Thrust/Price Questions

[Recon Chris]

I am questioning the thrust values of a duct fan system. It seems like every one I look at is incredibly weak for its size and price (about $18).

So I’m wondering if maybe you need to or can put two duct fans in one tube. Would this increase the thrust output by two?

Or is there some duct fan out their that I haven’t seen that is powerful and cheep

(Not to be picky: 15oz of thrust at 7.4 volts cost $25 or under for the entire system)

Something along the lines of that.

I’m trying to build a Sabre 86 that is probably going to weigh 14 to 16oz so I want it to have vertical or near vertical climb.

Duct fan systems are kinda new to me:roll: so any information would be great.



Thank you

[raido56]

I am questioning the thrust values of a duct fan system. It seems like every one I look at is incredibly weak for its size and price (about $18).

So I’m wondering if maybe you need to or can put two duct fans in one tube. Would this increase the thrust output by two?

Or is there some duct fan out their that I haven’t seen that is powerful and cheep

(Not to be picky: 15oz of thrust at 7.4 volts cost $25 or under for the entire system)

Something along the lines of that.

I’m trying to build a Saber 86 that is probably going to weigh 14 to 16oz so I want it to have vertical or near vertical climb.

Duct fan systems are kinda new to me:roll: so any information would be great.



Thank you

Hi Chris,
Did you ever hear the old saying "(How fast do you want to go and how deep are you pockets)":) J/K. You are leaving out a lot of info for what you want. What size fan unit, brushed or brushless motor what type of battery pack? Is the weight of 14 to 16 oz's with or without the battery pack? What size ESC will you be running? I see you want vertical or near vertical climb. You are not going to get that at 7.4 volts that's for sure. Below is my F-16 with a 55mm fan, 5100 Kv brushless motor 40 amp ESC and a UBEC running a 4 cell 2200 pack. All this get's me 1:1 thrust, vertical climb and speed of 100+mph with an all out cost of about 250 bucks.
Keep em flying :D
raido56/Herb

[Recon Chris]

Your right I was a little scarce with information.

The plane will be 16oz max with battery (hopefully).
The speed controller or ESC will be 18 amps and meant for a brushless motor
The fan diameter should be 45 to 55 millimeters. I’m not really picky about that as long as it has substantial thrust.
The thrust should be from 10oz and up and I’m willing to buy an 11volt battery.
However I don’t want to buy a duct fan set up that is over 25 dollars.
I was looking at some of these GWS ducts and they are the only thing close to what I’m looking for. Maybe I can put two of them in the same tube would it make the plane go twice as fast?

http://www.aeromicro.com/Catalog/gws_edf-75x4a_1697321.htm (http://www.aeromicro.com/Catalog/gws_edf-75x4a_1697321.htm)
Though it isn’t brushless.
I’m thinking though that a brushless duct fan would always be better, though I haven seen one for fewer than 25 dollars.

But how do you pull so many amps through that plane of yours. I always hear people doing that. They will have a 25amp maximum draw set up and they will use a 45amp ESC. Is that necessary for safety or you don’t want the ESC to heat up or is it mandatory and I need one too?

I also hear that you can only run number of servos with a certain amount of lipo cells.

[raido56]

Your right I was a little scarce with information.

The plane will be 16oz max with battery (hopefully).
The speed controller or ESC will be 18 amps and meant for a brushless motor
The fan diameter should be 45 to 55 millimeters. I’m not really picky about that as long as it has substantial thrust.
The thrust should be from 10oz and up and I’m willing to buy an 11volt battery.
However I don’t want to buy a duct fan set up that is over 25 dollars.
I was looking at some of these GWS ducts and they are the only thing close to what I’m looking for. Maybe I can put two of them in the same tube would it make the plane go twice as fast?

http://www.aeromicro.com/Catalog/gws_edf-75x4a_1697321.htm (http://www.aeromicro.com/Catalog/gws_edf-75x4a_1697321.htm)
Though it isn’t brushless.
I’m thinking though that a brushless duct fan would always be better, though I haven seen one for fewer than 25 dollars.

But how do you pull so many amps through that plane of yours. I always hear people doing that. They will have a 25amp maximum draw set up and they will use a 45amp ESC. Is that necessary for safety or you don’t want the ESC to heat up or is it mandatory and I need one too?

I also hear that you can only run number of servos with a certain amount of lipo cells.




You could go with this fan ETH550 "XF-Fan" 56mm Ducted Fan ..... $ 24.90 and with this motor will give you around 20 oz's of thrust on a 3 cell pack ETH5512 XF-Fan 5100 Inrunner Brushless Motor ..... $39.90 but you will need a 25 to 30 amp ESC. I would go with the 30 amp one. These items are sold by Hobby-Lobby here in the USA. Now as far as the amp draw on my motor it is between 30 to 34 amp's so I feel safer with a 40 amp ESC and yes to run the 4 cell pack I use a UBEC as I can not run the on board BEC with 4 cells. But with a 3 cell pack you can use most on board BEC's and still run 3 servo's no problem. I run a UBEC on all my jet's as I do not like the on board BEC's. Plus it is a bit safer if my ESC did burn up I still have control of my servo's and can land the jet with out it taking that dirt nap ::o. The UBEC's are about 15 bucks but it will be the best 15 bucks you will ever spend. I have an E-Flight Airliner that went in twice because of the on board BEC burning up as it has to run 5 servo's but in the book it does not tell you that. I learned it the hard way. Now that I have a UBEC in the Airliner no problems after 25+ flights and with it I can use up to 9 servo's. Here are a few pic's of the Airliner.
Keep em flying:D
raido56/Herb

[Recon Chris]

I saw the fan you are talking about but it doesn’t come with the $77 screamer motor. It only shows a motor on it.
Otherwise it would be great.

However I believe the GWS EDF-75X4A does come with its own motor.
Its charts say that it will generate 10.6oz of thrust with the intake ring.

For the price I am having a hard time finding people to beat it.

[Bill G]

The GWS EDF55 will easily put out over the 10oz thust spec you have, with a number of motors. With my latest jet, I'm getting 11.5oz with a Park 370-5400 on 3s, and I'm sure more could be gotten in a plane with simpler, straighter ducting. Probably could do 10oz with a 370-4100 if the plane had clean ducting.

[babylon5]

Hi, just to add on, some of this GWS 55 mm EDF are really affordable. If you know how to match this fan with the right brushless motor you could get alot out of this unit.

To-date my most efficient low cost EDF set up is a twin 55mm EDF GWS with a Walkera B20-40-3.2KV brushless motor,unobstructed intake/outlet setup.

The twin 55EDF gws takes in 24-26amps on 3S lipo and could haul 700grams model easily.

Alternately you could try a single 55EDF with a higher KV brushless motor from 3.8-4.2KV for 3S lipo setup. (you will lose some efficiencies as you go for higher KV and the motor might run hot)

I hope this will help you.
:)