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How to efficiently power EDF's

#1
Now I'm to expert on this topic and I'm posting in hopes to get some help.
I want to power 2 EDFs at 40mm with 8000kv motors on them
What is the best approach, best ESC's to use and best battery combo? I'm looking to get the most out of flying and extent the flight time as much as possible and not burn out the ESC's or battery.
What can I do???
Thx for helping.
 

b-29er

Active member
#2
EDFs and efficiency are like motor oil and and orange juice. They don't go together in any way whatsoever. The problem generally comes down to pitch speed, which EDFs are great at, but makes them horrendously inefficient. My best advice is to use an ESC with a slightly higher amperage than the manufacturer recommends, so if you're thinking something like this guy you could use a 30a esc, especially something like a multirotor ESC where they are designed small, you can easily keep in airflow and they can be programmed. As for a battery, that all depends on how much weight you can handle. You may want to try to glide the thing and see how much weight you are comfortable with for flying characteristics, then look for a battery in that weight class. If you use the motors i pictured, you want 60a, so you would want to multiply the battery capacity by the C rating. So if you got a 1000mah battery you need a 60c pck. 2000mah 30c, 3000mah 20c, etc.
 
#3
EDFs and efficiency are like motor oil and and orange juice. They don't go together in any way whatsoever. The problem generally comes down to pitch speed, which EDFs are great at, but makes them horrendously inefficient. My best advice is to use an ESC with a slightly higher amperage than the manufacturer recommends, so if you're thinking something like this guy you could use a 30a esc, especially something like a multirotor ESC where they are designed small, you can easily keep in airflow and they can be programmed. As for a battery, that all depends on how much weight you can handle. You may want to try to glide the thing and see how much weight you are comfortable with for flying characteristics, then look for a battery in that weight class. If you use the motors i pictured, you want 60a, so you would want to multiply the battery capacity by the C rating. So if you got a 1000mah battery you need a 60c pck. 2000mah 30c, 3000mah 20c, etc.
Well, I have 6 x 35C 2200 mah and 4 x 30C 2200 mah batteries. I also have 1 x 20 amp ESC, 1 60 amp ESC and 4 x 40 amp ESC's. So, my maiden flight I used 2 x 40 amp ESC's and ran a Y cable to the battery (35C 2200mah) powering with motors. The result was 1 minute at full throttle at bench test. Unfortunately I had crashed on the maiden due to loss of orientation. No big deal I'll make the same plane again. I'm curious how to get more out of the battery time wise. Also the ESC's were very warm to the touch.
Any advise on using these parts best???
 

b-29er

Active member
#4
not really. There's not a lot of wiggle room when you have the powerplants picked out. You could upsize to a 50/55mm edf, which would give you the thrust for takeoff, but wouldnt need the same high rpms to get you the thrust you need for cruise, which would get you a longer flight time. You could also use a y harness and double up on batteries so you get longer flight times.
 
#5
not really. There's not a lot of wiggle room when you have the powerplants picked out. You could upsize to a 50/55mm edf, which would give you the thrust for takeoff, but wouldnt need the same high rpms to get you the thrust you need for cruise, which would get you a longer flight time. You could also use a y harness and double up on batteries so you get longer flight times.
Hmmmm, ok... I do have 2 x 50mm 12 blade EDFs. They call for 4S 1800 mah batteries. I have 4 of them coming in the mail. Thanks for the help. I'll have to figure it out. I guess this is why they make single edf jets and fake the double engine look...
 

b-29er

Active member
#6
oh, i'd definitely do that then. More blades means less ripms, less ripms means more real jet engine noise and less hair dryer on steroids noise, and a lower pitch speed. On a side note, interesting tidbit i saw from the build video for the Freewing a-10 around the 6:30 mark
If you feel like ripping the whistles out of a Nerf football, you can add them to the insides of your engine nacelles (probably about where the ESCs should be hanging out anyways for cooling) and use them to add a whistling effect. That's a great looking Citation by the way, are you putting up a build log?
 
#7
oh, i'd definitely do that then. More blades means less ripms, less ripms means more real jet engine noise and less hair dryer on steroids noise, and a lower pitch speed. On a side note, interesting tidbit i saw from the build video for the Freewing a-10 around the 6:30 mark
If you feel like ripping the whistles out of a Nerf football, you can add them to the insides of your engine nacelles (probably about where the ESCs should be hanging out anyways for cooling) and use them to add a whistling effect. That's a great looking Citation by the way, are you putting up a build log?
Wow, what a great A-10!!! The whistles are a great idea. I'm going to have to think and ponder what the plan is going forward. Thank for the nice comment, the plan is actually modeled after a Learjet 70... they do look the same...
 
#8
Just curious, I searched EDF and this came up. If I were to order an edf off Amazon (see attached photo) it says 4s. Question 1: can I use a 3 s. 2. Is the ESC that's recommended in photo 1 good (I am new to ducted fans so I have no clue what I'm looking at!) 3, how big does the air inlet for the 50mm need to be. I'm doing a project that has a plane that wasn't a jet, so I'm modifying it, and I need to know how big the air inlet should be. Thanks!
IMG_3518.JPG IMG_3520.JPG
 
#9
Just curious, I searched EDF and this came up. If I were to order an edf off Amazon (see attached photo) it says 4s. Question 1: can I use a 3 s. 2. Is the ESC that's recommended in photo 1 good (I am new to ducted fans so I have no clue what I'm looking at!) 3, how big does the air inlet for the 50mm need to be. I'm doing a project that has a plane that wasn't a jet, so I'm modifying it, and I need to know how big the air inlet should be. Thanks!
View attachment 137031 View attachment 137032
That is the exact same edf I bought from amazon. I have 2 of them. The recommended battery is a 4s 1800 mah. It flew ok with a 3s 850 mah but was kind of just flying around. Not enough power. Amazon is great because I flew with them for a month then sent them back before the time expired and got my money back... now I'm still waiting on the 4s 1800 mah to show up. My C of G is going to change but the plane is going to tear up the sky with the 4s... I had build a Super Bandit off www.rcgroups.com. Great plans and great plane. Your esc is fine... IMG_20190607_1728080.jpg