Help with headspeed :)

[Phil777]

Hi, ive tried reading a few things on here, but im not 100% im doing this correctly.

Could someone please calculate my head speed for me, and explain how its done, if you have time

Sab goblin
scorpion 4525 520 Ultimate
Helijive 120 v11

I will be using helijive governor, since theres no warranty with vbar using a scorp.

my helical pinion is 20t the motor pully is 22t
the maingear is 204t the main pulley gear is 37t and the tail pully is 27t


Thanks! will finally be doing my late maiden (been waiting for my replacement pully)

What rpm are you running your first flights in? and how many

[SimStream]

Provided your throttle end points are still at 100% and your lipo is 12s 65c,your helijive set for mode 4 or 5 then

Throttle 55%: 2085
Throttle 60%: 2194
Throttle 63%: 2259
Throttle 67%: 2345
Throttle 70%: 2410
Throttle 73%: 2475
Throttle 76%: 2540
Throttle 80%: 2627

Your main gear is actually 68 tooth but as its two stage the overall gear ratio is caculated as if your main gear is 204.

[Phil777]

Thanks, Thats what i got

Sounds about right for the jive, although i hear some are using a 21t instead of 22t

[SimStream]

I would use a 21 tooth pulley if you want headspeeds of 2200+ or a 20 tooth if you want 2000-2200. the Hjive works best with throttle between 65 and 70,

Oh and Goblin say to run first flights at 1700-1800

[SimStream]

If using mode 5 make sure your first spool up is done with zero pitch untill gov kicks in. and you should get close to those figures.

[justindewoody]

You need to use the 21 tooth motor pulley with a 26 tooth tail pulley (for awesome tail authority). I have the 4525-520LE motor, Heli Jive 120 V11, and I run the Heli Jive governor. My 3 head speeds are 2000, 2100, and 2200. The 21 tooth motor pulley allows the ESC to run in its sweet spot at these head speeds. If you plan to run similar head speeds, you NEED to use the 21 tooth motor pulley. And if I were you, I would go ahead and get the 26 tooth tail pulley. Good luck and happy flying!

[SimStream]

Originally Posted by justindewoody

You need to use the 21 tooth motor pulley with a 26 tooth tail pulley (for awesome tail authority). I have the 4525-520LE motor, Heli Jive 120 V11, and I run the Heli Jive governor. My 3 head speeds are 2000, 2100, and 2200. The 21 tooth motor pulley allows the ESC to run in its sweet spot at these head speeds. If you plan to run similar head speeds, you NEED to use the 21 tooth motor pulley. And if I were you, I would go ahead and get the 26 tooth tail pulley. Good luck and happy flying!

Yes except it doesnt run in the HJive sweetspot. You have your throttle between 42 and 62. The HJive sweetspot is 65-70 it says so clearly in the manual

Decrease pulley to 20 tooth will bring your throttle up to around 58-72. Much less work for all the electronics and better results

[strokermtr]

Originally Posted by SimStream

Yes except it doesnt run in the HJive sweetspot. You have your throttle between 42 and 62. The HJive sweetspot is 65-70 it says so clearly in the manual

Decrease pulley to 20 tooth will bring your throttle up to around 58-72. Much less work for all the electronics and better results

+1 and you don't need go up on the tail pulley, as long as your 2000 head speed and up.

[Thunder Fighter]

I would be worried about over speeding the tail with 2200rpm and the 26 tooth tail pulley. SAB rate it up to 2100 only.

//Dennis.

Sent from my HTC Desire using Tapatalk 2

[justindewoody]

Originally Posted by Thunder Fighter

I would be worried about over speeding the tail with 2200rpm and the 26 tooth tail pulley. SAB rate it up to 2100 only.

Where did you read this?

[gww528]

Originally Posted by justindewoody

Where did you read this?

Page 33 (manual v1.3)

However, if you prefer flying at low/medium speed [< 2100 rpm], for best results we recommend changing the tail pulley for a smaller one to increase tail rotor rpm. In this way, you will have extremely precise tail control even at low RPM. This pulley is available in the upgrade list [H0049-S]

[SimStream]

Originally Posted by gww528

Page 33 (manual v1.3)

However, if you prefer flying at low/medium speed [< 2100 rpm], for best results we recommend changing the tail pulley for a smaller one to increase tail rotor rpm. In this way, you will have extremely precise tail control even at low RPM. This pulley is available in the upgrade list [H0049-S]

The front pulley now has an extra tooth as well so that adds extra speed anyway

[Thunder Fighter]

Originally Posted by justindewoody

Where did you read this?

I asked the question on the Goblin Forum after the new main pulley that has an added tooth was released and referred to that in the question. The answer back was that it was ok for 2000-2100rpm.

//Dennis.

[gww528]

Originally Posted by SimStream

The front pulley now has an extra tooth as well so that adds extra speed anyway

SAB Goblin Tech states the recommendation does not change. (Goblin Forum)

Originally Posted by Goblin Tech

http://www.goblin-helicopter.com/for...ull=1#post2560

The ratio Main Rotor / Tail Rotor is: (68/20) x (37/27)
The recommended RPM does not change.
If you are flying at low rpm (less than about 2000/2100 rpm) is always recommended the pulley 26 teeth.

[emoe]

Ok guys...are you using Mr.Mel's Calculator?

http://www.readyheli.com/headspeed-calculator.html

Can you answer me two questions...
1. What motor efficiency are you using?
2. Isn't the lower number battery percentage left?? Not Throttle position.

So how are you getting such exact numbers for throttle position?

Throttle 55%: 2085
Throttle 60%: 2194
Throttle 63%: 2259
Throttle 67%: 2345
Throttle 70%: 2410
Throttle 73%: 2475
Throttle 76%: 2540
Throttle 80%: 2627


What am I missing. Where did you get this info..Am I miss reading his Chart?

[SimStream]

Originally Posted by emoe

Ok guys...are you using Mr.Mel's Calculator?

http://www.readyheli.com/headspeed-calculator.html

Can you answer me two questions...
1. What motor efficiency are you using?
2. Isn't the lower number battery percentage left?? Not Throttle position.

So how are you getting such exact numbers for throttle position?

Throttle 55%: 2085
Throttle 60%: 2194
Throttle 63%: 2259
Throttle 67%: 2345
Throttle 70%: 2410
Throttle 73%: 2475
Throttle 76%: 2540
Throttle 80%: 2627


What am I missing. Where did you get this info..Am I miss reading his Chart?

1 motor efficiancy is usually best left at 90% some pyro motors run at 92%, some odd motors at 85%

2. No its throttle percentage .....enable 'gov' and select your esc type and then enable 'extended results' to see list of throttle percentages and expected headspeeds as above

when it reads throttle 73% 2475 it means that with your setup and your throttle curve set as 73 73 73 73 73 the headspeed you should see is 2475 rpm

[emoe]

SimStream. Thanks. How could I have missed that.
Thanks again.

[Phil777]

Throttle 55%: 2085
Throttle 60%: 2194
Throttle 63%: 2259
Throttle 67%: 2345
Throttle 70%: 2410
Throttle 73%: 2475
Throttle 76%: 2540
Throttle 80%: 2627

with 22t pinion,

Can i still use this 22t till i get my 20t?
e.g do my first flights at 2085 instead of 1900, with no issues?

And use Governor between 55-60?

without wreaking anything?

[Phil777]

Throttle 20%: 460
Throttle 30%: 821
Throttle 40%: 1182
Throttle 50%: 1543
Throttle 60%: 1905
Throttle 70%: 2266
Throttle 80%: 2627

just realized
with helijive mode 6,

Would this be ideal for 22t pinion?

[MrMel]

Originally Posted by Phil777

Throttle 55%: 2085
Throttle 60%: 2194
Throttle 63%: 2259
Throttle 67%: 2345
Throttle 70%: 2410
Throttle 73%: 2475
Throttle 76%: 2540
Throttle 80%: 2627

with 22t pinion,

Can i still use this 22t till i get my 20t?
e.g do my first flights at 2085 instead of 1900, with no issues?

And use Governor between 55-60?

without wreaking anything?

You can use lower % without issue, it's just that 1% makes so much difference there so I cannot really calculate it with good accuracy.