todd

I'm sure most of you know the Warthog in Halo. It's definitly my favorite part of the game. I really enjoy driving it, and have gotten pretty good at it.

Anyway, I had some free time this week. I thought it might be cool to figure out some of it's general specs, as if it were a real vehicle.

The first thing I did was figure out how long the Warthog is, and use that to measure some distances. To do this, I extracted the Warthog's 3D model from PC Halo1, and measured it to be 19.2 feet long (according to Bungie's map modding tutorial, 1 'world unit' in the 3D program is equal to 1 foot).

To find top speed, I used Warthog lengths to measure off a 76.2 meter (13 warthog lengths) track on the streets of Headlong, and timed how long it took for the Warthog to drive that at full speed. The average time for this was 3.5 seconds. Using this information, I found the top speed to be 48.5 MPH:

at max speed - 13 lengths in 3.5 sec
distance=76.2m
time=3.5s
velocity=distance/time
velocity = 76.2m / 3.5s = 21.7m/s

Next I found it's acceleration, which will be used to help find the horsepower.
The easiest way to do this is to just find how long it takes to reach top speed, since we can easily tell when it does by watching the speed meter on the dash, and studying the sound the engine makes. I found that it took 4 seconds for it to reach top speed, and again used the Warthog lengths to measure that it traveled 32 meters (8.8 Warthog lengths) during this time:

to max speed - 8.8 lengths in 4 sec
distance=32m
time=4sec
velocity final=21.7
acceleration = (v final - v initial)/time
a=(21.7m/s - 0m/s)/4s
a=5.4 m/s^2

Then find force:
force = mass * acceleration
mass = 2948.3kg
acceleration = 5.4 m/s^2
F = 2948.3 * 5.4 = 15920.82 Newtons

And finally, power:
power = force * velocity
force = 15920.82 N
velocity = 21.7 m/s
power = 15920.82 * 21.7 = 345481.79 watts = 463 horsepower (because ~745 watts = 1 HP)

Now for torque, calculations and explanation provided by Nimisys:
Power (hp) = Torque (ft-lb) * RPM / 5252
as well as:
Power (hp) = Force (lb) * Velocity (MPH) / 374
463 = X * 48.5 /374
Force = 3570lb at peak velocity, at wheels

However that number will be different than at the engine in a normal vehicle because it does not take into account gear ratios in the trnasmission and final drive units. furthermore in this example the engine output can not be derived based on the performance of the electrics as we lack any gear reduction data as well as the effiency data of both of the eletric motors and generators. furtheremore with an electric motor peak torque is avilable at zero rpm. assuming we ignore this, and base torque off of a HP reading of 463hp @ 5000 RPM, then we can calculate the torque at 5000 rpm.

Power (hp) = Torque (ft-lb) * RPM / 5252
463hp = X * 5000 / 5252
X = 486.33 ft-lb @ 5000rpm (at engine)




And thats it. The Warthog puts out approximatly 463 horsepower, assuming we have a perfect system. If not, it's probably closer to 500 before the loss between engine and wheels. I can't really comment on the error that might have been involved in taking my times and measurements. Only so much precision can be achieved in a video game, but fortunatly Bungie has done a good job in that department.
Read below for my justification as to why 463 is a seemingly accurate number.

I didn't just fine how much horsepower it has, I found all the general specs that one would find on a car spec sheet. Some of the stuff is just from observation, while others were taken from official sources or determined with accurate (i.e. the measurements I took from the 3D file that I mentioned earlier) means. Thus, everything on the list is true (not just made up randomly), so if you want to know how I figured something out, please just ask


M12 Warthog LRV
Curb Weight: 3.25 tons = 6,500 lbs = 2948.3 kg
Length: 230.4in
Width: 117.12in
Height: 88.2in to rollcage, 124.08in to gun
Wheelbase: 155in
Front/Rear track: 93in
Ground clearance: 22in
Top speed: 48.5 mph
(theoretical) 0-60: 4.7s (?)
Engine: 4x Electric Motors powered by a M12 V8
Transmission: 3-speed electronically controlled speed hub; suggested by Nimisys
Power: 463 BHP
Torque: 486.33 ft-lb @ 5000rpm; provided by Nimisys
HP/LB: 14 lbs per BHP
Suspension: Hydraulic levers, 60mm monotube gas shocks
Brakes: 4x Self-actuating drum brakes; handbrake
Drive wheels: full time 4WD
Seating: 2 + gunner

Just for comparison, heres some basic Hummer H2 specs:
Power: 315 BHP
Curb Weight: 2902 kg
Length: 180in
HP/LB: 20.3 lbs per BHP
The Warthog is only a bit larger and heavier than the Hummer is, but anybody who has driven the Warthog (on Halo of course) can tell you that it handles like a gokart. I'd love to see a Hummer do the kind of stuff the Warthog can do. Obviously this is because of the horsepower differance. The Warthog is only pushing 14 pounds per horse, where as the hummer is pushing over 20. I don't know a ton about the mechanics of engine power, but I do know that 463 horses is a very reasonable number, considering the agility of the Warthog in comparison to the Hummer H2 and the power it has.

Waste if time? Probably. Fun and interesting? Definitly.
If anybody else has any ideas of what else I could add to my spec list, let me know and i'll see if I can figure it out

actinic

Heh, that would be a fun machine to drive around town.

Great real life transposition of the Warthog todd...double thumbs up!!!

GetRdone

seems more like a topic for tilted gaming.........but its about a car, kind of..... none the less its pretty cool

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userasdf1234

Thats some good analysis you have done todd. It does seem like you had a lot of free time but who doesn't every once in a while. None the less, i think its pretty neat that you figured all this out from a game.

TexanAvenger

Damn... I wouldn't've ever thought to check this out, much less have known how to, even less likely to have put out the effort.

Truly amazed at your having done this and hold you in a much higher respect for it.

Just... awesome.

wakelagger

This is where highschool physics, a pension for gaming, and a whack of free time combine to form something beautiful.
One question though, where'd you get the weight of the warthog? Did the map modding tool give it a weight value?

todd

Thanks guys, was hoping at least somebody would appretiate it.

wakelagger - The weight, for some reason, is listed in the manual booklet that came with the game - it says 3.25 tons. Not really sure why (but glad) they chose to just list the weight, the only other specs it lists is the type of machine gun/rocket launcher they carry.

Wingless

You should post this on the bungie.net forums - I'm sure the devs and fans there would love this stuff. Nice work

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Nimisys

why would a gas enigne powering an electric generator need a 3 speed transmission?

actinic

Jeep Hurricane concept. I couldn't remember when I posted. A few mods and we got the Warthog...LOL

http://www.tfproject.org/tfp/showthr...highlight=Jeep

todd

Good question. But apparently thats what it is.
-On Halo2 if you break away the edges of the hood, you can see headers, valve covers, an intake, air cleaner, and what appears to be a muffler (or cat. converter perhaps), meaning it's some sort of internal combustion engine. Not to mention the sound it makes when at idle is obviously made by a combustion engine.
-By listening to the sound the engine makes as you accelerate, if you listen closely you can pick out when it changes gears several times.
-If I remember correctly, an article on Bungie.net said it was powered by electric engines in each of the pods that the wheels are connected to.

I don't know much at all about electric engines or how they work in conjunction with gas engines (hybrid), but maybe the transmission allows differant levels of power to be sent to the electric engines?

Or perhaps the 'transmission' is actually just a few gears attached to each of the electric motors in the pods, rather than the gas engine.

Or maybe the sound that sounds like gears changing isn't actually what it was meant to be? Maybe that was just a goof up and there is actually only 1 speed. The Warthog in the first Halo only had 1 speed, so that would probably make more sense. I'll study the sound again later and see if I can figure out what else it might be.

Nimisys

well it could be game devs playing engineer in an areana they do not know all that well or it maybe they are using gear reduction in the wheel pods, a la the H1 and its 2:1 reduction in the gear hubs. multiple speed hubs could be a reasonable argument for the difference in tone. BTW this is how deisel locomotives, heavy equipment function, diesel engines powering electric generators powering electric motors at the wheels.

BTW torque calaculations:
Power (hp) = Torque (ft-lb) * RPM / 5252
as well as:
Power (hp) = Force (lb) * Velocity (MPH) / 374
463 = X * 48.5 /374
Force = 3570lb at peak velocity.

However that number will be different than at the engine in a normal vehicle because it does not take into account gear ratios in the trnasmission and final drive units. furthermore in this example the engine output can not be derived based on the performance of the electrics as we lack any gear reduction data as well as the effiency data of both of the eletric motors and generators. furtheremore with an electric motor peak torque is avilable at zero rpm. assuming we ignore this, and base torque off of a HP reading of 463hp @ 5000 RPM, then we can calculate the torque at 5000 rpm.

Power (hp) = Torque (ft-lb) * RPM / 5252
463hp = X * 5000 / 5252
X = 486.33 ft-lb @ 5000rpm

This is why dyno charts display both torque and HP as a function of RPM.

so 486.33 ft-lbs at the engine and 3570 ft-lbs at the wheels indicates a 7.34:1 reduction at 5000rpm. thats roughly equivalent to 2nd gear in most 5 speed vehicles with a mid 3.x:1 final drive.

todd

Nice work, Nimisys. Thanks a lot for that.

I also looked into multi speed hubs and read a bit about them. I now have no doubt that is what is used in the wheels. It makes a lot more sense than any of my previous ideas. They would fit perfectly, and like you said, they're what are actually used in real life applications.

etla

This is cool. Thanks.

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