EDF Size?
02-19-2011, 03:36 PM
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EDF Size?
OK ... for all you EDF guru's out there. I am scratch building an EDF flying wing. I want to use one EDF only. So ... How do I determine the suze of the unit to buy? Certainly there must be some formula out there which I can apply to my design before I start the actual plans. Thanks!
02-19-2011, 04:32 PM
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RE: EDF Size?
Decide on what the "mission" is to be. Landing gear, hand launch, bungee????
Aerobatic, vertical or just lazy cruising?
Construction method - balsa with iron-on, solid foam, FG over foam???
Once you have an idea of what you want, you can then look at thrust vs weight. For true vertical, the t/w > 1
Once you have an idea of the weight you can start looking at fans, motors and packs.
Many decisions to be made, no silver bullet...
Aerobatic, vertical or just lazy cruising?
Construction method - balsa with iron-on, solid foam, FG over foam???
Once you have an idea of what you want, you can then look at thrust vs weight. For true vertical, the t/w > 1
Once you have an idea of the weight you can start looking at fans, motors and packs.
Many decisions to be made, no silver bullet...
02-19-2011, 08:01 PM
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RE: EDF Size?
Thanks for the reply ... the plane I am designing will have somewhere between a 3' and 4' span ... landing gear ... and should weigh somewhere around 3 to 3.5 lbs. Certainly there must be a formula for calculating the proper edf unit. Thanks again!
02-20-2011, 12:28 AM
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RE: EDF Size?
Sounds like you will be wanting a 70mm fan, and at 3.5lb AUW you will be wanting a fan that runs around 1100-1300 watts to get over 1:1 thrust to weight, or around 800-900 watts to getjust over3lb thrust.
Good combos are the Wemotec Minifan PRO with an HET 2W18-V2 motor, this runs around 55-58A on 4 cells, 850 watts or so and around 1.4-1.5kg thrust which is 3-3.3lb. This sort of setup is about as light as you will get for the power, the fan comes with an intake lip that will be very useful for your design, all you will need to do is fabricate an exhaust duct from some plastic sheet.
You will be able to use a 60A ESC easily as it will be in the airflow somewhere for sure on a flying wing, and 2500-2600mah 4 cell packs will give you a light and powerful setup. You could go milder than this of course, there are plenty of well known combos out there, but unless you want insane power I would stick to standard plastic 70mm fans, the Wemo being the best of the lot for quality and performance.
Good combos are the Wemotec Minifan PRO with an HET 2W18-V2 motor, this runs around 55-58A on 4 cells, 850 watts or so and around 1.4-1.5kg thrust which is 3-3.3lb. This sort of setup is about as light as you will get for the power, the fan comes with an intake lip that will be very useful for your design, all you will need to do is fabricate an exhaust duct from some plastic sheet.
You will be able to use a 60A ESC easily as it will be in the airflow somewhere for sure on a flying wing, and 2500-2600mah 4 cell packs will give you a light and powerful setup. You could go milder than this of course, there are plenty of well known combos out there, but unless you want insane power I would stick to standard plastic 70mm fans, the Wemo being the best of the lot for quality and performance.
