Helicopter Safety!!!!!!

[Helicrazy2]

Hello.

Would like to see more on Helicopter Safety (http://www.helifreak.com/forumdisplay.php?f=71)!!!!!! The do's and don't , Please post more on the issues!!!! Thank's


Helicopter Safety (http://www.helifreak.com/forumdisplay.php?f=71) :hug:

[Jungle Bob]

Fair enough, what do you need to know?

[drakenn]

Did you read the sticky?

[JasonJ]

Just treat it like it's a firearm. If you use that level of caution, you will be alright. When people ask me if they are dangerous, that is what I tell them.

[Old Sloppy]

True, that works well, but it kind of makes fire arms sound bad...

I tell them a heli is simply an inverted lawnmower, with no deck.

they seem satisifed to hear that.

Harry

[JasonJ]

True, that works well, but it kind of makes fire arms sound bad...

I tell them a heli is simply an inverted lawnmower, with no deck.

they seem satisifed to hear that.

Harry

Firearms are dangerous if handled improperly, everybody knows it, and everybody can make the connection. For most, lawnmowers mean the smell of freshly cut grass and nice summer Sunday mornings. Most people's first thought isn't what that mower blade can do to you, they think about what the lawnmower represents in their life. Might as well tell them your helicopter is like a box full of puppies or a trip to Disneyland. Puppies can grow into dogs that can kill you, a ride at Disneyland could fail and kill you, but people don't think like that. If you tell them to treat it like a firearm, they get that. A firearm is a firearm, no gray area there.

[bluecrackers]

Make that a loaded firearm or a running lawnmower and maybe.

I'm honestly scared poop-less of anything that rotates at these speeds. Chainsaws, circular saw, jigsaw, sawzall all come to mind. I got kissed by my dremel one time, and I will never forget that. Everyone knows that firearms are dangerous, but its all the little things that people get used to, like 3,000 rpm rotor blades. You become complacent and forget about the dangers, then you have an accident.

All these videos I see with the new pilots (or seasoned ones) with new heli's or new electronics etc having a chopper spin up by accident could have been avoided easily. I strapped mine down to a ironing board with climbing rope, to be sure it reacted the way I wanted it to. I saw a video somewhere (finless bob?) where he attached the helicopter to a pole so it could spin, but I don't want mine to move an inch when I first turn it on.

I even made a video lol. Oh and I am more than 10 feet away, but I did risk my laptop and webcam, der...

(http://www.youtube.com/watch?v=66-HWB5KiK8)

[Sonny]

Every section in the HF forums has recomendations associated with whatever the detailed issue are surrounding this's and thats. How much safer do you think a helicopter can get? Without banning them all together? No that wouldn't be fun...

[bluecrackers]

Better not ban them, but certainly need a good eye and some common sense. :thumbup: I would like it if everyone had a good time flying 100% of the time.

I noticed the video's of strapping down a chopper (and its subsequent destruction), and realize that full bore spin up was not what I was attempting by strapping mine down. Just in case it did spin up 100% I wouldn't end up with a hole in my ceiling haha. Maybe its not the greatest idea, I donno.

[Finless]

I saw a video somewhere (finless bob?) where he attached the helicopter to a pole so it could spin, but I don't want mine to move an inch when I first turn it on.

I even made a video lol. Oh and I am more than 10 feet away, but I did risk my laptop and webcam, der...

YouTube- Blade 400 3D (http://www.youtube.com/watch?v=66-HWB5KiK8)

It certainly was not one of my videos! I would never do something like that. So it wasn't a video from me!

Bob

[bluecrackers]

Sorry, I am not sure who made the video, I can't even find it now, ha.

[rdlohr]

Make that a loaded firearm or a running lawnmower and maybe.

I'm honestly scared poop-less of anything that rotates at these speeds. Chainsaws, circular saw, jigsaw, sawzall all come to mind. I got kissed by my dremel one time, and I will never forget that. Everyone knows that firearms are dangerous, but its all the little things that people get used to, like 3,000 rpm rotor blades. You become complacent and forget about the dangers, then you have an accident.

All these videos I see with the new pilots (or seasoned ones) with new heli's or new electronics etc having a chopper spin up by accident could have been avoided easily. I strapped mine down to a ironing board with climbing rope, to be sure it reacted the way I wanted it to. I saw a video somewhere (finless bob?) where he attached the helicopter to a pole so it could spin, but I don't want mine to move an inch when I first turn it on.

I even made a video lol. Oh and I am more than 10 feet away, but I did risk my laptop and webcam, der...

YouTube- Blade 400 3D (http://www.youtube.com/watch?v=66-HWB5KiK8)

Man, that is SOOOOO dangerous. Please don't tie down a heli and spin it up! Those skids are not made to hold down a heli. Things can go so wrong so fast and its just all bad!

Rick

[bluecrackers]

Ok, I have taken down the video. I understand that full bore would probably pull the screws out of the skids, but whats the harm in turning it on while tied down? I am total newb and my only experience is in realflight and what I read. I guess my thought was that I could easily reach under and unplug safely while the blades were going, since it wouldn't be on the ground, you can stoop and clear the blades.


I guess that the absolute best way to test your electronics setup would be to take the blades and flybar off, along with the tail rotor, or remove the motor, or move the pinion away from the spur.

[rdlohr]

Ok, I have taken down the video. I understand that full bore would probably pull the screws out of the skids, but whats the harm in turning it on while tied down? I am total newb and my only experience is in realflight and what I read. I guess my thought was that I could easily reach under and unplug safely while the blades were going, since it wouldn't be on the ground, you can stoop and clear the blades.


I guess that the absolute best way to test your electronics setup would be to take the blades and flybar off, along with the tail rotor, or remove the motor, or move the pinion away from the spur.

Now you are on the right track. With the mass of the blades spinning, once they start wobbling for any reason, it gets uncontrollable pretty quick and you would never be able to get near it for anything. It doesn't even need to be full bore for things to go awry.

Rick

[bluecrackers]

So what happens if your blades are out of balance when you go to spool up? I guess you would have to be 100% sure you are in control before putting those on eh? I am rebuilding after a crash now, hoping to start rebuilding the head tonite.

[halley]

The issue rdlohr is raising is called ground resonance.

Basically, if the helicopter is strapped down, and there is a sudden bump in the torque at the head, one blade might pivot in its grip more than the other blade. If that happens, the whole head is in imbalance, and the entire helicopter will tear itself to pieces in a matter of moments due to resonating vibration.

Now, while I agree with rdlohr that your video looks dangerous, I'll comment in detail. I've done a bit of research on ground resonance because the topic comes up occasionally.

(1) ground resonance can strike models as well as full-scale, but most of the youtube examples show full-scale disasters, and there are reasons why.

(2) ground resonance is strongly influenced by head design: multi-bladed heads (more than two) are at higher risk, and specifically, fully-articulated heads with lead-lag pivots. Articulated heads are more common in full-scale helis and high-detail scale models that mimic them. Most models have a single bolt at the grip which has less of a problem with it.

(3) ground resonance is somewhat influenced by skid and frame design: stiffer models are at higher risk, because they will transmit bumps against the ground through the helicopter to reach the head. If you have soft plastic skids, and/or you're strapped against a softer surface (like the towel I saw in your video), this goes a long way to avoid ground shock that triggers the initial imbalance, and damping the vibrations that follow.

(4) ground resonance often happens after a bump in a non-vertical landing or sloppy takeoff: this is the kind of initial force required to transmit an imbalanced torque to start the effect. Landing on a firm surface while slewing to the side, hitting on a skid corner, bumping the ground with the skid after lifting taking off, all are risky. Bouncing up and down has less imbalance in the force transmitted.

Now, that said, your helicopter in your video seemed imbalanced enough, it wanted to be tilted WAY back instead of level through most of the video. It was pulling at the restraints to sit back more and more. I'd adjust that right away, ground resonance or not.

I've used a turntable rig to adjust the tail on both my T Rex 250 and my T Rex 600 ESP. However, I only did that after I was sure that my model was balanced and vibrations were low during a 10% throttle test. I also did not try any positive pitch. I think it's possible to be quite safe about using such a rig, and some ground resonance paranoia on the forum is due to the lack of hard information on the phenomenon.

Of course, standing ten feet away (or farther, or behind barriers) is prudent any time the motor is in operation.

[rdlohr]

Resonance was part of my worry, and it was well explained, but for most models, I would agree that it is unlikely.

I was actually more worried about are other things that make a heli unstable after a new build or a crash.

1) Gyro set for wrong direction
2) Center of balance way off
3) Servo problems
4) Receiver problems
5) Bent Main Shaft
6) Bent feathering shaft
7) Transmitter set up wrong
8) Twisted belt
9) Blades too tight
10) Missing parts

Any of these things can make a heli go out of control.


Beyond that, the whole idea of tying down a heli probably means you plan to be within 20 feet of the spun up heli. I don't recommend that. Here are a few reasons:

1) New main blades may break and the internal weights or other shrapnel may hit you.
2) The tail blades may break and hit you
3) Transmitter antennae may hit blades (72MHz)
4) You may knock something into the blades
5) You may inadvertently hit the blades.

You may get hurt at 20 feet but its way less likely.

And to my original point, the skids, the frame and the screws connecting them are just not made to handle the loads you will most likely put on them. No pitch, or slightly negative pitch may be OK but I still don't recommend it.


Rick

[rdlohr]

Beyond all this, you really don't need to do it. If you build your heli carefully, you will need to do very little adjustment spun up. For the last two helis I built, I only had to adjust my gyro gain and sometimes the tracking by one turn. Those adjustments can quickly be done at the field.

Rick

[bluecrackers]

Well after my crash rebuild I changed a few things, did the blade grip flip, but somehow (being a total flipping newb helps) didn't screw on the flybar paddles, just tightened down the setscrews. First test run the battery was dead, spun up fine but when I got past 50% collective it died. Charged it up, got it spun up and the second I reached 50% and flipped the switch to flight mode 1 both flybars ejected. I found both of them somehow, tightened them down. I am usually so good at fixing things, but not so with the helicopters. Got it up and running now, working on getting the tail locked again. I have noticed since the rebuild it really sings, I bought it used, so the parts may have been slightly tweaked, the one-way may have been worn, I donno.

[pkfrizzlefry]

tear itself to pieces in a matter of moments due to resonating vibrationThis must be what happened to me when i flipped it inverted and THEN hit IdleUp, it wobbled then just exploded :roll:http://smileys.on-my-web.com/repository/Confused/redface-oops-6.gif


Worse explosion/crash i ever had, took out all the servos along with the usual stuff http://smileys.on-my-web.com/repository/Sad/sad-049.gif


Note to self: Never hit idleup when inverted...http://smileys.on-my-web.com/repository/Unhappy/you-fool-038.gif

And BTW, GUNS are WAY WAY WAY safer, there isn't nowhere near as many parts that could fail in a gun as in a heli! STAY SAFE!

[bluecrackers]

At least with guns the bullets only come out the end. Helicopters can fling parts in every direction!