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Jul 07, 2013, 05:21 AM
Tony Audsley Retired Locksmith
Lockey's Avatar
Thread OP
Quote:
Originally Posted by kadil
Wonder how thick that fin is when it is compared to a polaris where it is supporting the nacelle?Also the bigger the gap between the jet and the fin, the better. My simple hypothesis

Also intake ducts look very cool, but are they big enough?
Just playing at this stage Kadil and listening to you guys and looking for any advice

Lockey
Jul 07, 2013, 08:54 AM
We shall serve the Lord
kingsflyer's Avatar
Here are my general impressions on EDFs:

They require more power to obtain the same performace level as prop driven applications -- i.e. they are not as "efficient".

They fly faster -- this can be good or bad depending on your perspective.

They can be pretty picky on inlet ducting and outlet tube diameter.

The "COOL" and "WOW" factor is off the charts! This is what makes the reduced flight times and all the other problems "worth it".

I'm looking forward to your results!

McD
Latest blog entry: LEDs on my T-28
Jul 07, 2013, 09:24 AM
Retired CAD guy
birdofplay's Avatar
Part of the Slide on Ground beauty is ...
NO finger chop worries during launches
and
NO Prop damages on landings.

EDFs , I agree, are way less efficient.
and more finicky.
and all that speed simply cost more $$$.

I like flying Close In as Dots Across the sky is kind of a silly hobby.

So, Even though I do like the SOUND of the new multi blade Fans,
my vote is to forget the EDFfort !
Jul 07, 2013, 12:50 PM
AMA16634...Just Me
Quote:
Originally Posted by Lockey
Just playing at this stage Kadil and listening to you guys and looking for any advice

Lockey
Some of the best advice you can get on here about EDF's is right here...

https://www.rcgroups.com/dons-rc-548/
Jul 07, 2013, 02:17 PM
Retired CAD guy
birdofplay's Avatar
I am sure everything is in that Forum.

But that IS the problem, you almost have to read it all ( some with a grain of salt)

What is lacking around "here" is a concise summation of the essential info.
With all the chitchat filtered out.

Yes ! I am just a guilty as the rest for adding lots of unnecessary blather to otherwise
interesting threads.
Jul 07, 2013, 03:50 PM
AMA16634...Just Me
Quote:
Originally Posted by birdofplay
...........But that IS the problem, you almost have to read it all ( some with a grain of salt)..........
Nonsense...not a problem at all.....if you have a specific question related to EDF's, just direct that question to Don. He is very knowledgeable and freely shares his knowledge on these boards.
Jul 07, 2013, 06:11 PM
Retired CAD guy
birdofplay's Avatar
OK then DON is our guy, thanks :-)
Jul 07, 2013, 11:35 PM
Altitude is my friend...
Depronicus's Avatar
Quote:
Originally Posted by kingsflyer
Here are my general impressions on EDFs: They require more power to obtain the same performace level as prop driven applications -- i.e. they are not as "efficient".

They fly faster -- this can be good or bad depending on your perspective.

They can be pretty picky on inlet ducting and outlet tube diameter.

The "COOL" and "WOW" factor is off the charts! This is what makes the reduced flight times and all the other problems "worth it".
Agreed, but add to that something that must be kept in mind when flying EDFs: With most EDF planes you have no propwash blowing across your control surfaces. Speed is critical. Slow-flying an EDF is extremely risky.

A great source for EDF equipment is Fan Jets USA. I got the following for a 38-inch Mig-15, and it's a very good combination:

EDF2W20 | HET Typhoon EDF 2W-20 motor

FJUTUBE | Fan Jets USA Thrust Tube

EDF6904 | HET 70mm EDF Fan Unit 6904

A 4-cell 2200 45C battery yields flight times of maybe four minutes if you take it a bit easy. Designing a plane around this strong powerplant would not be a bad idea.
Jul 08, 2013, 03:43 AM
unconventional :-)
kadil's Avatar
Quote:
Originally Posted by Depronicus
Agreed, but add to that something that must be kept in mind when flying EDFs: With most EDF planes you have no propwash blowing across your control surfaces.....
Hi Depronicus,

Your point makes total sense, but different physcis is the enabler for completely new designs. Think of this, if you had a twin boom plane with the jet right at the front with long booms, and a small thin control surface in the stream would be very effective. The other option would be to thrust vector the edf.

I am sure great slow flying models will be created with edf's in the future, but you are right, you cannot just retrofit a prop with an edf and retain the slow flight characteristics of a control surface in the prop wash.
Jul 08, 2013, 05:38 AM
Tony Audsley Retired Locksmith
Lockey's Avatar
Thread OP
The low tail Dualis (apart from the rudder) had little or no control surface in the prop wash and it seemed to do OK

I will experiment with the EDF in the same position as the prop and see what it does

Thanks for throwing in some ideas and comments guys

Lockey
Jul 08, 2013, 06:00 AM
unconventional :-)
kadil's Avatar
Quote:
Originally Posted by Lockey
The low tail Dualis (apart from the rudder) had little or no control surface in the prop wash and it seemed to do OK

I will experiment with the EDF in the same position as the prop and see what it does

Thanks for throwing in some ideas and comments guys

Lockey
Yeah, I reckon there was something else happening there. Of course light models fly slow well but there might be something with the taileron inline with the main wings that also works well. Look at all those foam F22 and MIG 29 type models work very well at low speed.

My vote, just do it, everything you touch seems to glow Lockey. More power to you.
Jul 08, 2013, 06:08 AM
Tony Audsley Retired Locksmith
Lockey's Avatar
Thread OP
Thanks Kadil

Now ... how do I test the thust of a motor/prop etc against a EDF? or even one motor and prop against another motor prop

For instance ... I tried this motor https://www.hobbyking.com/hobbyking/s...idproduct=5684 on the new build and with a 2 bade or 3 blade 6 x 4 it didn't seem to have much thrust at all ... (holding the model at the front and giving it full throttle) compared with this https://www.hobbyking.com/hobbyking/s...dproduct=12919 which I use all the time and it has LOTS of thrust

Lockey
Last edited by Lockey; Jul 08, 2013 at 06:52 AM.
Jul 08, 2013, 06:17 AM
unconventional :-)
kadil's Avatar
Quote:
Originally Posted by Lockey
Thanks Kadil

Now ... how do I test the thust of a motor/prop etc against a EDF? or even one motor and prop against another motor prop

For instance ... I tried this motor https://www.hobbyking.com/hobbyking/s...idproduct=5684 on the new build and with a 2 bade or 3 blade 6 x 4 it didn't seem to have much thrust at all ... (holding the model at the front and giving it full throttle) compared with this https://www.hobbyking.com/hobbyking/s...dproduct=12919 which I use all the time and it has LOTS of thrust

Locey
https://www.rcgroups.com/forums/showthread.php?t=252722


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