Varieze Fuel Vent

[Kevin Clay]

I've got this ugly and draggy fuel vent on my Varieze, and I'm finally going to redo it.  Any advice?  I need to make sure it does not end up inadvertently creating negative pressure, but I want to minimize it as much as I can.

Thanks for any recommendations or pictures of proven vents.

[go ez]

Do you have ram air for your carb? And a NACA scoop?
If so, you need good ram effect on the vents so  be careful about tucking the vent in too close.

We had NACA and Ram air and experienced fuel starvation at high revs and slow airspeed during initial flight testing  - hard to pinpoint but eventually found to be all due to having the vents too close to the strake & side. Gary Hertzler told us this & said  that there is large boundary layer there.

Some guys have put them protruding under the mid spar so they dont have interference from the effect of the strake/fuselage juncture.

[Waiter]

I have a LongEZ, I put mine on top of the turtledeck.

http://www.iflyez.com/LongEZ_Retrofit_APR_05.shtml

Scroll down to 18 april 2005

Waiter

[go ez]

As the dualled  - fed together tanks of the  O-200 Vari Eze is normally gravity fed, you need to gain max ram effect by venting below the wing - two linked vents are mandatory.  

With the two tank pumped Long Ez,  the two separate tank vents'  positions are  much less critical  - hence the plans position above the canopy line.

[Kevin Clay]

Thanks for the feedback.  Since it an O-200 with ram air into the carb, it sounds like I'd better keep it as is to get ram air into the vent.  Maybe I'll make it more like a fin pitot to get it out of the boundary layer but reduce the drag a bit.

[Gilbert DRIEUX]

Thanks for the feedback.  Since it an O-200 with ram air into the carb, it sounds like I'd better keep it as is to get ram air into the vent.  Maybe I'll make it more like a fin pitot to get it out of the boundary layer but reduce the drag a bit.

And instal it as per plan : under the spar. The best place to get as more preasure as possible in double wing's tanks.

Gilbert

[Bill James]

The fuel vents can be continued down to exit in front of the gear legs.
Their drag is insignificant there and fuel doesn't drain onto the gear legs.

I've heard that while the boundary layer thickness can vary, 1/2 inch is
good for our  purposes. With 3/4 inch distance to start, adjustments closer or away
from the fuselage have worked to balance the fuel flow. My strake vent lines
dont join, but go up in front of the spar and over inside the turtledeck
or whatever the space behind the passenger's head is called,
to the opposite strake.