Gws Edf 50

[jon-AMIG]

Hi All. Im wondering whats the maximum weight of a plane can a GWS EDF50 with original brushed motor power? Voltage = 7.4V(2 cell lipo), Current = 1.4A(measured from a multimeter).

From GWS site, At 9.6v, 2.16A, it can generate 64g static thrust, power 20.74watt.

Please advice. Thanks

[Babylon5]

Hi Jon, notice that few people will response to your query because it is very narrow. Moreover GWS50 with brushed motor, as you have already discovered have very limited thrust. Therefore it is very hard for ppl to answer what is the max weight this power plant can sustain a flight.
How the jet performs in flight ,(thrust) depends among other factors very much on the wing loading, co-efficient of lift /drag of the wing . A high efficient wing/airfoil like a sailplane or a glider will required little thrust (thrust to weight ratio of 0.3 to 0.4) to sustain flight or even lower figure if the wing loading is light.

On the other hand Jet plane has small wing area and generally have heavier wing loading. Thust to weight ratio of 0.8 and higher are generally required for sucessful launch and flying.(Although there are exception to the trust requirements for jet)

If you want to enjoy good EDF flying you may want to move on to brushless
motors and bigger fan unit. i would suggest you start at 55-70mmEDF size.
With the right motor match, the EDF power generated is 400grams and beyond. Can read similar thread at Daddy hobby forum.

all the best

[jon-AMIG]

Oh ic..ok! Thanks Babylon5 So to compensate for the poor thrust power from the fan unit i have to limit the weight of the plane down below est. 64grams to get the thrust to weight ratio lower than 1. And also to get the wing loading as small as possible by increasing wing area but keepin weight of the plane small. Correct?

How about increasing the tail area & decreasin the diameter of the exit area? The original GWS EDF50 has a 30mm duct behind the fan blades, equal exit diameter as the intake. Can somebody advice any formulae to calculate?

Thanks!

[Babylon5]

Hi Jon, Pm you just now.
In generall practice, by narrowing the exhaust outlet jet flies faster at level flight but reduce the static thrust due to back-flow pressure. For a small EDF 50 to 55mm of small diameter, narrowing the exhaust tube or tail pipe is not necessary.

Note increase intake lips or better shaped intake lips improve the efficient of the EDF.

The other note is where the EDF is mounted. Is it inside the body of the plane or outside the plane(open intake/exhaust)? The latter(open intake/exhaust is more efficient where the airflow for the EDF power plant are least restricted..

Another note,For brushless motor setup usually require at least 3lipo cells(11.7V) for successful setup/flying.

I hope this will help and welcome to the ducted side.