On-board Electronic on/off ?

[Dereck]

Been a long while since I last held a handle, but CL was the first type of model I got to fly ( a fair number of years back ...) and have always had a soft spot for roundy-round flying.

Anyway - this idea nearly made it a couple of years back, in that I heard of a garage industry ESC maker working on it. However, nothing came of it and he quit production of his ESCs.

The idea was a cross between an ESC, a timer and a BEC cut-off. You'd load up your ukie with a charged pack, get to the handle and all your #2 had to do was push a 'start' button and release the model - the motor would run up and continue to run. As the battery started to run down, the controller would recognise the dropping voltage and switch the motor off. Idea was to skip that overly interesting spell between the battery not supplying enough juice to fly and the model slowing up on the ground enough for the helper to grab it and switch it off.

It would also allow flying handlaunched models over grass - you'd be landing "deadstick", which is a much nicer thought than stalling a running electric motor by stuffing its prop into grass...

A refinement for solo ops would be a start delay - allowing the pilot to push to start, dash to the handle, pick it up and get ready to launch. Which I suspect would have the safety weeny lobby in spasms, so maybe we'd better forget that.

Whatever. It also gets around having to haul a receiver and whatever in the model, and having a controller of some sort scattered around one's person.

Stew Myers, in his recent FM e-flight column, describes a little on/off timer for small FF electrics. This only allows for short FF type motor runs with low currents, but maybe a 40A capable version with 5 - 7 minute capability, coupled with a talking timer on your belt syncro'd with the on-board timer would allow you to land with the motor stopped.

Good idea? Utterly Daft? WHY?

Regards

Dereck

[hfljr]

Do you use cables for your control lines? If so with a little fiddeling you should be able to put a switch in the handle and run connections to the switching circuit of the ESC, you won't even need one if you are running the motor at full power. This way you can also switch off the motor when you notice the drop in power.;)

[hfljr]

I just checked out the regular CL posts and found this link.
http://www.buzzflight.co.uk/ pretty much as I invisioned it.:D

[steve lewin]

Perfectly reasonable idea Dereck. I've built several of them of various sorts, usually with a standard ESC and a simple timer circuit. Indeed the really simple relay controllers described several times in this forum have the same effect. The relay drops out when the voltage gets low, switching the motor off. I even built one for solo flying where pulling the pin out of the stooge switched the power on.

Since then I've moved on to infra red controls which are IMO even neater. Put the plane down, walk to the middle of the circle, point your i/r zapper at it and switch it on. When you're bored, dizzy or the power is getting low blip again to switch off. Finally a use for those old TV remotes ;). Actually the zapper can be much smaller than that so it's not really much of a pain having a controller about your person.

Of course serious fliers like Mike Palko are using the ZTron I/R system to give them full throttle control. It works at least as well with an electric motor/ESC as with a servo and IC power.

Steve

[steve lewin]

hfljr, the Buzzflight thing is interesting for a trainer but it will only fly on very short lines. The aerobatic one I believe flies on 6m (20ft) lines and need an 18V battery because so much is lost down the lines.

It's a simple and cute way to introduce new fliers ot C/L but I'm not really convinced that power down the lines has much going for it long term. There's a real problem with diminishing returns. If you want more power you need thicker wire to get the current down without too much loss but then you need still more power to drag those thicker lines around with you. Oh well, basic physics wins again ;).

Steve

[hfljr]

I realized after reading the part about the 2 lead acid batteries it was now what I had invisioned. My idea was to have the switch in the handle control a relay to turn the motor or speed control on and off, no real current. I liked the idea of the ZTron I/R system, but wouldn't it be great if the I/R system was built into the control handle along with a trigger like the RC Car transmitters use. See quick PS sketch below.

[steve lewin]

In the past I've used a signal down insulated wires to drive a standard ESC on the plane. You can either have full throttle control or just a switch. There are a few simple circuits on http://www.slewin.clara.net/elec/ecl.htm for that (must update that page one day).

In a way it would be even simpler to just switch a relay or even MOSFETS but I've not bothered trying . ESCs are so light and cheap these days plus of course a basic switch will never work with brushless motors.

I've also played with IR emitters on the handle. The problem is that, if you think about it, the handle is very rarely pointing directly at the plane. It's too easy to get problems with sunlight swamping the IR receiver so you need to use a very narrow acceptance angle Rx etc.. I like Windy U's solution of having the emitters on his hat. At least you're usually looking at the plane....I hope.

Steve

[Dereck]

Vaguely recall someone flying indoor ECL at the Model Engineer or whatever its called now. He had a belt mounted battery pack with an obscene amount of volts involved and a rewired motor that used very low current - a lot of work really.

My thoughts on an onboard on/off were for very simple small space models (looks out window at conference centre parking area across street ...)

Steve's idea of an IR switch on is icing on cake - until we go to Lipos, switching off would be mostly to land the thing without it doing several laps under waning power before it stopped. The trick with cheap, small, simple models is to keep them cheap, small and simple.

The S400 powered soarer with hundreds of dollarpounds of moulded airframe, a half dozen supermicro servos and expensive inline gearbox all wrapped around five dollarpounds of motor springs lightly to mind here :)

Maybe with tarmac ops in mind, just start the thing, run to handle and pull the stooge release, then land when it runs out of juice isn't too bad an idea?

Cox sell / used to sell a 'down the lines' plastic BARF ECL. They crop up in shops 'over here' on ocassions, but the lines are pretty short - 12 - 15 feet maybe?

All I really need is the time to experiment! Right now, would like time to fly :(

D