Gerry Parent wrote:This is all becoming a lot more clear. Thank you both.
Now, if I can reiterate what was said for clarity.
The port for a 6" batch box from Peters chart is 2.19" x 9.5" = 20.81 sq in (52.86 sq cm) Nope, 20.81 x 6.5416 = 134.257796 cm².
So 5% of 20.81 (52.86) = 1.04 sq in (2.64 sq cm) Nope again, 134.257796 X 1.05 = 140.97 cm²
Total hole or slot size on top of riser then needs to be: 20.81 + 2.64 = 23.45 sq cm
With this second port added to the riser, its now sounding a lot like Matt Walkers riserless core design which also has 2 ports with an expansion space inbetween them (just laid down level)
Think I might try a circle first made with cf blanket.
Cf board would be a better choice but I don't have any on hand.
Also, with the wrinkled nature of the cf blanket at the top of the riser, doesn't make it a real accurate science but I guess close enough will have to do.
Peter van den Berg wrote:For conversion of imperial to metrics and vise versa I am using Cleave Books Specialist Calculators. About any conversion is in there, money excluded. Satamax is right, but you are gonna use imperial I'd think.
Peter van den Berg wrote:Gerry, in my DSR setup the distance from the riser port to the end port seems to be crucial.
Peter van den Berg wrote:OR you could try other doughnut diameter holes to see if it would make any difference. The length of the riser ought to be a factor also, and last but not least: I honestly don't know whether this trick will work on a vertical riser, ever.