[DeTomaso] SORC # 135 Pictures

[Mike Thomas]

Vortex Generators were first developed during flight test of the Boeing XB-47 in 1947-8.  The XB-47 was the first large swept-wing jet powered aircraft, and what they realized was that over a certain speed, the outer tips of the wings would begin to lose lift.  As that happened, and the portion of the wing closest to the aircraft and thus, further forward on a swept wing design, maintained lift, it shifted the CG, or Center of Gravity, forward, forcing the aircraft to pitch up in a manner that could not be negated by trim or the horizontal stabilizer (tail).  Adding the VG's to the outer ends of the wing prevented the loss of lift, enabling much higher speeds.

I'm currently working with Capt. Steve Taylor, Chief Pilot for Boeing Flight Services.  His father, Capt., Dick Taylor, was the Chief Test Pilot for Boeing on the XB-47.  He want on later in his career to create ETOPS and work for its' approval with the FAA for long-range twin engine over-water flight when the 757 and 767 were developed in 1978-83.

My .02 from the history books.
Mike Thomas
Pres., Panteras Northwest
Yellow ’74 #6328





-----Original Message-----
From: DeTomaso [mailto:detomaso-bounces at server.detomasolist.com] On Behalf Of Daniel C Jones
Sent: Thursday, August 18, 2016 7:52 AM
Cc: detomaso <DeTomaso at server.detomasolist.com>
Subject: Re: [DeTomaso] SORC # 135 Pictures

> I think those devises redirect or concentrate air flow, not keep it 
> from
separating from the surface.

Vortex generators reduce drag (or delay stall) by tripping the boundary layer from laminar to turbulent flow which delays separation.  That generally increases the skin friction but decreases the pressure drag which is usually the larger component.  If you can maintain laminar flow without separation, that has lower drag.  In the case of hood, I'd be surprised if there is separation and don't think VGs would be of much use.  An easy test is to tape yarn strings to the hood.  If they streamline, the flow is laminar.  If they moved around a bunch, it's turbulent.  If they are still, there's separation.

Dan Jones