Linear or logarithm? That is the question.

[Heli Yea!]

I've got a Flying 30A ESC w/BEC (same as Hobbywing ESC different sticker half the price!:thumbup:) on the way along w/a programing card I've already done my reading on how to program it. The throttle curve program is: linear makes throttle 60% at 1/2 throttle and logarithm makes it 80% at 1/2 throttle. I'm using a stock TX I don't 3D, (yet) but I can fly around pretty good tail-in. What is the closer setting to stock Esc? What are the pros and cons of each setting? Or any other helpful info would ROCK!:Bang

[tom dubya]

um i think your asking a tx question, throttle curves have nothing to do with the esc. They are programmed in with a computer tx, which if you have the stock tx you might already know you can't do it with.

[Heli Yea!]

Yes, and that's why I'm a little puzzled.:thinking Maybe this'll help get to the bottom of this. Here is a link to the program card in question: http://www.dynam-rc.com/products/esc/programcard.htm

[tom dubya]

Ah i see, sorry didn't understand what you were asking. I am also a bit puzzled then. I have the hobbywing program card and it doesnt have that. I would assume ,as i think you have, it would depend on how the stock tx is. And off the top of my head i'm not sure which way it is. But i'm sure by tomorrow someones gonna answer it for you. Sorry i couldn't help ya.

[Heli Yea!]

Thanks anyway Tom hows your belt doin?:cheers

[tom dubya]

Its good. You know i had the perfect opportunity to fly today but the weekends activities left me to want to just sit on the recliner watching the latest die hard movie on cinemax. Which i promptly fell asleep to.

[Heli Yea!]

Sometimes ya fly hard others ya sleep to die hard!;)

[another_finn]

Never seen that before either. That's an interesting feature, though - I suppose it was invented to get around the limitations of stock transmitters like the Esky 0406A. The linear setting is closer to what you have now, but the logarithm curve allows you to get something approximating a real throttle curve on a programmable tx. Might be worth a try.

[copterboy]

I may have answer, but I am a newbie so need to test my knowledge, and hopefully someone will confirm it is correct. I had to setup a sonix 30A ESC&UBEC, but this was not a feature.

I recognise the lingo from setting up my TREX with programmable Throttle/Pitch curves.

I am assuming it is asking you to select the default throttle curve (I agree this maybe to get around stock Tx simplicity). So I would go with Linear, as your default setting. Then when you use the 'idle up' on your tx, the ESC will use the logarythm setting.

The throttle/pitch curve for my trex is linear for normal/hover mode:
Throttle/Tx Stick/Pitch
0% Stick/0% throttle/0 degree pitch.
25% stick/40% throttle/pitch between 0% and next setting.
50% stick/60% throttle/5 or 6 degrees pitch.
75% stick/80% throttle/pitch between 5/6 degrees and next setting.
100% stick/100% throttle/pitch should be maximum ie. 10/11 as per the manual.

The throttle/pitch curve for 3d mode/idle up mode (which is how you should set it up with the motor disconnected) is a logarythm curve follows :
0% stick/100% throttle/-10/11 degrees pitch.
50% stick/ 80% throttle/0% pitch
100% stick/100% throttle/+10/11 degrees pitch.

Hope you can understand (if you do you will pass maths no problem!). You could also try and download the trex manual as it has some extra inforamtion in there.

(I;m on my lunch break and gotta go.....will check back with you later!

[Heli Yea!]

Sounds like a decent explanation to me CB.

( I got straight A's in math years back!:thumbup:) I'm wondering if I set it to linear mode if it will limit the throttle when I idle up to 60% at mid stick, or if I need to set it to logarithm to get the proper throttle/pitch curve in normal 60% throttle and when I Idle up 80% throttle at mid stick?

[mnwizard]

Its good. You know i had the perfect opportunity to fly today but the weekends activities left me to want to just sit on the recliner watching the latest die hard movie on cinemax. Which i promptly fell asleep to.

With me it was the original Miami Vice made for TV movie :)

[copterboy]

I didn't get to say earlier...
(you can tell I was in a rush cause of the typo's)

The only thing I couldn't figure out was, why you would want the logarythm setting as your default anyway? Could this be to suit different stock tx's default?

I haven't flicked the switch myself yet, but I'm guessing the only point you can do it, without a massive change in throttle/stick postion and pitch is 100% stick!!!:badair:

That is why you have to be really careful & know what you are doing when your ready for your first switch flicking flight!!!

I can only anticipate that you would experience a slight increase in pitch (2/3 deg.) if you flick the switch at 100% stick, so once in 3d mode, you would adjust the stick back down and off you go in 3d mode?

Man there is soooo much to learn!!! Feel's like I'm studying for an exam I will never sit!!!

[Heli Yea!]

Im sure you flip the switch at mid stick and decide to go up/down or upside-down from there, but is this going to kick in extra throttle or will it be a smooth transition with the throttle at 60% or 80% constantly at midstick in idle up or normal?

[copterboy]

I agree, if you flick it at mid-stick on the stock tx, you will get too much extra rpm from the motor and loose control of the tail - because the throttle will change from 60% to 80% (I've done similar with trex and crashed).

That's why I can only think that the easiest way to get inbetween modes with the stock tx is at full stick...Can you imagine throwing up the throttle(copter will start to rise), flicking the switch, then bringing the stick back down to try and control it, all as quick as you can!!

That's why your better off with a computer tx, you can set it all up on screen and observe the graphs and curves :smokin: - makes it easy to see where the stick has to be to find the ideal throttle/stick crossover point from hover to 3d mode.


All seems very scary :wow2: so I'm just sticking to my baby steps - got binding issues and no cash to replace my pulley & belt!

Try and locate/download instructions for the ESC, see if you can get confirmation of the throttle curve/setting in there, you may not get a graph but it may explain it in the text somewhere. Good luck!!

[Heli Yea!]

:...:Sorry CB but flipping the switch at full throttle is just not a good Idea it will pitch up the blades. If you think the heli would rise fast at full throttle add more pitch and see ya later belt! The heli is designed to have 0 pitch at mid stick for a reason like shifting gears in a car you can't put in gear if you dont push in the clutch (makes a neutral point). Same with a heli the neutral point is mid stick 0 pitch( doesn't thrust either up or down). Extra RPMs don't matter at 0 pitch because it's not going anywhere.(except by gravity pulling it down)

[copterboy]

Well, I said I could be on the wrong track earlier, but will try to help you sort it out. :thumbup:

I've had a result on my first thread so have more time on hands now (apart from when me battery is charged!) - funnily enough it was an ESC setting that was the solution to my problem! (Motor losing power at mid-throttle thread), so want to give something back as they say...

[Heli Yea!]

Ironic huh?

[copterboy]

Now considering this...:shock:

If you read tom-dubya's first post - it could be about the kind of tx you're using. Linear is stock type tx's and logarithm is computer tx's where you program the throttle curve in yourself.

However, like most manuals.... it's rubbish at explaining anything! 'throttle curve linear : half throttle is equal as 60% of maximum RPM', and 'throttle curve logarythm : 'half throttle is equal as 80% of maximum RPM' what the heli does that mean!

Which leads me to a second and possibly most likely answer - it is exactly what it says it is! I.e. It is where your throttle curve will be at mid-stick on a stock type tx, unless you have a computer tx to change/program it yourself.

I wonder if anyone can confirm if this logarithm setting is for RC planes, as they require a higher RPM gain as you push the throttle stick upward? I think I recall a conversation with someone once, saying some ESC's are made with somekind of heli and plane mode.

Must go sleep now...will check back 2m....:dontknow

[tom dubya]

You know that was one thought i had that one was for planks and one for helis. But not real sure whats for what.

[Heli Yea!]

I think you guys may be on to something here! I think that Copterboy is right in saying LIN60%(for short) is for helis LOG80%is for planks.:thumbup: Look at the card again it is sold for helis and these are the default card settings(not the ESC): brake is off, it is in LIN60%, set to outrunners, and voltage cut is slowdown all good traits for a heli. If you reverse them all except outrunner motor type seem like good traits for a plank! Now the motor part of the card either setting can be used for a heli or a plank. Maybe LOG80% could have benefits for helis too?:thinking

[another_finn]

You guys are making this way more complex than it really is ;)

Planks don't benefit from a logarithmic throttle curve, helicopters do.

Assume you're running a stock transmitter that won't allow you to tweak the throttle curve. When you're flying in normal mode, your throttle varies wildly with your collective input - you're revving the motor up and down all the time, you're mostly flying outside its efficient power band, and you can't come down from wind gusts without losing heaps of headspeed. Now, if you were to program that ESC for logarithmic throttle, you're mostly flying at 80 - 90% power under all conditions. That translates to better stability and cyclic response, and chances are you'll be able to pull tiny negative pitch without losing too much headspeed to recover quickly. Throttle changes will be small in relation to your stick movements, so you're using collective instead of RPM and it's easier to maintain altitude accurately.

When you flick to idle up above mid-stick, you won't get a huge jump in RPM because you're already in the vicinity of the new throttle setting. If you switch anywhere near a stable hover point, odds are the change in blade pitch will be small enough to only require a tiny correction on collective - no more than flying into a small wind gust.

It's more or less like the throttle curve I program on all my CP models in NORM mode. The only reason it's not default in heli mode is that people do have programmable transmitters, and you would want to specifically enable something like that if you need it.

[copterboy]

That does sound like the explanation you been looking for heliyea - both are heli settings!! :woohoo

So which setting you choose is down to what kind of throttle response you prefer, in hover mode (on stock tx's) - Shame they don't print advice like that in the manual!

Got a Trex and DX6i, so I can try this setup when new blades arrive next week. Also on same order is a Spektrum Rx for the CP, so I can try the logarithm curve in the not to distant future.

It's the part about bringing it down with a little neg. collective pitch and not to much loss of head speed that appeals to me - it's a feature I would certainly think is better than stock setup (hence why A.Finn has all his CP's setup this way?). And as the good man says, when you are ready to idle up, you won't have the huge change in RPM's. Genius!

P.s. Don't have manual to hand - What is the throttle curve for idle up mode on stock tx - 100%/100%/100% all the way?

[mnwizard]

Here's the official Esky throttle curve info -

I just post 'em, I don't claim to understand them :lol:

http://i34.tinypic.com/rscz0j.jpg

http://i36.tinypic.com/10pcy6b.jpg

[Heli Yea!]

Thanks Another Finn. That clears things up for me. In other words LIN60% is like flying a FP heli. (dependent on throttle/head speed for lift) LOG80% has a more consistent head speed and provides lift with the pitch rather than the throttle.:noteworthy Great stuff! I'll have to do some toying when I get it!

[copterboy]

I don't beleive it, instructions for stock Tx!!!! I didn't get a copy with my RTF pakage, and didn't know they existed till now.:shock:

Will have to go find a download then. If I had know that, I wouldn't have struggled with my DX6i settings....lol!
Can have a go at explaining the graphs though!

The first graph which is the NOR (normal mode) throttle graph shows on the horizontal axis the stick positions L,1,2,3,H (the 5 stick positions 0% (Low),25%,50%(Mid-stick),75%,100%(High)
So the diagonal black line going up from left to right shows the throttle% at each stick point.
The pitch graph to the right shows the same stick positions on the horizontal axis, but the vertical axis shows the change in pitch - Think of the black line as your swash & pitch movement from -2 to +6/7 as per the manual).

The 2nd graph for IDEL UP (3D mode) is 100% throttle at 0% stick, 50% at 50% stick and 100% at 100% stick. The pitch will change from full positive +6/7 to full negative -6/7, with zero at midstick (which is how the manual saying to set up).

So the throttle between 50% and 100% stick are the same on the stock tx, and you can IDEL up at 50% but the pitch will drop (if all setup ok).
I might give it a quick flick at 50% on my next batt, just to see what happens to the throttle. Will report back with what happend....