I am new to jets and setting up my first ducted fan.

I'm setting up an OS .91 VR-DF with a Byron fan. The OS .91 came with a remote needle valve assembly with mixture control arm.

If I use this remote needle valve and control arm will I get sufficient mixture range or should I just invest in a BVM mixture control?


Thanks!
Al Teich

The OS mixer will work ok . Just make sure your hose connetions are tight. Mount the mixer on some vibration isolation to prevent from future leaks.
Good Luck!!

Hi,
The remote needle as supplied by OS does work but the
range of adjustment is limited due to the fineness of the
needle, if you feel you have to use remote adjustment then
go for the BVM.
Personally in 10years have not used remote adjustment on
the OS91 although have always mounted the needle remotely.

To adjust, start the engine, wind in until on peak then pinch
the fuel tubing between the needle and carb body for a split
second (you will soon get a feel for how long), if it dies then
its too lean, restart and try again until it dies and picks up, then
back off 3 clicks, this is about right, the main thing is not to run
lean or it will cut/blow the plug. Better to be rich and reliable.......
Mike

The OS will work but as stated earlier the threads are really fine so it will take full atv in both direction to make it work. You really need an on board needle mixture valve. For this reason alone. When your tanks are full, the weight of fuel is helping feed (the next tank) the motor. When you get down to about a half tank in flight you will notice the motor to start to leanout. This is where the remote mixture valve will come in real handy.

If you decide to run without an onboard mixture, i would set my mixture control when then tanks are about 1/3rd full. Gonna make for a sloppy rich top end when the tanks are full but as the flight progress it will get better. USE LARGE FUEL TUBING. yes medium tubing will work, but it is easier for the fuel to flow through the larger fuel tubing causing less fluxuation due to fuel weight.
Hope that helps some
sean

Hi Guys,
How did this work out for you? I am going through this right now. I have a just completed Byron F16 with the OS .91VRDF. I will also use the given remote adjuster arm. I disconnected it for now so I can get an approximate NV setting and then I'll put it back on before flight tests.
RickP

Also agreed that the BVM mixture valve will make things easier, I used them on all of the DF I had.