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diesel_john · 05-14-2008, 07:45 PM

I found info on this offset plate test. Reseached by Hucho[1987] in the late 1970's. Full scale test's in 1988 at Nasa's Ames Research.[Lanser et. al 1991].

The results showed that the highest drag reduction came with a plate of 0.36w and inset of 0.06w, where w is the width of the trailer. For a full sized enclosed semi-trailer this translates to a plate length of 33 inches inset at approx. 7 inches form each edge. For this configuration the researches recorded an overall drag reduction of approx. 10% over a +/- 15 degress yaw range.

interestingly the tangent of 0.06/ 0.36 = 9 1/2 degrees. vs. the 10 to 12 degrees often quoted for the smooth boatail.

05-14-2008, 07:45 PM	#48 (permalink)
diesel_john MP$ Join Date: Jan 2008 Location: SW Ohio Posts: 595 Thanks: 5 Thanked 19 Times in 14 Posts	I found info on this offset plate test. Reseached by Hucho[1987] in the late 1970's. Full scale test's in 1988 at Nasa's Ames Research.[Lanser et. al 1991]. The results showed that the highest drag reduction came with a plate of 0.36w and inset of 0.06w, where w is the width of the trailer. For a full sized enclosed semi-trailer this translates to a plate length of 33 inches inset at approx. 7 inches form each edge. For this configuration the researches recorded an overall drag reduction of approx. 10% over a +/- 15 degress yaw range. interestingly the tangent of 0.06/ 0.36 = 9 1/2 degrees. vs. the 10 to 12 degrees often quoted for the smooth boatail. Last edited by diesel_john; 05-27-2008 at 12:44 AM..