Fun, Learning, Friendship and Mutual Respect START  HERE

Go Back   HeliFreak > R/C Helicopter Support > Scale Helicopters > Mechanics

Mechanics Mechanics Discussion

Thread Tools Display Modes
Old 07-16-2012, 09:25 AM   #1
Registered Users
Posts: 111
My HF Map location
Join Date: Jan 2011
Location: Mendoza, Argentina
Default 4 blade Trex 500 target head speed???

Hi helifreak friends, im hands on in a trex 500 with the align 4 bladed head and heliartist scale blades, to be mounted ina heliartist hughes 500D with 3gx module. Im a bit confused with head speed for this machine. Ive read in some threads that i need to lower head speed with multibladed. Low head speed with the original motor-pinion combo will raise temp, so i need to pick a new motor pinion combo. Can you with your experience tell me where to start? Thank you all!!!
HK/Trex 450 ProFBL, Atom 500 FBL, Trex 500 FBL Hughes 500D, Compass 6HVFBL, Trex 600 EFL Pro
PieroCapredoni is offline        Reply With Quote
Old 07-17-2012, 02:47 AM   #2
Registered Users
Posts: 4,141

Join Date: Apr 2008
Location: Brisbane, Australia

I would guess somewhere around 1800rpm for a 4 blade 500, but I only have a 1300rpm 4 blade 600, so I don't know for sure.

Assuming you have something like (for 3D heli);

1600kV x (6 x 3.7V) x 0.9 (Efficiency) x 15T / 162T = 2960rpm at 100%

You might want something like;

1210kV x 22.2V x 0.9 x 14T /162T = 2090rpm at 100%, so 1800rpm would be governed at about 86%. Could even go with a 15T and govern closer to 95%.

Something like a CC Ice 75 may be useful as it has a nice big heatsink and would not get as hot inside a fuselage.

Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon )
Andy01 is offline        Reply With Quote
Old 07-17-2012, 01:09 PM   #3
Registered Users
Posts: 11

Join Date: Oct 2011
Location: Miami, FL

Head speed is a matter of preference and a factor of total weight, type of blades, motor type, voltage and gear ratio.

You need to do your math:
(Motor kV) x (# cells x 3.7V) x (Efficiency) x gear ratio = RPM

My recommendation is to first find the ideal head speed with your current stock configuration by testing it at different flat throttle speeds (65% - 75% - 85% etc) to see if the heli lifts well and flies well (doesn't feel too heavy).
If you have your throttle well matched to your ESC you can determine your preferred RPM by matching the % efficiency without using and external tachometer and plugging in the numbers into the equation.

Warning: don't run the motor below 85% for too long or you'll overheat...

Once you found what head speed you like (i.e.; anywhere from 1500 to 2000 rpm), do your math to find the best combination of motor, batteries, and gears.

Best bet is to start with a motor around 1200kv 6 cells 162t gear 12t pinion and that should get you 1800 rpm with a Castle ESC.
With that you can experiment at the cost of a pinion by going little lower to 11t on the pinion or higher up to 17t.

Good luck,
jfmsam is offline        Reply With Quote
Old 07-17-2012, 07:23 PM   #4
Registered Users
Posts: 341

Join Date: Aug 2010
Location: RI

I recently finished my first scale build: an Align A-109 fuselage with TRex 500E mehanics, Align 4 blade head, 3GX, Align 3g blades, and stock 2 blade tail and 500MX motor.

Using 162T main gear and 12T pinion. I ended up setting a head speed of 2000 RPM in governor mode on my Castle Ice 75. This seemed to be the best balance of efficiency, performance, tail authority, and available parts.

Hope this helps.

poconnell is offline        Reply With Quote
Old 07-20-2012, 06:02 PM   #5
Registered Users
Posts: 111
Thread Starter Thread Starter
My HF Map location
Join Date: Jan 2011
Location: Mendoza, Argentina

Thats exactly the same I using, the only difference is that im using hobbywing platinum 60A esc. I will try 85% flat and tach with two blades installed.... will see....
HK/Trex 450 ProFBL, Atom 500 FBL, Trex 500 FBL Hughes 500D, Compass 6HVFBL, Trex 600 EFL Pro
PieroCapredoni is offline        Reply With Quote
Old 07-24-2012, 01:42 PM   #6
Registered Users
Posts: 439

Join Date: Feb 2007
Location: Monterey, CA

I have the Align UH-60 with the four bladed head, and I'm running Edge 473 blades at 1850, and it flies really well. I plan to start dropping the headspeed until it no longer feels good, as 1850 seems high for 4 blades. I really want to find a 4-bladed tail and tail blades that are closer to scale. I'm worried about the micro gears in the tail holding up though. I've been thinking of changing over to belt instead of TT. Has anyone done this?

Trex 500 I2RC swash/Radix/BLS153/Quark/DS520/AR7000/ICE50/Neu1706H/1.5Y
Trex 600E-Pro QUK/Radix600/BLS255HV/Quark/BLS251/AR7110/ICE280HV/HKIII4035-530
Trex 700LE Align 91H/SB20/Radix710/BLS451(8V)/DS760/BLS251/AR7100R/QUK clutch/tail
jones007 is offline        Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Copyright © 2004-2016 by, LLC except where otherwise indicated. The logo is a trademark of, LLC.