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Old Feb 02, 2016, 10:21 PM
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Why Idle Up at 85%?

Newbie question... Why does it seem like 85 is a target percentage for a lot of people for idle up? I run the Spirit governor on an Oxy 3, have the Spirit set to 4000 and use 92% and 97% as my idle ups. As far as I know, the Spirit just takes 4000 and multiplies it by the percentage.
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Old Feb 03, 2016, 12:05 AM
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Some people run 85% governed because it allows the governor some headroom to maintain your headspeed. If you're running a 100% flat throttle curve you're governor will essentially become useless (unless you use a smart ESC such as YEP/YGE that learn what's the best headspeed with reasonable overhead at a given throttle percentage) since you're giving it no head room.
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Old Feb 03, 2016, 07:07 AM
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I may be wrong, but I think it's pretty simple. A fully charged LiPo cell has 4.2 volts, while its nominal voltage is 3.7 volts.
3.7/4.2=0.88, so if you want to maintain the same head speed at 3.7 volts that you get at the beginning of the flight when your battery is fully charged, you need to limit that initial head speed to 88 percent or less.
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Old Feb 03, 2016, 10:52 AM
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Hi I second that it for the governor to work ,you may find that the head speed is lower when you land as the Spirit does not look at battery voltage as the ESC does on its governor
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Old Feb 03, 2016, 12:32 PM
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Originally Posted by holtneil View Post
Hi I second that it for the governor to work ,you may find that the head speed is lower when you land as the Spirit does not look at battery voltage as the ESC does on its governor
I've noticed the lower headspeed at landing. But why isn't the Spirit governor keeping up with the requested rpms? I have an RPM sensor going in from a Hobbywing 50a v3. Thanks
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Old Feb 03, 2016, 01:27 PM
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It just can't, because by the time you land your battery voltage is simply too low.
If you were to control your motor RPM manually by a separate lever on your radio, you would keep increasing that channel during your flight, starting at the 92% you chose for your governor. After a few minutes you would notice that you are giving 100% to get the same RPM, and from then on your head speed would slow down because you are maxed out.
If you start at 85% for your "manual governor", you would reach those 100% at the end of your flight, so your head speed would remain constant for the duration of your flight.
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Old Feb 03, 2016, 02:21 PM
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I second that I have the spirit pro fitted to my Goblin 630 comp ,but I use the castle ESCs governor and it works really well I use 2x zippy compact 4000 mah and after a 8 min flight at 1900 rpm the battery reads 3.89
If your ESC has a good governor your better using that as it works on voltage as well as gearing recovery will still work just needs to be set up in a different way
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Old Feb 03, 2016, 06:08 PM
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Originally Posted by getsuyoubi View Post
It just can't, because by the time you land your battery voltage is simply too low.
If you were to control your motor RPM manually by a separate lever on your radio, you would keep increasing that channel during your flight, starting at the 92% you chose for your governor. After a few minutes you would notice that you are giving 100% to get the same RPM, and from then on your head speed would slow down because you are maxed out.
If you start at 85% for your "manual governor", you would reach those 100% at the end of your flight, so your head speed would remain constant for the duration of your flight.
What if the governed rpm is not maxed out? Say I'm requesting 100% of 4000 rpm, but the motor and gearing can handle up to 4500. Will the Fbl governor keep increasing the "lever" during dropping voltage to maintain 4000 rpm?
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Old Feb 03, 2016, 09:04 PM
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Yes, in theory it should work. Usually when you're trying to run governed headspeeds, you increase your pinion's tooth count by one to "overshoot" your target RPM. This way your governor will have plenty of overhead to work throughout your flight.

Since your head speed is basically a function of voltage (disregarding drag/load/pitch for simple calculations), as your battery drops its voltage, your head speed will sag along with it. Since we don't usually run our batteries below 3.7v/cell, this nominal cell voltage is useful for headspeed calculations.

For instance, on my Castle ESC's, everything is calculated on a 3.7v/cell basis, so at the beginning of the flight I have a lot of headroom, but towards the end the head room decreases until it matches the current heads peed (by which time you should be getting ready to land!). This is why sometimes head speeds seem lower on castle's software when compared to other calculators out there.

On the other hand, my YEP ESC uses something called governor store. This means that for the first couple of flights, my ESC 'learns' what throttle percentage I usually fly at (flat throttle curves necessary for this). Say I fly at 100% flat out. After a couple of flights, the YEP will find a reasonable head speed that it'll be able to hold regardless of battery voltage (depending on your calibration of course). Similarly, if my IU-1 is 60% and my IU-2 is 100%, the YEP governor will learn which head speed works best at each of the above throttle percentages.

Personally my understanding about governors is relatively limited. I recently started using them in my models, so take whatever I say with a grain of salt
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Old Feb 04, 2016, 07:57 AM
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Hi when you set up the YAP it has to be done with the battery no more then 4.0 to 4.1 volt per cell this then after esc has stored the max rpm ( which is done with all the blades off ) the next time you use the fully charged battery it works on the set RPM it has stored as the battery is full it has head room to keep head speed right ,I have this fitted to my 500 pro and for the cost is a really top esc , the Yap works the governor on voltage where the castle works on gearing and voltage , but both work really well its just if you want extras like data logging etc the Yap will not do this ( hobby king clone)
the only way to use it as it is will be to run a low head speed so the battery at its lowest can keep up with the RPM wanted
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