Coreless Motor measurement - RC Groups
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May 25, 2012, 03:54 PM
Team WarpSquad
Daryoon's Avatar

Coreless Motor measurement

I just tried a 9958 motor (rev 2: blue, red wires) versus a mSR X motor versus white cap Bravo SX motor. All using 8teeth pinion.

On a stock 9958 with stock 9958 blades...

9958 rev2 (5g): 58.5g of thrust.
mSRX (5.7g): 61g of thrust.
BravoSX (5g): 63.5g of thrust.

I hooked up 4 Eflite 25c 150mAh in parallel and charged all 4 cells between each test. So the voltage should all be stable. I wanted to see peak thrust output.

The tail motor wasn't running.

However, if the tail motor was left to run, the stock 9958 motor went from 58.5g to 54.5g.

The mSR X motor was almost a gram heavier than the Bravo SX motor. This is because it's 23mm versus 20mm.

Now, I wonder the difference between a black capped BravoSX motor versus the white capped one.

caveat: The 9958 and mSRX motors are used. The BravoSX was new. I'll take a look a new mSRX motor I have in my possession.

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Jun 14, 2012, 02:11 AM
Brosol's Avatar
Have you thought about trying the SP 270A main motor? I noticed its cheaper than BSX main motor but don't know if it has the same thrust.

I had good results modding parts which I transplanted to my 9958 frame based Frankencopter with V911 Rx:

- Bravo III lower head with 2mm OD CF rod main blade pivot bar, thin profile linkage guide rods to prevent binding

- SP 260A main blades modded with linkage balls from XTreme Solo Pro swash hub, 14mm linkage balls spacing amplifying main blade pitch & cyclic, 3/32 drill bit enlarged pivot holes

I was putting off sorting out the mess of Bravo III, NE 210A, SP 260A parts for recycling such as using Bravo III lower head & SP 260A blades instead of the MCX head & blade parts.
I was forced to do these mods after I crashed the heli which snapped off a MCX blade linkage ball.

After I fixed some issues with binding which caused bad wobbles & vibration the Franken 9958 now flys great with Bravo III lower head & Solo Pro blades combo.

I also tried out the 9958 9x Tx settings you so generiously posted and I must say Wow!!! What a big difference it made!!! The crazy uber-responsive settings actually help to make aggressive flying indoors easier with more control. My attempts to use toned down settings were actually working against me. Now I'm more able to succesfully do FFF indoor turns without losing control & hitting a wall.

I think Bravo III lower head, Solo Pro blade, XTreme MSR flybar combo is a viable cheaper alternative to MCX & MSR parts for performance modded 9958-V911Rx helis.
Last edited by Brosol; Jun 14, 2012 at 05:22 AM.
Jun 14, 2012, 03:49 AM
Team WarpSquad
Daryoon's Avatar
Last edited by Daryoon; Mar 31, 2013 at 12:26 AM.
Jun 14, 2012, 03:51 AM
Team WarpSquad
Daryoon's Avatar
About the T9x settings. Yeah, having the sticks more sensitive makes for easier flying. I also find adding positive expo to dampen the heli to make it easier for "beginners" to handle actually does the opposite effect for me. It makes me more likely to crash.
Jun 14, 2012, 05:18 AM
Brosol's Avatar
Originally Posted by Daryoon
I thought of using the lower Bravo III head before. But never purchased one to test out. Thinking about it, the lower Bravo III head is essentially a v911 head, with the top part cut off. The v911 has stronger pivots, so no need to drill and insert a CF rod. Plus, parts are pretty cheap too. Or buy a bnf unit to harvest the head, blades and RX.
I was forced to use CF rod pivots after I crashed and broke off both Bravo III head pivots.

I used a 3/32 drill bit to increase the Solo Pro blade pivot hole dia to fix wobbles caused by binding on the unmodded Bravo III lower head before the crash.

I found the combo of the CF rod and the enlarged pivot hole allowed the main blades a increased teeter angle tilt.

Even without dampener o-rings, the heli flew super smooth, vibration & wobble free at all speeds. It flew just as well as my V911-XTreme with delrin head feathering shaft & dampner o-rings.

Similar Anti-Wobble Mods by EQMOD, h2osteam:

How to stop NE solo pro wobble (1 min 29 sec)

I stilll have the head & blades from a Banggood BNF V911 which was modded to my V911-XTreme heli.

I will try to use the V911 head & blades with anti-wobble mods if I crash & break the MCX head & blade parts on my V911-BellHiller heli.
Last edited by Brosol; Jun 14, 2012 at 11:49 AM.
Jun 14, 2012, 11:48 AM
Brosol's Avatar
Originally Posted by Daryoon
As for motors, after my experience modding the mSRX for's an eye opener. So much more power with a brushless motor. And even with the mounting plate, wires, ESC, still comes out lighter than the stock brushed motor.
From the mSRX brushless experiments, is it possible & worth it to do a BL conversion for V911 Rx based Frankenheli?
Jun 15, 2012, 05:37 PM
Brosol's Avatar
$4.90 SP 270A Main Motors - miracle-mart

Shipping to your area may be cheaper than myrcmart

I asked miracle-mart to beat the myrcmart's 270A main motor price and they did!
Jun 15, 2012, 06:36 PM
Team WarpSquad
Daryoon's Avatar
Nice. But Greyhoundfan just put three new Bravo SX motors into my hands last night. All white capped version from MyRCMart.

I did find a point on the v911 RX to solder the brushless ESC to. And it works with the BLHeli Tail code. Just need some time to finish the mod.
Jun 15, 2012, 07:12 PM
Brosol's Avatar
Cool, looking forward to the V911 Rx BL motor mod results.

I'll do a SP 270A vs BSX motor thrust test.
Jun 18, 2012, 12:55 AM
NE solo free spirit V2
Lurking to see the BL V911 combo.

9x almost in my hands. Your hacksandmods are inspiring. I'm going to try implanting the DSM module in the 9x.
(probably been asked before but: can't the same trick be performed with putting the NE Tx module into the 9x?)
Jun 20, 2012, 11:10 AM
Team WarpSquad
Daryoon's Avatar
Can't wait to get back to this as well. I am currently modding my garage so that's taking up my time.

Thanks for the feedback on hacksmods. I appreciate it.

About putting the NE TX module into the 9x. I have thought of it. But I don't know if the NE module simply takes a PPM signal. If it dosesn't, then some sort of conversion needs to happen.

There is a NeXT thread that I think you saw, where the OP's goal was to create a rear module for the NE TX module. I don't think effort has been put into Nine Eagles compatibility because of the disparate protocol Nine Eagles chose to use between their older lineup and the new one. Transmitter incompatibilities really put a damper on the adoption of hobby grade heli IMHO.

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