Goblin 500 (stretch 550)

[HeadHunter86]

Hy Guys,

This week I bought a Goblin 500. I have a few questions.

My config:
Goblin 500 (stretch 550)
Kontronik Jive 100+
Xnova 4020-1000Kv
BK DS-5001HV + BK DS-7005HV
MSH Brain
Almost every tunning (Lynx).

Now I have 3pcs A-Spec 4000mah 65C, but not new, so I want to buy some new batteries.

My goal some soft 3D on "normal" headspeed (2200-2300 or maybe, just maybe 2400 RPM), about 4 min flight time.

I do some calculations,
Now I have a T18 pulley (Ratio 9.18): 1000kv*22V/9.18 = 2396RPM (MAX).
On 90% throttle: 2156 RPM. I think is not too much.

So I ordered a T19 pulley (Ratio 8.7): 1000kv*22V/8.7 = 2528RPM (MAX)
On 90% throttle: 2275 RPM

I think is enough power for 550 machine.

What do you think guys? 2275RPM, 4 min flight time, 4000mah lipo. Is it possible?

Is this RPM ok? Do I need bigger lipo?

[tonys-heli]

you will get longer flight times with smaller pinions and using the gov in the fbl or esc. im using 16t and gov at 2300 with 4000mah and get 6min..you need to tach you present setup, I don't think your numbers are right

[HeadHunter86]

Do you have 1000KV motor?

Here is an another calculation, but the result is almost the same.

[tonys-heli]

Originally Posted by HeadHunter86

Do you have 1000KV motor?

Here is an another calculation, but the result is almost the same.

• 16T Pulley (P/N 0215-16-S) Ratio 10.33:1
• 17T Pulley (P/N H0215-17-S) Ratio 9.72:1
• 18T Pulley (P/N H0215-18-S) Ratio 9.18:1
• 19T Pulley (P/N H0215-19-S) Ratio 8.7:1
• 20T Pulley (P/N H0215-20-S) Ratio 8.26:1

• 21T Pulley (P/N H0215-21-S) Ratio 7.87:1
• 22T Pulley (P/N H0215-22-S) Ratio 7.51:1
• 23T Pulley (P/N H0215-23-S) Ratio 7.19:1
• 24T Pulley (P/N H0215-24-S) Ratio 6.91:1

goblin goes by ratios when calc headspeeds..yes I have same motor..you still need to tach it..im not at 90% tc but im governed..if you got 90% and a 19t pinion, that thing is screaming..goblin doesn't have just one maingear

[HeadHunter86]

Hmm. But you can calculated the ratio with the main gear teeth.
Here is Goblin 500 calculator!

[tonys-heli]

mine isn't stretched either, I did tach mine and im at 2300 with 16t..sorry my timer is set for 5:10 with 4000mah..6:00 with 4400mah

[HeadHunter86]

I don't understand. Because the math is tell me totally different.
16T is the smallest pinion, I hardly believe it.

[tonys-heli]

did you use a tach on your setup yet?

[HeadHunter86]

No, but I will. I just preparing my maiden flight.
I just want to know the correct settings.

[tonys-heli]

90% sounds high..do all the math you want..you'll never know anything unless you tach it. you could have weak batts/motor etc..tach it ! settings for one person might not be ideal for another..different flying styles etc. I kinda like low headspeed and dont need it screaming..90% and 19t I think is gonna be high, I could be wrong..good luck

[Chris Nifty]

Yep, 19t is high. I'm flying that setup with 17t @ 85 - 90% which gives me 2200 - 2350 rpm with cool running and 5.5 - 6:00 minutes flying time.

[HeadHunter86]

Originally Posted by Chris Nifty

Yep, 19t is high. I'm flying that setup with 17t @ 85 - 90% which gives me 2200 - 2350 rpm with cool running and 5.5 - 6:00 minutes flying time.

Yeah I belive you, if you have a 1120Kv motor.
Because:
((1120kv*22v)/9,75))*0,9 = 2281RPM

But I have 1000KV motor...

[Chris Nifty]

Actually I have the 1000kv in the Goblin and the 1120 in the Diabolo.
I think in another thread somewhere I may have mistakenly said the 1120kv in the Goblin.

[Chris Nifty]

Also, so far these Xnovas seem to end up giving you 100 or more rpm than expecting...

[HeadHunter86]

Here is mine calculation from the manual.
With Xnova 4020-1000.

If this motor really 1000kv, then 2350RPM impossibe with the 17T pulley.
Sorry, possible. In the first ten second, while the lipo on 4.2V/cell...



(This excel made for Goblin 700, and I edited)

[tonys-heli]

no one said it wasn't possible.. im doing it with a 16t pinion and im only at 75% tc governed. checked it today 2300 for 5:10min came down with 37% left in pack 4000mah

[Chris Nifty]

Headhunter, sometimes theory and practice can be quite different.
Chuck on that 18t and go flying already! I think you'll find that'll give you your 2400 rpm.

[HeadHunter86]

Originally Posted by Chris Nifty

Headhunter, sometimes theory and practice can be quite different.
Chuck on that 18t and go flying already! I think you'll find that'll give you your 2400 rpm.

I'll do that. I set 70 and 85% govenered throttle. And I will see.