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View Full Version : Car setup for realism


CrashTest
2008.12.02, 01:57 PM
I'm not sure if this is the correct section of the forum, but I was wondering if anyone has previously done work to achieve a more realistic mini-z setup. If 50 feet is representative of a scale 1/4 mile, than even a stock mini-z shows highly unrealistic power-to-weight ratios.

If a given car weighs in around 2600 lb. then a 1/28 scale version would still weight about 93 lbs. Given that this would be difficult or impossible to achieve, could the weight of the car be increased *somewhat* to give more realistic performance. The alternative is decreasing power, but when if that ever fun?

I know there is a lot more to the equation: motor power delivery, transmission (or lack there of), tire and suspension differences, etc. I was just wondering if anyone has thought about adding weight to these little car to gain some realism. It runs counter-intuitive to a lot of mini-z enthusiasts who seek competition, but if the car already replicates the drivetrain layout (RWD/AWD) and comes with pretty good independent suspension, maybe someone has already gone the next step to seek a scale power-to-weight ratio.

imxlr8ed
2008.12.02, 05:43 PM
If the full scale car is 2800 lbs, the 1/28th scaled car will weigh .13lbs or 58.967 grams.

Then there is the whole scaled durometer of the tires to deal with as well... I'm not even going there! Have fun figuring those scaled spring rates and trying to find an accurate representation of scaled macadam.

But really... it's a cool idea, but there's a month's worth of math there for me! :o

CrashTest
2008.12.02, 10:10 PM
If the full scale car is 2800 lbs, the 1/28th scaled car will weigh .13lbs or 58.967 grams.

Then there is the whole scaled durometer of the tires to deal with as well... I'm not even going there! Have fun figuring those scaled spring rates and trying to find an accurate representation of scaled macadam.

But really... it's a cool idea, but there's a month's worth of math there for me! :o

maybe i'm having an extended brain fart, but isn't 1/28th scale one twenty-eighth of the real thing? so 2800/28? If I'm missing something about model scales, please clue me in...

imxlr8ed
2008.12.03, 01:25 AM
Easiest way to explain it... you're only scaling per two dimensions when you do it that way, you can't do that with weights concerning three dimensional objects.

Here's something to chew on...

http://galileoandeinstein.physics.virginia.edu/lectures/scaling.html

franciscantony
2008.12.03, 02:40 AM
maybe i'm having an extended brain fart, but isn't 1/28th scale one twenty-eighth of the real thing? so 2800/28? If I'm missing something about model scales, please clue me in...

it is 1/28th as tall, 1/28th as wide and 1/28th as long as the real car. so you
need to divide by 28*28*28.

-Francis

CrashTest
2008.12.03, 08:34 AM
thanks for the link. i didn't consider scale volume vs. length.

marc
2008.12.04, 11:53 AM
I'd have a real problem carrying around a 93lbs car! LOL!
I think the most realistic thing to do is use an eco-motor to slow it way down to more scale-like speeds. But the slower they are, the more boring they are. One thing that makes theme fun is the speed and trying to get it to handle it's best.

MikeL
2008.12.04, 02:01 PM
Every time I drive my real car I wished it handled like my scale car... something to chew on :)

Action B
2008.12.05, 02:10 AM
thanks for the link. i didn't consider scale volume vs. length.

I think your about to make the most boring to drive mini-z EVER. lol.

imxlr8ed
2008.12.05, 01:39 PM
Yeah, it'll be slow... but if he put's it on a true scale roadcourse with the low traction levels required by scaling it down in a true fashion, it will be exciting to drive. You'll basically have a true to life racer. (can't wait to see the crashes into the true to scale tire piles!)

pomme de terre
2008.12.07, 01:56 PM
Scaling down something to 1/28th doesnt really work by just dividing everything by 28. Thats why when testing prototypes that arent full size (say in a wind tunnel), dimensional analysis (http://en.wikipedia.org/wiki/Dimensional_analysis) is often used.

Skv012a
2008.12.10, 09:52 AM
Neat idea, but I think they handle VERY well stock. Just don't floor it and it feels pretty real-to-scale. I love the way MRs slip/drift when turn speed is a bit over the friction limit and that they can spin out extremely easily. Very true to no-TC real cars (judging by sims like GT or forza, FRs spin the heck out when goin just a hint too fast through a corner). I'd say throttle and a lil bit more weight should make this idea work right.

RobinZ
2008.12.10, 01:04 PM
..its always nice to philosophize a bit. Therefore, i'd like to throw in some more; 'precision of control', 'feedback' and the 'gain factor for excitement'

Real cars are much more presice when control is concerned. The control of a Z is very sensitive, meaning that if you turn the wheel on the transmitter a bit the wheels of the car turn very much. The same accounts for throttle control. Your finger isnt able to control the throttle as accurate as in 1/1 scale your foot can. Even on scale speed control isnt that precise. Now, I think a lot can be improved using an adjustable transmitter with non-lineair control functions, but having the precision as in 1/1 would be very nice. (now I think of it, has anyone tried to connect a computergame steering wheel and pedals to his tx? LOL, that would be fun)

Another one is feedback. Its obvious, but steering and hitting the throttle with the tx and looking at your Z driving around feedback is completely differnt from being behind the wheel of a 1/1 car.

..and going to 1/28 there is also a down scaled impact on costs, space, safety, .... and not so much on excitement, so there is a gain factor somewhere...:D :D:D:D

marc
2008.12.13, 09:07 PM
We've seen racing games with steering wheels that have a force-feedback feel to it. Meaning, you actually feel the car gripping around the turns and what not. It would be interesting if that can be done here. A sensor on the car, say example a reverse gyro? that could send the info back to the transmitter's steering wheel and give you that same force-feedback feel with tiny springs in the steering wheel itselfe.
Gryo maybe wrong device, but some sort of sensor at the wheels that sense grip. Just some thoughts for yea.
Kyosho has the weight setting kit which I have not tried yet, but seems you can give more weight to the car to make it feel more life-like?

andreophile
2008.12.13, 11:40 PM
I use to think along the same lines too. Force feedback will definitely make for better car control if the delay is negligible enough. I think an accelerometer paired to another sensor that reads the steering and throttle inputs from the TX, will be perfect to sense grip. You can then employ an algorithm that gauges the available grip from the extent of lateral acceleration to the corresponding throttle and steering inputs. It'll be easy to tell if the car is skidding or tracking well using these sensors.

marc
2008.12.14, 11:43 AM
Perhaps something from the Wii gameing system might be usefull?
I also wonder if we would then be able to feel the different suspension settings in how the car/wheel grips. In theory, tighter springs, tighter grip, softer springs, less grip. Stock springs, neutral.
I see no methods of getting the sense of acceleration feel through the transmitter, but certainly I'm sure steering feel can be accomplished.

LOL! Maybe when we hit the other car's or the railings we get a vibration in the transmitter? :D
Too many hit's and the cars power goes off.

andreophile
2008.12.15, 10:17 AM
I should've put that properly. What I mean is that the multi-axis accelerometer will be in the car and not the TX, it will read the various accelerating forces experience by the Mini-Z and supply these readings to a microprocessor to inerpolate the data with the throttle and steering input readings obtained (wirelessly) from the TX.

This interpolation will be performed using an algorithm that will then give you accurate reading of the grip levels. The multi-axis accelerometer will be able to tell the lateral G forces as well as the amount of suspension dive in any direction.

This will be kickass because this data can then be used by a force feedback system on the TX to give feedback through the steering wheel. For example, the steering will be gradually weighted as you experience more lateral Gs and it can also lighten up to convey a loss of traction. Man, this could kick so much ass!

marc
2008.12.15, 10:06 PM
Yea, but if Kyosho did make this, imagine how much more expensive our cars would be! We'd have to sell BOTH kidneys to race!

andreophile
2008.12.15, 11:52 PM
Accelerometers are inexpensive. Do you know that the Wiimote (well, Wii remote) senses user input using the same accelerometers? Even most cellphones and cameras today automatically switch their display orientation by 90 from portrait to landscape according to the way you're holding them? Well, that's also achieved using simple, inexpensive accelerometers that sense whether the device is being held upright or sideways. Why can't the same be employed to check if the Mini-Z is going sideways? :p

Look at the economics; electronics required for force feedback today are quite cheap, which explains the minimal $10 difference between force feedback and non-force feedback equipped game controllers. All Kyosho would need is an inexpensive processor, some hardwired code and a few motors in the TX to create an ultimate force feedback system for the Mini-Z.

I'm surprised no one has tried it out yet. This will make driving so much more tactile and involving! Definitely worth an extra kidney or two I say :p

marc
2008.12.16, 10:19 AM
Can we live without Kidneys?
Anyway, yes my Iphone has it built in and some of the games use it's technology.
I agree, it would make racing more exciting especially if we can feel the car's hitting obsticals. And like I said, enough hit's, and the car should shut off leaving you out of the race like in real life.