On Sunday, October 23, 2016 at 4:54:27 PM UTC-7, Jonathan St. Cloud wrote:
Just curious if there is research that compares blow holes versus tabulator tape as to effectiveness and drag? i.e., are the bow holes worth the maintenance or is tape effectively just as good? Does the new Ventus have tape or blow holes?

Blow holes don't involve much extra maintenance. When I was polishing the wings on my DG-303, I'd just put a piece of wing tape over them. I only checked whether any holes were clogged once, as I decided it was unnecessary. Hook a low pressure air source to the intake (I used a vacuum cleaner exhaust port). Hold a lit stick of incense over each one, if it failed to brighten up, run an appropriate size needle through the hole (carefully, so as not to push out the brass tube insert). It took longer to replace old turbulator tape on my other gliders.

DG offered a DG-300/303 Club with (among other things) dimple tape replacing the blow holes, I guess they decided the blow holes were worth a premium for that particular airfoil.

Marc