Eco 8 Rotor Speed

[cej]

Just finished my Eco 8, seems to me that the more teeth on the pinion the faster the rotor head but that is not what the manual says. I have 8cell 3000Mah NiMh with the performance motor. Is the manual right ?

[BertVK]

Welcome to the nut house mate. /ubbthreads/images/graemlins/grin.gif

yes, the manual is right.

Suppose the motor runs at the same speed using different pinions. It won't be in reality, but let's keep things easy.
Now suppose you mount a 10 tooth pinion on the motor. The main gear has 180 teeth, so it will take the motor 18 revolutions to the main gear make one revolution (180 / 10).
Now I replace the motor pinion with a 20 tooth. The motor only needs to revolve half as many times to make the main gear revolve once. One motor revolution will give you twice as many teeth passing. So only 9 motor revolutions are needed for 1 main gear revolution (180 / 20).

Now if the motor keeps it revs, the main gear will revolve twice as fast when using a motor pinion with twice as many teeth. So the main gear will revolve twice as fast too.

It's very easy if you count the difference in teeth like I did above.

HTH

[cej]

Thanks for the reply.

More pinion teeth, faster main gear (rotor) with constant RPM, thats what I thought. Then why does the manual say good natured with 12 teeth and sparkling with 10 teeth, should be more responsive with higher rotor speed ?

Electrics are new to me, more familiar with gassers with throttle curves etc to set rotor Rpm

Thanks

[SeismicCWave]

>>seems to me that the more teeth on the pinion the faster the rotor head but that is not what the manual says.<<

Bigger pinion gear will spin the rotor head faster. Can you point me to the location where you think the manual says otherwise. I looked at the second to the last page when the manual discussed about the gear ratio. The discussion didn't say anything about slower rotor head with bigger pinion.

[cej]

Page 29, Pinions for brush motors.

Reaction is good natured with 12 teeth 8cell to acrobatic with 10 teeth 10cell, Think I just misunderstood what it was saying and did not account for the difference in cells.

Thanks

[SeismicCWave]

>>Reaction is good natured with 12 teeth 8cell to acrobatic with 10 teeth 10cell, Think I just misunderstood what it was saying and did not account for the difference in cells.<<

I was chuckling when I read that. I had forgotten about the descriptions. Some how I never considered my heli "good natured". /ubbthreads/images/graemlins/grin.gif

Anyway yes the main difference is in cell count.

[Malcolm]

There are so many varibles.

If you had 8 cells then the rotor speed will be higher using 12t pinion than using a 10t pinion. If you had 10 cells then the rotor speed will be higher using 12t pinion than using a 10t pinion. But if you had 10 cells and a 10t pinion the head speed will be higher than using 8 cells and 12t pinion because the motors RPM will be a lot higher.

[HARRomeo]

[ QUOTE ]
If you had 10 cells then the rotor speed will be higher using 12t pinion than using a 10t pinion. But if you had 10 cells and a 10t pinion the head speed will be higher than using 8 cells and 12t pinion because the motors RPM will be a lot higher.

[/ QUOTE ]

Yes, but don't forget that he's using a brushed motor, so performance on 10 cells will be awesome.... for about 5 - 10 flights... then he'll be needing a new brushed motor again lol! /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

I remember when I read that in the manual as well.. had me figuring that a 10 cell pack was acceptable with the brushed motors as they were recommending a pinion for it. /ubbthreads/images/graemlins/shocked.gif

[Malcolm]

Yea should of mentioned that.

One thing, Ikarus advertise the "upgrade" (should be re-named conversion /ubbthreads/images/graemlins/smile.gif ) kit to transform an 8 into a 16. Wonder how long a brushed motor would last on 16 cells /ubbthreads/images/graemlins/shocked.gif

[z1300]

about 3 seconds.
but what of the radio ?
some one new to electric helis may be new to B E C also !!!