setting idle on electric model
 

I am using a 14 MZ, and have to adjust the throttle trim before each flight to get the idle where I want it to be. IS there a better way to do this may'be put it on a switch?


TIA

RE: setting idle on electric model
 

I'm using the throttle trim, can't see what's wrong with using it. What else are you going to use it for?

RE: setting idle on electric model
 

I use the throttle cut function on the 14MZ assigned to a switch . I set the throttle cut 'on' setting just low enough to arm the ESC and when I flip the throttle cut switch 'off', the motor goes to my selected idle speed without touching the trim at all. When I am ready to kill the motor, I just flip the throttle kill switch back 'on'.

Works great every time.

Woodie

RE: setting idle on electric model
 

Hey Woodie can you exapnd a little on how you set it up, what function you went into on the 14 to get it done?


TIA

RE: setting idle on electric model
 

I use something similar to Woodie except I use the slider on the left side (LST) to be my throttle trim. That way I can adjust it quickly and easily without having to use the digital trim.

RE: setting idle on electric model
 

Here is how I do it

http://www.futaba-rc.com/team/team-tip-004.html

Leaves the normal trim level intact for coarse adjustments and allows fine tuning etc to be done by a slider/dial etc.

RE: setting idle on electric model
 

Another way is to copy your regular flying condition to a condition called startup, assign it to a switch, give it the highest priority. Set the startup condition throttle curve afr to 100%, make it seperate, set the normal condition throttle curve to 85% or whatever needed to get the idle you want, leave it grouped. Use the startup condition when arming the esc, switch to your regular flying condition when ready to go.

RE: setting idle on electric model
 

The Jeti Spin ESCs have the ability to set the actual pulsewidth as parameters both ways. Then you get all values fixed and don`t have to arm the ESC with full throttle each time. Combined with an "idle-up"-setting would give you both idle and cutoff as you prefer every time...

RE: setting idle on electric model
 

Specific to the Jeti Spin 99…

At what point does the brake come on? Is it any time the motor RPM is exceeding requested RPM or does it only come on when the throttle stick is in the off position?

If the latter, then will not setting up an idle effectively disable the brake?

My last ten or so flights have been with the brake off and I don’t really see the need for an idle (or the brake!) RPM never drops below 1500 according to the data logger.
…although I did flop a stall turn or two :eek:

RE: setting idle on electric model
 

Scott

I have always been taught that the brake on an electric motor is only for gliders. For pattern and sports you want the brake off so that the prop idles when you cut the the throttle.

RE: setting idle on electric model
 

Brake comes on at the off position so your right, you won't be able to use an idle. Some manuevers its nice to have, if you don't want it to activate just stay a click or two above the off position. I've got mine set pretty weak, just so the downlines are constant speed. 45 lines I don't let it activate.

RE: setting idle on electric model
 

OK, here's how I do it.....

But first, a little info on the Jeti 90 and Jeti 77 ESCs (non Spin version)

The default end points for the non- Spin Jetis are approx 1.1 ms for low and 1.8 ms for high throttle. I set up my radio so the default is not disturbed during a flight. When I say 'disturbed', the Jeti 77 and 90 will reset the high throttle ms setting to anything it sees over 1.8ms. So if your ATV on high throttle goes to 2.0ms then the Jeti will reset to 2.0ms at full throttle and expand the overall range of throttle throw. It does not increase the power to the motor, it just expands the range of throttle 'throw'.

Because of this, and I hate doing full throttle run ups or immediately after take off to set the high end ms setting, I limit my ATV on the throttle to never exceept 1.8ms. I have a Jeti programming box that reads the ms timing of a channel and that is how I determined where to set my ATV. This seems pretty consistant across 2 radios and 2 Jeti ESCs.

If you like to do full throttle runups (or you have Jeti Spins which are programmable for end points) then you can ignore my comments on high throttle ATV.

My throttle ATV settings in my 14MZ are shown in one of the attachments below. HIgh throttle ATV is at 73% and low is at 99%. The 99% setting is low enough for the Jeti to 'arm' (you have to be below 1.1 ms for it to arm). This is also with my throttle cut switch 'on'. The 73% high throttle setting is 1.8ms timing, equal to the default setting in the Jetis.

The second attachment is my throttle cut screen. I use the Throttle Cut (Linkage Menu) to set this up. I assign my throttle cut switch to SW-B but you can use any switch convenient to you and not currently used for something else. I have used SW-B for so long I don't want to 'switch' (pun intended). You can see the settings on the attachment below.

So I plug in the ESC with the throttle cut in the on (kill) position, the ESC beeps several times indicating the cookies are done ;-) and when I am ready to start I flip the throttle cut switch off and the motor starts at idle. You may need to play with your throttle trim a little to get the idle where you want it but after that, you don't have to touch the throttle trim. Same everytime.

Woodie

RE: setting idle on electric model
 

Thanks guys for all your help. I finally got it to idle without adjusting the trim everytime. Turn on 14MZ--- hit throtlle cut, trun on plane, take throttle cut off bump throttle up a tad and viola; motor runs on low rpm:D

RE: setting idle on electric model
 

I recently tried to set fixed end points on my Jeti Spin and couldn't get it to arm in the airplane. I thought I had it figured out when using a pulse generator. If I turned the system on with a pulse width above the 1.0 msec I had set, and then dropped it to less than 1.0, it would arm. I couldn't do it in the plane. I gave up and went to auto low end and fixed 2.0 msec on the high. Seems to work.
What is the trick to get the fixed low end to arm? You mentioned something about arming with full throttle?

Jim O

RE: setting idle on electric model
 

Hi Jim,

I has similar results trying to set a fixed low point. I emailed Jeti and their response was:

For low stick position it is necessary to set longer impuls - if you measure 1.095, set 1.12 - 1.15
There are some differencies due to mechanical construction of sticks and temperature.
For high stick position set shorter impulse - 1.90 or 1.85

RE: setting idle on electric model
 

Thanks Scott,

I reset the fixed low end to 1.1 and now it arms every time. However, it doesn't actually start until some higher value. I suspect the clock in the Jeti is not accurate but it doesn't matter as long as everything works. The Spin 99 does not start as smoothly as the Hacker/Jeti 90 and seems to have a lot of hysteresis between start and idle. In other words after it starts you must back off for a slower idle. Once set, you can almost see the blades.

RE: setting idle on electric model
 

Jim, I experienced the same thing on my Spin 75. Took a little more than idle to get it started then you could slow it down again. My Jeti 77 is very predictable on start (smoother than the Spin) and idle is the same each time..... Must be something in the softward of the Spin controllers.

Don A

RE: setting idle on electric model
 

I have noticed something else with the jeti 90 and the hacker C50. If the prop comes to a stop it will not start up again unless the idle is brought all the way down. Luckily the prop is unlikely to stop while flying even at idle but it may occur on the runway. I may have something set up strange but this has been my findings. As long as the prop is still moving even if by wind it will restart but once it stops totally I have to lower the idle first.

Anyone else find this?

Stuart

RE: setting idle on electric model
 

I have noticed the same thing with my Jeti and Hacker A60 - not a big deal at all.

RE: setting idle on electric model
 

Interesting to hear this. I thought it was my inexperience with the setup. I also had the motor "freeze" where it would not startup again until throttle was brought all the way down. I also find it interesting that the Jeti non-Spin effectively recalibrates itself if it sees a pulse width greater than 1.8ms. I have been having a hard time smoothing out the throttle response and it seemed to me that it was always changing. Since I have just started running mine (as of last weekend) I am still climbing the learning curve and figured that it was my inexperience rather that component "features".

I have been struggling trying to get smooth throttle response with my Jeti 90 and Axi 5330. The only way I can explain it is that it seems "notchy", and seems to jump from one level to the next without smooth seamless transition. Once again, that may just be my setup.

Steve

RE: setting idle on electric model
 

Back to the original question. I believe it is a good idea to set the trim before each flight. Here is how I do it. Transmitter is a 9ZAP. I enable the throttle curve and use the left slider as the throttle trim control. On the throttle curve screen I set the low to 80% and that allows the low trim to go to the extreme position set by the ATV and AFR. I set it up to get the following PPM pulses out of the receiver:

low trim - .922 msec
medium (beaper sounds) - 1.000 msec
high -1.175 msec

High throttle -2.000 msec

Motor is Hacker C50 14XL
ESC is Hacker/Jeti ) O-90 set to auto start and auto end point
Battery is TP5300 10s4p

Start up sequence:
Turn on transmitter with throttle stick low and trim lever low. (.922 msec)
Plug in arming cable
Turn on receiver, ESC arms

Slowly increase throttle trim (left slider) until beeper sounds. Come up another 3 or 4 clicks( about 1.035 msec) motor starts at reasonable idle.
Push throttle to full power and bring it all the way back slowly. Reset the idle. One click either way.
Taxi out and take off. I have found this to work consistently, flight after flight. Therfore you could put it on a switch.
Before landing, I bring the trim back to the mid position (beep). This turns the motor off but it does not stop the prop. I very seldom have it stop on the runway and almost always am able to turn around and taxi back. It will stop if you come to a complete stop for a few seconds but seems to windmill as long as the plane has forward motion.

If one had the competition ESC with a setable brake it could be engaged with this setup. In fact I borrowed one last year and found it quite effective especially on landing. Just bring the trim back to slightly less than the start position with the slider or a switch and then it will engage when the throttle stick is pulled all the way back.

Today I duplicated this setup in my Abbra with a Dualsky 6360 and Jeti Spin 99. It seemed to work exactly the same with a smooth start. After touching up the trim it idled smoothly at 420 rpm. Top end yielded 5750 rpm on an APC 22x12 at 63 Amps and 34 volts according to the watt meter. The ESC readout had it at 61 Amps.

Hope to fly it this week. I doubt that I'll need the brake but I may play with it.

Jim O

RE: setting idle on electric model
 

Good info Jim,

I was wondering why my motor wouldn't shut down all the way on landing approach. I guess that's just normal. It did seem, however, that the idle is too high after flying and that I had to drop throttle trim all the way in order to slow down enough for landing. Maybe I am just landing too hot and it is free wheeling too much. I'll have to watch it closely.

RE: setting idle on electric model
 

Hi Steve,

Happy you are thinking about pattern again. Yes, I found out that the electric motors are easily driven by the forward speed of the plane and really need a brake to slow down rpm wise. Without a brake the best you can do is turn off the motor and let it free wheel. With a light airplane this should work fine.

One thing I didn't mention is to be sure and set the failsafe to turn the motor off if you go into failsafe.

Hope to see you at a contest this year, Jim O

RE: setting idle on electric model
 

Hi Jim,

I've got a lot to learn.....

I've already set the fail safe to shut down (I think it is about 840ms pulse width now). My first eye opener was when I was testing this beast in my garage and the throttle was reversed.......

I'm hoping to make it to Hemet in August. I don't think I will be ready for Riverside in June, seeing as how that is only a couple weeks away and I still haven't flown the sequence yet. I've got at least one more IMAC event that I need to take seriously so I can have a chance to qualify for the shootout. After that, I can focus on pattern.

I love the power of the AXI/Flightpower setup but I am having trouble smoothing it out and getting it to shut down when I want. I should probably start a new thread on this topic but I have also seen a big difference in throttle performance between my flight packs (both Flightpower 5350 F3A packs). That is driving me nuts.

RE: setting idle on electric model
 

I saw this behaviour on my Jeti 90 Acro/C50 14XL this weekend, when I set idle on a switch to activate brake only in some maneuvers. When idle is too low it seems Jeti 90 doesn't have good "sincronization" or something like this and makes the prop to stop (a friend has a MasterSpin 99 and have better idle). When this happens then you have to thottle back and accelerate to have it runing again. In the air it doesn't seems a problem but is not a nice thing to hear this in the pits, it looks like the gear is going to break ;)