slanted pinion/main gear upgrade question?

[killshot]

So what is the reason that the slanted pinion/main gear is better than the standard straight gears on the older Helis? Any better performance etc....?

[Steemo]

There is debate as to if there is a performance improvement or not.

One thing is certain: all other things equal (inc correct mesh), helical gears generate less noise than straight cut.

Keep in mind sound is energy, so you could say the helical gears are marginally more efficient just for that fact.

Aside from that there is a big can of worms to be opened on this topic

[killshot]

Originally Posted by Steemo

There is debate as to if there is a performance improvement or not.

One thing is certain: all other things equal (inc correct mesh), helical gears generate less noise than straight cut.

Keep in mind sound is energy, so you could say the helical gears are marginally more efficient just for that fact.

Aside from that there is a big can of worms to be opened on this topic

Let's open the can of worms! Lol. I was thinking about upgrading to the helical gears, but looking on Heli direct, I can only find a 12t pinion and a 121t main gear. I think my kit came with a 15t pinion and not sure about the main gear size. Just don't want to loose out on vicious headspeed

[ranchhand]

They both wind up being 10 to 1 ratio. I have a scopion 2221-6 with 4400kv, when running a 12 tooth pinion I could of got head speeds well over 4000rpm. Not that it would of stayed together very long. lol
But I went to a 10t because the 2221-6 likes high rpms and I can still get about 3450 hs which is more than enough.
The motor was pulling way to much amps with the 12t on a governor so that's why I went to the 10t. I also tried an 11t but the amp draw was still a little high, but I was trying to govern it at 3250. If I would of pushed it up to 3500-3600 it probably wouldn't have drawn that much amps, but that is a hs I don't really need to use right now with my flying ablility, maybe someday when I become a pro i'll put the 11t back on. lol

[Steemo]

Originally Posted by killshot

Let's open the can of worms! Lol. I was thinking about upgrading to the helical gears, but looking on Heli direct, I can only find a 12t pinion and a 121t main gear. I think my kit came with a 15t pinion and not sure about the main gear size. Just don't want to loose out on vicious headspeed

As ranchhand said the ratio is nearly the same.

Straight cut main gear has 150 teeth so using a 15 tooth pinion gives a 10/1 ratio
Helical/slant cut main gear has 121 teeth so using a 12 tooth pinion would also produce nearly 10/1 ratio

[ranchhand]

And the only reason I went that route was because that's what came on my 600, I got the 450 afterwards. So I don't know if their better or not, I just know its working for me with this motor gear combination.

[obsconder]

Originally Posted by Steemo

There is debate as to if there is a performance improvement or not.

One thing is certain: all other things equal (inc correct mesh), helical gears generate less noise than straight cut.

Keep in mind sound is energy, so you could say the helical gears are marginally more efficient just for that fact.

Aside from that there is a big can of worms to be opened on this topic

I don't think it's good to assume that just because something is quieter means it's more efficient because sound is energy. I'm not saying you're wrong in this instance, I'm not sure, I'm just saying there are alot of variables and things to consider. It might be making less noise because the gears seat more gradually and rub (more friction and energy loss) than just direct contact hits.

For example, drop a golf ball on hard concrete, it will bounce several times, making noise each time. Then say you drop a ball of silly putty and it'll just land flat, absorbing all the energy (inefficient), but make less noise than the golf ball.

I doubt the performance difference is huge enough to really notice either way, and the noise reduction is a plus.

[togy]

And not to forget is the axial load on the motor shaft that comes with the slant cut gear. I'm running slant cut now, but to be honest I think the old straight cut is better. Also, the material in the slant cut pinion is aluminum which I believe has higher friction than the old straight cut steel(?) pinion. Hope they start making herringbone gears and bronze pinions.

[toys2cars2toys]

Hi, just got my Pro DFC

Do you set the mesh on the helical gears with a similar amount of lash to straight cut gears?

Thanks in advance

[Steemo]

Originally Posted by obsconder

...For example, drop a golf ball on hard concrete, it will bounce several times, making noise each time. Then say you drop a ball of silly putty and it'll just land flat, absorbing all the energy (inefficient), but make less noise than the golf ball...

You got it bckward

We are talking about efficient energy transfer, in your senario with the concrete the golf ball was very inefficient at transferring energy to the other surface and rebounded with a large noise, every time it rebounds it wastes energy that could be transferred to the other surface generating sound, with the silly putty almost all the energy is efficiently transfered from the falling golf ball to the silly putty with little noise.

[Steemo]

Originally Posted by toys2cars2toys

Hi, just got my Pro DFC

Do you set the mesh on the helical gears with a similar amount of lash to straight cut gears?

Thanks in advance

same

[toys2cars2toys]

Originally Posted by Steemo

same

ta

[Tukmol]

Noise is the only difference. Buy ear plugs, easy to setup lol.

[Danny Dugger]

I have the KDE straight cut 150 main and 15 pinion and they actually run very quietly. I never ran them directly back to back with the slants but I didn't notice hardly any increase in noise. When its airborne I mostly just hear the rotor blades in the wind... my buddy's 450 SE on the other hand has some noisy gears.

[RCpilot13B]

So, with the slant pinion, you need to get slant main gear as well? Sorry if this has been adressed, I'm pretty new to larger helis.
I ask because I am about to build 2 new 450's (one 450L 6S and a regular 3S 450).

[CrashNburn420]

Yes you need the slant pinion if you have a slant main gear. The 450L Kit should have a slant gear. The regular may or may not depending on what version kit you bought.

[wrench567]

The slanted or helical cut gear gives you more tooth contact. Taking the same thickness gear and giving you up to 10 to 20 percent more tooth contact equals stronger mesh.
The old Road ranger truck transmissions were straight cut gear. In the late seventies they came out with the helical cut gears to take the higher torque from the ever increasing horse power diesels. As a side note, the straight cut transmissions were quieter than the helical cut gear trannys.
Old truck mechanic.
Pete