This is probably a totally out to lunch idea but here goes.

Has anyone ever thought of feeding one EDF into another? Exhaust from the first into the intake of the second. I am really curious what the results would be.

Dave

While I have not done any heavy duty field work with DF, the way I understand how it works is that the exhaust speed is the result of what the rotor is capable of giving out. Having one boost the other won't increase the output speed if both are the same. Example if the output speed of DF #1 is 80 mph having another fan the does 80 mph behind it won't increase speed at all. However two units side by side would increase the amount of output overall but not more than 80 mph. The primary diffrence between DF and turbine is that a turbine gives continous thrust vs a max airspeed output of the DF.

Makes sense. I was wonder if there would be any benifit say due to the increased air pressure and density at the intake of EDF 2. I was also wondering about setup mimicking a high-bypass engine.

Dave

you would just end up loosing thrust. If you used one and made the air exit smaller the exit speed would be faster and therefore the model would be faster.

but what if the one in the back was not turning the same speed but much faster? Say you used a 2000Kv motor in the front and a 4000Kv in the back. It might work since the front one is effectively reducing the load by feeding the air to the rear one. It might be better for speed than side by side since the crossection would be smaller and the outlet could be kept larger thus keeping the thrust up but boosting the eflux speed.
Sounds like a fun experiment.

Ok I told you this was off the wall. How about really off the wall!!!!!!

I would love feedback on the following picture. Imagine 2 of these engines in a 93" long F4 Phanton. Works really great or blows it to pieces.

Dave

http://www.rcgroups.com/forums/showt...ut+ducted+fans

Post 120 Klaus an engineer looking over the matter explained that not only for the extra weight to gain but that more can be accomplished with a well designed fan unit.
Read the entire thread. you 'll start to see why and what makes EDFs perform to the limits.

But can't hurt to test the sam date again.