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Old 04-07-2015, 08:41 PM   #1
Flysohigh
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Default scale throttle and pitch curve suggestions

I have neg 3 low stick, 5 deg mid stick and 10 deg full stick

Based on the rpm calculation

23x1400=32,200 rpm 100% throttle

12t/162m =0.074

32,200 x 0.074= 2382 HS / 80% throttle = 1900 rpm

2144 rpm 90%
1906. Rpm 80%
1787. Rpm 75%
1668 rpm 70%
1430 rpm 60%

What rpm should i target? Also need to know a flat throttle curve will work better than a increase curve with pitch?

TC- 0,60,80,80,80
PC- 30,62,80,90,100

Having -3 bottom and +9 at top i have center stick at 5 degrees for takeoff...any suggestions?

Heli is a scale 500 esp in hughes 500 fuselage scorpion 1400kv
12t/162m

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Old 04-08-2015, 08:27 AM   #2
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your calculations dont take into account 'slip' of the motor from it's theoretical Kv x v RPM. When the motor is loaded it will always turn slower than it's theoretical 'no-load' Kv x V calculation. For a motor under reasonable load you need to apply a factor of 0.7 -0.8 to get the actual RPM

You are already running low gearing and a relatively low Kv motor compared to standard for the Trex 500. Unless you are swinging larger blades I think that you will need to run pretty much 100% throttle to get acceptable performance, even then with the extra weight of the scale body it might be a bit lacking especially as the battery starts to run lower. The 500 really needs something like 2000RPM to fly, preferably higher especially if you are heavy.

PS.. your calcs also assume too high battery voltage. You need to work on a voltage that represents a pack under load toward the end of a flight. something in the 3.5-3.6V range per cell is reasonable which gives around 21V for a 6s pack.

Taking all this into account I really do think that you should look at your gearing reduction. Even with 100% throttle you are probably going to have quite marginal power toward the end of your battery pack.
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Old 04-08-2015, 05:15 PM   #3
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I lowered the pinion to 12t from 13t and got a 1400kv motor , i dont really want to change the gearing just find the right rpm to have a nice tame scale flight. I will consider maybe getting heavier paddles although i cannot find the weights.

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Old 04-08-2015, 06:49 PM   #4
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The easiest option is just to run a 100% throttle curve and see how you find it. Give it a flights and see if it feels like it's got enough power, or (unlikely IMHO) if it feels like too high a headspeed. If it feels down on power put the 13t pinion on, if it feels too high a headspeed use a lower % curve.

It's really how it feels in flight that's important not the theoretical RPM on paper.
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Old 04-08-2015, 07:16 PM   #5
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Whats odd is right now it flies great at a lower headspeed 82% feels really tame bjt i have to use about 75% stick to keep at a hover having positive 5 deg at mid stick. Jjst trying to lower that to takeoff at exactly half stick. Maybe its more rpm that i need, ill give 95% see how it does and get back to you

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Old 04-08-2015, 07:24 PM   #6
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Originally Posted by Flysohigh View Post
Whats odd is right now it flies great at a lower headspeed 82% feels really tame bjt i have to use about 75% stick to keep at a hover having positive 5 deg at mid stick. Jjst trying to lower that to takeoff at exactly half stick. Maybe its more rpm that i need, ill give 95% see how it does and get back to you
Sounds to me very underpowered. If you have to use 75% of stick travel (about 7.5 degrees of 10 available) just to hover it leaves very little for climbing, forward flight or to recover if the heli gets into a fast descent. You will also likely end up using almost full collective just to hover when the batteries run down.

But it's not my heli, it's yours, so if you are happy with how it flies that's fine. If you want it to hover at mid stick just measure the pitch that the blades have with the stick in your current hover position and increase the pitch curve so you have that same pitch at mid stick.
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Old 04-08-2015, 07:35 PM   #7
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Do you think it may also have to do that im currently running 85% TC? Increasing the HS should allow me to lift off before 70% stick?

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Old 04-08-2015, 07:50 PM   #8
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Yes if you have limited max to 85% without using a curve to just limit the last part of throttle : collective then you will have reduced your throttle near mid stick too.

My experience says more head speed is easier to fly.... as long as you aren't pushing it past the stress limits of the head's parts.

for your expected head speed calculations... assume the motor runs appx 80% of kV when under peak acceptable load and you'll be closer to actual results when you use a tach.
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Old 04-08-2015, 07:57 PM   #9
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Got it ill try 95% throttle flat tomm morning and keep you updated, thanks Bud

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Old 04-08-2015, 08:08 PM   #10
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I'd go 100% and use a tach to check head speed.

I always found it easier to hover by getting the heli light on the skids (getting head speed up as high as it would go before lifting) then go to acro mode for the higher head speed at 0 deg pitch.

Never did get very good at flying the things... but I still try occasionally and have 4 working helis.
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Old 04-08-2015, 08:50 PM   #11
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I have neg 3 low stick, 5 deg mid stick and 10 deg full stick

Based on the rpm calculation

23x1400=32,200 rpm 100% throttle

12t/162m =0.074

32,200 x 0.074= 2382 HS / 80% throttle = 1900 rpm

2144 rpm 90%
1906. Rpm 80%
1787. Rpm 75%
1668 rpm 70%
1430 rpm 60%

What should i target?

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Old 04-08-2015, 09:24 PM   #12
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BASIC setup... start with a straight 0-100% throttle "curve"... and adjust from there.

Tweek throttle curve midpoint for lift-off (in non-acro) a bit above mid stick... at the makers recommended hover pitch.

Use a tach to adjust max throttle to prevent over-speed. Preventing over-speed is the only reason to not have 100% throttle available.

What max head speed is recommended for your mechanics set? Something tells me you probably can't get there without leaving the pitch to 0...
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Old 04-08-2015, 09:59 PM   #13
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2650 seems ro be max per manual. I cant achieve that with 12t 1400kv motor

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Old 04-08-2015, 10:02 PM   #14
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Originally Posted by Flysohigh View Post
I have neg 3 low stick, 5 deg mid stick and 10 deg full stick

Based on the rpm calculation

23x1400=32,200 rpm 100% throttle

12t/162m =0.074

32,200 x 0.074= 2382 HS / 80% throttle = 1900 rpm

2144 rpm 90%
1906. Rpm 80%
1787. Rpm 75%
1668 rpm 70%
1430 rpm 60%

What should i target?
As already noted, your calcs are fundamentally flawed mainly because you aren't considering motor 'slip' under load and also to a lesser extent because your voltage is a little too high for a battery at the end of a flight.

Use 21.5V and an 0.8 'slip' factor and your RPM will be closer to what you really see late in your flight.

FWIW as a general rule you would expect to hover at around 4 degrees pitch. So if you have 5 degrees at mid stick and it wont lift off at that then by the normal 'rules' it's more RPM you should be looking at, not more pitch.
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Old 04-08-2015, 10:55 PM   #15
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"FWIW as a general rule you would expect to hover at around 4 degrees pitch. So if you have 5 degrees at mid stick and it wont lift off at that then by the normal 'rules' it's more RPM you should be looking at, not more pitch."

Absolutely.........!

Flysohigh,

We've been down this road before in the other thread you started related to the Trex 500.

Setting throttle to provide a higher head speed is preferred over increasing the blade pitch.....on all CCP's.

Hover is most effective (12t pinion) with pitch set a 5* and around 2050 to 2150 RPM's, on anything less than a 30KV brushless.

Another issue (which has not been mentioned) is what setting your using to set the pitch and throttle curves......standard idle speed or Idle-Up position.....?..........The pitch curves need to be adjusted depending on the idles speeds. The higher the throttle idle RPM, the lower the pitch curve......and vice-versa.

Almost any 1/2 arsed CCP guy can recommend a (safe) standard baseline 12t idle pitch/throttle curve that will get you to hover and putt around comfortably. But most of us (who know better), won't recommend anything more due to several factors......one being, not really knowing your true experience and comfort level, two, whether or not the bird is really equipped and mechanically set-up properly to perform your desires and three, what we (those of us who are experienced fliers) find to be manageable and comfortable may not suit your tastes or ability to set-up or fly..........
Anyone who gives you more than that over the forums and chat lines without having physically touched your bird, is really doing you a disservice and setting you up for possibly more frustration and disaster, which is not what the goal here........

It's not a cop-out or lack of knowledge if some of us appear to be a little reluctant to get down to the fine hairs with set-ups.......speaking for myself, I'd rather point you in a basic direction that is accepted by the standards in the industry, and let you do the research and find a mentor to physically walk you through this, rather than throw a bunch of what-if's and maybe's at you and eventually here you've blew-up or worse, walked away from the heli all together due to frustration and subjective forum-chat line intervention......just saying!

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Old 04-08-2015, 11:14 PM   #16
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I feel it flying good just need to increase my throttle a bit ,, btw i fly in IU 83% throttle is what i have now, i believe increasing it to about 92% should get me to be where it feels good. Ill test tomm morning

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Old 04-09-2015, 01:32 AM   #17
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eventually you might even try 100%..... since its impossible for your motor to push the head speed above redline.
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Old 04-09-2015, 02:29 AM   #18
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interesting enough MOST all people here are telling me to increase my throttle. i just set up my radio to reflect these settings:

at low stick -3.5 mid stick 5.5 and top at 13

i just flew one of my packs that was at 50% capacity

TC- 0-75-85-87.5-90
PC- 40-55-65-75-85

At practically 85% throttle and using a pack that was half drained it flew amazingly stable. i added +35 expo increased from +25

with this said i was able to get light on the skids at exactly half stick stick and not to mention a half drained pack at 23v. If i were to increase the throttle it will get too touchy on the cyclic and not feel the way i want it to feel. Im just wondering this heli must have a throttle of 80-85% throttle to feel scale like tame characteristics and smooth cyclic movements. i would say this RPM has to be around 1700-1900 anything above 2100 will not fly tame like it does like this. Tomorrow morning i will fly a fully charged pack and see if it feels ok. if i see its a bit touchy ill decrease the throttle until i can get it to feel just right. Ill keep you guys updated. thanks


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Old 04-09-2015, 02:18 PM   #19
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Setting IU TC to 85,85.5,86,86.5,87 should be close to the effect of a governor with a linear pitch curve with about 8 deg total collective right?

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Old 04-09-2015, 05:43 PM   #20
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No, not really, a flat throttle curve isnt like a governor. In fact no throttle curve will maintain constant headspeed as a governor does.

Having the throttle curve sloped between maybe 80 at mid stick and 100% at full will to some extent offset the bogging that you would otherwise get when you add collective pitch, but it will never be as good as a governor. A few % difference like you suggest wont make any appreciable difference at all.
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Old 04-10-2015, 01:54 AM   #21
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[QUOTE=JetPlaneFlyer;972067]No, not really, a flat throttle curve isnt like a governor. In fact no throttle curve will maintain constant headspeed as a governor does.

Having the throttle curve sloped between maybe 80 at mid stick and 100% at full will to some extent offset the bogging that you would otherwise get when you add collective pitch, but it will never be as good as a governor. A few % difference like you suggest wont make any appreciable difference at

I personally likr the feel of a flat throttle curve as i use very little collective to fly around , i have a governor but never set one up before so i dont want to fix something that isnt broken. Personally i like the flat throttle as it feels good. Noe the day i get my governor set up im sure i will not look back anymore. I just dont have a tachometer to make sure the governor is set up right so i dont know where to start

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