Stephen Jones Posted March 19, 2017 Share Posted March 19, 2017 Hi, I am playing with the idea of making a Ducted fan for my Micro Sipa 200 . Although the model is already flight proven and can be flown indoors the propeller at the back strikes the floor and so breaks and so not practical . So fitting a EDF unit would be the next step . But what if i could make my own . So i tested my original set-up, which was a 1504 Brushless motor, 12amp Esc, 3 inch prop , Which pulls 12 watts of power but i only need half of that to fly. Steve Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 19, 2017 Author Share Posted March 19, 2017 And so............ I took the fan blades of an old Pc Video card and glued to the Can of my Brushless Motor with expanding glue to take up the gap. Then made up a simple Duct from Layers of Depron Sheet. A small battery for scale. And it works pulling about the same Wattage. Steve. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted March 19, 2017 Share Posted March 19, 2017 Stephen An interesting idea and I look forward to hearing the result but I fear you will find such a fan remarkably inefficient at shifting air when compared to an axial as in an EDF. I took a 5" vacuum cleaner fan rotor and coupled it up to a 2700 kV helicopter motor. At some 23000 rpm and 350 W it produced an impressive high velocity air blast but the actual thrust was tiny, about 1/5th, of that the same 350 W produces in a 70 mm EDF. I appreciate your particular fan is intended as a high volume device where as a vacuum clear is not but I was still surprised just how little thrust is created. It sounded nice though! Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 19, 2017 Author Share Posted March 19, 2017 Hi Simon, You may well be right, The model does not need a great deal of thrust to fly indoors so i may just get away with it. Not had chance to compare thrust as of yet, i will have to make something to gauge the output. Steve Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 19, 2017 Author Share Posted March 19, 2017 Some more pictures, There is a lot of space inside the model for a Ducted fan unit of some sort. A quick Video, Steve Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted March 19, 2017 Share Posted March 19, 2017 Good luck Steve! Quote Link to comment Share on other sites More sharing options...
onetenor Posted March 19, 2017 Share Posted March 19, 2017 I feel that regular straight through duct would yield more thrust.The fan should be good for it though. Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 19, 2017 Author Share Posted March 19, 2017 Posted by onetenor on 19/03/2017 23:27:25: I feel that regular straight through duct would yield more thrust.The fan should be good for it though. I hope so, but it is just a Experiment i have other fan units i can test/adapt if needed . I may well just buy a 50mm EDF unit . Steve Quote Link to comment Share on other sites More sharing options...
OZ e flyer Posted March 20, 2017 Share Posted March 20, 2017 Hi Steve, Have you thought about making your own EDF? Your workmanship certainly looks like it's up to the task. I've seen the base of cool drink cans cut and shaped in to fan fins. They make excellent fans/turbines. You have the motors already it just needs a vortex type cowl/duct to concentrate and direct the airflow. Just a thought. Good luck with the experiment though. Keen to see how it works out. TP Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 22, 2017 Author Share Posted March 22, 2017 Hi, Just done a quick test by resting the fan on top of some scales then i tare it to zero the scale and i am getting 50 g of thrust. The model weighs in at 100 g Auw with the original gear still in it. How ever their is a lot of vibration from my fan unit so i will have to take it apart to balance the fan. So when i have done that i will re test. Steve Quote Link to comment Share on other sites More sharing options...
Mowerman Posted March 23, 2017 Share Posted March 23, 2017 If it is no good as an EDF you could always give it to a little girl to use as a hair drier for her dolls Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted March 23, 2017 Share Posted March 23, 2017 Stephen, You may have something like one of these already. A 28mm dia. fan and perhaps you could reduce the jet pipe outlet to 24mm to augment the thrust. I don't know if that would be too far out of scale or indeed whether it would produce enough thrust for your model? Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 23, 2017 Author Share Posted March 23, 2017 Posted by Piers Bowlan on 23/03/2017 10:43:58: Stephen, You may have something like one of these already. A 28mm dia. fan and perhaps you could reduce the jet pipe outlet to 24mm to augment the thrust. I don't know if that would be too far out of scale or indeed whether it would produce enough thrust for your model? Hi Piers, No i don`t. And i have not seen those before and that looks perfect too. Thanks for posting, Steve Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 23, 2017 Author Share Posted March 23, 2017 Hi again, Thought i had better do some more testing, So my original set-up on my indoor Sipa is a 3x3 prop on a 1504 brush less motor on a 2s 240ma Lipo battery gives me 54 g of thrust yes i was surprise considering how well it flies on that . Steve Sorry forgot to mention how i measured the thrust , Rather that balancing the model on the scales i directed the thrust directly onto the scales by holding the model above the scales. Edited By Stephen Jones on 23/03/2017 22:59:50 Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted March 23, 2017 Share Posted March 23, 2017 If you are getting 50gms from the centrifugal fan it ought to fly the plane. Definitely worth finding out! Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 23, 2017 Author Share Posted March 23, 2017 Now that the fan is balance i stuck it back together and re tested . This time i tried a different way of measuring the thrust, 1st time around i measured the thrust by balancing the motor on top of the scales this time i held the fan above the scales at about the same distance away as when i tested the prop version. This time although the fan runs very smooth i am only getting 15g of thrust . So i think i will give that to some little girl as a hair drier , Or may be not as i have an other cunning plan. Steve Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted March 23, 2017 Share Posted March 23, 2017 That is a shame, although not a surprise. Interested in the cunning plan though. Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 23, 2017 Author Share Posted March 23, 2017 Ok , So Pc Fans, In my spare box i found some 50mm fans and a 40mm Fan, Took both apart and the 50mm Fans will be too big but the 40mm fan looks much more promising. More pictures to come, But i have stripped the 40mm fan apart and fitted a 1504 motor to the back and as the motor has a long prop shaft that will allow me to fit the fan back in place . The idea is to make a tube that will reduce the 40mm square fan to a 26mm tube. Steve Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted March 23, 2017 Share Posted March 23, 2017 Stephen As you say 50g thrust should fly a 100g plane well enough but with a centrifugal unit like yours there will be no benefit to the fan from forward motion as there is with an axial unit or a prop for that matter. I used two of these 35 mm AEO fans in my Canberra. As you can see the motor is a relatively huge diameter and when I did the sums to find the actual available area (its quite a bit smaller than the FSA!) and then reduced that area by the recommended 15% the exhaust came out to be just 22 mm diameter! Scale size exhausts - the diameter of a 20p coin! It flies very nicely outdoors on a 2s. Hobbyking have still smaller AEO fans, 30 mm and 27 mm, although they are out of stock at the moment. Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 23, 2017 Author Share Posted March 23, 2017 Hi simon, Yes they would do the job , but when i search HobbyKing i can not find any micro fans. Steve Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 24, 2017 Author Share Posted March 24, 2017 Hi Simon, Are these the fan units from Robot Birds But needs Motor, Is this the Motor Or this one Also see here Cheers Steve Edited By Stephen Jones on 24/03/2017 22:41:47 Edited By Stephen Jones on 24/03/2017 22:43:08 Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 27, 2017 Author Share Posted March 27, 2017 Ok, So i had a play with 40mm Pc fans, 1st i tried just one Fan, It sounded nice and was balanced nice. But when tested only gave me 10g of thrust . So i then put two fans on the same motor. As expected 8g of thrust what a waste of time. arr well at least it did not cost me anything and it gave me something to play with for a while. Steve Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 27, 2017 Share Posted March 27, 2017 Steve. Did you try boxing in the gap between the 2 fans to avoid any leakage? Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted March 27, 2017 Share Posted March 27, 2017 Steve This is the smallest (27mm) that Hobby King do. It always seemed a bit pricey to me as their big 70 mm version gives over 900g thrust yet is quite a bit cheaper! Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted March 27, 2017 Author Share Posted March 27, 2017 Oh , Robot Birds is cheaper, Opps , thats for the 30mm one. Steve Edited By Stephen Jones on 27/03/2017 23:39:25 Quote Link to comment Share on other sites More sharing options...
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