To
create a feasible vehicle design I will need to read H-Point: The Fundamentals
of Car Design and Packaging in its entirety. Thus, I will dedicate these blog
posts to sharing knowledge from my readings so you can also walk away with an
understanding of vehicle design.
So without further ado, let’s
dive in!
Every vehicle comes with its
own unique set of hardpoints. Hardpoints are features of the package that have
specific constraints, based on the objective(s) of the vehicle and regulation
requirements. I will use the following diagram from H-Point as a reference.
Here are some that I picked
out: (numbers correspond to the diagram)
2) Front Wheel and Tire: The
front wheel’s position depends on the position of the transmission’s output
shaft (for front wheel drive vehicles) and the vehicle’s weight distribution.
The tire envelope is determined by the jounce and turn of the wheel. Jounce is
the vertical movement of the wheel as allowed by the suspension system. You do
not want the top of the tire to hit the envelope. Similarly, the tire envelope
must allow the wheel full motion when turning left and right.
3) Chin Height: Do you know
what the height of a standard parking block is? Answer: 162mm. The “chin” of
the car must clear this height at a recommended approach angle of 10 degrees.
For off road vehicles, however, the recommended height jumps up to 28 degrees.
This allows the vehicle to clear larger obstacles without damage to the
exterior.
4) Front Bumper Location: In
the event of a collision, the bumper must have enough crush space in front of
the occupant’s feet. Rigid objects like the engine and steering rack increase
the amount of crush space needed. There are also pedestrian safety laws that
govern the shape of the front fascia. For example, the front of the car cannot
be pointed like a rocket. Even if it improves the aerodynamics, that would
hurt!
7) Cowl / Windshield Touch
Down: This part of the car must provide enough room in front for engine
maintenance and maintain good proximity between the driver and the controls.
Also, the windshield should be no more than 25 degrees above horizontal, above
which which the driver’s view is distorted due to refraction.
8) The header location should
allow for adequate upward visibility, which is at least 11 degrees from
horizontal.
18) Belt-line location:
Designers must consider the height of the belt-line relative to the occupant to
ensure the seat belt is comfortable and there is sufficient shoulder room.
19) Body Side Profile: It is
important that the glass has enough room to drop inside the door’s outer
profile, missing all of the hardware and side impact protection systems within
the door. This puts constraints on the height of the side glass windows and the
door. I have rolled my window down countless times but I never thought of where
the glass went.
Certainly all of the
hardpoints in the above diagram are essential to designing a car, but I wanted
to give you a taste of automotive design with the ones that I found most
interesting.
Thanks for reading!
-Alek
Hey Alek! Forgive me as I know next to nothing about cars, but do you know which hardpoints vary the most depending on the type of vehicle you are designing? Sorry if this didn't make sense, but it seems like you are enjoying yourself, and the work is very interesting!
ReplyDeleteHey Kayla! I think that the hood profile (labeled 6 in the diagram) varies a lot among the different vehicle types. If you have a front wheel drive car, the hood must leave enough room for the air intake systems (called manifolds) which cool the engine. There is also new pedestrian safety legislation which increased the required hood clearance to hard components, primarily the engine. These factors all raise the hood profile up relative to the car body. The Hummer, for example, has a hood that is almost parallel to the road! By contrast, cars with a mid-engine or rear engine don't need as much space under the hood, just for storage. Especially for high performance cars, like a Lamborghini, the cargo space is limited, resulting in a hood profile nearly parallel to the windshield! This will dramatically improve the aerodynamics of the overall vehicle.
ReplyDeleteHope this helps!
Thank you for sharing the information as you go along. It seems they more you teach us the less we actual know. Which hard point stands most out for to you?
ReplyDeleteI think that the leading edge (number 5) of the front fascia says a lot about the car you are making. For typical 4-door family passenger cars, which are designed for comfort and safety, the leading edge is often noticeably steeper than the hood. The 2017 Toyota Camry is one example. By contrast, the leading edge on more aerodynamic cars is more harmonious with the hood profile. Arguably, the LaFerrari doesn't even have a leading edge!
ReplyDelete