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Old Feb 05, 2013, 07:21 AM
Keep calm and carry on.
Oso M's Avatar
United States, VA, Falls Church
Joined Jan 2012
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Quick vid of my electronics set up. Still haven't placed antennas for optimal. But I wanted to show Dragonlink with APM2 and RFD900 telemetry.

UAV/FPV Setup (3 min 47 sec)
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Old Feb 05, 2013, 07:25 AM
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Plainfield, New Jersey, United States
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So what exactly makes these parts worth $75? Is it the ability to disassemble the wings and wingtips using screws? Couldn't these parts be made from some other light material that costs a little bit less?
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Old Feb 05, 2013, 10:22 AM
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Originally Posted by williamjames View Post
$75 is almost half the price of the plane. Isn't that quite a bit? I know some people are gonna say, "it's a small price to pay if your sending up a thousand dollars worth of fpv gear up"... but really, don't you think that's over priced?
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Originally Posted by Pattaya01 View Post
That was exactly the same thought I had when I saw that.
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Originally Posted by chillybee View Post
So what exactly makes these parts worth $75? Is it the ability to disassemble the wings and wingtips using screws? Couldn't these parts be made from some other light material that costs a little bit less?
While I agree that's a lot of money for what seems like a few little pieces, one has to consider that almost anything made for a limited aftermarket is going to be pricey. Of course, we all have the choice to not buy it if we think it's poor value for the money.
This same philosophy applies to specialty car aftermarket. Years ago, I came up with a simple device that cost me less than a buck in materials to make and 5 minutes of my time, yet people were willing to pay me $20.00+ for it.
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Old Feb 05, 2013, 02:47 PM
wep
https://vimeo.com/wep800
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Originally Posted by ttucker View Post
How does that setup effect the aerodynamics when lowered?
It is even gonna effect in a positive way when you compare it with placing a camera on top talking about an X8.

I haven't seen this plane in a windtunnel but when you look at this plane you can imagine that the body itself also has the shape of a wing and thus will produce some lift.(maybe more then we think)

Placing a Gopro on top is like placing a spoiler in the up position, removing all lift for the width of the Gopro.
By placing the camera on the bottom you only have parasite drag which you always will have
Parasitic drag is drag caused by placing an object in streaming air.
To reduce that is streamlining.
The parasite drag stays the same is the same when you place it on top or below.


Another trick to reduce this loosing lift problem is to place the Gopro a lot higher on a pole so most air can flow freely beneath the GoPro.

The MAIN reason I am building the retractable camera is because then I have full free 360 view and down.
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Old Feb 06, 2013, 05:46 AM
When a hobby gets a passion
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Originally Posted by wep View Post
I haven't seen this plane in a windtunnel but when you look at this plane you can imagine that the body itself also has the shape of a wing and thus will produce some lift.(maybe more then we think)
Just the fact that so many people loose the hatch already indicates the body gives considerable lift. If the hatch is being sucked away, it means there is quite some low-pressure on the surface of the fuselage.
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Old Feb 06, 2013, 06:13 AM
Keep calm and carry on.
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United States, VA, Falls Church
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Quote:
Originally Posted by Pattaya01 View Post
Just the fact that so many people loose the hatch already indicates the body gives considerable lift. If the hatch is being sucked away, it means there is quite some low-pressure on the surface of the fuselage.
Sometimes I wonder if losing the hatch is caused both by the lift, but by the positive pressure created from the forward inlets. If that air didn't exhaust fully it's definitely creating an extra outward push on that thing.
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Old Feb 06, 2013, 06:22 AM
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United States, KY, Hardin
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I was thinking the same thing Oso M

in fact I was thinking about replacing the 2 front magnets with to small nylon screws
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Old Feb 06, 2013, 07:26 AM
The Flying Circus
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Adelaide South Australia
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I dont trust magnets. I just use gaffa tape
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Old Feb 06, 2013, 09:23 AM
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Canada
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I made a lip out of balsa ply and hot glued it to the front of the hatch in the middle. I continue to use all the magnets supplied. That hatch has never come off, even in high velocity conditions or in a lengthy dive.
The trouble with magnets may be in the installation. If the two opposing magnets at each point aren't lined up or if they don't touch when put together, the hold is a weaker. Rare earth magnets are strong. It's the installation that may be weak.
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Old Feb 06, 2013, 04:14 PM
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Originally Posted by Oso M View Post
Sometimes I wonder if losing the hatch I'd caused both by the lift, but by the positive pressure created from the forward inlets. If that air didn't exhaust fully it's definitely creating an extra outward push on that thing.
did you find that your hatch sat high when you installed it? mine needed me to shave a 1/3 of an inch off the tabs for it to sit flush. though the magnets hold well i to believe the pressure build up could pop the canopy. i've had this happen before with large canopy models.
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Old Feb 06, 2013, 05:07 PM
Keep calm and don't blink
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Hamilton, New Zealand
Joined Jun 2005
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Here's what I did on mine: http://www.rcgroups.com/forums/showp...postcount=6498
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Old Feb 06, 2013, 08:17 PM
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United States, CT, Fairfield
Joined Jan 2012
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Funky winding on stock AX2820?

Hey everyone,

I've got an X8 with a few improvements that I'd like to share, but it's crunch time for my research and I need to get it back in the air ASAP. Here it is anyway:

AX2820 customized for X8, stock from BEVRC
70A AX ESC from BEVRC, internal BEC powers servos.
6S 5000mAh Zippy Flightmax, 30C
Prop was 12x7 or so, whatever came stock with the power kit.
ZD-FLY T6A transmitter with custom mixing, ZD-FLY 6ch receiver with stock single whip antenna
915MHz 3DRadio clone as 3DR was out of stock
APM2.0 with onboard GPS disabled, 2.5 case modified to fit
3DR LEA-6H, have yet to update firmware
3DR airspeed kit
HK ~3.6KG standard servos mounted through top of wing. Note: I got 3 as obviously HK quality is not that good, one malfunctioned during maiden flight leading to crash.
Thunder Power 5V 3A linear BEC (just for APM/telemetry)
BEC battery: Custom 2S 5500mAh NCR18650 pack

So, my problem today is that the stock BEVRC motor burned out while flying, due to a combination of one of its wires being pulled out and possibly overdone ground testing. W/E; I took a few pictures and then unwound it, whereupon I discovered something strange.

The AX2820 780Kv motor that comes stock with the X8 isn't wound thread-by-thread; it is wound with 8-strand strands wrapped ~5-7 times around each of the 12 stators. At least, that was the only way I could unwind it. It appears to be 26-28AWG wire, but it could be as small as 30AWG -- I'm not quite sure as it was blackened and my caliper is missing.

So am I supposed to take 6 strands of ~26 gauge wire, twist them together, and start winding? Or am I missing something? Is it possible this is what SW was talking about when they said "customed [sic] for X8"?

Thanks for any help, especially from the pros. It'll be blizzarding around here for the next few days, so I won't be flying anyway

P.S. I hand launch with the motor off. Running with it and then hurling it into the wind may look a little silly, but it's a lot simpler than a catapult/winch and avoids pretty much all of the danger of launching with the motor on.
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Last edited by Zedtwitz; Feb 06, 2013 at 08:26 PM.
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Old Feb 06, 2013, 08:35 PM
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Quote:
Originally Posted by Zedtwitz View Post
AX2820 customized for X8, stock from BEVRC
70A AX ESC from BEVRC, internal BEC powers servos.
6S 5000mAh Zippy Flightmax, 30C.
Isn't that motor meant for 4S? How did you "customize" it to be run on 6S? I would think 6S would fry that thing.
I have a HobbyKing 1000kv motor. I started using 4S and it got extremely hot. I backed off to 3S and it's been running great since.
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Old Feb 06, 2013, 08:53 PM
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United States, CT, Fairfield
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Upon re-coiling the unwound wire based on the bends left in the metal, I counted approximately 91 (+/- 8 for rounding error) loops. That means seven (84 loops) or eight (96 loops) loops per stator. I should ask BEVRC if they know anything about the motor's construction, but odds are they won't be very helpful.

If you're curious, the total length of 22-28AWG wire needed to rewind this motor is 1440 inches, or about 120 feet. Not including bullet connector wires. (1 180in strand of 8 separate wires equates to 1 1440 inch long wire). Maybe that will help with calculations?

This is certainly going to be a task to rewind.
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Old Feb 06, 2013, 08:55 PM
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United States, CT, Fairfield
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Originally Posted by xviper View Post
Isn't that motor meant for 4S? How did you "customize" it to be run on 6S? I would think 6S would fry that thing.
I have a HobbyKing 1000kv motor. I started using 4S and it got extremely hot. I backed off to 3S and it's been running great since.
Oh, I didn't customize anything. BEVRC says that their motor is customized for the X8, and the (BEVRC) ESC is rated for up to 6s. I haven't had any problems up to now. I think the main problem was the control wire ripping out, causing a temporary lockup/short, rather than the higher voltage. The ESC still works fine, though.

Alternatively, maybe I could rewind it differently to handle the higher voltage. Hmmm... anybody from the Power forum here?
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