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Old Apr 14, 2014, 01:50 AM
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Joined Jan 2013
88 Posts
Help!
Got a few basic questions on EDFs

Well first of all I this is not a jet but for a hovercraft's lift power system. So the EDF will be stationary all the time, blowing air out to fill up the skirt of the hovercraft.
Here are the questions:
1) Thrust is my primary requirement. Are EDFs good at providing thrust compared to props?

2) Can EDFs run in the opposite direction, that is, can it push air from the front instead of sucking air in by interchanging 2 wires?

3) I am thinking of buying this EDF : http://www.banggood.com/RC-Model-12-...-p-912234.html
Is it any good, keeping in mind that thrust is my primary concern? I will be running it in 3S configuration.

I am completely new to EDFs. So don't hate on me if my questions are too basic or screwed up. Thank you.

P.S: My first language is not english. So sorry about my bad grammar.
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Old Apr 14, 2014, 08:15 AM
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Larry Dudeck's Avatar
Williamsville, NY, USA
Joined Sep 2000
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In answer to quest. #1. Amp for amp, dollar for dollar, diameter for diameter, an EDF will not beat a prop in thrust.

#2. Probably not but that applies to props as well.

#3 no basis to form an opinion

For someone whose who is not a native English speaker, your grammar is just fine. In fact, it's better than a lot of what is read on this forum
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Old Apr 14, 2014, 08:49 AM
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Quote:
Originally Posted by Larry Dudeck View Post
In answer to quest. #1. Amp for amp, dollar for dollar, diameter for diameter, an EDF will not beat a prop in thrust.

#2. Probably not but that applies to props as well.

#3 no basis to form an opinion

For someone whose who is not a native English speaker, your grammar is just fine. In fact, it's better than a lot of what is read on this forum
Thank you for the reply Larry.
What if I only care about the diameter and the budget and current drawn is not a problem. Will a EDF perform better? Considering the space to mount the power system is limited.
Or is pusher prop the way to go?
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Old Apr 14, 2014, 12:45 PM
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Williamsville, NY, USA
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I would use the largest diameter prop I could fit The resulting weight of the power source (prop, motor, battery, ESC) will be less than an amp hungry EDF. Lower weight will result in a better flier
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Old Apr 14, 2014, 01:44 PM
Jet-Addicted!
United States, SC, Greenville
Joined May 2012
170 Posts
I'm not trying to start a flaming-campaign here.. I'm sure there are many guys who would argue otherwise, however I am a frequent EDF flyer, and I've had enough wins (AND losses!) that I think I can chime in meaningfully here - since this is def. a "macro" question- (not enough details in the question to be "micro")

1) In general, EDF power systems WILL NOT be nearly as efficient as a prop system - IN GENERAL. YES_ I concur there are guys on here that are literally WHIZ-wizzard class at putting power systems together. (They are WAY smarter than me) and YES- they ould probably engineer an EDF so perfectly, that they could eek-out near-equal efficiency! However for the rest of us in the real world, we can't. EDF"s are a compromise, and in general, if I were you- reading your (macro summary) of your application, I'd try to go prop

2) EDF's can be VERY demanding on batteries - definitely more so than prop, AND they typically yield lesser flight times. Once again, THIS IS NOT SET IN STONE - and furthermore, let's call a spade a spade: some pilots are discipllined better than others and are less apt to fly like an arsehole - those guys WILL (for sure) experience LESS poofy-puffy LipO packs, than the undisciplined sot who does not. EDF's are HARD ON LIPOS. PERIOD.

3) EDF's comparatively have less "forgivingness" to either points 1 and/or 2 (above) as it pertains to their design [ and this is contingent on the aircraft in question of course] . So what's im saying is since you may not have alot of benchmark numbers to compare to (for a hovercarft app) I would say try to go prop, and aim for conservative numbers for amperage draw, and keep that in mind for the sake of your lipos.

hope that helps and hope that is not preachy sounding. Again, I know there are guys that will argue, but I FLY EDF's - and I am a jet addict. I know full-well I'd be better off converting half my damned planes to pushers, but I just can't let myself.. EDF's Are in-fact getting better, and at least catching up (that's the good news). TO me, while they're a big pain in the arse, I also think they're worth it and very VERY fun and rewardng to fly. Conversely, if it were a hovercraft and not a jet, I would NOT bother trying to use EDF's - you'd 90/10 be better suited with props, and have a little more leeway in terms of beating up your lipos.
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Old Apr 14, 2014, 08:08 PM
Aka: Tom Jenkins
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United States, FL, West Palm Beach
Joined Aug 2008
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Quote:
Originally Posted by kartiksriramk View Post
Well first of all I this is not a jet but for a hovercraft's lift power system. So the EDF will be stationary all the time, blowing air out to fill up the skirt of the hovercraft.
Here are the questions:
1) Thrust is my primary requirement. Are EDFs good at providing thrust compared to props?

2) Can EDFs run in the opposite direction, that is, can it push air from the front instead of sucking air in by interchanging 2 wires?

3) I am thinking of buying this EDF : http://www.banggood.com/RC-Model-12-...-p-912234.html
Is it any good, keeping in mind that thrust is my primary concern? I will be running it in 3S configuration.

I am completely new to EDFs. So don't hate on me if my questions are too basic or screwed up. Thank you.

P.S: My first language is not english. So sorry about my bad grammar.
What I see there is a Change Sun 12 blade, They are not very good with back pressure and low power.
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