field accident

I'm sorry to hear that as I know how it feels,as I have 35 stiches in my left hand from a radio interference accident with a prop... Not trying to make light of a bad accident but we all know that there are two kinds of fliers.. those who have been into a prop and those who are going to be in a prop.... I always instruct new flliers that you are looking a buzz saw in the face.........BD

At our last club meeting I told our guys that they all thought they had an engine on their plane but they were wrong. It is actualy a vibrating meat slicer!! Eddie Fulmer AMA 63713 I just wish I wasn't right.

Why can't they make the leading edge of the prop blades out of rubber like my desk fan. I like sticking my finger into the blades and hearing that annoying noise. :) Luckily that not a habit I take to the field with me.

We had one guy at our field starting a giant scale plane. For some reason he reached over the blade and got a nice slash in his arm. He said he didn't even feel it, he didn't realize what happened till he saw the blood on the top of cowl.

That has become something I make a point of teaching I had a rather independent older student go full throttle with no restraint in place. Lots of stitches in HIS leg, but it should not have happened and it could have been MUCH worse.

I think I'll stick to small electrics thank you :)

Ouch ! Get well soon.

Remember, an IC engine will probably stall if you stick your finger in it, whereas an electric will keep slicing that salami finger !!

Hmm. Not yet. Gimme a chance.

As others have pointed out a 400 sized electric can snap an antenna and cut to the bone, but probably won't cut THROUGH the bone.

You've got me thinking now...

I'm just about to finish up my first scratch-build. Space in the fuse is tight, and the way things fell out, it made the most sense to hang the battery under the motor, where I could reach the leads and connect power from the front of the plane, reaching through the prop arc.

Sometimes when I'm hooking up my Piper, the prop will give a small blip. I thought that might happen on the larger plane, but with no momentum, I figured my hand would stop it, since it would only have a quarter-turn worth of force.

I'm using a Graupner 11x6 on an AXI2820/10 motor on ten cells.

Who do you think will win? Should I turn the battery around and put the leads at the other end? I'd have to take the wing off between battery charges then, which I was hoping to avoid...

Thanks for your perspective... Dan.

| Sometimes when I'm hooking up my Piper, the prop will give a small blip. I | thought that might happen on the larger plane, but with no momentum, I | figured my hand would stop it, since it would only have a quarter-turn worth | of force.

You're probably right -- even if it does go off (which is always a possibility) I wouldn't expect it to slice and dice your hand. You could burn the motor or ESC out really quickly if you don't remove your hand, however.

Still, I'm not sure I'd want to take the risk.

I guess you should test it -- hook up the battery, put the meaty part (not your fingers!) of your hand in the range of the prop, perhaps wearing leather gloves, and go to full throttle for a second. If there's not much force, try removing the gloves. I wouldn't test on your fingers, however (too easy to hurt yourself.) Then make your own decision.

If you feel that using your hand is reckless, test on a chicken stick or something similar first. I'd definately test it, somehow.

| Who do you think will win?

Both could lose, you know :)

| Should I turn the battery around and put the leads at the other end? | I'd have to take the wing off between battery charges then, which I | was hoping to avoid...

I can understand that.

Brushless shouldn't 'blip' on connection, but you have almost as much pwower as a full blown .40 there.

I'd definitely put the leads at the back.

Switches that will do 40A plus are not exactly common, or light, and are a point of failure, that, if using a BEC, would result in a free flight glider.

Swiches in the radio line to the RX will do nothing to stop the ESC if it goes faulty and thinks it has receiver signals, from blipping.

I always assume the prop will turn one day when connecting up packs.

Use a surface mounted 50 Amp automotive fuse as your switch.

I've NEVER done that! ;^)

No, since the switch islates the reciever, it makes no odds whether the reciver is on teh right freq or not.

ESCs can be faulty and switch on without a receiver attached. Having a switch in the power leads between the battery and ESC is the only sure-fire way to prevent accidental startups.

There's already a low-current switch on the ESC, which I believe is used to arm the motor. Maybe that will be sufficient to guard against accidental startup (provided I remember to use it). At first, I thought it was a cutoff for the BEC, but that would possibly leave the battery and ESC connected to the motor, with no input from the receiver - that can't be right! It's a Jeti Avance 40-3P.

I haven't made the cowl yet, so I can expiriment with hookups from behind the prop plane, until I know for sure what's going on.

Thanks to all who responded (even those I didn't see)! I can tell from some of the replies I'm still missing a lot of posts in my news reader. Not sure whether to suspect the reader or my ISP.

Thanks! Dan.

I've still got the scar from doing something like this on a Speed 300. The ESC was bad and allowed the motor to go full throttle as soon as the battery was plugged in. Usually you have to to a Tx throttle stick wig-wag before they start up. 3 or 4 slices to the bone on my thumb with blood everywhere.

Now I always treat the prop as live.

It is right. Controllers under no input conditions will always cut the motor. In fact all my modles fly around teh field occasionally burping like they are too rich, as they fly through the (now known and identified 'dead zones'

However, some recivers on switch OFF will shove a pulse down teh wires which can cause SOME controllers to fire up teh motor for a tenth of a second or so.

I doubt a brushless would tho - it needs to go through its twitch and wobble session to establish phasing which takes a little time..

What a switch like that does NOT do, is guard against comtroller faulure: However the modes in which a 3 phase controller might fail and still mange to spin the motor is almost impossible, unlike brushed controllers where a short circuit FET will fire the motor up full throttle. On brushless, this will resulty in a nasty smell and smoke, definitely from the controller, and possibly from the motor too.

However its still good practice to stay away from the prop at all times when the model is connected to the flightpack If you want to be really safe, a removable shorting plug on the outside of the model is no bad thing. I don't fly big enough stuff yet to warrant it tho. You coudl also wire a red LED and resistor across the pack wiring, to remind you when you have a plane with juice in it.