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Old Aug 24, 2004, 03:30 AM
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Tel Aviv-Yafo Sde Dov, Israel
Joined Nov 2002
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Alfredo, I've made a thrust check in pusher and tractor configuration and couldn't see any noticeble change. They are home made. From a book I have about Jet models I understand that they used pusher duct in the past but nowdays it's only tractor as you said, but all the reasons for doing so were related to the use of piston engine and not to rotors / stators configuration. Also, it says that 1/3 thrust should fly good, 1/2 thrust should have aerobatic performance and 2/3 thrust - Jet like! So I'm in the entery level now, and I just want it to fly, but I'm planing on reducing the weight.
Zlatko, I agree that one fun looks better, but right now there is no chance for it to fly with just one. Pete is going to send me some of the 7mm motors and that might make the differance. My prefferance is to use only one duct-fun.
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Old Aug 24, 2004, 04:10 AM
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RNAF's Avatar
The Netherlands
Joined Dec 2003
2,307 Posts
Hey Nachman,

I've read about using bigger motors but I think it'll become too heavy unless they give 4-5 grams thrust:

1.2V 10 Ohm
7x 17 mm 2.78 g -->7mm Didel motor
axis 1.00mm

0.5V 3 Ohm
6 x 12mm 1.32 g -->6mm Didel motor
axis 0.80mm

I hope I am not saying stupid things hahaha

Dave
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Old Aug 24, 2004, 09:58 AM
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Land of cajuns
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nachman have you done a rpm test on your funs The books I have say About the same thing I have noticed at this scale a curve in the Stators will Not help any but The Cure and angle of attack in the blade will..
I have yet to use a didel motor....just the high rpm Bit charger motors with some success.....Motors have allways been the problem
You could put a N20 or M20 Motor More weight but 3 or 4 times the Thrust
Hope you get it air born Free flight or r/c......Nice Bird


aerogel
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Old Aug 24, 2004, 10:28 AM
RIP THE BRING!
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Rhode Island
Joined May 2004
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omg i was drooling with one fan and i havn't checked this page sense i said that but 2 fans im in shock i don't know wat to say, that is the sexiest thing i have ever seen.
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Old Aug 24, 2004, 12:57 PM
Faroe Islands/Germany
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Quote:
Originally Posted by aerogel
The Cure and angle of attack in the blade will..
Surely this must be a first in model flight: A pop band having direct influence on ducted fan thrust. The Cure seems a very unlikely candidate; I would have assumed AC/DC or Aerosmith would have been more suitable. Hmmm..., maybe I should be playing Bachs "Air" to my 4.5ohm pagers to keep them from frying or read poetry to Depron to make it lighter. Think of what Dizzie Gillespie could do for 3D models.......

Michael
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Old Aug 24, 2004, 01:08 PM
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RNAF's Avatar
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LOL EPILOT
I also was wondering why I saw all those capital letters
AC/DC will be good enough

Dave
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Old Aug 24, 2004, 01:22 PM
Thanks for the Fish!
aerogel's Avatar
Land of cajuns
Joined Dec 2001
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LOL
so pull on your hair pull on your pout cut the
conversation just open your mouth pull on your
face pull on your feet and let's hit opening time
down on fascination street

10 grams Thrust!!!!!

Aerogel
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Old Aug 25, 2004, 01:25 PM
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South of Boston
Joined Mar 2004
846 Posts
Man, that thing is SO nice!! Have you thought about putting the 2 motors in a pull-push fasion one in front of the other?? I believe that'd save some space. Also, I think you can get a tad more thrust by putting the vanes in to make the airflow straight. Just a thought :-) But sexy anyway! ::licks finger, touches jet's tailfeathers:: Tssss!!
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Old Aug 25, 2004, 02:07 PM
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RNAF's Avatar
The Netherlands
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Quote:
Originally Posted by Pete P.
But sexy anyway! ::licks finger, touches jet's tailfeathers:: Tssss!!

Whahahahahaahaaa that's one thing for sure!!

Good job Nachman, keep up the good work!! (and updates of course )


Dave
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Old Aug 25, 2004, 04:32 PM
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massachusetts
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hmmm with the dual motor setup it looks like it would be a good candidate to make an a10 out of....
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Old Aug 25, 2004, 09:27 PM
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Your stators are not cambered! if you camber them it will increase thrust quite a bit you can probably use a more aggressive blade angle and just sweep it near the ends, you want to keep the hub bigger so you can have the blade thicker where it meets the hub, in general hubdiam=motor diam.
have you seen the EDF-30? that is just a bit bigger than what you are doing right?
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Old Aug 26, 2004, 03:03 AM
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Tel Aviv-Yafo Sde Dov, Israel
Joined Nov 2002
288 Posts
Zlatko, I've tried your suggestion and it reduces static thrust by 5%.
Ssyed, your right about everything. Cambered stators should help, but not easy to machined if done as a single piece with the shroud. How ever, camberd and twisted blades should also imrooved efficiency and are no more difficult to machined then the current flat blades. So this weekend I'm going to give a try to a better rotor design. The hub was 4mm becouse it was originaly ment for a 4mm motor. I'll make the new hub 6mm as suggestted.
I havn't seen the 30mm EDF. I'll check it out.
Thanks all for the nice comments !!!
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Old Aug 26, 2004, 03:16 AM
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North Plains, OR
Joined Nov 2003
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How about a photo of the BD-10. SEXY! Got to see it fly at Oshkosh a couple of years...

matt
http://rob.com/pix/matt
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Old Aug 26, 2004, 06:22 AM
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Melbourne City Hlpt, Australia
Joined Jun 2004
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Hi nachman,
Sorry, generally if the fan is inside a tube then the thrust is higher. I don't know.
What material did you use to machine the duct and fan? Is it acrylic?
Very good idea about a micro A-10 or a BD-10.
Cheers
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Old Aug 26, 2004, 10:41 AM
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LOL,
when I first saw these pics I thought about an A-10 too.
I said it too about a BD-10 in a previous reply in this thread Thanks for the pic, beautiful huh?

Dave
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