Timing at lower RPM vs higher RPM - RC Groups
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Oct 21, 2017, 12:37 PM
Under new management.
Discussion

Timing at lower RPM vs higher RPM


Been wondering ::and {wandering}?? Hmm

Anyways, I decided I would like to dwell back into lower headspeed again without changing any mechanics.

Question is, wait let's talk about setup first.
700 heli with 701 mm blades hDFC mod.
530kv @12x112 hearing
12s
Hobbywing 100amp HV 32kHz pwm governed
30C kickbutt lipos

Okay.

So, let's talk timing. Due to the lack of heavy understanding, I'm assuming, when dropping to lower RPM, having lower timing will produce less amp spikes and will make for smoother power consumption vs having higher timing?

I'd like to try lower headspeed and would like to make it easier on the power system to work it..any way I can without modding mechanics.

Let the bright minds b
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Oct 21, 2017, 12:42 PM
Heligamist
BrokeDad's Avatar
ESC {BEC} Is it time ? Hard or soft {start} or ware
Where to go .. already there ?
Slow down, speed up {gear up?}
Winding down
Oct 21, 2017, 01:02 PM
Destroyer of Threads
Steve_'s Avatar
The way I understand it, timing is one of those minor tweaks after everything else is perfect.

It won't fix an ESC running hot due to sustained operation at 50%, or a motor overheating from improper gearing.
Oct 21, 2017, 02:01 PM
Under new management.
But what about 65%? Cooler weather here.

Btw, timing gave me a significant boost on cortex wax and sk3 motor. Going from low to edium sent it to overdrive power
Oct 22, 2017, 05:27 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Is 'cortex wax' a treatment for the hair brained?

As the gearing on your 700 is fixed then your best bet is a lower Kv motor
Last edited by JetPlaneFlyer; Oct 23, 2017 at 12:51 PM.
Oct 22, 2017, 06:25 AM
Under new management.
Copterx esc, it autocorrect.
Hearing,is good on my 700 quite loud
Ids like to keep it stock.
Any idea on timing? Or should I just experiment? I only have 2 flight,acs
Oct 22, 2017, 01:19 PM
Bro, it is Christmas season!
Bro, we can do the research in our workshop
Oct 22, 2017, 04:38 PM
rc user
Vik, help stimulate the RCG economy and buy this:
https://www.rcgroups.com/forums/show...x-700-FBL-Head
then you will have a proper zeroDFC head you can run low as you like.
maybe he'll accept a low ball offer

oh, i missed the last part, without modding mechanics..
Oct 23, 2017, 03:37 AM
Registered User
Thoemse's Avatar
Quote:
Originally Posted by JetPlaneFlyer
Is 'cortex wax' a treatment for the hair brained?

As the hearing on your 700 is fixed then your best bet is a lower Kv motor
This really!
You can lower RPM quite a bit but once you are in the 50% range you really need a a lower kv motor.
You can run at 50% with active freewheeling but the ESC tends to get a bit warmer nevertheless and it will be prone to bogging.
My experience showed me that I can get away with 60 to 65% throttle, anything below that is not great. On my Protos 500 I tried 50% once. The ESC overheated even with freewheeling active. Thanks god it did not shut down but only gave me warning beeps.
Oct 23, 2017, 05:20 AM
Under new management.
Thank you Thoemse.
Oct 23, 2017, 12:58 PM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Quote:
Originally Posted by Flying Pitcher
Copterx esc, it autocorrect.
Hearing,is good on my 700 quite loud
Yes, i fell foul of the dreaded iphone auto-correct too

But boy you guys are a tough crowd. I thought the "'Is cortex wax' a treatment for the hair brained" joke was a rib tickler


Anyway.. back on topic. Timing isn't going to help. As Thoemse said, too low a throttle curve will just cook your ESC. The best fix is lower gearing but failing that lower Kv. I appreciate that you dont want to spend anything but sometimes you just have to.. Either that or just fly it like the makers intended at a 'proper' headspeed
Last edited by JetPlaneFlyer; Oct 23, 2017 at 01:53 PM.
Oct 23, 2017, 01:38 PM
Heligamist
BrokeDad's Avatar
I fly my second Oxy 3 at a low HS but I put in a HW 60A V4 ESC instead of the normal 40A size.
Oct 23, 2017, 02:08 PM
Under new management.
JPF, me nd my frnd Denis did a lot of research according to this project on helifreak, "tight tolerances" on forums create overheating flights. Some loosened and slop is better.

Anyways, when it,comes to flying 50%, I cn just switch to 6s instead of 12s. Lighter and no stress on esc. I was thinking more of 65%.. Because if I fly single 6s and pull the stick hard, tail gets a bit loose. I end,up in tricky situations often.

Ps-
using lg keyboard and it,likes to replace "with" into "28th" or "38th"...nty sure why. Also likes to add million commas.

I'll stick,to normal intended,flying I guess.
Oct 24, 2017, 02:23 AM
Registered User
Thoemse's Avatar
Quote:
Originally Posted by Flying Pitcher
JPF, me nd my frnd Denis did a lot of research according to this project on helifreak, "tight tolerances" on forums create overheating flights. Some loosened and slop is better.

Anyways, when it,comes to flying 50%, I cn just switch to 6s instead of 12s. Lighter and no stress on esc. I was thinking more of 65%.. Because if I fly single 6s and pull the stick hard, tail gets a bit loose. I end,up in tricky situations often.

Ps-
using lg keyboard and it,likes to replace "with" into "28th" or "38th"...nty sure why. Also likes to add million commas.

I'll stick,to normal intended,flying I guess.
Yeah 50% (or 6S only) is probably too low. The t-rex 700 tail ratio is just not made for that low headspeeds.
65% I think you could get away with. I'd just try it for 2 minutes, then land and see how warm the ESC gets. If it does not get extremely hot you should be good.

What ESC do you use? It must have active freewheeling or you will cook it.

If you want to 3D it at low headspeed you got the wrong heli though. You need a good tail ratio.
My Diabolo 800 for example has no issue holding the tail at 1200 RPM and below. It does however have a three bladed tail with big tail blades to achive that. The T-rex is made for RPM around 1900 to 2200. Going very low will allways lead to tail blowouts. As far as I know you cannot change the tail ratio. You could experiment with longer tailblades but you'd have to get a longer boom and the raked landing gear for that.
Oct 24, 2017, 05:11 AM
Under new management.
I got hobbywing 100a HV. Its barely warm when I land regardless of throttle. Must be the fan helping and my collective management(management? o dear)

It actually works fine on single 6s, but because no,headroom on rpm, when it bugs below that, tail gets tricky. Like say, doing a loop and miscalculating exit height..
I even went so far as,to trying, partial hrpttle in 6s mode. Id,memory,serves me,roght, i,went all the way down to somewhere 70% throttle while,using 6s and,it seemed,good. Would be fine,for soft sport flight is assume without anything unexpected,while,flying.


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