Matt Carlton Posted April 27 Share Posted April 27 (edited) Hello all. I'm contemplating building a Middle Phase 2 as an electric model as an alternative to foamy lot. I would normally aim for around 100w/lb for something like that, but one of my ideas is an EDF unit on top of the wing and I'm not sure if the same formula applies to EDF My initial thought would be something like this, but on 3S rather than 4, or would it need 4S because of the higher kv motor? EDF unit But I'm not at all experienced with edf so working out power systems is a new thing. Any thoughts? I'm not sure how things like diameter, fan pitch, nacelle length etc work in comparison to a prop. Edited April 27 by Matt Carlton Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted April 27 Share Posted April 27 Matt Consider the diameter of the EDF versus prop. It is likely to be 1 to 3 or even greater. To help make up for the small diameter a multi blade and coarse pitch fan will be used but a multi p=blade is less efficient than a 2 blade and a coarse pitch is good for speed but limits the static thrust. As a minimum you have to consider doubling the Watts/pound prop to EDF. This explains why EDFs tend to have short flight times coupled with the fact that most EDF planes are based on "jet" type airframes so speed tends to be an objective. Quote Link to comment Share on other sites More sharing options...
Matt Carlton Posted April 27 Author Share Posted April 27 Thankyou. That's basically what I needed to know. My assumption then, is that to get the performance I'd want from the model, I'd be looking to have more wattage (cost, weight etc) than I really need, given that I could shove a reasonable size outrunner in the snout for very little outlay and probably better performance. That said, there are some examples around but I have no experience of them, the Max Thrust Aggressor Extreme being one of them. I could just go for one of Stan Yeos electric jobs like the Pzazz. I just happen to really like MPs (nostalgia I guess) Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted April 27 Share Posted April 27 It is not that you can't drive even a glider type with an EDF but a glider is not optimised for high speed flight whereas an EDF is. In addition an EDF is fixed in the airstream whereas a prop can fold to reduce drag. It comes down to a personal choice. I note the MaxThrust Aggressor is recommended for experienced pilots. Compared to the Aggressor Sport with a folding prop it uses a different wing and a 4s rather than a 3s LiPo. Quote Link to comment Share on other sites More sharing options...
SIMON CRAGG Posted April 28 Share Posted April 28 Oddly enough I have just completed the same. Middle Phase + Powerfun 70mm EDF. Flew it a few times and sold it on. I am now looking at the TOP RC Swift, which is a similar design, but carbon reinforced thin wing etc. 100mph +! Quote Link to comment Share on other sites More sharing options...
PeterF Posted April 28 Share Posted April 28 This is an outcome of fluid flow dynamics, for a specified thrust it takes less power to move a large mass of air slowly (prop) than a small mass of air rapidly (ducted fan). Quote Link to comment Share on other sites More sharing options...
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