltd Cat High Points
    '11 NAMBA [P-Ltd] : Mono, Offshore, OPC, Sport Hydro; '06 LSO, '12,'13,'14 P Ltd Cat /Mono

  6. #6

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    What prop did you end up with? I'm putting an 8S, Leonard 40X72 1050kV to start, then I have a 1250 40X82 motor to kick it a little harder. It's been a while for me, but I'm really looking forward to going electric, gas powered boats were a PITA! I was wondering if you could share what prop you are currently working with. I have Grim Race 38X55, 2 blade High Lift to start out with. I have a Grim Racer 40X57, 3-blade high rake prop to step it up. Is a 42X63 prop about it for this hull?

    I'll get some picks on the sponson mods I'm going to be doing. The room in this hull is awesome, love that! I plan on putting the length of the four 5200, 2s batteries across sideways, just starting at the top of the hatch. They go out across the drop off for the sponsons. Thinking of mounting a floorboard for the batteries in there. I want the CG weight components split out, getting weight well forward and placing the front of the motor 13-7/8" from the back of the transom. That still leaves ample room for the ESC and Cap Board in between the motor and the battery pack. I think about CG like a teeter-totter. The longer the arms are from the fulcrum, the slower they move. When the arms get short, then the speed of the teeter-totter goes up dramatically, which represents the boat porpoising, which is not the play. I'm setting my rudder to the left like your model. That seems to make the most sense for a right turning boat running a CCW prop. Prop torque will try to pick up the left side, so setting the rudder left helps stake that side down.

    Another trick I was going to employ was to shim the left side sponson up about 1/8" from the right. This really helped in GP boats for turning. My brother is still running in GPW, has a 28', 500CI blown on alcohol motor. (Check out YouTube, search for GP55) I know the dynamics don't entirely scale, but weight shift and corner planting should involve the same physics.

    Sorry to load you up this way, I just loved the way your hull turned out and value your building skills and experience tremendously. One more point to ask you, strut angle. I'm looking at 17 degrees, going into a single 10" radius bend to the strut. There is something I want to try... I found that the stainless steel tubing on OSE was a perfect fit for the 0.187" flex cable without a liner. It has about 0.004 - 0.005" per side clearance, perfect for grease. The stainless has a thicker wall than the copper tubing normally used. Also, I find the "stickiness" of stainless to be far less that copper, something that is termed "stiction", so I believe it will not have a tendency to grab the cable. You think it's worth the try?

    Well, ProperChopper, getting long here. I hope that we can meet up some time, I have enjoyed getting to know you some on the forum. I promise to get pics out on the build. You know I just hate stopping work to take pictures, but they can be very valuable and may help others enjoy this great sport!

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    8S in a 10th scale boat?
    "Our society strives to avoid any possibility of offending anyone – except God.”
    Billy Graham

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    Yes, but slow motor. Looking at the motor specs, which Leonard is good about, the lower kV motors have higher stator resistance and pull less current. I'm trying to develop the power using voltage, to drop the amperage draw on the batteries. If you don't change to a higher resistance motor, then you're really asking for trouble. I have a 4074 1050kV and a 4082 1250kV to get crazy on.

    So spin slower, use lower amperage draw motor and keep the prop reasonable. Was going to start with a 40X57, 3-blade lifter...

  9. #9

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    Like your quote Jim, ain't it the truth!

  10. #10

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    Here's a print on the motor mount setting. I put it on AutoCAD to try and break old habits of cutting first and thinking second! It's nice to just be able to move stuff around and get out the imagination...
    Attached Files Attached Files

  11. #11

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    Hi Craig,

    Let's move this from Jim's thread to a new one (this started about a Thriftway). Jim's a moderator - He can do this. We have lots to discuss - be glad to chime in after move
    2008 NAMBA P-Mono & P-Offshore Nat'l 2-Lap Record Holder; '15 P-Cat, P-Ltd Cat 2-Lap
    2009/2010 NAMBA P-Sport Hydro Nat'l 2-Lap Record Holder, '13 SCSTA P-Ltd Cat High Points
    '11 NAMBA [P-Ltd] : Mono, Offshore, OPC, Sport Hydro; '06 LSO, '12,'13,'14 P Ltd Cat /Mono

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