This will be my 2nd scratch built edf. Will be cs 70mm 10 blade . Exceed 2700kv on 4s

Nice !

stingeragents Some interesting reading here on the CS 70mm in an F-15 You could start here. Might want to go nack a few pages or read on from this page .


http://www.rcgroups.com/forums/showt...n+fsa&page=204

Thanks. Only read the 1 page but not enough intake it seems. Im hoping with the larger ones on this plan it will work. Ill measure them tomorrow and figure out the surface area
Just did some more reading and its useful stuff . Thanks again

Edit 1: Thought I'd post some more on the build. Fan should be in mail today. Gonna start working on the intakes. My electronics for this build will be in tomorrow. I plan to make the wing removeable for easier access to everything. Was contemplating 2 wooden dowels on the front that will slip under the strake and then some magnets on the back. I think the magnets aren't gonna hold though. I'm working on an idea of putting a strip of balsa on the rear of the wing, and fabricating something on the fuesalage where I can bolt it down. I'll give that 2nd idea a shot to see if it will pan out. If not suppose I'll just be gluing the wing on. Also, depending on what my weight is I may glass the whole thing. I had been doing newspaper covering on some planes but lately I can't get it to stick very well to the foam. It dries hard but peels off rather easily in some spots. Ended up glassing a plane yesterday that the newspaper was coming off. Anyways, on the F15 don't think i'm gonna do the full flying surfaces like the plans calls for because of the thrust tube. I will probably just glue them on

Doing these ducts is a bit harder than i thought. What can i use to melt the foam mold?
Edit. I have decided to forgo the fabricated intakes. Is just gonna be too much work for me. I am however going to test something. I will do the first setup with just fan in middle of plane and the thrust tube. For my 2nd setup i will put in an air diverter into the intakes. This will force all the air coming in from the front into the fan. Setup 1 will allow air.to pass by the fan on the 4 corners. I wont do any static yests as that will be pointless. Will simply go by how fast it flies with the 2 setups

lacquer thinner and acetones make short work of foam

why would you go with bifurcated ducts in such a design?i would squash the thrust tube to an oval. fsa is fsa, doesnt really matter what shape its in
You could still do flying stabs with an ailivon setup would be lighter tieing them to the ailerons.

Make the ducts out of mylar or petg, etc...

The intakes were gonna be dual not the exhaust.

Motor came in today. After some fitting issues got it in the fan. I balanced rotor yesterday so did a test spin up. Super smooth. Need to go by transparency for thrust tube tomorrow. Also got the fan mount built last night. Once i get tube done ill glue fan in and get to finishing it. Aiming for maiden sun or mon

Thrust tube dialed in at 51mm. My last 70mm plane i did a 56mm and wasnt super impressed with speed of it so figured that will help a bit. Should still get out the door at over 1:1.
Edit. Well glued fan into plane and did test run up. Could immediately hear vibration. Ugh. Downloaded a vibration app for my phone and put it on fan . Looked like an earth quake. There was one spot where it smoothed out and vibration ceased and could tell a very noticeable difference in sound. But it vibrated more at just a hair more throttle. I balanced fan with a heli blade balancer but it was kinda gheyto rigged. Gonna pick up a prop balancer from lhs tomorrow and then dynamically balance the fan. Ive never balanced an edf before but my 50mm jpower plane fan exploded on 4s so im gonna do it right on this one.

Edit 2. Ok so i was curious. Took the fan rotor off and did vibration test again. It vibrated just as bad with no fan on it. What does this mean

Im no expert on ED's but I may have an idea why you still have vibration...If you just took the fan rotor off and left the shaft adapter still on your motor, there is a good possibility the center hole that mounts to the motor may be off center...A lot of less expensive fans have very poor adapters... Try loosening the rotor adapter and moving it on the motor shaft to a new position and try tightening the set screws evenly.. If it is a collet type adapter, make sure it is fit down on the motor shaft as far as it will go, then try running the motor again without the fan...when you get the vibrations down as far as you can..try putting the rotor on in different 'rotation' points and check for vibration.. By 'rotation' points, I mean put the rotor iin and try a run up..if vibrating..losen rotor, turn about 45 degress, retighten and try again...keep this up unit you find point of least vibration..
I hope this helps
Wayne

Ok ill try that. Im gonna take the adapter off, remount the motor and check for vibes. That should narrow it down to either the motor itself or the housing

Well got vibes sorted. I couldnt wait to see how fan sounded in air so i ripped fan out of my 70mm f22. Put the cs fan in and went to fly. No go. Even at full throttle couldnt keep it in air. So its either intake or thrust tube. This plane flies great with dynam 70mm so dont see how intake could be problem. My thrust tube is at 51mm. Could that be problem? I did 56mm on dynam fan but wanted a bit more speed

I might be wrong on this, I am sure someone will correct me , but how many bades on the dynam rotor? Seems I had read the the CS fans, because of higher blade cout need more air( intake ) . Might just be starving for air.
Just my quess.

Yea has 10. Dynam has 6. I had put in air diverters to direct air to dynam fan. The cs might be overloaded also. I took out the diverters and largened thrust tube to 56mm. If it still wont fly its definitely an intake issue. Not sure how i would go about fixing that though as i dont know if i have too much or too little. That fan did sound sweet though as i tried to limp it across field

stingeragents, I re-read the thread, and no mention of using an intake ring.
Are you just going with raw ducting and no intake ring?


http://www.rcgroups.com/forums/showt...+size&page=247
posts 3695 and 3702 exhaust dia. Might be a good thing for reference, later on.