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EDF Booster

#1
Loved the ep. where David installed the afterburner on the vampire,
BUT,
what if the plane has a prop on the front?
Would love to see a short ep. and results on an EDF booster because, will adding an EDF unit increase the speed of the aircraft a bit, or enough to tear the wings off ?
 

Fensone

Master of the stock AXN
#2
what if the plane has a prop on the front?
Do you mean a brushless motor with a swinging prop, or another EDF unit?

Would love to see a short ep. and results on an EDF booster because, will adding an EDF unit increase the speed of the aircraft a bit, or enough to tear the wings off ?
Nightflyer (Dave), made something like this. I will look it up for you.
 
#4
Sorry if I wasnt clear, I meant having a conventional plane with a propeller and adding an extra edf motor so that the plane now has 2 motors. A propeller for normal flying and an edf for added speed that can be turned on and off like a booster.
 

Ak Flyer

Fly the wings off
Mentor
#5
Interesting, but there's some problems. One is the extra weight that an edf and all of it's gear will add. Plus at higher speed you have drag from the propeller. You'd have to have a folding prop and shut it off when the edf came on. The airframe would have to be designed for carrying more weight which would hamper it's performance for speed. Or it would be barely able to fly on a small prop until the EDF took over. Not saying it couldn't be done in fact I'd like to see it but I don't think it's practical at all.
 

OutcastZeroOne

Fly, yes... Land, no
#6
I think the big issue is that people mistake an EDF for a jet engine. A traditional prop will produce far more power then an EDF. All an EDF really is is a small propeller spinning at very high speeds.

Here is a comparison. Breath out through your mouth and feel how much air flow there is, now do the same but this time do it through a drinking straw. Same amount of air, but now its coming out through a much smaller opening much faster. There may be more force behind it, but its like trying to push a car with a pencil. A prop will move a larger amount of air for nearly the same amperage load of an EDF. EDF's just allow for a smaller power plant and can make a scale jet look right instead of having a prop slot or big pusher prop.

The way a jet works is burning fuel in that rush in of air. That air expands and even though the same amount of air comes out the back end (burned up into CO2 and other elements) it being so much hotter it has a larger volume and gives a bigger push.

Not saying the EDF booster is a bad idea, just impracticle. A lot of guys find that they have to do a lot of tweeking with the inlet ducts and outlet ducts to maximize the EDF's performance. I've seen build logs of guys who would have to totally redesign the inlet of their ducts to get the performance they needed. You often hear Josh B talk about cheater holes in air frames of EFDs to get the needed airflow for that EDF, this is what he is talking about.
 
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Ak Flyer

Fly the wings off
Mentor
#7
A turbine or "jet" is really just the powerplant that spins the fan. A passenger jet uses a turbofan engine or turbine powered ducted fan. An EDF is an Electric Ducted Fan. They're not all that different. He's right though in the way that they make power. They have to pull in huge amounts of air and direct it rearwards in a powerful jet. They typically fun much better at faster speeds where they can be efficient. Same goes for big turbofans. EDF's in RC are almost pointless from a performance perspective because we have to fly within sight of the model. They can't really be used to their potential. Also, like Outcast and Josh both said they usually can't use scale type ducting. The cheater holes most models use are necessary just to take flight. Most scale fuselages starve the engine whereas a prop is always out in clean air.