Safety

12/28/08

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This page list safety issues and advice. If you want to help me and provide tips, please Mail them to me.

Horror stories and about what can go wrong. It is very useful to read the real life stories to become convinced of the relevance of safety.

Building:
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Build the heli with great care. Exactly follow the manual. Only use 12.9 hardened bolts for any bolt that is being loaded. Use shouldered bolts for e.g. the Jezus bolts, the blade bolts etc.

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Make sure you use a thread locking compound (e.g. Loctite) to prevent nuts from loosening (clean the bolts before applying thread lock). Use nylon locking nuts where appropriate, don't replace them with anything else! Don't use a threading compound on bots in plastic, the compound makes the plastic brittle. I use a small drop of CA instead for those small screws in plastic parts.

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Make sure that no wiring scuffs against the frames or anything else. You can use Teflon spiral (from e.g. an electronics shop) to prevent the wires from touching anything sharp or hard. It is very obvious that no wiring is allowed to come close to rotating or hot parts :-)

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Make sure that it is never possible for different metal parts to rattle against each other. This can give reception problems of your RX! Make sure there is no free play where it should not be.

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Check your gearing to make sure that the gear mesh is correct.

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Make sure that the blades and paddles etc are all in balance.

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Use good and trusted electronics, don't use an old servo of which you do not know its history. Use a good battery, and more important, use a voltage monitor to monitor your battery (e.g. VoltSpy).

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Use a good charger that actually indicates the amount of charge that got into you battery and the amount that was left after the last flying session. This way you know what is in your battery, and you can monitor the quality of your battery and thus replace it in time.

Fail-safe:
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What is it?
PCM receivers have the capability to set the servo's at a specific position whenever the communication between the TX and the RX is lost which is called fail-safe. This is a very important feature for helicopters. Just imagine a helicopter hitting people with full power, that is very VERY bad.

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Throttle
So for safety reasons, the very first thing you have to program with fail safe is that the throttle goes to idle in case control is lost. If there is just a brief intermitting problem, this also clearly indicates that you have a serious problem. Make sure that you also program the governor such that it indeed goes to idle (if you have one).

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Other controls
For the pitch, elevator, roll and rudder you have two options. You either program that the servo's stay put in case you loose control, or program them such that they also move to a preprogrammed position.
My personal preference is to program these controls such that they go to zero pitch, zero elevator, zero roll and zero rudder. The reason for the pitch is that in this position the energy is removed from the blades in the most modest way. This gives you a chance in case control comes back (you don't stand a chance if the blades have nearly stopped). For the other controls, I just want it to stop rotating in any direction. I strongly believe that this gives you the best chances of recovery whenever control comes back.
Note that I can speak from experience, I had one flight in which fail-safe kicked in three times (with the settings above), and I managed to land the heli safely! The problem was another pilot turning on his radio on the same channel. I guess that yelling: "I lost control, RUN" saved me because it triggered him to turn off his radio :-)

Starting the heli for the first time:
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First make sure that an experienced heli pilot checks your heli and your TX programming.

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Next, make sure that an experienced heli pilot checks your heli and your TX programming.

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And last but not least, make sure that an experienced heli pilot checks your heli and your TX programming.

Starting safety measures:
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Always check the switches on your TX before starting the engine (e.g idle up switches etc.).
It is useful to configure the radio such that all the switches should be in one direction (e.g. forward) to get the heli in a safe mode for starting. It is then very simple to check if all the switches are correct to start the engine. This reduces the likelihood of starting the heli with one switch in the wrong position.

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Always physically check your throttle position on the heli before you start the engine.

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Get any stuff out of the way of the heli before starting.

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Hold the blades tight when starting the engine.
Never let go of the blades, you can hold them for sure, even when the engine is running such that the clutch engages. You will not succeed in letting them go and run away if it is at full throttle, it will bite you. Therefore it is always safe to start the heli with someone else available who can pull the fuel tubing or block the exhaust, especially when starting the heli for the first time.

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When walking with the heli and the transmitter (better not) then make sure that throttle hold is switched on!
Otherwise just touching the throttle stick gets you into trouble.
When walking with the heli to the heli pad, and you leave the TX with your flight gear, then make sure that nobody touches the TX! Some people might think that they help you in picking up the TX for you???

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Check controls before spooling up the engine.

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Check the controls when it is spooled up just before takeoff.

Flying safety measures:
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Take it easy on the first flight of the day.
Give your self time to get on to it again.

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Never fly close to people nor to yourself.
The further you are away from the heli, the smaller the chances are of it hitting you. Furthermore, if some parts decide to leave the heli (e.g. they get afraid of your flying capabilities) distance between you and the heli greatly reduces the chances of being hit by such angry parts.

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Never fly the heli between you and other spectators.
Be aware that estimating distance is difficult. Position yourself with your back to the spectators, and fly in front of you.

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Avoid flying at "head height"
It is very obvious, if you can fly at that height, then you can also fly at 0.5m higher. If something comes loose from the heli the chances of severe injury are reduced.

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Do not overestimate your capabilities, take small and save steps while learning to fly the helicopter.

Spooling down the heli:
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If you want to slow down the blades, then be careful that nothing of your clothing gets in the blades! Of course it is the safest to let the heli stay put for some time so that the blades can spool down without your interference or you getting close to it.

Some figures to convince you:
bulletA 30 sized heli running e.g. 1800 revs on the head has a blade load of approximately 120 Kg on each blade! This means that that 3 or 4mm bold is being pulled at with 120kg. Better make sure that you use proper 12.9 hardened and shouldered bolts.
bulletThe tip speed of each blade is about 400 Km/h for a 30 size helicopter! The blade has lead in the end to make them more heavy and ensure that there is more energy stored in a running blade. I assure you, you don't want to stop such a blade with your body. You can imagine the amount of energy stored in the more heavy higher speed blades of a 90 machine.

Here you can see what happens if one blade departs from the heli.

I got this video from the internet somewhere, can't remember. It is not mine, I hope the owner does not mind me using it here.

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This site was last updated 12/28/08
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