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FT Alpha EDF(?)

slipshift

Active member
#1
Has anyone built an Alpha EDF? I really liked flying the Mini Alpha on Phoenix so I built one, not yet maidened. Then I found a ducted fan setup http://www.ebay.com/itm/POWERFUN-50mm-11-Blade-4900KV-EDF-3S-LiPO-770g-Thrust-XRP-CHANGESUN-Replacement/132930701544?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649 and got a wild hair and decided to put it on an Alpha. It was a standard build and then I started gutting it. The thrust tube was made from a Walmart 50 cent plastic notebook paper folder. The fan should be getting enough air volume but it may be turbulent. Any tips or criticisms are welcome. Since my piloting skills are pretty much maxed out flying a kite, this should be an exciting maiden.

Jim

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AkimboGlueGuns

Biplane Guy
Mentor
#2
How did you make your thrust tube? As a general rule of thumb you are going to want the exhaust end to be roughly 85% of the fan swept area (area that the fan covers minus the area of the motor). Other than that, the inlet looks fine to me. Unless you want to get creative with posterboard or 3D printing there's not really a good way to get a smooth inlet with DTFB and it should perform just fine with what you have. You may want to make a posterboard fairing to go over the thrust tube to prevent any damage from landing, as well as to clean the plane up from an aerodynamics point of view.
 

slipshift

Active member
#3
I just rolled it by hand, the plastic keeps its shape well. I used attached spreadsheet to get an outlet about 90%. Smaller is faster but larger gives better thrust from what I've heard. I like your idea of a posterboard fairing and I'm going to use it.
I guess I can't attach the spreadsheet, I get a "The uploaded file does not have an allowed extension." and I forgot where I found it.

Jim
 

AkimboGlueGuns

Biplane Guy
Mentor
#4
I just rolled it by hand, the plastic keeps its shape well. I used attached spreadsheet to get an outlet about 90%. Smaller is faster but larger gives better thrust from what I've heard. I like your idea of a posterboard fairing and I'm going to use it.
I guess I can't attach the spreadsheet, I get a "The uploaded file does not have an allowed extension." and I forgot where I found it.

Jim
Should work just fine. You'll have a bit more low end grunt with that setup, which is probably better for small EDFs like that.