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Old May 05, 2010, 01:13 PM
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Gloucester UK
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Hi Rudolf...Im very new to EDF still working my way around things.however, my battery is rated at 20C and the motor is a brushless 12mm inrunner 5300KV .
The fan unit you have found Im sure is worth giving a try at the price , the figures given seem to show alot of thrust for the size.
I probably will paint the canopy black once I have got her flying well. Thanks fior your interest
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Old May 06, 2010, 03:42 AM
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Australia Sunshine Coast
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Thanks davezoom for the info. If you have trouble with the thrust borrow a higher c rated battery and watch what happens. Can you tell me the wing span please.

Thanks
Rudolf
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Old May 06, 2010, 03:04 PM
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Gloucester UK
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Wingspan is 46cm... Just got a 5800kv motor so im going to rig that up and see what thrust i get...
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Old May 07, 2010, 04:31 AM
James L
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Beck Row Mildenhall
Joined Mar 2009
789 Posts
davezoom with that much thrust and with the AUW where it is it should be lively about 30 mph and above. Your battery 500mah at 20C should give 0.5*20=10A without any problems and that motor will run happily on 3s at about 4-6A on a 40mm.
What is the diameter of the exit of the thrust tube?
Are you running a 2s battery?

James
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Old May 07, 2010, 11:02 AM
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Hi James.....Im running 2s and the exit diameter is now 35mm (Ive just made a new and improved one). Hoping to check the thrust later tonite. 3s might be to heavy so im keeping it to 2
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Old May 07, 2010, 05:56 PM
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Gloucester UK
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I read somehere recently that a 40mm EDF works best with a 35mm exit duct. My original duct was more like 30mm so the new one is made exactly 35mm and what a difference!! Not measured the thrust yet but the jet shoots along the floor at full throttle. Ill measure it tomorrow as i dont want to wake the house up with the noise....
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Old May 10, 2010, 03:30 AM
James L
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Beck Row Mildenhall
Joined Mar 2009
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I find that EDF is not just about the fan it really should always be considered that the duct fan duct is one complete unit and we need to design our planes with that in mind from the outset. Then they work so much better. I went through a painful learning experience before I found RC Groups and had just about got to grips with it from trial and error. Generally I find that the exit should be 85-90% of FSA the lower the power the nearer 90%.
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Old May 10, 2010, 03:18 PM
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Gloucester UK
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Found she flew better without the cockpit guess it produced to much drag so decided to make a foam one and sleeker. Cockpit will be held on with velcrose eventually. Pictures of the new thrust tube and cockpit below. She glides nicely now in this form just need another powered flight to test for real.
Tangosierrarom Ive found it is a learning curve and there is alot to think about regarding these EDFs...
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Old May 10, 2010, 08:21 PM
James L
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Beck Row Mildenhall
Joined Mar 2009
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The cockpit is a way forward of the CG and the fins are not much further behind it so you may find if you enlarge the fin area that it will glide better.
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Old May 11, 2010, 05:15 AM
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Australia Sunshine Coast
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Davezoom just a quick one, get a steel ruler and lay it along the edge of ya bench overhanging slightly, now lay ya foam along the steel ruler 6mm in from the edge of the ruler, now put another ruler along the top 4mm in from the edge of the foam, the foam is now sandwiched between the two rulers run a stanley knife blade along the edges of the two rulers from underneath (watch out you dont slice a nice piece of skin off ya thumb and forefinger of ya left hand) turn the foam over and do it again. My scratchbuilds fly heaps better since I have been doing this.

Let me know how ya go looks good too UUUU. Looking end on you should have a nice 2 or 3mm flat in the middle and two angle cuts, one up and one down. Hope this makes sense.
Rudolf
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Last edited by rudes; May 11, 2010 at 05:22 AM. Reason: oops
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Old May 11, 2010, 05:38 PM
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Gloucester UK
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Thanks rude ...i think i understand , it makes a beveled edge rather than a square one, will give it a try..
Have increased size of fins and applied some colour . Thank you for the advice..
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Old May 11, 2010, 07:12 PM
James L
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Beck Row Mildenhall
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I like this, should fly very sweet.
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Old May 11, 2010, 07:31 PM
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Thanks Tango... seems to want to fly , there is plenty of thrust from the fan , hoping to give it a whirl over the weekend...
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Old May 15, 2010, 03:36 AM
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Gloucester UK
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Extender the wings more forward to get the cockpit back in effect...glides very nicely now
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Old May 15, 2010, 03:52 AM
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Looking good, when's the first flight.
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