burnt out speed control when prop is blocked...

My plane flipped over and the prop hit the ground staying a few seconds locked with 1/2 throttle. When I finally releases the prop, noticed the speed control had burnt out! Shouldnt the speed contls come with any sort of protection to avoid?

thanks guys.

It was a Great planes c-5 nano spc, hoocked to a 600mah, 7.2V batt.

Reply to
Eduardo B.
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The current has to go somewhere, and will pick on the 'weakest link'. Therefore, "Speed Controller.. You ARE the Weakest Link....goodbye."

KayCee Foamie Experimentation Engineer

Reply to
KayCee

In the earlier days of electric flight, it was standard practice to put a fuse in the circuit. Its purpose was to blow in case the motor was stalled in the event of a crash. Does anybody still do this today?

Morris

Reply to
Morris Lee

Some might, but this protection would add to the weight and cost of a speed control.

... | In the earlier days of electric flight, it was standard practice to put a | fuse in the circuit. Its purpose was to blow in case the motor was stalled | in the event of a crash. Does anybody still do this today?

Yes, people still do this. In fact, just about everybody should.

A fuse is almost always a good idea on any circuit where a lot of current can flow.

Exactly where you should put it depends on a few things ...

In any plane, you can put one between the ESC and battery, and that's often the safest place, but the danger is that if the fuse blows and you have a BEC, your receiver just lost power and your plane is out of control. Of course, it's likely that your plane is on the ground when this happens, but it's possible for your motor to sieze up in the air too. So for a brushed motor, the best place for the fuse is usually between motor and ESC if you have a BEC, because if it does blow, you can still land your plane.

For a brushless motor, you'd need at least two fuses between ESC and motor -- one fuse on one wire would not be adequate. And if your motor has a sensor, don't put a fuse on that wire, but instead on two or three of the three power lines.

But one fuse between battery and ESC would certainly work too. In that case, you need to weigh your situation and decide what to do.

Reply to
Doug McLaren

Morris Lee opined

For larger motors, yes. But when a model is under 16oz there is little room for fuses and switches.

-ash Cthulhu for President! Why vote for a lesser evil?

Reply to
Ash Wyllie

Kill the throttle if you are about to meet with the ground! Works every time. No additional weight, cost or complexity. You can train yourself to do it, or add parts to your plane and hope they actually work when you do something stupid and preventable. Fuses don't always burn through when you need them to and sometimes do burn through when they shouldn't. Pick an amp value too high and the ESC will burn out anyway. Pick a value too low and they will burn out just when you need full power to get out of a bad situation.

Reply to
mike tully

Yes, if you don'=t mind the extra half ounce, the extra $10 and the extra 5% power loss....

Reply to
The Natural Philosopher

| > My plane flipped over and the prop hit the ground staying a few | > seconds locked with 1/2 throttle. When I finally releases the prop, | > noticed the speed control had burnt out! Shouldnt the speed contls | > come with any sort of protection to avoid? | | Yes, if you don'=t mind the extra half ounce, the extra $10 and the | extra 5% power loss....

You're exaggerating quite a bit here ...

It could be built into the ESC -- an extra chip that cuts the throttle off if the ESC gets too hot or too much current goes through it. There's a few ways they could do this that wouldn't increase the resistance (i.e. reduce power) at all. It would probably only require a single chip, so the added weight would be much less than one gram, let alone half an ounce.

I doubt it would add $10 to the cost to manufacture, but they might jack up the price by $10 for the extra feature.

The other option is to add a fuse. An automotive mini blade fuse weighs about one gram (I just measured it) and the resistance added is miniscule (I couldn't even measure it when I tried.) The cost was about 40 cents if I remember right.

Somebody else suggested just cutting power when your prop is about to hit the ground -- which is a good idea, electric or glow. But it's not the complete answer. First, you can just plain forget. And if your plane starts getting hit with interference and crashes, the motor may try and start up without you even moving the stick. Or if you forget to turn off your plane before the transmitter, it might start up as soon as you turn off the transmitter. And I had an ESC catch fire for some unknown reason right after hand launch -- obviously a fuse wouldn't have stopped whatever the problem was, but it might have saved the ESC well enough for me to figure out what the hell went wrong. Instead, I got to send a melted hunk of ESC to Astroflight and they replaced it for $60 or so. That, and it messed up my plane somewhat.

If you ask me, park fliers and ESCs should come from the factory with a fuse already installed inline with the motor or battery. Something large -- like for a 10 amp ESC, a 20 amp fuse, so there's no danger of it blowing during normal use.

If somebody wants to remove/bypass the fuse, they certainly can, but they should know the risks first.

| > It was a Great planes c-5 nano spc, hoocked to a 600mah, 7.2V batt.

Reply to
Doug McLaren

thanks for the replies. I think I have to put in mind that throttle needs to be cut off. In gas, when the prop hits the floor it stops the engine right away and you never have to bother with it. I was taxing when it flipped over, wasnt flying, thus I didnt cut the throttle. Now I learned my lesson.

Thanks and have a good time Electric rocks!!!!!! so quiet, so clean....and yes, underpowered... so what? :-)

Reply to
Eduardo B.

| Thanks and have a good time | Electric rocks!!!!!! so quiet, so clean....and yes, underpowered... so | what? :-)

Not always underpowered. You can certainly have an electric that will go straight up and keep going straight up until it's out of sight. It'll just cost a bit more -- and not always that much more.

Reply to
Doug McLaren

snipped-for-privacy@frenzy.com (Doug McLaren) wrote in news:yzvOc.18589$Gk4.16490 @fe1.texas.rr.com:

My take is that the relative cost depends on the size. At the small end, electrics are actually cheaper than their glow equivalents, all things considered. Unfortunately, while big glow engines don't cost much more than little glow engines (frex, an OS .65LA costs about twice as much as a .10LA, with >6 times the power), this is NOT the case for electrics, especially when you throw in the battery costs.

To do a more-or-less fair comparison, I'm including the Motor, ESC, and battery for the electric vs. the engine, tank, throttle servo, and receiver battery. At the low end . . . you can have a lot of fun with a $19 GWS RXC motor - I get about 4 oz thrust, and it's not difficult to build a plane for it that's

Reply to
Mark Miller

Mine aren't.

LIPO cells young man.

Reply to
The Natural Philosopher

It tends to start evening out on the high side, NOT including the batteries. The biggest AXI outrunner & controller prices out in the middle of 1.20 4 Strokes. It's weird to see aircraft that big flying with just prop noise....

PCPhill

And yes, I know (believe me, I Know!) the batteries cost more than the motor.

Reply to
PCPhill

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