Author Topic: EEVBlog #230 - Arducopter  (Read 12026 times)

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Offline Psi

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Re: EEVBlog #230 - Arducopter
« Reply #25 on: December 31, 2011, 07:16:32 am »
More likely to protect fingers e.t.c.  :P :P :P

Actually what damage such a motor/blade can cause to a leg, knee, thigh, finger e.t.c.?


Friend of mine had his finger sliced down the middle from end to end and his fingernail torn off by an RC prop this Christmas.
Although, he was using a prop which had sharp edges (for cutting through the air), so it wasn't a typical prop.

He was holding the plane and testing the engine when he moved his hand and..... bang..... blood everywhere and Christmas night in hospital having surgery.

So yes, they can do ultra damage depending on blade sharpness and speed.
Also the angle at which they hit you various the seriousness as well.

« Last Edit: December 31, 2011, 07:23:37 am by Psi »
Greek letter 'Psi' (not Pounds per Square Inch)

Offline IanJ

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Re: EEVBlog #230 - Arducopter
« Reply #26 on: December 31, 2011, 04:20:51 pm »
I did inspect it before I started, I just missed the pins shorted pins inside the connector

There's something wrong if any electronics engineer hasn't been you are in good company Dave.

Ian Johnston
Manufacturer of the PDVS2 & PDVS2mini

Offline Kilroy

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Re: EEVBlog #230 - Arducopter
« Reply #27 on: January 01, 2012, 03:55:33 am »
Note that if you're using AC, the old HP 547A current tracer is also an option. It was designed to find shorted logic gates in combination with the HP 546A logic pulser. It only gives a quantitative measure for current and has one fixed range, but this may be enough for finding shorts. On the used market (it's discontinued) it's a lot cheaper than the TTI probe. Not sure about the current/frequency range, I believe there's a manual available on the net.

The 547A current tracer is an outstanding tool for locating elusive short faults. Sensitivity is specified at 1ma - 1A but actual performance exceeds has no problem sensing CMOS current less than 1ma. The low noise frequency bandwidth is out to 20Mhz and it can be powered with any convenient DC source between  4.5v - 18v. Performance is particularly good when injecting pulsed current into the circuit using the 546A logic pulser.

These are the best tools I have found so far for fast, accurate short fault detection. HP's peerless attention to engineering detail and quality execution is clearly evident in their construction and performance.
« Last Edit: January 01, 2012, 06:14:47 am by Kilroy »
The fool generalizes the particular; the nerd particularizes the general; some do both; and the wise does neither.

Offline Lightages

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Re: EEVBlog #230 - Arducopter
« Reply #28 on: January 01, 2012, 06:58:15 am »
The shrouds will produce some additional turbulence from the blades in addition to the lateral drag, more and more as the design is poor. The fact that they are not already aerodynamic is even more reason to spend time improving it. Quad copters are nearly always travelling at an angle of attack where something like a shroud will always reduce the efficiency. Inefficiency adds to the poor range a lot of these drones have, the more efficient you make them the bigger the potential radius you can operate them at.

I don't understand how the shrouds add turbulence from the blades. The shrouds should counteract the losses at the blade tips and add thrust. The shrouds also do not need to have cylindrical walls on the outside. They can be aerofoil  or round nose shaped on the outside so as to be more aerodynamic in somewhat horizontal movement.

Please forgive as I have not researched quadcopters, I am just a nerd who also is a pilot.

Offline IanB

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Re: EEVBlog #230 - Arducopter
« Reply #29 on: January 01, 2012, 09:13:38 am »
I am not an aerodynamicist either, but from observation it would appear than fans (small cross section, high air velocity) tend to have shrouds, while props and rotors (large cross section, lower air velocity) do not. So I would guess the importance of shrouds to the quad-copter depends on the extent to which the blades are fans rather than rotors...? In general engineering terms, I think open bladed impellers tend to be less efficient than shrouded impellers due to the way that shrouds and casings can channel and direct more of the air in the right direction rather than the wrong direction.
I'm not an EE--what am I doing here?

Offline Hobgoblin612

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