bvm .91 viofan actual thrust? - RC Groups
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Oct 20, 2017, 07:30 AM
Theuns
T. van Vuuren's Avatar
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bvm .91 viofan actual thrust?


Guys I need some advice please.
I have installed a BVM .91 viofan (7 blade) into my Mirage 3 EZ I molded
The fan swept area as I worked out is 9536mm sq.
My thrust tube is 600mm long and at the rear it is 95mm diameter.
It works out to be about 81% OF fsa.

The engine screams like no banshee can but the thrust at the back of the tube and the suction at the intake does not feel remotely like my old mavric with 91 OS/ramtec setup.
I measured the static thrust on the BVM in mirage but i only get 2800 gr if my scale (standing vertical) is acurate.
For a plane that is going to weigh about 6.5kg it will NEVER fly .

Am I restricting the flow to much at 75% ?

Thanx

Theuns
Last edited by T. van Vuuren; Oct 21, 2017 at 01:48 AM.
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Oct 21, 2017, 01:49 AM
Theuns
T. van Vuuren's Avatar
Here is the whole setup removed.
The FSA is 8708mm sq, the otlet @ 95mm is 7089mm sq (this is 81% FSA)
the whole thrust setup from back of fan to outle it 650mm long (cant really go shorter)
The rear of the shroud around the engine is 130mm diameter, cant chage this either.

In theory it should have worked at these measurements.....
I am out of ideas. Sugestions??

Theuns


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