Planning a 12S setup for my T-Rex 600 - field tests today 20.05.07 - RC Groups
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Oct 05, 2006, 06:28 AM
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northwood's Avatar

Planning a 12S setup for my T-Rex 600 - field tests today 20.05.07

I've been looking into getting a motor to run 12S in my T-Rex 600, and so far I've found one that looks promising: an Actro 32-3 (KV:555).

With the gear ratio I use with my Z-Power 50 (9.44 - 18T pinion on stock straight cut gear), motor spinning at 24642 RPM (44.4 x 555) should give me a headspeed of about 2600 RPM (24642 / 9.44 = 2610.38) - in theory. This should give me a insane amount of power, but does anyone see any dangers with running such a high headspeed?

Also, now I use a pair of EVO20 NF 3700's for 10S, I haven't checked the amp draws with the Z-50 but the packs are way within the temp limits after a 8 min flight (putting back around 3000 mAh). ESC (85HV) never get's hot to the touch. Anyone want to guess approx. amp draw on the new setup?

Any suggestions for 12S packs? I was thinking of just stepping up to 2x 6S 3700's but I don't know about CG with that amount of weight strapped in the front. Maybe I'll test some 3300's.

Let me know what you guys think about this! I want to address every potential problems with doing this before I order the motor.

Last edited by northwood; May 20, 2007 at 04:50 AM.
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Oct 05, 2006, 06:35 AM
Renewed interest
ozace's Avatar
I think the 32-3 is overkill, that motor is a stump puller in a 700 bladed heli.
I think the Z-50 should be more than enough power in that airframe. Lighter batteries will make a big difference ie use 10-12s of the 3300's instead of the 3700's or keep your existing motor and get a bigger pinion.
Oct 05, 2006, 06:46 AM
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northwood's Avatar
In my eyes overkill isn't a bad word. Overkill means power to spare.

If I could use the Z-50 on 12S, I would. But I don't think it can handle it. In fact if the Z-50 accept 12S it would give me a tad higher HS than the Actro would because of the slightly higher KV.
Oct 05, 2006, 06:50 AM
A man with too many toys
2600 headspeed is way too high for a 600mm helicopter. Anything higher than 2100 is just wasting energy. 600mm blades at 2050-2100 is just right. 620mm blades at 2000-2050 is just right. Longer blades turning slower age more efficient.

Also check the blade specifications – most CF blades are good to 2100-2400 depending on the manufacturer. You don’t want to go to the ER with a carbon blade sticking out the side of your head!

Oct 05, 2006, 10:56 AM
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northwood's Avatar
Ok, I was expecting the blades possibly wouldn't be up to the task.

Plan B: I could turn down the headspeed to a more optimal range and have a lot of headroom on the power. What you think about that?
Oct 05, 2006, 11:32 AM
misskimo's Avatar
32-3 , over kill , YES! in that size heli , the difference between the 24-4 and the 32-3 would be just alike, a tad more power , bt not enough to account for the extra weight , VBlades test there at 3000 , that even the 690s , now the other problem , head can it handle it without slinging the blades off , seen that at IRCHA , smaller packs will be needed , and if you can get this to work good , theres a hole new kind of power under your thumbs , its like adding a turbo, well unless you got one heavy heli ,

Oct 05, 2006, 11:40 AM
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northwood's Avatar
I'm definately no expert, but with metal blade grips I don't think it'll sling blades. But I'll never ever try running a setup that's so close to deadly as running carbon blades over the limit. All I want is some serious power. Yes, my Z-50 kicks ass in the T-Rex already, but I've been wanting something extra after I saw the true potential of this machine. Maybe I'll just get a Ion...
Oct 05, 2006, 12:09 PM
misskimo's Avatar
hey , I ran 12s in my Razor , 45-06 13.5 to 1 ratio , and compared this with the 45-08 on 10s , its like night and day , the good thing about my test , the 45-06 12s with the math , runs 1000 motor rpms less than the 45-08 on 10s , but 10 to 15% more power , run times with the 45-06 , 6 min with TP 3850, with some left over of corse. 10s 4600 with the 45-08 , 8 to 9 mins , 45-08 is good for mild 3D . 45-06 3D YYYeeehh
May 20, 2007, 04:22 AM
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northwood's Avatar
I'm kicking this thread to the top again.

Going to the field to test 11S and 12S on the setup mentioned in the first post (Z-50 and CC 85HV).

Now I'm hoping the weather will remain as it is for now.

I'm first testing 5+6S and then a 6+6S to see how it goes on 11S first. I hope the motor is up for it.

As discussed in the thread the blades (MAH) might not be up for the task of over 2500 rpm HS, so I'll be taching my headspeed, trying to tune it down to around 2100-2200. It's a shame I don't have a logger...

Maybe I'm just insane or just dumb, but wish me luck.
Anyone foreseeing any trouble?
May 20, 2007, 05:16 AM
Renewed interest
ozace's Avatar
I wouldnt run the MAH's that high. I have a couple of sets here and they are happiest just below 2000, any more and they loose track. For 2500's something super stiff (V)
May 20, 2007, 11:13 AM
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northwood's Avatar
Darnit... Didn't get any flights today. Terrible weather and bad settings in the ESC.

Got a sort of twitching when I tried to hover. I suspect the governor gain was too high so the gyro started fighting it and that resulted in twitching... If it's not the CC85HV not liking 11S...

Will have to wait until next weekend before trying again...
May 20, 2007, 04:53 PM
misskimo's Avatar
hey , mine in a hover twitchs about every 4 to 7 seconds, it kicks the tail out about 20 degrees, looking through a skytach , the HS rises real quickly is the reason , dont know why , but while flying it dont bother it , I also heard the Z50 800 might not be good on 12S , someone was telling me they were having problems with it ,
May 20, 2007, 05:26 PM
Misskimo wins the Most Commas Used award ;]
May 20, 2007, 05:30 PM
Registered User
CC says throttle response should be set to low in gov mode. Might want to check that.

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