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Old 03-23-2014, 11:01 PM   #107 (permalink)
freebeard
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Hersbird -- You know what you really don't want? A vortex street. Buffeting that can amplify into sway.

Slowmover -- I always listen when you speak, but I have trouble with a radius expressed in degrees.
Quote:
A page taken from 1940's travel trailer design (Wally Byam, et. al.) is that sidewall radius to roof and undercarriage should be 12-22 degrees.
Is that like 1/16th to 1/8th of a circular arc? Or following Mair, the angle where it might as well be a straight line from there on?

bikenfool -- Yup, teardrops are crap. Here's my solution. The rear entry is a valid criticism. But it would be a cot with storage on either side and a kitchen that butterflies open at the hitch end. A sink would fold out of the top of the fender (you don't see).

ChazInMT -- I'll have to digest that paper. So far I've run it through Summarize to see what it's about:
Quote:
In Chapter 4, the problem formulation developed in Chapter 3 were used to study flow over a pickup trucks with add-on devises: Tonneau cover, Rear Roof Garnish, tail plates, Airdam, Traditional canopy, Aerocap with rear inclination angel of 50,100,120,150 and 18.770.

...By comparing the pressure distribution plot on the symmetry plane of the pickup truck with Tonneau cover, shown in Figure 4.1.2(a), with that of the baseline model in Figure 4.1.2(b) it indicates that the pressure distribution plot over the rear end of the Tonneau cover is larger than the pressure distribution plot over the under body of the vehicle.

...Similarly, the total pressure behind the cab of the truck with Tonneau cover is about - 6.39* Pascal as shown in Figure 4.1.4 and it is higher than that of the baseline truck, which is -8.71* Pascal as shown in Figure 3.17, signifying a reduced aerodynamic drag and lift in the case of the pickup model mounted with Tonneau cover.

...By comparing the static pressure in Figure 4.3.2 with that in Figure 3.16, it is seen that the static pressure acting on the tail gate of the base line truck is about -3.55* Pascal which have a suction effect at the rear of the vehicle.

...Figures 4.6.3, 4.6.4, 4.6.5, 4.6.6, and Figure 4.6.7 shows the total pressure contour in the symmetry plane and over the surface of the pickup model with Aerocap when the rear inclination angle is specified as α=50, 100, 120, 150 and 18.770 respectively.

...Figure 4.6.8 to Figure 4.6.12 shows the static pressure contour in the symmetry plane and over the surface of the model truck with Aerocap when the rear inclination angles α=50, 100, 120, 150 and 18.770 are specified, respectively.

...The thesis studied the flows over a pickup truck with add-on devices: (1) Tonneau cover, (2) Rear Roof Garnish, (3) Tail plates, (4) Airdam with 3in and 6 in clearance from ground, (5) Traditional canopy, Aerocap at 5 different rear inclination angles, and (6) a 3D curved Aerocap.
The bolded part is at Summarize's minimum setting. Looks about right.
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