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32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) was -
Nope I totally agree with Larry. I had at the beginning started with a pair of 950kv Y winds and switched to a pair of 1020kv's and the RPMs went up more that just that 70kv difference. So did the amps though. Went from 120-30 amp peaks to 150-60 with the D's. The D's are the newer style(but not newest) but they didn't really change that much.
Bear in mind I did not change anything else besides motors.Comment
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No, I don't agree with that at all. But I don't agree with your statement about the boat not going faster with increased voltage and LMT motors either. I think your results are from running too large of a prop for the motor kv in the first place, and your limiting factor was the ESC more than it was the motor. LMTs are capable of pretty extreme loads. I turn X470s with mine without issue.Comment
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The way I'm reading your post is a little contradicting to itself? So it picked up more rpm with the d wind. Goes along with my statement of a d wind being more efficient at higher rpm, no? But pulling more amps is agreeing with Larry. Just checking to make sure I'm understanding correctly.32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
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The mono was definitely under Esc-ed and possibly over propped. The Rivercat I'm no so sure. It was pulling in the low 200's max. 90mph on 6s and 95 on 7s. I wouldn't think an m645 would be too much as it slows down a lot with a m445... I felt like it was just running out of steam. I dunno, I didn't get enough runs in to know for sure. I did change props and went 96 on 6s but the prop I went to was just as aggressive but just massively detounged. But hey, I've been wrong once or twice before lol.Last edited by kfxguy; 06-10-2015, 08:48 PM.32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
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I suppose one could take it as more efficient at high rpm due to the torque that enabled the motor to push that prop. This make sense?
BTW I am dang sure these D's are pulling more out of the packs in a shorter period. I do recall thinking I had a decent run time with the Y's. D's not so much(not that I run this for 5 mins mind you, just paying attention to what goes back into the packs).Comment
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Shawn
When you changed the motors, did you change the timing on the ESC??
"D" Wind - 0 Degrees Minimum or 1 Degrees Maximum
D's are effected very-very little (RPM) by timing, as the timing goes up the HEAT multiplies.
"Y's" on the other hand like timing, 12 to 20 Degrees
LarryPast NAMBA- P Mono -1 Mile Race Record holder
Past NAMBA- P Sport -1 Mile Race Record holder
Bump & Grind Racing Props -We Like Em Smooth & WetComment
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The total pitch of a 645 is 2.832, a 445 is under 2.478........ For comparison/perspective, the closest in total pitch to a 645 on a x4 is the 452 at 2.87
Sent from my SM-G920V using TapatalkMy private off road rc track
https://www.youtube.com/watch?v=XC3H...yaNZNA&index=8Comment
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I ended up just ordering a custom wind neu to the kv I'm looking for
32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
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Since this discussion has started down the road of being more detailed, there are several factors that have not been taken into consideration. On the basic level, comparing two motors for the same application in the same hull, one motor may weigh more than another. At the same time, one motor may be rated for higher wattage vs. another. After lengthy discussions with Andreas, there are also cases where a particular motor has a stronger power band than another at a given RPM. So these are a few other things to consider.
When switching from one prop to another, one may be more efficient at a particular speed than when you go faster. At the same time, the opposite may be true because the prop is experiencing less slippage in certain cases which may also depend on the hardness of the water you are running in. As we all know, aerodynamic effects on a hull have to be taken into consideration as the speed increases. For example, you have a model that runs extremely well on a certain prop at a given speed. When you attempt to get more speed out of the model by increasing voltage or kv, ultimately increasing the RPMs, the model may create more aerodynamic lift which can lead to the prop unloading more or conversely, reduce the amount of the prop that may be in the water. This is often compounded by the depth of the strut for a given prop and numerous other factors I'll leave out of this discussion such as aeration of the prop at higher speeds.
So far as 'this motor is faster than that motor' or 'this motor has more torque than another', please consider what is going on with the prop itself. You may find that once you find the right power band that the electronics setup likes, a simple prop change (even for the same prop in some cases) may make a big difference. Of all of the things that we can see with our eyes, a rooster tail may give you some good indicators. If you have a huge rooster tail and could divert some of that energy into thrust by cupping or running a similar prop with more cup (or have someone help prepare one for you), then you most likely would see higher speeds. That is, of course, as long as the model doesn't suffer from the loss of lift at the strut for the given speed.
Hopefully this is helpful and provides another perspective to consider while you are testing. You may find that going back to a motor you liked, with lower amp draws, and making some slight adjustments to the prop, you may achieve the higher speeds you are seeking. Also don't forget that a sharper prop on the leading edge, especially near the hub will help reduce prop walk which means less drag on the rudder for correction.
Have fun and keep that strut neutral!Last edited by Meniscus; 06-12-2015, 03:26 PM.IMPBA: 7-Time FE World Record Holder "Don't think outside the box. Rather, refuse to admit that the box exists in the first place!"
MGM Controllers - Giant Power Lipos - ML Boatworks - Wholt's Wire Drives & Struts - Nano-Oil
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Can't go wrong with Neu. TP will wind one for you too BTW.
I ran my first TP just this past Wed. Pretty impressive to be honest. It's a loaner. I'll likely race it at the cup. The Neu motor I wanted to run is at the bottom of the lake still. Been a month or two now. I'm sure it's fine..........bahahahaNoisy personComment
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Well they had a tp close enough to the kv I wanted but I wasn't sure if it would do the deed. You can tell they are built decent but a neu has more copper in it and iirc the strands are a little ticker on the neu. Plus I know they are tried and true for me. Plus I really wanted an 8mm shaft (which tp does not offer....yet) because I've had it flex at the rpm I'm turning and the rotor was hitting the stator. I think with the motor I chose, it's going to haul. I was mainly looking for just a tad more kv than my original 1521 which was 1860kv. I wanted to get more out of it on 6s. The original 1521 did 83ish on 6s. The 1972kv lehner did 90mph on 6s with the same prop, the unloaded kv of the lehner should be about 2170kv so I ordered a 2100kv neu to try and get it close. Keep in mind that this motor may not be an end all for me. I can change motors at any time. If I like it, great, if not I'll try something else. I feel pretty confident the neu won't let me down. They still sell lehners so if need be I'll buy another. Heck I may even get mine back that's at the bottom of the lake. And yes this time the strut will be neutral. I'm not making that mistake again! Lol32" carbon rivercat single 4s 102mph, 27” mini Rivercat 92mph, kbb34 91mph, jessej micro cat(too fast) wasComment
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I have a number of different Neu. I have a 2500kv with an 8mm shaft that's an absolute beast. I had a 2300 with a 5mm but I abused it and eventually it retaliated. LOL It could probably be fixed but at some point they become a do over.
Neither motor would I recommend for a daily runner by the way.
8mm shaft is totally worth it IMO. You can tell the difference. Especially at the p'scillion rpm you like to run.
I'm only teasing by the way.Noisy personComment
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