Do I need a governer

[supamansuper]

Hi,I've seen a lot of post about governers over the last week,but none really say what there for.Can someone please let me know if I need one.
I'm not thinking of going nitro for a while,although I have a nitro heli sitting there.I have a flasher 450 which I intend on learning with,do I need a governer or a tacho for this.
I've have four helis,two of which i've had for three years and never flown them due to the fact that I keep seeing threads about other bits and pieces I might need,but dont know what they do.Any advise would be much appreciated as I do intend on flying really soon,the wife keeps nagging about having £1500 worth of stuff I dont use,so if I dont get in the air soon I'll end up having to sell up.

[kungpo]

I beleive governers only apply to Nitro, and the short answer is no, you don;t need one, certainly not at beginner stage anyway. My Nitros don't have governers attached.

[alex]

A governer maintains the same head speed on the heli- as you change pitch when flying, you increase the air resistance of the blades and they will try to slow down, so the governer gives them a poke by giving them more power.

Electric helis can be governed via the ESC- personally I like it, but intially, you can do everything with throttle curves. As you start to push the heli a bit more, you will start to notice a change in the rotor noise if you do any rapid pitch changes, epecially using the elevator. Nitro helis can also be run purely on throttle curves and some people feel this is a more elegant and pure way of setting up the heli, along with adding some throttle mix in.

You can also set up electric helis to have a flat throttle curve from point 2 onwards- this is a little like governing the head speed, but will not compensate for any drops in head speed- it means you fly on pitch alone with a fairly constant head speed.

You do not need governers, but I like them- I would just get out there and fly and have fun

[scallybert]

A good governor is brilliant for beginners.

I've got ESCs that allow you to programme the head speed in RPM, and it will recommend gearing, etc.

Given the option, I can't see why anyone would do anything else.

[darrens]

A govenor for either nitro or electric is a good thing to have, but not essential. You can get very close to a constant rotor rpm by setting up the throttle curves well, but you will never get it as good as with a govenor. Throttle curve sets a throttle level at any given point of your stick position. Imagine when you are at 75% stick position, you may have set say 80% throttle for example. This will then give 80% throttle whenever you are at 75% stick position and will not distinguish whether the head is currently under load or off load. If off load the head will over speed, if under heavy load it could bog a little.
A govenor will adjust the throttle continually to maintain a constant head speed at any position and whether under load or off load. It will reduce the chance of your head bogging or overspeeding so is a "nice to have" at beginner level and almost a "must have" for a 3D flyer.

I hope this helps explain this for you

Regards
Darren

[supamansuper]

Thanks a lot for replies thats helped a lot.Think I'll just stop thinking about all the extras and go have some fun.
thanks again.

[scallybert]

[...]and will not distinguish whether the head is currently under load or off load. If off load the head will over speed, if under heavy load it could bog a little.
A govenor will adjust the throttle continually to maintain a constant head speed at any position and whether under load or off load. [...]

Also, on an electric the head speed (for a given throttle & load) will drop as the pack discharges.

Hence, if you don't use a governor, the head speed (and the heli's handling) can chaneg significantly during a flight, or with different packs

[darrens]

Also, on an electric the head speed (for a given throttle & load) will drop as the pack discharges.

That's partially true, but only at the very end of the discharge curve (assuming reasonable quality batteries). The reason is that your ESC will compensate and at a given throttle demand and will pull more current to supply that throttle level if required. Another thing to remember, if lipo you should only take out a max of 80% of capacity prior to charging, so should never reach a point of the voltage dropping off.
If you use a govenor mode on an esc, the throttle curve you set (let's assume 80% flat line) is just a reference point really, telling the ESC that 80% = X headspeed and to maintain that level. The ESC will then vary between say 50% and 100% to maintain that referencer headspeed.

[supamansuper]

how do i know when I've used 80% of the lipo?I got a free battery checker with a tool kit I bought,Can I leave this attached to the heli so as I know when lipo is at 20%?
Also which governer would be recomended for the flasher 450?

[darrens]

best thing to do is fly for say 2 minutes then recharge the battery. Check how many amps the battery takes to recharge after 2 mins. Lets say your battery is a 2000mah pack and it takes 400mah after two mins = 200mah/minute. 80% 0f 2000mah is 1600mah (max recommended discharge) so this gives you a flight time of 8 mins (1600/200).
You can then set a timer on your radio to go off at 7 mins 30 seconds and have enough time to land thereafter.

[scallybert]

Also, on an electric the head speed (for a given throttle & load) will drop as the pack discharges.

Hence, if you don't use a governor, the head speed (and the heli's handling) can chaneg significantly during a flight, or with different packs

That's partially true, but only at the very end of the discharge curve (assuming reasonable quality batteries).

What you're saying is at odds with theory and my experience.

The reason is that your ESC will compensate and at a given throttle demand and will pull more current to supply that throttle level if required.

IMO that's fantasy.

With constant throttle the (non-gov mode) ESC will maintain a constant PWM ratio. The ESC won't compensate for anything.

The current is determined by (amongst other things) the voltage at the LiPo terminals. However, the back EMF varies with revs, as does rotor drag - so there's a balancing act going on.

Another thing to remember, if lipo you should only take out a max of 80% of capacity prior to charging, so should never reach a point of the voltage dropping off.

I'd be interested to see a reference supporting this.

IME the LiPo V varies reasonably linearly with charge.

If you use a govenor mode on an esc, the throttle curve you set (let's assume 80% flat line) is just a reference point really, telling the ESC that 80% = X headspeed and to maintain that level. The ESC will then vary between say 50% and 100% to maintain that referencer headspeed.

You're telling the ESC to maintain a specified headspeed. It will vary the PWM to attempt to maintain that headspeed as load, pack charge state, etc vary.

It's a god idea. Otehrwise variations in load and pack state will cause variations in headspeed.

I have a flybarless (and stabiliserless) heli with no governor. I need to use different throttle curves (on different flight modes) throughout the flight to maintain headspeed and handling characteristics.

[darrens]

What you're saying is at odds with theory

IMO that's fantasy

Then rather than shooting, why don't you share your experience and the theory you work to, I'm genuinely interested.

IME the LiPo V varies reasonably linearly with charge

Are you really suggesting a lipo pack which is at 50% charge is only giving 50% (or close to 50%) of the voltage it was at when fully charged? In my experience, a fully charged lipo pack is around 4v/cell and nominal voltage is 3v/cell. I have lipo protection set 10% higher than that yet manage to get 80% out of packs without going into lipo protection mode.

That said, I'll bow out of the thread which is my usual action when a thread takes a confrontational slant.

Supermansuper, good luck with your flying Buddy and happy flying to all.

[scallybert]

Then rather than shooting, why don't you share your experience and the theory you work to, I'm genuinely interested.

I thought I did briefly ?

Experience: Head speed drops noticably as the pack discharges.

Theory (rough): back EMF is proportional to revs. Motor terminal V is approx current*R + (back EMF)

At constant current (ie constant torque), the revs have to drop as the ternminal V drops.

However, it's all made more complicated by (amongst other things) drag being a function of RPM & rotor pitch; and torque has to equal drag to maintain headspeed.

Are you really suggesting a lipo pack which is at 50% charge is only giving 50% (or close to 50%) of the voltage it was at when fully charged?

Not at all. Under no load, it's roughly halfway between 3.7V & 4.2V

A load will make a difference, depending on cells internal resistance (which is a functiion of many things...)

In my experience, a fully charged lipo pack is around 4v/cell and nominal voltage is 3v/cell. I have lipo protection set much higher than that yet manage to get 80% out of packs without going into lipo protection mode.

My LipoGuard is set at 3.3V/cell. Dafault is lower than that - 3V, IIRC.

The terminal V is going to depend on current. ie a big current might prematurely trigger the protection. Though that might not be a bad thing.

That said, I'll bow out of the thread which is my usual action when a thread takes a confrontational slant.

Sorry - I was feeling a bit patronised.

[darrens]

Scally, sorry if you felt patronised, was never my intention. I was just trying to assist an obvious newcomer, hence my terminology.
Apology over, hope your feelings are intact and I hope you find batteries with a flatter discharge curve than those you are currently using.

I shall remain withdrawn.

[scallybert]

Scally, sorry if you felt patronised, was never my intention. I was just trying to assist an obvious newcomer, hence my terminology.
Apology over, hope your feelings are intact and I hope you find batteries with a flatter discharge curve than those you are currently using.

Don't worry about it. I'm not exactly Mr Tactful, so I can hardly moan...

Dunno about a flat discharge curve. I'm not sure any do have.

I just bunged this in Google
Google

Some of it's worth a look.

Strangely, the curves get flatter at higher discharge rates.

I think pack internal resistance is a significant issue.

I shall remain withdrawn.

If you must...