what sort performance would you expect?

[Alex Hasell]

Hello all,

I haven't been flying long and have started with I.C but i always intended to do electric flight as well. My question is quite simple i have my eye on a kit  not an ARTF as i always wanted to build as well i'm looking into the future here but like to be prapared i'm considering EDF using a wemotec mini fan 68mm unit in a model weighing 1200g it say's that it runson a 480 size motor 40amp esc and 3 cell lipo of around 3200 mah capacity. I have no experience in electric flight as  i said so your thoughts about likely performance using this set up would be appriciated as well as what you would suggest to use say if i wanted to give it that bit extra....... its mainly chosing the motor that i am struggling with..

Regards, Alex

[Myron Beaumont]

Alex 

  If its any consolation you're not the only one struggling .I used to go flying every spare minute  ic _now I spend hours with maths (which i love by the way -hence the challenge ) working out power etc from my myriad of meters /wires/batteries/to fit  in my conversions to some of my ic  creations !  No problems with any of them apart from the music created. re :  Merlin etc (sorry I.m supposed to say decibels like the ones created by lawn mowers/hedge cutters/chainsaws etc)  that the average foot ball supporter type/hooligan / knife brandisher non productive Joe public is responsible for & thrives on  & loves cos thy've never actually created anything.

Grumpy

[Tim Mackey]

Hi Alex. if your model is weighing almost 3lb, then for reasonable performance, you should aim for at least 100 watts per pound EG: 300 watts. However, as you want it to be EDF then this needs to increase, as fans are not as efficient as props. I suggest you start with a regular prop driven electric model first....and see how you get on - EDF ( successfull EDF at least ) is more complex, and potentially expensive.

exactly what sort of model is it you are planning/ will it be suitable for EDF? what flying style will you expect / be capable of? The wemotec mini fans are good ( as are all the wemotec fan units ) but generally speaking, EDfs need very high revving motors - usually inrunners - and these drink quite heavily.

More model detail please mate.

[Alex Hasell]

Timbo,

Thanks for the reply there, well i was thinking along the lines of 100w per pound but want to try to increase this to about 130-150w. See i have become fasinated with jets! but could never afford one so thats why EDF. And please understand this is some time off yet i'm simply thinking ahead obviously my piloting skill need to be up to it first. The model in question is a hawk a west wings model of the red arrow although its finished in blue which i think is nicer anyway. As such it is designed to be EDF from the start even though its a kit not ARTF. The flying style is pretty run of the mill for this type of aircraft i would say  but i would ideally love it to have blistering speed in a straight line like the jets i've seen while i know i wont ever match them i just want an idea of what IS POSS with this type of model before i comitt to any thing this is why i am asking this question.

It's intended for the wemotec mini fan which is stated to be able to handle 700w max. maybe this will be able to give the speed i want ooor i might be better going up a size of fan unit i don't know don't worry im not saying i want 700w its just its max. Its stated to be designed for the wemotec a 480 motor and 3200mah 3s lipo, ive said what i want in terms of speed. Flight times i don't really expect to be very long if i could achive the  speed i would like to i would be happy with about 8 mins between charges 

I  have repeated some of the info here (sorry) But hope what else i have put is enough if not let me know what else you need to know to evaluate this for me. MAny Thanks Alex

P.s have you seen i have cracked it with the Boomer ha a full day yesterday with it and its brilliant!!!! cant wait to go again. And i've started building something for that 52 as well cheers mate

[Tim Mackey]

Ah...a little clearer now Alex - that model is designed around the wemotec mini fan 480 - NOT a 480 motor which are old fashioned brushed can motors and completely unsuitable for EDF.

You will need a  brushless motor of high Kv running on 3s battery something like an HET typhoon 2W or so.

If you want a really high quality and high performing motor then I can heartily recommend the mega series ( John Emms at Puffin has these, along with the necessary minifan shaft adaptors and so on. ) Something like the 16EDF will be superb and could even take a 4s Lipo if you really wanted to go ballistic, although on 3s at around 30 -35A you will be fine - should produce approx 360 Watts so you are at 120 WPlb.

This also keeps the ESC smaller and lighter ( and cheaper )

On a tighter budget ? try this from BRC - should also be OK on 3s and the mini fan. 

[Alex Hasell]

ok thanks for the help there timbo i was aware that it would bea brushless set up i would need reasoni said a 480 is thats what its states in the article that goes with the model i can only presume that they mean a size eqvillant in terms of pysicall size rather than the motors rating

I have been looking at the tests you have been doing with EDF's really fair play mate take my hat off to you. Good Stuff!