? ? Sent:?Wednesday, April 06, 2016 at 12:20 PM From:?"Mike Stirewalt via KRnet" <krnet at list.krnet.org> To:?krnet at list.krnet.org Cc:?laser147 at juno.com Subject:?KR> Holes in belly board Joe Nunley said,
> " . . . and put holes in your belly board. ;) We've talked about this subject some years back . . . it'll all be in those great archive resource we have. In my experience and in looking into the subject, the main plane we think of as having holes in their dive brakes was the SBD Dauntless. I think the Stuka had them too. My KR came with holes in the belly board so back when I first got it (ten years ago this July!) I was wondering if I could get better drag from it if I covered up the holes. So as an experiment, I did. I covered the board with duct tape thus creating a flat surface. Having the holes covered made a very, very slight improvement in the drag effectiveness of my belly board. It also did a better job of creating a bit of lift, thus reducing stalling speed. The difference was very slight. _____snipped short_____ Mike KSEE It's probably worth noting that the dive bombers used these as dive brakes. They had a bottom perforated surface to the flap that extended downward, and a top perforated surface that extended upward when deployed, essentially a split flap with both halves deployable in opposite directions. That allowed them to dive nearly vertical without exceeding max structural airspeed and deliver a bomb with a straight down drop, yet still be slow enough to pull out of the dive without pulling the wings off the plane. That was the core mission behind the design of these perforated dive brakes. That mission is significantly different from using them as flaps to slow for landing. Maybe I should take the hole saw to my flaps next. Yeah, that will be something really different.... -Jeff Scott Los Alamos, NM
