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Last night I bored my strut for ball bearings, and I decided to run the bearings To break them in. Well I used the flex and my drill at first. Not enough Rpm. So I hooked up a 1515 2200kv motor on 4s to it. Then I noticed some things which made me experiment further. Out in the open of course the cable would whip and oscillate. If supported it got better. Put in a tube it got better and put a curve in it helped alot too. But it could still be seen whipping in the tube and you could feel some Vibration. What if I put a few short pieces of brass tubing inside of the stuffing tube to help support the flex more? Seems like it would help, no?
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32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) was -
Unless you positioned the pieces at the cable's vibrational nodes, they would just makes things worse. The vibration nodes will change with load and rpm - you would be chasing your tail. And really, who cares about cable whip on the bench? Once loaded in the water everything changes. To eliminate this kind of vibrations would require a solid shaft. That was tried forty years ago - fail.
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I also wouldn't care with the bench experiment and add brass pieces will increase the drag!GO FAST AND TURN RIGHT !
www.grsboats.com.brComment
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Just two days ago I was looking for that fraction of a mph to up my P-Ltd Cat record. SAW record time trials are like that
I pulled the teflon from my .250 stuffing tube to free the .150 flex just a tiny bit. Picked up less than I needed but there was some rather noisy harmonics coming from the boat during the passes. The law of conservation of energy states that energy cannot be created or destroyed, only converted. In this case, the energy from the motor was being converted to the normal amount of heat (helped by icing down the cooling circuit prior to the passes) and NOISE from the driveline harmonics. Put the teflon back in, eliminated the noise/harmonics/energy loss. Finally got the new record btw 
Jay is correct (as always) ; when underway the flex has linear force exerted on it that differs from unloaded bench trials - keep that in mind.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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thanks for the replies fellas. Let me be more specific. When i wrote the first post earlier, I got busy and had to cut it short. Heres my thoughts...I could be way off, over thinking it...who knows... but I'll lay it out there...
Does the cable under load, make like a SPIRAL? My reasoning for this: the cable shrinks or pulls (or is pushed by the prop?) inward under load, correct? So what happens??? the cable spirals against the tube and creates drag at each contact point? maybe it whips too...causing power robbing vibration and/or harmonics? maybe I dont know what i'm talking about...or maybe i'm on to something...but it wont hurt to try it.
What i was going to do is put 3 or 4 short (about 1/4") pieces of 3/16 i.d. brass in the stuffing tube, to more or less help support the flex and help it from whipping, twisting...whatever it is it does.... and see if things smooth out. I drill a couple small holes at each collar and solder them in place so the dont move. Has anyone tried something like this? I cant help but think that it would help... maybe not..... but it wont cost me anything but a little time.32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
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Maybe you already realize it, but the brass tube is measured by outside diameter, not inside, you would use the 7/32" to fit inside 1/4". You may have to modify the way you grease the cables also, as much less would pass by the smaller sleeves.My private off road rc track
https://www.youtube.com/watch?v=XC3H...yaNZNA&index=8Comment
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32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
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I usually put a flaired bushing at the motor end of my flexes, seems to help with whipDSC02850.jpg http://www.offshoreelectrics.com/pro...=ros-spdsd-187Last edited by flraptor07; 11-12-2014, 09:40 AM.Comment
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I solder a piece in the end to take up the slack and help with water going up the shaft, but now I have the aeromarine flex shaft seal which now has a sealed Ceramic bearing in it. I don't get a drop of water in now. I'm gonna make another stuffing tube and try out what I'm talking about. I'll Baseline the boat on 5s. Make some passes. Then recharge batteries and run it with the new tube. Might help. Might not. Don't know till I try.32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
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You could mount a AIR prop on the flex and bench test Travis, More controlled environment. It would load the flex.Comment
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Scared I might cut my hand off or something. I got hit with the flex last night lol. I had it in a bend where it was running smooth right to the very edge of top rpm...then it started whipping. Ripped the motor out of my hand and the cable hit me in the finger so hard I it's swollen a little and can't move it much. Lmao. Yea, I'm a dummy sometimes32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
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Man, I'd pay good $$ to see a video of that. Here is an epic boat test failure: https://www.youtube.com/watch?v=fqVLmB2KlcA
I have no idea who those guys are, but my brother and I laugh every time we watch the vid. Enjoy.Comment
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Why would you do that....lmao
Sorry that was to shooters post.Comment
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