In Response To: Analysis of the Warthog *long with images* (Speedy)
You got all this info from a single vehcile in Halo, with no outside information (save the Halo manual)? It amazes me how much people can deduce even with the seemingly simplest things.
: A Thorough Examination of the Mechanical Aspects of the M12 Warthog LRV
:
: First, I'd like to apologize for the MS Paint images, it's the best I could
: do without my copy of photoshop or time to download GIMP on dial-up.
: As an engineering student, I was immediately fascinated by the Warthog when I
: first got to drive it in March of 2002 (Has it been three years already?).
: Many people have made Lego models of the Hog, or compared it to the
: Peugeot Hoggar concept SUV. However, most people don't realize how
: inherently different the construction of the Warthog is from any vehicle
: of today. It's actually a very unique vehicle, centering mainly on the
: suspension and transmission. As a result of this, I've decided to write up
: my observations of the vehicle's structure, and present a few of my ideas
: about how it would all work.
: I based this little examination on various screenshots I've taken using the
: debug camera in Halo CE. Due to this, I've gone to Halo 2 to check up on
: the differences, and have determined they are all purely cosmetic, and do
: not effect the fundamental construction of the vehicle.
: The Chassis, Transmission, and Steering
: The suspension and chassis of the Warthog are where it differs from any
: modern vehicle. In short, it doesn't really have a chassis. Each wheel has
: its own separate suspension, and each of the 4 suspensions are identical.
: There is a large strut that extends out of the body of the Warthog, on the
: end of which is the wheel.
:
: Given the fact that each wheel has its own separate axle, suspension, and
: complete housing, it would be extremely impractical to have a normal
: mechanical transmission.There would be a tremendous amount of power loss,
: as well as an uneven distribution of power as each of the four required
: transmissions (would be 2, but this is a four wheel drive vehicle.) ages
: and wears down differently.
: My theory for the solution to this transmission problem is electricity.
: Simply put, the Warthog's engine would act as an electrical generator,
: sending power to an electric motor mounted in the "pod" attached
: to the end of the strut. this would mean that to transmit power to the
: wheels, you would only need 2 wires: a positive and negative. Using this
: system, you also don't need to worry about having several gears for
: acceleration, which could explain why the Warthog never shifts. In order
: to have a reverse, all you've got to do is reverse the rotation of the
: magnets, which could be done by throwing a gear in between the engine and
: the electricity generator. That would literally be the entire mechanical
: extent of the transmission, which is very, very simple compared to most
: modern transmissions.
: Also mounted in the pod would be the brakes. The calipers would be secured
: against the wheel housing, allowing them to clamp down on the discs when
: needed.
:
: The biggest difficulty with this pod-wheel system is the steering. I think
: the best method would be something similar to the electric motors powering
: the wheels.... a small motor that drains a bit of power from the engine to
: turn the wheels back and forth by rotating the "ball" of the
: ball and socket joint that the wheel is mounted with. However, it would
: also be possible to have a hydraulic steering system as well.
: The Suspension
: The suspension is where the Warthog's design really shines. Using the simple
: physical properties of leverage, the Warthog's entire suspension can be
: reduced to a mount for the strut (which would serve as the fulcrum) and a
: relatively low-strength spring. Since each strut/pod system is identical,
: I will only describe one.
: Note: you could use a lever where the spring and wheel are on the same side
: of the fulcrum, but this would mean you would have to cut out a hole in
: the body large enough to account for the up and down motion of the strut.
: With the fulcrum-centered lever used for this system, the hole only has to
: allow for several inches of travel.
: So, we'll make the Warthog's suspension a lever system. This will transfer
: the up and down forces of the wheels to a spring connected to the body of
: the Warthog. To maximize the efficiency of the spring, you would have to
: put the fulcrum (in this case, the point the suspension actually mounts to
: the body) as close to the wheel as possible, with the spring connecting to
: the strut as far from the mount as possible. With the system as such, the
: spring would have to exert less force to counter the up and down motion of
: the wheels. This is because the force transmitted in a lever is relative
: to the distance from the fulcrum, such that: F1*D1 = F2*D2
: To put it in simpler terms for those who don't know physics, basically it
: works like this: You have a 100 pound girl and a 10,000 pound elephant
: standing on a very strong see-saw.
: If the Elephant is standing 1 foot from the fulcrum of the see-saw, and the
: girl is standing 100 feet from the fulcrum (Like I said, it's a strong
: see-saw.), their weights will actually balance out. This is roughly
: similar to how those scales at the doctor's office work.
: Thus, if you mount the spring the same distance from the fulcrum as the
: wheel, it will have to exert exactly the same amount of force in the
: opposite direction to balance the vehicle. If it's mounted twice as far,
: It only has to exert half the force, and so on.
: However, due to the appearance of the Warthog, I've decided the spring can
: only be positioned roughly the same distance away. Actually, the front
: struts enter the body directly in front of the two seats, and the rear
: struts directly behind. With the angle at which they go up, extending them
: just as far into the body would make a Marine's ride a bit uncomfortable.
: This can be fixed very simply by offsetting the spring's side of the strut
: a bit on the mount.
:
: Also, since the mounts require no up or down travel, both front wheels and
: both rear wheels can actually share the same mount to swivel around,
: decreasing cost, and allowing you to make the body stronger by using the
: mounting rod to brace it.
: With the struts now offset to avoid spearing the driver, the Warthog's
: springs can now be mounted under the center console, which I would suspect
: would be very strong to prevent the cockpit from crushing closed in case
: of a head-on collision.
: Engine
: With the suspension settled, all we need to figure out now is were to fit the
: engine. There simply isn't room at the front of the vehicle, and the
: center console now houses the suspension. So where does all the power come
: from?
:
: Right from under the turret, that's where. You may notice the bulge downard
: below the gunner's seat on the underbody. You may also notice the four
: holes that look like exhaust pipes. The biggest problem here is that even
: this space is kind of small, so I decided to do some analysis.
: Now think about it. The Bungie guys have mentioned before that the vehicle
: can only reach about 50 miles an hour in perfect conditions. It doesn't
: really need to go much faster considering the work it's used for anyway.
: To reach 50 miles an hour, even when accounting for power loss in
: generating electricity and converting it back to mechanical energy, you do
: not need very much energy.
: But instead of just saying it doesn't need much, I'm going to do some
: physics: First: the guess. I'm going to be realistic and say if the
: Warthog were real, it'd take about 10 seconds to reach a maximum speed of
: 50 miles per hour. This is also going to be a "perfect" system,
: meaning there's no loss of power between the engine and the wheels, and
: allows us to assume things like constant acceleration.
: Now, our givens: Our velocity is 50 mph (22 meters/second), it takes us 10
: seconds to get there. The Warthog weights 3.25 tons (2954 kilos) according
: to the Halo 2 manual
: Alright, so we begin with Power = Work/time.
: Work is defined as Force*displacement, so we can redefine power as
: Power = Force * displacement/time
: Displacement/time = Velocity, so Power = Force * Velocity
: Since we gave the Hog a 0-50 time of 8 seconds, we can use Force = mass *
: acceleration to get: Force = 2954 kg * 22 m/s / 8s = 8123.5 Newtons
: (kgm/s/s)
: Thus,
: Power = 8123.5 Netwons * 22 m/s = 178717 Watts
: Now, 1 Horsepower is roughly 750 Watts, so converting that, we get 238.3
: Horsepower needed at the wheels to reach 50 mph in 10 seconds
: We'll give it some leeway, and estimate that we lose about 30% of the
: horsepower between the engine and the wheels (modern mechanical
: transmissions lose about 15%, so this is a very conservative estimate).
: This gives us 310 horsepower required at the engine.
: Now the question is, can you fit a 310 horsepower engine in that space? It
: would be a bit of a feat today, but it's been done. Giving us 500 years of
: a benefit of a doubt, it's very easy to see a normal internal combustion
: engine as the power source for the Hog.
: And that's about it, hope you enjoyed it.
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