EDF 3 Blades or 4 Blades?

[mirage2k]

lol edmond22,

i understand the debates that went through between people and the 'b' . i guess you really have to ignore them if you dont feel good about it, its up to individuals. you cant judge everyone, we are humans. y make yourself miserable. for me i am neutral.

my opionion will be i would not even try to cut the blades because of the balancing problem and the blade spacing issues etc. it is a waste of time. i would just get one, try out, cannot work then put aside, wont ask experiments, wont show, wont leave a thing in forum. what actually happened to me is that i was dissapointed running the HET FAN & HET2W ( so called most recomendations for 3s ) and bloated my lipo ( 5 of them ) . well it could be my lipos problem . so i tried with my heli motor with a less KV and it flew faster ( by eyes ) & did not bloat my battery but still hot. so for that saving my risk of my batteries i kept thinking low kv handles more blades / higher pitch etc, with this i went to lower my blade count to 3 instead. but after doing so, i tested a layman way and the fan didnt lift well ( so called static trust ). i am afraid of something like putting a 55mm ducted on a 1kg 70mm plane ( layman term ). my plane needs to be glued together & if it is done, i cant do anything about it, so i want to understand what earlier spoken before i make decision. For me i dont need the plane to zooooom super fast, as long it lifts off and not like a kite's speed / propeller, i am fine you see. But i dont want my plane to become a diving bird after a hand launch. But i have relatively clear understanding already.

to be honest i have no knowledge to comment on any technical issues on earlier posts like the 5000mah 4s, thats y i stated ' i dont really know much' but as a layman looking at it it was like weight = no good thats all. i didnt try but friends flying 4s lipo 2200mah works well with good speed, so i guessed if more load means = problem, u see. weight problem happened on my heli, propellor planes too. especially batteries.

thanks for the above technical help and links. i will try to figure out step by step how to use the program etc. sometimes please pity the layman out there with little time for hobbies but love them. i will put it that hobby is a hobby, dont really have to put it like 'working'. stress man . lol

cheers
nite

[edmond22]

lol edmond22,

i understand the debates that went through between people and the 'b' . i guess you really have to ignore them if you dont feel good about it, its up to individuals. you cant judge everyone, we are humans. y make yourself miserable. for me i am neutral.

my opionion will be i would not even try to cut the blades because of the balancing problem and the blade spacing issues etc. it is a waste of time. i would just get one, try out, cannot work then put aside, wont ask experiments, wont show, wont leave a thing in forum. what actually happened to me is that i was dissapointed running the HET FAN & HET2W ( so called most recomendations for 3s ) and bloated my lipo ( 5 of them ) . well it could be my lipos problem . so i tried with my heli motor with a less KV and it flew faster ( by eyes ) & did not bloat my battery but still hot. so for that saving my risk of my batteries i kept thinking low kv handles more blades / higher pitch etc, with this i went to lower my blade count to 3 instead. but after doing so, i tested a layman way and the fan didnt lift well ( so called static trust ). i am afraid of something like putting a 55mm ducted on a 1kg 70mm plane ( layman term ). my plane needs to be glued together & if it is done, i cant do anything about it, so i want to understand what earlier spoken before i make decision. For me i dont need the plane to zooooom super fast, as long it lifts off and not like a kite's speed / propeller, i am fine you see. But i dont want my plane to become a diving bird after a hand launch. But i have relatively clear understanding already.

to be honest i have no knowledge to comment on any technical issues on earlier posts like the 5000mah 4s, thats y i stated ' i dont really know much' but as a layman looking at it it was like weight = no good thats all. i didnt try but friends flying 4s lipo 2200mah works well with good speed, so i guessed if more load means = problem, u see. weight problem happened on my heli, propellor planes too. especially batteries.

thanks for the above technical help and links. i will try to figure out step by step how to use the program etc. sometimes please pity the layman out there with little time for hobbies but love them. i will put it that hobby is a hobby, dont really have to put it like 'working'. stress man . lol

cheers
nite

To be real honest with you bro, just like you say individuals handle things differently, I get a kick from a good discussions. It exercises my brain and it is quite nice to exchange knowledge.

RC Hobby never really felt like work to me though it does get very tiring at times doing things like repair etc. But I guess some of us (esp me) get a kick from these stresses and keeps coming back for more. LOL I have no idea why. I went through bungee launches, new setups, untested design, heli, 3D etc etc to renew the kick and adrenaline from there, it is funny but I actually enjoy the trembles it gives me in the finger and legs (like trying piro flip for the first time).

1 thing I would like to share with you is I noted that you love this hobby enough to want to build and fly and even ask questions, but you prob also looked for a bit of short cuts and thus not understanding the basics of amp draw, electric motor consumption got you into trouble of bloating the 5 lipos. I can actually tell you that between Wemotec and HET fans, I like HET one more and esp more so its 2w20 and 2w25. I also like the GWS EDF 55, GWS EDF 50 and the Wemotec micro fan. The rest I have ever bother to lay hands on did not cut the job (I experimented and never quite got worthwhile results). The quickest way of getting results and increasing the chance of buying right is to simply google or ask in this forum for a particular kit. See Youtube and see their setup. Most of them can give you readings and flight time and what batts they are using. Those are good references, that is why I keep emphasizing on research and reading on forums, it helps to also weed out nonsense from contributions. I am sorry I appear to you that way mate. But I just hope you can look from another angle a bit and think for a bit, did I attempt to shield you or did I attempt to run you down? Keke, I intended the former to put in a bit of balance to the B fellow, maybe overdid it and the fire spill over your end as well. If you are like what you say, can tell it is not a good idea to cut blades and never contemplated it, that is good, but there are so many new comers and with these kind of postings like cutting blade and putting ever more powerful BL motors, it is very highly probable to be running past recommended RPM and manufacturer spec of the fan, what started as merely a ignorable posting can lead to a newcomer losing a plane, gets dissappointed and give up the hobby. Worse still, what about crashing into MRT tracks or expressway? It all happened before, and far too often, we get the no control, no power, not my fault answer. Every bit counts to counter misinformation, trust me on that.

Tell me agaim your setup, like your fan, motor, batts config and kit. I can run some numbers for you and we see how it progresses. RC Warbirds, ever try asking them, they know their stuff very well too.

[Vortices]

Hi Guys,

Take it easy, it is a hobby, however it is one of the most complex and technical hobby there is. As such some background knowledge is needed to understand how it all work and to improve set ups.

Thru my homework and experiments and mis-adventure, following are my understanding.
-EDF is a little more complex than motor and propellor combination, simply because props are cheap, if one doesnt work just change the prop. Not so for EDF, the fan units can often cost as much as the motor therefore due economic, there is a relunctance to mix and match as readily as props, hence proven combinations are the way often chosen.

-EDF plane has a much wider speed range, slow for to and landing and hair on fire speed on low passes-would be the prefered choice. This ability takes into consideration many factor, some are less obvious than others. Simply pumping more amps and more voltage for more RPM is a very coarse approach to improving speed, nonetheless it works-not very well but it does.

-To acheive high speed, one major factor that is often missed is the airframe. The more dragy the airframe the more thrust it need to speed up and to maintain speed. And most of this comes from the wings not the fuselage(assuming it is reasonably shaped) .
Therefore if speed is what you want, choose a suitable airframe to start with. Max speed is always determine by airframe not engine, the cleaner the airframe the faster it goes. Take gliders for example, it hasnt got an engine, speed performance is a direct function of the airframe.

-Powerplant, what edmund suggested watt/thrust or amp/thrust (on every GWS publication) is a good indication of suitability of combination. Cutting blades on a edf MAY improve thrust! I have successfully proven that. It even improves efficiency! however that is because it was a wrong combination to start with. Eg, a 150watt 5300kv motor on a 55mm GWS edf will give you more thrust/watt on cutdown 3 bladed than uncut original 6 bladed. But on 6 blade you get marginal more thrust on full throttle. However if you up the motor to 300 watts, the thrust/watt recovers significantly and still gives very high full throttle thrust. Simply put, a good combination is critical for EDFs. If you are into 64mm fan, 400w motor on 3s at about 4300kv is about the most efficient, one can get on a reasonable weight.

-Ducting, this is the third pillar of all successful edf planes. IT IS SUPER CRITICAL! and it can further fine tune the motor to fan combination. The understanding of this is too long to state simply, just do a seach on the net, there are multiple write ups on it. Things like convergent /divergent, FSA all needs to be address. A fan without duct is like a bad stalling shrouded prop.

So there you go..
1) choose a plane
2) choose a fan/motor
3) correct the ducting
4) hold your breath, full throttle and launch
5) hope for the best.

Good luck.