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Originally posted by devo
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The boat in the video is a Carbon Fiber Shocker Twin driven by Mark of Dinogy Lipo's -
"Need some experienced words of wisdom....." " I don't really know what I'm doing here since this is my first RC boat."
Building a 40K+RPM screamer as a first boat isn't for the faint of heart (or pocketbook)
For those that expect making any FE boat go past the 60mph - 70mph wall, know that it's very analogous to competition Rodeo Bull Riding - It's easy to stay on the bull out of the gate; staying on for seven seconds is the tricky part
And yes, unless I'm missing something
, that's Mark F's CF Shocker twin ( I was there & shot the video)
Zi6_0540.jpgLast edited by properchopper; 05-21-2014, 02:50 PM.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 /MonoComment
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I cut my teeth on RC airplanes back in the late 80's/early 90's when planes were built out of balsa & plywood sheets, rib by rib, spar by spar, stringer by stringer. I know all too well the feeling of watching, helplessly, as all your time & money smashes into the ground at 90mph. So I'm gathering from the vid you shared that these hulls take flight often. Has anyone ever tried any boundary layer tripping devices (vortex generators, wire, turbulator tape) on that middle span of the hull that acts like an airfoil...or even a front splitter for a little down force?Building a 40K+RPM screamer as a first boat isn't for the faint of heart (or pocketbook)
For those that expect making any FE boat go past the 60mph - 70mph wall, know that it's very analogous to competition Rodeo Bull Riding - It's easy to stay on the bull out of the gate; staying on for seven seconds is the tricky partComment
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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 /MonoComment
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That would definitely advance the transition of laminar to turbulent flow over the bottom of the bridge/deck. You've seen the little fins across the roof of cars or on airplane wings...same premise. In airplane wings it helps the airflow cling to more of the airfoil, increasing stall angle of attack and giving better fuel effieciency...same for the airflow over the back of a car. I was just looking online for something related to flipping full-scale cat powerboats, and I can't find a single discussion on methods of prevention in full-scale boats. I suppose its the lack of weight for the RC boats that makes it an issue. In aircraft, cruise climb or level flight occurs where the weight of the aircraft equals the lift force on it. I guess it doesn't take much lift force to overcome the weight of these RC cat's. I think a front splitter may help...have to look into that. Too much downforce and you have a submarine...Comment
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I'll go out on a limb here with two observations that may not sit well with some. Firstly, tunnel hulls are designed to pack air to free them from the parasitic drag of the hull in the water. There's an optimum speed where this takes place after which, like an airplane taxiing for takeoff there occurs enough lift (by the airfoil characteristics of the wings on a plane) or the air pack in the tunnel of a boat that the hull or plane takes flight [often enhanced by wind puffs or a bumpy water launch]. Air dams can play a role in balancing out these forces but in my experience there's lots of guesstimating and trial and error which doesn't interest me since I no longer care about gonzo speed runs to entertain myself ['tho my SAW Competition rigs may use some air dams plus ballast as required by wind/wave conditions] .
My second (likely not to be well received) observation is that most of the hulls we commonly play with are not designed to be operated at the speeds the chronically addicted gofaster crowd feels the need to push them to. Each hull has a window of stable operating velocity but many feel the need to go way past this point (with predictable results). Watching these attempts reminds me of a line in Douglas Adams' Hitchiker Trilogy where a character says that " For one to learn how to fly without a plane, it's simply a matter of mastering the art of throwing ones'self at the ground, and missing"Last edited by properchopper; 05-21-2014, 10:23 PM.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 /MonoComment
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Dial in a ton of negative and see what happens. Our boats have adjustable stingers and 4mm of adjustment in either direction goes a very, very long way to lift the nose or drop it.
I'm not about to get into a debate on how much negative you should or shouldn't run, trial and error, find what works for you. I will say these SAW style boats can be setup reliably without aero mods to run 80+ mph reliably, like not needing a retrieval method often. Its a balancing act for us hobbyists and I think you're going to have a lot of fun finding the balance with the powerful setup you've mentioned.
With a build thread and some video, more than enough guys on here can get you running in the 80+ with ease!Comment
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@ properchopper & iridebikes247...
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