vega2614

I was wondering if anyone was familiar with the situation where the transmitter's full throttle setting is not full throttle for the motor. For example, I push the throttle stick all the way up, but the motor only spins at 80% of full speed.

The reason I am posting is that my new brushless motor is giving about half the thrust it should, so I'm thinking maybe the transmitter is not sending true full throttle to the ESC/motor.

Is it guaranteed that if you listen to the motor at full throttle with trim all the way down, and then increase the trim, and you don't hear a difference in motor RPMs, it means your transmitters full throttle is motor full throttle? In other words, if changing trim at full throttle does not change motor RPM, does that mean the transmitter is definitely sending full throttle?

On my new brushless motor (2408-21T), I hear no difference between trim down and trim up full throttle, but on an old brushed 380, I do hear a difference. In fact, the stock transmitter that came with the RTF kit with the 380 (SDM Cub) causes the motor to give higher RPMs than my other transmitter (E-Sky Lama), even though they give the same max RPMs for the aforementioned brushless motor.

Do some ESCs come with a programming option to set true full throttle? Why would the brushed ESC give difference performances between transmitters but the brushless ESC exhibit no difference? Any help would be greatly appreciated.

FMB42

Hi Vega, some ESC units do need to be programmed before use and I recommend that you run a search on "ESC setup and programming" for more info on this. This, in some cases, involves removing the prop and setting the low, mid, and full throttle programming according to the number of "beeps" emitted from the ESC while holding the thrott at each range. The unfortunate thing is that many ESC units do not come with any info or instructions on how to do this.

Good luck and good flying!

P.S. Your SDM cub should really fly with that 2408 BL motor!

vega2614

Thanks for the info FMB. Do you know offhand where I could find the instructions for other ESCs that allow you to set the throttle ranges? I'll search around and see if I can find anything about that.

dalelvn

some esc's Arm differently also when you plug in your bat do you have your throttle stick above the bottom limit, have it at the full setting? with some esc's where it see's the throttle setting when first plugged in is what it sees as the full setting. so if you have your stick at say 1/2 throttle when you plug in the battery it sees 1/2 as full throttle and will not go any higher

Glacier Girl

My Feedback: (4)

Also if you are using one of the Chinese version esc's like Tower Pro, Hextronic, B/P, etc.,
you sometimes have to go into your tx settings and change the endpoint adjustment.
I've had a couple of them where I would get no throttle until half way on the tx stick. Changing the endpoints to max made it a lot better, not perfect but better.
I'm guessing you are using a china version esc with the info you listed for your motor.
The other fun thing is how many programming guides are out there for these esc's. The joy comes in trying to find which one will actually program your esc, as often what you get does not work with the instructions that come with it.

Best of luck.

vega2614

Yep, it's a TowerPro ESC (and motor). A lot of people have been suggesting adjusting the throttle endpoints in my Tx, but I have no idea how to do that or if it's even possible with my transmitter. I have an E-Sky Lama 4-channel transmitter. I tried finding some more information about it, but unfortunately I think it's a pretty basic Tx.

Glacier Girl

My Feedback: (4)

Did you not get a manual for it? I'm sorry but I know nothing about that Tx.
I know you played around with your trim a little, maybe try setting the trim all the way up.
Do this before plugging in the esc. Maybe the increase will make the esc recognise the additional travel and give you some more.

Something else I just thought of. You sure it's the tx and esc that are the problem? Not maybe something like a pack that's being pushed to it's limits, or maybe a case of over propped, or too much amp load for the esc? Any of these could give you a similar feeling that the motor isn't winding up.
Maybe check out the setup with an Astro or Watt meter and see what's actually going on. It could be you're looking in the wrong direction for a cause.

vega2614

Yeah, that's a good point, but I've looked at prop data from others using the same prop/batteries and I'm getting less amp draw and thrust than others. I'm using a 2-cell 12C 850mAh lipo with an 8x6 prop and I should be getting 9.5A with 386g of thrust, but instead I'm only getting 5.5A with <180g of thrust:

http://www.aero-nuts.com/product_inf...7e2d398f71667c

I've tried about 3 different lipos (from my Lama) and 3 different NiMH packs (8.4V and 10.8V). Peformance is weak for all of them. I get about 7A with the 10.8V, so at least jumping to a higher voltage helps, but now that pack is way too heavy for flight. I've also tried 7x6, 8x3.8, and 9x3.8 props, and I'm still getting almost half amps/thrust that I should.

People have suggested it's the length of wire and soldering quality, but I had a pretty soldering-savvy friend do it (I suck at soldering) and it looked pretty good and there's not much extra wiring.

I was able to get customer service to send me a new motor (same one: 2408-21T), and I have a 11.1V 20C lipo on its way, but I'm afraid that won't help because its a transmitter/ESC communication problem.

As far as playing around with the trim, I've given that a try and it doesn't effect it. The only thing the trim does is change the minimum throttle location on the stick, not max. The manual is horrible unfortunately. E-Sky prints the same manual for all their choppers, ranging from coaxial 4-channel to 7-channel collective pitch helis.

Thanks again for your advice. Maybe I just need to try out the new motor when it comes. It's just that the one I have doesn't seem to have anything visibly wrong with it, just poor performance.