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A four-inch increase in waist-to-head height (going from 5’8” to 6', for example) will result in approximately a 5% increase in drag force, if we assume drag coefficient remains constant. This will be more noticeable if we decrease the car's overall width.
Additionally, the roll cage height would have to be increased, adding extra mass.
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Based on these calculations, adding 10cm to the height of the rollcage would add at least 1.2kg of weight in tubing. This number will probably end up being larger, since the moment arm during a rollover is longer meaning the rollcage will have to be reinforced.
The overall center of gravity of the car must also be considered - raising the height of the driver raises the center of gravity. We must ensure that it still stays within the tip table bounding box.
There is also a minimum waist to height of around 42cm (driver eyes must be over 700mm from ground).
Hip-to-Shoulder
The higher the shoulders, the higher the body of the chassis (everything thats not the rollcage) has to be. This increases chassis weight and frontal area. This has more effect if we are minimising aerobody width and height.
Hip-to-feet
The longer the waist-to-foot distance, the longer (or taller) the occupant cell of the chassis will have to be. Not accounting extra supports this would entail, it would cost about 860g per 10cm of length.
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Any weight over 80kg will be directly added weight to the car. For drivers under 80kg, bllast will be added to the car to bring the driver+ballast weight up to 80kg. Drivers must lift their own ballast, so they must also be able to comfortably lift their weight subtracted from 80kg.
Note as well that the more ballast a driver has, the lower the cg of the vehicle (assuming the ballast box is bellow the driver.
Adjustability
The higher the difference between the tallest and shortest driver on the roster, the more adjustable the vehicle will have to be. This might mean adujstable pedals, adjustable steering column etc.
Implications
A taller driver will most likely mean a heavier car with higher drag, although not by a huge amount. Wider shoulders (or body in general) will also mean a heavier car with higher drag, although probably not by a huge amount. The weight of the driver basically has to be under 80kg.
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The car is almost guaranteed to be less optimal if it is built for taller, wider people. That being said, we are a relatively tall team and a chassis made to accommodate 6” drivers will accommodate for almost everyone on the team. If members are more motivated to work on the car if they can drive it, accommodating them could benefit the team in the long run. It should be noted that there is tolerance built into occupancy cell, so basically everyone would be able to test drive the car if it was designed for a 5’9 driver, they just wouldn’t pass regs. It is highly recommended that every driver is within 1-2inches, regardless of chosen height.