Throttle trim for electric scale models

[David Ovenden]

I'm looking for peoples' experiences on setting up the throttle on electric scale models. I'm used to I/C scale where the prop is always turning (hopefully) when the modelis in flight. With electric scale what is the norm? At min throttle does one keep the motors turning - or do you stop the current completely. What about the throttle trim - how do you experienced electric flyers set this up? With I/C I have reliable tick-over at mid-trim and set for engine stops at min trim. But this is not needed with electric so what's the norm?

Plus I'm used to analogue throttle trim. I now have a new digital trim tx.Is there any difference in setting these up for electric?

Your experiences would be appreciated.

Thanks

[Phil 9]

I have the motor stopped when the throttle stick down with the trim central. the trim is never used after that.

[Former Member]

[This posting has been removed]

[A.T.]

Posted by David Ovenden on 21/11/2012 19:15:51:

I'm looking for peoples' experiences on setting up the throttle on electric scale models. I'm used to I/C scale where the prop is always turning (hopefully) when the modelis in flight. With electric scale what is the norm? At min throttle does one keep the motors turning - or do you stop the current completely. What about the throttle trim - how do you experienced electric flyers set this up? With I/C I have reliable tick-over at mid-trim and set for engine stops at min trim. But this is not needed with electric so what's the norm?Plus I'm used to analogue throttle trim. I now have a new digital trim tx.Is there any difference in setting these up for electric?Your experiences would be appreciated. Thanks

All RTF kitsets and general ESC instructions show that the trim should be at 50% or less and that the motor is stopped when throttle stick is in lowest position. Please refer to:

EPA, ATV, Dual Rates & Expo Differences & Caution + ESC BEC Set Up

ESC - 101 on what and ESC Is & How it Operates

Much more information available under sub sectionsMuch more information available under sub sections
"ESC & BEC - Setup to prevent majority of all RF Problems, Brownouts & Crashes"
"Radio Systems, Accessories, Alterations and FAQ.

under
Alan's Hobby, Model & RC FAQ Web Links

Alan T

[Danny Fenton]

Hi David, you have raised an interesting point, because this is something Chris Bott and I have been playing with. A free wheeling prop or one with the brake applied do not seem to slow the model as well as when the motor is at a low idle. This could be something to do with the high pitch props that I use. Anyway what we do, and this has to be used with care, is we move the trim up (after arming) to start the motor spinning slowly. This has a two fold effect, firstly it gives us a good amount of decelaration on approach. The second thing and it is very important when flying scale, is that it means the prop will always be spinning. A scale model on finals with a stationary prop is very unscale like.

Anyway before switching the model etc off, remember to move the trim back to the normal central or lowest position. Most ESC seem to recalibrate the travel on power up.

I think Chris uses some fancy mix so that he can switch this in and out via his Tx, I am not so clever so have to do it manually.

I would use this method with caution, especially in a model where the prop could strike the ground as the motor will try and keep turning, and you could let the smoke out

Cheers

Danny

Edited By Danny Fenton on 22/11/2012 09:10:17

[Chris Bott - Moderator]

Hi David

I have been experimenting a little with using a tickover setting on electric models.

What I've done is I've set up a switch that switches between motor not running and motor just running at a slow tickover.

The advantages are that I get instant pickup of the motor when I open throttle, without the big bang of torque from the motor starting up. I think I'm getting a better braking effect from the prop that I did with either the brake set on or off before, and on landing, the prop keeps spinning in a very scale like manor.

The BIG DISADVANTAGE is that if I crash or even nose over on landing, then I have to remember to flick the switch to stop the ESC trying to keep the motor running, there's no automatic function.

[Martin Harris - Moderator]

Easy really - proper scale models have IC engines! (can we have a tin hat smiley?)

[Pat (rActive) Harbord]

Posted by Martin Harris on 22/11/2012 12:36:14:

Easy really - proper scale models have IC engines! (can we have a tin hat smiley?)

Incoming!!!

[David Ovenden]

Thanks to all who have replied.

Danny and Chris have got to the heart of what I was concerned about. I'm used to flying scale I/C models with a continuously turning prop and find it hard to imagine a landing approach when the prop stops completely (if you pull the throttle stick right back). The braking effect (and the look of the model that matters so much with scale flying) are to my mind big considerations. They also affect the flying of the model. As I'm so used to flying I/C (and will continue to fly I/C) I'm trying to keep the throttle control as similar as possible between the 2 power sources.

I'm tempting towards setting up the model with motor cut at low throttle (with trim centred) then increasing the trim to give low revs (like tickover on I/C) for flying. I can then use the throttle cut function on the tx to cut the motor after landing (or nose-over!). If that's not good I'll try a mix as Chris suggests.

David

[Pat (rActive) Harbord]

The throttle cut function on my tx is momentary. E.g. It only closes the throttle for 5-6 seconds before returning to previous position. You are going to have to be very careful. Might be safer (more predictable) just to use the trim

Edited By rActive on 22/11/2012 22:34:32

[Former Member]

[This posting has been removed]

[David Ovenden]

I've tried experimenting with a mix (linked to a switch) to cut the throttle when using "idle-up" mode for flying. This seesm to work fine on the bench. I'm going to try it on a twin engined model first. If that noses over the props don't touch the ground so stalling the motors is not an issue in this case.

[Martin Harris - Moderator]

I've had a quick think about this. I suspect the following would satisfy your requirements should you wish to persist with the perverse notion of trying to make an electric powered model appear scaleish!

This works on my Futaba FF10 and I would imagine that any other reasonably capable transmitter would do much the same.

Set a throttle to throttle free mix of an appropriate minus value at the low end activated by a switch of your choice on the transmitter. This will allow the motor to run at a low throttle setting with the stick at idle after initialisation when you operate the switch (after leaving the pits of course).

So how do you get it to warn you that you've left the mix activated next time you turn the transmitter on? Simply set up an idle down mix on the same switch/direction at 0% - this will activate the "mix" alarm without affecting the setting of the mix.

Edited By Martin Harris on 28/11/2012 00:55:58