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closed jet tunnels. Reynolds Number studies of 3/8 scale models in­

dicate that in the range tested (8 x 10^ RN to 12 x 10^ RN based on

model length) all dimensionless aerodynamic force and moment coefficients

are virtually constant. This is in agreement with the work done by

Gross and Sekscienski (1)* where they showed the coefficients to be

relatively constant above a Reynolds Number of 2 to 4 x 10^.

Fiberglass reinforced with metal and wood structure was used for the

model. Although the strength of fiberglass lends itself to high
bas 0

c n peed testing, significant changes in model shape cannot be readily
made. For this reason, the front end of the model was made removeable

so that other clay and fiberglass front end shapes could be easily in­

stalled and the rear window area was prefitted with lay and fiberglass

shapes.

Attempts were made to accurately reproduce the underbody detail and

cooling airflow of the full scale car. A simulated underbody treatment

including the gas tank, suspension, C U xhaust system and structural mem-

bers was fabricated with particular care taken to accurately reproduce

the detai towards the front of the model. Grille, wheel well and

engine compartment openings were also closely simulated in an attempt to

duplicate engine compartment airflow. A scale fan driven by c o model

motor was used to adjust airflow through a scale radiator to equivalent

full sized car levels.

MODEL INSTALLATION - Of major concern in the tunnel tests of auto­

mobiles is proper imulation of the flow conditions between the model and

* Number in parentheses designates Reference at end o paper.

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