Somebody explain motor kv please

[pgkevet]

I haven't seen any "half assed assumptions" here at all, only correct info from people with "experience with electric Helis" Not really that much to be a guru about. It ain't rocket science.

No it's not rocket science .. it;s motor design and there's a heck of a lot of possible variables there from winding type to pole numbers to magnet strength, magnet spacing, bearing support, stator configuration, wire guage etc to have a bearing on the efficiency, torque at rpm etc and importantly for responsiveness of the motor.

If a 520KV motor and 12T pinion gives the rpm you want and a 480KV and 13T gives the same as does a 560KV on 11T then which is the most efficient?

[heathy]

Hey Don, nothing wrong with the turdnigy esc, isn't it really hobbywing?? Just use a phase sensor and v bar gov. I have a new phase sensor here you can have. Pm me your address and it's yours.

[pgkevet]

Thanks Pete the helidrive is at the top of my list until I can afford to upgrade but by all accounts they are bang for buck a very good choice

So I've head and I'm guessing (honesty) that rewound plus possibly improved bearings ought to improve on an anecdotally good option.

[heathy]

No it's not rocket science .. it;s motor design and there's a heck of a lot of possible variables there from winding type to pole numbers to magnet strength, magnet spacing, bearing support, stator configuration, wire guage etc to have a bearing on the efficiency, torque at rpm etc and importantly for responsiveness of the motor.

If a 520KV motor and 12T pinion gives the rpm you want and a 480KV and 13T gives the same as does a 560KV on 11T then which is the most efficient?

Yes but..... Buy a scorpion 4525-520 ultimate and you know your going to be very close to 90% every single time. It's a YY 1.4mm strand and is hand wound.

Buy a pyro 700 - 750 and again the efficiency is going to be bang on every time.

[trillian]

Hey Don, this is something I have looked into as well, the question of, for example a 450KV motor with pinion of x teeth vs a higher KV motor with smaller pinion and why to go with one or the other.

This is what I think based on just general physics logic and what seems to be borne out by different people's experiences with motor KVs and the headspeeds they're running, impression of 'bogging' etc.

Basically my thinking on this at the moment is that if you have a choice of gearing / kv (given the same size motor) going higher KV / smaller pinion will result in more perceived torque vs lower kv with bigger pinion. My reasoning is simply due to the extra inertia of the higher KV motor as it has roughly the same mass spinning faster. This follows on from thinking about the differences between electric and nitro. With nitro you have a much greater spinning mass in the drivetrain because you've got the engine crank, clutch, fan, etc. and all that inertia driving the pinion.

As far as what's the most efficient between lower or higher KV, I don't know. I'm tempted to say the lower KV for the same reason but I could be wrong.

[milly0812]

Hey Don, nothing wrong with the turdnigy esc, isn't it really hobbywing?? Just use a phase sensor and v bar gov. I have a new phase sensor here you can have. Pm me your address and it's yours.

Wicked mate pm on the way ta

[pgkevet]

Yes but..... Buy a scorpion 4525-520 ultimate and you know your going to be very close to 90% every single time. It's a YY 1.4mm strand and is hand wound.

Buy a pyro 700 - 750 and again the efficiency is going to be bang on every time.

Based on hearsay or independant study or manufacturers own claims? I'm still beaing a grudge over the scorp motor I stuck in my 450 6/7yrs ago and I do like to bear my grudges for a looooong time - as in I wouldn't touch another one with the proverbial long pole

[trillian]

Just to add, I have a Helidrive 480KV motor in my Rave at the moment and it's got plenty of punch. I just kept having issues with the gov on the Castle Ice, almost like the Castle doesn't like the Helidrive motor or something. At my previous settings that worked well with a Scorpion 4035/450 it was getting 2100 headspeed, which was fun I must admit, but when I tried to get lower headspeeds the Castle kept losing the plot big time. Soooooo, I might try fitting a Hobbywing 120 I have as I'm pretty sure it will just work without any fuss but the soft start was a bit harsh (but to be fair I may not have set the throttle end points properly so maybe it's not as harsh as I think)

[heathy]

Around the time they started making motors. Look at skoda. Now look at them.

[Ross Northcott]

Based on hearsay or independant study or manufacturers own claims? I'm still beaing a grudge over the scorp motor I stuck in my 450 6/7yrs ago and I do like to bear my grudges for a looooong time - as in I wouldn't touch another one with the proverbial long pole

What motors do you now use instead of Scorpion?

[pgkevet]

Around the time they started making motors. Look at skoda. Now look at them.

Hardly a meaningful comparison. Skoda have been around for yonks (first cars circa 1930) .. but under Soviet occupation their target demographic was necessarily to build cheap. As you know they got taken over by VW in 2000. Now if scorp got taken over then I might reconsider. Note also that all czech cars were Rt hand drive until Hitler marched in and his army drove on the right. The motor car museum in Prague is worth a look (near the Fontana). A lot to see in the Czech Republic if you've never been.

[pgkevet]

What motors do you now use instead of Scorpion?

My only leccy's are the 450 and 500. 450 has an align motor. The 500 align motor finally died after several years of general neglect and frequent crashes (and even 2 hot starts) and was replaced with an HK motor. None of which I've ever lubricated or changed bearings on in many hundreds of flights.

[waveydavey]

No it's not rocket science .. it;s motor design and there's a heck of a lot of possible variables there from winding type to pole numbers to magnet strength, magnet spacing, bearing support, stator configuration, wire guage etc to have a bearing on the efficiency, torque at rpm etc and importantly for responsiveness of the motor.

If a 520KV motor and 12T pinion gives the rpm you want and a 480KV and 13T gives the same as does a 560KV on 11T then which is the most efficient?

The 560 and 11t

[pgkevet]

The 560 and 11t

As it goes I'm inclined to agree from simple logic.. but do you know at what point upping the KV and reducing pinion teeth reduces effciiency? And that is a genuine question as a 9t pinion should still be quite sane...700kv?

[Ross Northcott]

My only leccy's are the 450 and 500. 450 has an align motor. The 500 align motor finally died after several years of general neglect and frequent crashes (and even 2 hot starts) and was replaced with an HK motor. None of which I've ever lubricated or changed bearings on in many hundreds of flights.

i have 9 scorpion motors in my heli's, the most any one motor has done is in my Mikado over 550 flights now, 4 major crash's even broke a motor shaft in one of them, apart from that i changed the bearings as a maintenance thing, the bearings were fine, never ever had a bad one, and not one single problem with any of them