Strange Motor Behaviour

[Terry PlumridgeParticipant @terryplumridge66794]

Have just completed my winter project, an Aeronaut Jenny. Have been bench running the motor in the finished model and can hear what I can only describe as a "2 stroke motor 4 stroking", strange sound for an electric motor! The driveline is a Johnson Race 650 running on 8.4v, MtronicsViper Marine 40 esc, a Huco type coupling, also tried a solid coupling, a 4mm propshaft 36cm long and not bent.

Slow speed running is fine, but as the revs are increased a point is reached where thing start to go wrong. Any ideas guys.

Cheers, Terry

[Terry PlumridgeParticipant @terryplumridge66794]

[ashley needhamParticipant @ashleyneedham69188]

Terry. I usually find this sort of thing is a radio glitch.

perhaps some rearranging of components, different batteries (are you using bec?) and so on could be tried.

are you using 2.4 or 27/40 MHz? Not had glitches on 2.4 yet. Motor suppressed? Viper re-set?

could try a different esc ifavailable. There’s no magic solution to this, just trail and error!

Ashley

r

[Dave MilbournParticipant @davemilbourn48782]

Does it happen with the coupling uncoupled? If not then suspect the coupling, shaft or shaft bearings. If so then it's the motor. Like Ashley says, you'll have to eliminate each possibility one at a time until either you find the fault or you have only one thing left to change.

DM

[Malcolm FraryParticipant @malcolmfrary95515]

Do an incremental check – just the motor, then the motor coupled to shaft, then shaft with prop. There is no rule that says there is only one problem at any one time, but observing one test at a time and eliminating problems as found will save a lot of messing about.

The slightest imperfection on such a long thin shaft will show up when it gets spun up. If the problem isn't the Huco (first choice for noise but you've tried something else) then it might e the length of shaft needing a center bearing.

[ashley needhamParticipant @ashleyneedham69188]

Good point, personally I would not use a shaft that long in 4mm due to possible whip.

does the noise sound mechanical or electrical? When I have had a glitch, the boats are usually ok on say 1/2 throttle but start to go funny when more throttle is used (usually as the distance increases, but obviously not in your case)

Ashley

[Terry PlumridgeParticipant @terryplumridge66794]

The boat is kit built and I used the prop shaft as supplied, I checked the shaft for straightness very carefully, it was 100%. The sound I can only describe as previously written, a 2 stoke engine 4 stroking, I have run the motor connected directly to the battery, smooth as silk, held in the hand. Then ran it using the esc and could feel the motor twitching in my hand !! So next step, the esc will be substituted.

Thanks everybody for your replies

Terry

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