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Oct 30, 2011, 08:50 AM
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cap10jaf's Avatar
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Originally Posted by k.smith459
ill just close the thread the thread then i was going to put a kit into productoin but as you said " nobody really cares till a sucsessful flight video is posted" OH well
Ha! That didn't come out right! Sorry K. I didn't mean to insult you.

Greg
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Oct 30, 2011, 12:36 PM
BlackLivesMatter.
Keenan smith's Avatar
it alright
Nov 03, 2011, 08:47 PM
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cap10jaf's Avatar
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The wing is mounted.


I'm embarrassed by the time I wasted worrying about this.

Once I committed to cutting and gluing, it was one of the easier things to figure out.

Now that everything is together, I was able to get a flight-weight. The airframe with retracts and servos is exactly two pounds. The fans(with wiring), ESCs, and batteries weighs 2.1 pounds. So I'm looking at 4.2 pounds with 70mm fans/55A ESCs/2200 mAh 3S packs.

Thoughts?

GD
Last edited by cap10jaf; Nov 03, 2011 at 08:53 PM.
Nov 04, 2011, 12:56 PM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by cap10jaf
I'm embarrassed by the time I wasted worrying about this.

Once I committed to cutting and gluing, it was one of the easier things to figure out.

Now that everything is together, I was able to get a flight-weight. The airframe with retracts and servos is exactly two pounds. The fans(with wiring), ESCs, and batteries weighs 2.1 pounds. So I'm looking at 4.2 pounds with 70mm fans/55A ESCs/2200 mAh 3S packs.

Thoughts?

GD
Looks beautifull Greg! 4.2 pounds . . . . what are her dimensions
Sir?
Latest blog entry: RC 737 Max 7 Maiden flight!
Nov 04, 2011, 02:45 PM
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Quote:
Originally Posted by demondriver
Looks beautifull Greg! 4.2 pounds . . . . what are her dimensions
Sir?
Thanks Chris,

It's ~1:20 scale which puts the wingspan at 49" and length at 60".

GD
Nov 04, 2011, 03:12 PM
'Sit vis nobiscum'
PEDANTIC's Avatar
Man! Looks Great Getting close.....I am going to try to come down in Nov again. So keep it in one piece til I get there
Nov 04, 2011, 08:47 PM
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Quote:
Originally Posted by demondriver
Looks beautifull Greg! 4.2 pounds . . . . what are her dimensions
Sir?
Holy Crap. I just read that the E-flite super airliner flies at 3.25 lbs with more wing area.

I should've blown these plans up to 1:17 scale with the same power and retracts. It would still weigh the same!

Well it's too late to turn back now. I'm using a flat bottom airfoil set at one degree positive incidence with flaps. It might not fly like Neff's, but it will fly. I think.

Looks like he used smaller, lighter power with fixed gear. Smart!
Nov 04, 2011, 08:52 PM
'Sit vis nobiscum'
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Its going to perform well Stop It!! get back to work
Nov 16, 2011, 03:51 PM
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Is this normal?


Alright folks, I just did the first bench run of the power system. Everything is working properly, but when I get to full throttle one blade of each fan just BARELY touches and squeaks against the shroud at the same spot (lower-left) on each unit.

I'm afraid to sand anything because everything runs very smooth with no vibration. How should I handle this?

TIA,

Greg D.

P.S. I ran it between 1/2 and 3/4 throttle for 8 minutes and 30 seconds before audible change in RPM. ESCs and motors had very little warmth, and wiring was cool after the run. Power and sound are awesome!
Nov 16, 2011, 07:38 PM
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LuvEvolution7's Avatar
here's the easy way to do this.

first, figure out where the blades are striking the shroud.

second, tack glue a piece of sandpaper to the shroud in that location. at this point, you can either spin the rotor by hand, or power it up and spin it by throttle. the point is, to let the sandpaper do the work for you. once you are satisfied that the blades no longer touch the shroud, simply remove the sandpaper.

the beauty of this method, is that it'll remove the same amount from every blade and therefore, won't change the balance of the fan.
Nov 16, 2011, 07:39 PM
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LuvEvolution7's Avatar
I'm betting that it's the LE or TE of the tips that are touching the shroud. this method will shave a tiny bit off them and stop them from touching.

the reason they are touching, is because the blades are stretching slightly at high RPM. you may have to repeat this to shave the tips off, so I'de be leaving the room, or standing a fair distance back while it's doing its thing.
Nov 16, 2011, 08:36 PM
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Quote:
Originally Posted by LuvEvolution7
I'm betting that it's the LE or TE of the tips that are touching the shroud. this method will shave a tiny bit off them and stop them from touching.

the reason they are touching, is because the blades are stretching slightly at high RPM. you may have to repeat this to shave the tips off, so I'de be leaving the room, or standing a fair distance back while it's doing its thing.
I was hoping you would show-up here. Seems like sound advice, will do. I was hiding behind a door like a little girl, peaking around the corner with safety goggles during this first test. Every bolt is Loctite-secured, but I'm in uncharted water with these EDFs and I've read some of the horror stories.

Thank you LE7,

GD
Nov 16, 2011, 10:18 PM
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LuvEvolution7's Avatar
yeah, I hear ya! I do the same thing too. I figure that a 2-3 inch thick door has got to be solid enough, so I kinda hide behind it. LOL.

another way to do it, is to buy a piece of polymer that's relatively thick and make a shield out of it. it also needs a bend at the top, towards the fan to give a little bit of xtra shielding from stuff flying over the top. that should be enough shielding if you want to go that route. the nice thing about it is, most of the flying debris will be limited to front or back, which is where you won't be..........hopefully. LOL.

let me know how the sanding trick works out for you. I wouldn't go too high or too low on the grit of the paper though. probably around 160 should do it. I've gone as low as 80, but you take the risk of damaging the blades. I'de say 160-200 should be ok with a smaller rotor.

Rich
Nov 17, 2011, 01:07 PM
EDF rules... :)
AirX's Avatar
The way we used to do scrub a fan in is to hook up a watt meter and run the fan at a steady pace for a few seconds at a time on a test stand of couse. After a run check the shroud and if there is scrubbing clean it out using some sand paper or similar. Then run the fan again a few click more throttle but only for a few seconds also checking the watt meter to see if there are high amp spikes and then shut it down. Go thru the checking/cleaning sequence again and then do ti again till the throttle is wide open. This allows the rotor to fit itself to the shroud without breaking anything. Btw cold weather is not good for plastics, it makes them brittle so be extra careful running them in during the winter.

I have done this with numerous fans from 40mm to 90mm. All except my Stumax which I will follow his instructions for run in.

Cheers,
Eric B.
Nov 17, 2011, 06:56 PM
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cap10jaf's Avatar
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Thank you Gentlemen,

I started with 220 grit spray mounted to the inside, but it was too light. I switched to 150 grit and that did the trick. These things are screaming on 3S power. I can't imagine using 4S for this application. After the test today, I'm sure power won't be a problem. [knocks wood]

I'll build the nacelles tomorrow if I can find good thrust tube material on the way to work. Pics to follow...

GD


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