Blade 450 3D Motor Rpelacement Help

[Grappa]

Hi all,

Could do with a little advice on the above.

Looks like the motor in my Blade is knackered (some reading last night reveals this appears to be a common issue with these motors) and hence I need to replace. Was originally thinking of replacing with the 4200KV eFlight motor (from 450x) but having read reports of early failure issues etc. not so keen now and hence looking at different manufacturer.

Reading through various posts it looks like the Scorpion 2221-6 and 2221-8 seem to be being used with success however I'm now getting into an area I don't understand particularly well. Looking at the KV of the motors they are 4400 and 3595 respectively - how do I determine which one is the one for me? I fly 3d (but old school stuff - more big sky) so could do with some advice before I waste any money.

The other thing is that the shaft diameter on the Scorp is 3.17mm as opposed to 2.3mm on the eFlight so I will have to change the pinion - can anyone suggest where I can find a compatible replacement as I am struggling. Ideally needs to be plug and play as my engineering skills/equipment are a little limited!

Thanks for the help.

Simon

[tomatwalden]

Worth noting if you don't know it already that Kv in the context of brushless motors is "thousands of revolutions per Volt" - not kilovolts rather confusingly. So assuming the fixed voltage (12.4v) of the 3S LIPO, the Kv of the motor determines its speed for a given throttle input.

In short, if you change the motor for one with a different Kv, you would need to change the gearing (ie. pinion) too in order to achieve the same head speed.

If you really want plug and play - just go with stock again. If you have any problems with it, you'll be able to send it back to Horizon Hobby in Essex who will replace any failed units FoC.

The next alternative is to do the "locktite mod" on the motor to avoid any problems in the first place. See : https://www.youtube.com/watch?v=gZIa67Aa3eQ

Otherwise, if you do decide to change the motor, the stock one is 3800Kv - with a 10t pinion. Using Mr Mel's head speed calculator, you can determine an alternative pinion for a different Kv motor here : MrMel headspeed calculator v3. So for example ...

3800kv/10t = 3200rpm (stock, 100% throttle curve at start of flight)

3595kv/10t = 3000rpm
3995kv/11t = 3328rpm

4400kv/9t = 3300rpm
4400kv/8t = 2963rpm

As you can see, even with different pinions, you'll never get it exactly the same! But that's not an issue since you can always change your throttle value accordingly to fine tune it.

If I were you though - I'd go with the stock motor. The 450-3D is long out of production now - I wouldn't advise spending un-needed money on it! You'd be better off spending your dosh on a new Blade 360CFX or similar!

[Grappa]

Tom,

You're a diamond - thanks for the post.

I'll get a stock motor and perform the Loctite mod.

Regards,

Simon