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Way2evl · 11-30-2012, 12:58 PM

So I have been looking around the forums a lot and I see that the general consensus is a head speed of 2150. I have searched set ups witht the scorpion 4525-520 and have found that people are running the 13T pinion. So I purchased a 13T pinion. Through my calculations I have found that the 13T pinion is not the best pinion for efficiency which relates to heat, power, and flight time.

Calculations are as follows. Ratio w/ 12T pinion is 9.66 and 13T pinion is 8.92.

Motor RPM = Voltage(KV). Based on a 3.8 nominal voltage and a 520kv that is 23,712. Multiply that by a motor efficiency of 89% = 21,103.68. Divide that by gear ratio of 13T [8.92]= 2366. That would be the most efficient head speed for that set up. As far as I know not many are running that head spead. I could be wrong though, but through my research I found that 99.9% of the time you will only see a max head speed of 2200. So running any head speed considerable less say 2050-2150 will create more heat and lower flight times. Now if you do that equation on the 12T[9.66] it leaves you at 2185. Much better for a head speed of 2150 or even in the range of 2050-2200.

So my question would be, other than following the herd or wanting to run a higher head speed, why would anyone use a 13T pinion or higher?

Chris Sexton · 11-30-2012, 01:04 PM

Some governors require more head room than others. As well as some ESCs handle the lower throttle requests better than others.

Personally, I am running the 12t on 4530-500 and using my VBar gov to hold 2050. That is where VBar and Mr Mel says the sweet spot is for head room on that governor.

The Jive ESCs, for example, have a built in circuit that helps deal with the extra voltage when you request less than ideal throttle inputs and are great for having a WIDE range of head speeds on the same pinion.

I guess what I am trying to say is, you have to look at the entire picture. If you are using a Castle ESC and Castle Gov and shooting for 2050-2150 then 13T is what you want. It is all very subjective and there is no real perfect answer.

Way2evl · 11-30-2012, 04:09 PM

Ok, I will be using the vbar gov. Will 12t be better or 13t?

Chris Sexton · 11-30-2012, 04:43 PM

Yes. For 2000-2200

Sent from my iPhone using Tapatalk

4cyclic · 12-01-2012, 07:13 AM

Using the 12t pinion with Scorpion 4525-520 and YGE 160hv at 2150hs. Works great with vbar governor. Has plenty of headroom.

Way2evl · 12-01-2012, 07:34 PM

Thank you for the responses. So I will get the 12T. If anyone needs a 13T let me know. I don't ever plan on going any higher than 2150.

11-30-2012, 12:58 PM	#1 (permalink)
Way2evl Registered Users Join Date: Mar 2011	12T or 13T Pinion So I have been looking around the forums a lot and I see that the general consensus is a head speed of 2150. I have searched set ups witht the scorpion 4525-520 and have found that people are running the 13T pinion. So I purchased a 13T pinion. Through my calculations I have found that the 13T pinion is not the best pinion for efficiency which relates to heat, power, and flight time. Calculations are as follows. Ratio w/ 12T pinion is 9.66 and 13T pinion is 8.92. Motor RPM = Voltage(KV). Based on a 3.8 nominal voltage and a 520kv that is 23,712. Multiply that by a motor efficiency of 89% = 21,103.68. Divide that by gear ratio of 13T [8.92]= 2366. That would be the most efficient head speed for that set up. As far as I know not many are running that head spead. I could be wrong though, but through my research I found that 99.9% of the time you will only see a max head speed of 2200. So running any head speed considerable less say 2050-2150 will create more heat and lower flight times. Now if you do that equation on the 12T[9.66] it leaves you at 2185. Much better for a head speed of 2150 or even in the range of 2050-2200. So my question would be, other than following the herd or wanting to run a higher head speed, why would anyone use a 13T pinion or higher? __________________ MSH, Cyclone

11-30-2012, 01:04 PM	#2 (permalink)
Chris Sexton Registered Users My HF Map location Join Date: Feb 2011	Some governors require more head room than others. As well as some ESCs handle the lower throttle requests better than others. Personally, I am running the 12t on 4530-500 and using my VBar gov to hold 2050. That is where VBar and Mr Mel says the sweet spot is for head room on that governor. The Jive ESCs, for example, have a built in circuit that helps deal with the extra voltage when you request less than ideal throttle inputs and are great for having a WIDE range of head speeds on the same pinion. I guess what I am trying to say is, you have to look at the entire picture. If you are using a Castle ESC and Castle Gov and shooting for 2050-2150 then 13T is what you want. It is all very subjective and there is no real perfect answer. __________________ Synergy Factory Specialist / Rail Blades / Team Scorpion

11-30-2012, 04:09 PM	#3 (permalink)
Way2evl Registered Users Thread Starter Join Date: Mar 2011	Ok, I will be using the vbar gov. Will 12t be better or 13t? __________________ MSH, Cyclone

11-30-2012, 04:43 PM	#4 (permalink)
Chris Sexton Registered Users My HF Map location Join Date: Feb 2011	Yes. For 2000-2200 Sent from my iPhone using Tapatalk __________________ Synergy Factory Specialist / Rail Blades / Team Scorpion

12-01-2012, 07:34 PM	#6 (permalink)
Way2evl Registered Users Thread Starter Join Date: Mar 2011	Thank you for the responses. So I will get the 12T. If anyone needs a 13T let me know. I don't ever plan on going any higher than 2150. __________________ MSH, Cyclone

12-01-2012, 07:13 AM	#5 (permalink)
4cyclic Registered Users Join Date: May 2004 Location: Northern Vermont	Using the 12t pinion with Scorpion 4525-520 and YGE 160hv at 2150hs. Works great with vbar governor. Has plenty of headroom.

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