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Old Feb 28, 2012, 06:20 PM
Registered User
USA, MN, Bloomington
Joined May 2002
47 Posts
What kills high-KW EDF systems?

I have been researching power systems for my Cermark MB-339 and would like to find a reliable EDF setup. With an 11 lb thrust turbine it had a nineteen pound flying weight. Looks like 4000 watts would be a minimum to provide similar performance. My flying style suits a balance of speed and flight time.

If set up and used properly, what can go wrong with these EDF systems? I'd like to avoid damaging or degrading something after the initial outlay of some significant cash. Trouble-free performace is highly valued.

I'm familiar with keeping the battery drain less than 80% of capapcity and not getting the cells too hot. Is FOD a major problem? ESC or motor issues?

I'm looking at Stumax, Dynamax and BVM fans. Curious to hear your experience.
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Old Feb 28, 2012, 07:15 PM
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United States, TX, Grand Prairie
Joined Nov 2005
6,105 Posts
Undissipated heat kills a lot of things, proper airflow for motor, esc's and in some cases batteries helps go along way.

IF you have long esc battery wires put stiffing caps every 1.5ft or so and it's not a bad thing to use a spark resistor for extra really cheap assurance and for convenience I think there's a company that does an inline one that's easy to solder.

I like some slow start on the fan also either set on the esc or the radio because it doesn't slam the batteries and other components with burst current and sounds kinda scale with the right fan. I have my 70mm MB1 motor and SAPAC rotor set to wind up very similar to a p20 with the SUPPO heli esc...I think it sounds sick once it is WOT 1/4 into it's take off.

I have a Ramtec rotor, FOD isn't a real issue with it because of what it's made...you can put some ignorant power through it without having to be concerned about a blade being thrown.

On the packs the higher the C rating the better usually unless you like to fly with your hair on fire in that case they can save an aircraft on a bolter or 2...3 . I like to fly with a timer because of high C rating packs "knees" are sharp meaning the real high C rating packs don't gradually lose power they fly at 95% till their 100% empty depending on your amp draw.

Mostly EDFs are no fuss for the most part, the one thing that is a fuss is getting a 20kw charging system to field to "top off" your packs so turbine guys wont snicker while your charging.

Either the 20kw charging system or carry 2 sets of packs...
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Last edited by erh7771; Feb 28, 2012 at 07:34 PM.
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Old Feb 28, 2012, 08:40 PM
EDF all the way!
bruff's Avatar
Gilbert, Az
Joined Jun 1999
8,154 Posts
I have a friend building this same jet. He is using a XPS Dynamax w/Hacker motor. Great 4000 WATT system. Drop in fit. I been flying the same fan system with no issues for about 2 years.
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Old Feb 29, 2012, 08:24 AM
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Omaha, NE
Joined Jun 2004
237 Posts
Here was mine on a SM110-52. I loved that plane!

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Old Feb 29, 2012, 10:13 AM
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Swarthmore, PA 19081
Joined Dec 2004
2,854 Posts
I'd go Dynamax with one of the many outrunner setups that have be tried and proven.
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Old Feb 29, 2012, 10:32 AM
Build'em and Crash'em
Ken Lapointe's Avatar
Narragansett, RI
Joined Oct 2000
3,444 Posts
Question : What kills high-KW EDF systems?

Answer : Pilots
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Old Feb 29, 2012, 10:39 AM
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Tamjets's Avatar
San Jose, CA
Joined Jun 2006
5,453 Posts
Originally Posted by Ken Lapointe View Post
Question : What kills high-KW EDF systems?

Answer : Pilots
So truth. I kill my high power system often by pushing to the limit.
But 4kw is not high kw system any more.
Even my TJ80 can put out this power.

So here is my tip.
Find the system that are light as possible and rock solid at 4kw performance.
Goes to my YouTube channel Tamjets.
There is a lot of high kw system demo video.
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