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Old Dec 16, 2011, 07:59 AM
More coffee, please!
sir_clive's Avatar
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Originally Posted by 4x4rc View Post
I dunno. Why even bother with those things when you can just get a decent quality APC or Master Airscrew for $2 more and be done with it? Without mislabeling or risk of exploding into your face.

I'm all for cheap Hobbyking airframes and I love the Orange Rxs but for stuff like props I want quality and not have to worry about it.

Just my 2 cents...
From what I read, Dr Kiwi regards TGS props actually on par if not better than APC ones. He particularly bashed APC 5x5.

But you're absolutely right, the price difference is negligable. I ordered TGS because I was also ordering something else from HK. :-)

http://www.rcgroups.com/forums/showt...=992708&page=2
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Old Dec 16, 2011, 12:26 PM
More coffee, please!
sir_clive's Avatar
Austria, Wien, Vienna
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Ok, my first static test is done. Scary stuff, WOT in the living room...

2200 lipo, freshly loaded at 12.6, stock motor, all props TGS.

5x5e 16.1A, 186W
6x3e 17.0A, 200W
6x4e 19.8A, 233W

At the end, battery was somewhere at 12.2 (don't remember exactly). I first measured 6x3, then 6x4, then 5x5. Only 7-8 seconds at WOT.

Does that look plausible? It's a cheapo meter, Voltcraft pa-10 (looks exactly like hk-010), no idea how good it is.

Btw, wild stick movements never brought me over 0.8A (hxt900 servos, frsky rx w/o telemetry). I know it's not a very accurate measurement, but I don't have anything better.
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Old Dec 16, 2011, 01:05 PM
Fly, crash, glue. Repeat.
Belgium, Walloon Region, Plombières
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Originally Posted by sir_clive View Post
5x5e 16.1A, 186W
6x3e 17.0A, 200W
6x4e 19.8A, 233W

Does that look plausible?
Can't really comment on the stock motor but with a RCtimer 2208/8 and APC-E 6x4 I'm pulling 28A.

Quote:
Btw, wild stick movements never brought me over 0.8A (hxt900 servos, frsky rx w/o telemetry). I know it's not a very accurate measurement, but I don't have anything better.
Sounds reasonable. That's almost 10W or 2A on 5V. For a 2A BEC that's pretty much borderline. The HXT900s are known to pull a decent bit of juice.
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Old Dec 16, 2011, 01:12 PM
More coffee, please!
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Me again.

Just noticed that when I tighten my collet adapter, the prop is not perfectly centered, it's offset to one side by 0.75mm, which can be seen with bare eye. The small black plastic ring between prop and the shaft has a tiny bit of play on both inner and outer side, the adapter itself seems perfectly centered.

During the static test, i felt no vibrations. Is that normal?

I now managed to center it, after quite a few attempts, at least in the direction I can measure (perpendicular to the prop), but have no idea how well the other direction is centered!
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Old Dec 16, 2011, 01:33 PM
More coffee, please!
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OMG... does one calculate it like that? I'm a software engineer, not knowing much about electronics , but I thought the measured current at the "entry point" (say near battery) would be the sum of all currents on all branches, so it can't be lower than the current on any given branch in the circuit.

Thanks rc4x4, maybe I should order that 5$ 5A BEC after all!

Edit: I was thinking about what you wrote - those 10W must also cover the heat dissipated by the BEC during regulation of 12V to 5V, which can't be very low I think (but don't know ). So, I'm confused why you used the total 10W / 5V to come at 2A?

This could be seen as way off-topic I'm afraid. If you also think so, I'd be thankfull for a PN.

Edit2: the numbers add up to support my oppinion: 0.8A at 5V is 4W for servos.12.6-5=7.6V voltage difference to dissipate as heat at 0.8A, giving 6W. 6W + 4W = 10W, as it should be (12.6 / 0.8). I am pretty convinced now that the servos don't pull 2A, but rather the measured 0.8.
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Old Dec 16, 2011, 02:27 PM
Fly, crash, glue. Repeat.
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Erm? I assumed you measured .8A between the ESC and battery, or where did you have your meter hooked in?

If you pull .8A at 11 Volts that's 11x.8 W, let's say 9W. You're right the BEC doesn't have 100% efficiency. A switched BEC is relatively efficient (low heat dissipation), a linear one burns off a lot of energy uselessly.

Another thing to remember is that servo current draw is highly non-linear. The wattmeter will give you an average reading but momentary spikes will be much higher.

This is an interesting link. Note the spikes on the oscilloscope displays. The HXT900s are rated at 750 mA peak apiece: http://homepages.paradise.net.nz/bhabbott/Servo.html
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Old Dec 16, 2011, 02:42 PM
More coffee, please!
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Yes, I measured it between ESC and Battery. And yes, I have a linear BEC, so a lot of those 9-10W was eaten away by the heat and not by servos.

This means I still don't know how much those servos actually pull, because of the low sampling rate of the measuring device, I was already aware of it.
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Old Dec 16, 2011, 02:54 PM
Fly, crash, glue. Repeat.
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You'll not get a good reading anyway because all you're doing is measure the no-load scenario. As opposed to in flight with air streaming over the control surfaces and multiple servos moving (or holding) at once. Better safe than sorry -- go with the max. values. That would be 4 x 3/4A = 3A. And that's the reason people tell you to either buy an ESC with a 3A BEC or get a separate SBEC.
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Old Dec 16, 2011, 03:02 PM
More coffee, please!
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Bah, I know. Unfortunatelly, I was listening to wrong people as i was buying my 2A setup.

i'm not keen on even more cables in my cockpit (external BEC), I guess it will be a new ESC.
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Old Dec 17, 2011, 04:15 AM
More coffee, please!
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Extended ailerons

Hi,

to come back on-topic, here my finished "extended ailerons" creation. You can see the carbon rod I added to support the ailerons, which now need to take different (twisting) load due to the extensions.

The extension is 8cm long, going 1.5cm beyond the wing trailing edge. It's made from the transparent collar inlays you receive with a new shirt.

I'll remove the wrinkled tape covering the rods and replace it by a new, "nicer" one as soon as the glue is cured.

Unfortunately, it's way too windy to test-fly the mod. I hope tomorrow the weather will be friendlier.

Interestingly, this doesn't seem to be a very popular mod - I googled for it for an hour, found nothing.
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Old Dec 17, 2011, 02:55 PM
Maiden>Confident>Cocky>Crash!
argo-2's Avatar
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Quote:
Originally Posted by sir_clive View Post
Hi,

to come back on-topic, here my finished "extended ailerons" creation. You can see the carbon rod I added to support the ailerons, which now need to take different (twisting) load due to the extensions.

The extension is 8cm long, going 1.5cm beyond the wing trailing edge. It's made from the transparent collar inlays you receive with a new shirt.

I'll remove the wrinkled tape covering the rods and replace it by a new, "nicer" one as soon as the glue is cured.

Unfortunately, it's way too windy to test-fly the mod. I hope tomorrow the weather will be friendlier.

Interestingly, this doesn't seem to be a very popular mod - I googled for it for an hour, found nothing.
Best of luck with the test-flight s_c!!
Video!!

Only point of note that occurs to me is if you are using flapperons/spoilerons the augmentation out at the wingtips may cause more of a chance of getting tipstall. Just a thought/caution
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Old Dec 17, 2011, 03:45 PM
More coffee, please!
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Thanks argo! I'm afraid the test flight will have to wait, the weather forecast for tomorrow looks bad. I don't feel like testing this mod in 25km/h winds.

I am still not using spoilerons/flaperons, actually my ailerons are still on the Y cable. I'm waiting for my protostack to arrive, as soon as er9x is flashed, I'll give it a try.

Speaking of er9x, I just tried out the eepe - man, it's a work of a genius! I already LOVE it, it's almost too easy to use, and the possibilities are endless!
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Old Dec 17, 2011, 10:09 PM
Callsign: Zulu
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Originally Posted by sir_clive View Post
Speaking of er9x, I just tried out the eepe - man, it's a work of a genius! I already LOVE it, it's almost too easy to use, and the possibilities are endless!
Speaking of the 9x, apart from endless possibilities, is it really necessary to flash it? Say I just want a basic radio with 6 channels. I mean the soldering on the board leaves me a bit scared. I'd hate myself to destroy a new radio!
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Old Dec 17, 2011, 10:28 PM
Maiden>Confident>Cocky>Crash!
argo-2's Avatar
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Quote:
Originally Posted by sir_clive View Post
Thanks argo! I'm afraid the test flight will have to wait, the weather forecast for tomorrow looks bad. I don't feel like testing this mod in 25km/h winds.

I am still not using spoilerons/flaperons, actually my ailerons are still on the Y cable. I'm waiting for my protostack to arrive, as soon as er9x is flashed, I'll give it a try.

Speaking of er9x, I just tried out the eepe - man, it's a work of a genius! I already LOVE it, it's almost too easy to use, and the possibilities are endless!
Just to throw it out there - have a look at Companion9X. If you like eePe, C9X (derived from eePe) has gone one more step (simulates the 9X LCD screen as well!). Its the 'Companion' to Gruvin9X and runs all ER9X and eePe configs (so pretty much everything to do with the 9X TX).

And just to go further OT - Gruvin has just released the V4 (final release) swap-out computer board. Only catch is, its only the PCB - you would need to solder on the components (not easy!). But a fully-built board is in the works. BTW it can use a SDcard to store & move data files around.

Again apologies for OT.
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Old Dec 17, 2011, 10:38 PM
Maiden>Confident>Cocky>Crash!
argo-2's Avatar
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Originally Posted by Stuka_99 View Post
Speaking of the 9x, apart from endless possibilities, is it really necessary to flash it? Say I just want a basic radio with 6 channels. I mean the soldering on the board leaves me a bit scared. I'd hate myself to destroy a new radio!
You're in the same boat as Aero Andy. If you look at the comments in the blog s_mack and I put Andy onto SmartieParts. s_mack offers a daughter-boeard with special spring-loaded contacts - no soldering required! Also comes with a EL backlight. Feel free to ask any questions - probably best do it on the blog to avoid more OT
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