Hi everyone,

I have been thinking about scale speeds and how slow a TJET would have to run to get in the ballpark for GreenRun Speedway. GreenRun is approximatley 984 scale feet long for 1/72 scale. To get an average speed of 120 mph I would need to turn a lap of approx 5.3 seconds. Is my math right? 176 ft per second for 120 mph? So all I need to do is turn the power down till I get in the mid 5 second range to get the scale speed where I want it?


Roger Corrie

If it is all straight track yes. 1:1 cars slow in the turns and accellerate up to speed on the straightaways. But this stuff is way too complicated for me to figure out. Mid 5's sounds good!! LOL ;)

Roger----- how long in real ft is your track? If we know that, we can come up with an approximate time. Also why are you saying 1/72nd scale?

Roger I think you are a touch low. The track is .186 scale miles. It takes 5.376 laps to make a mile. To do 120 mph you need 1 mile every 30 seconds. Divide 30 seconds by 5.376 laps and you get 5.58 seconds per lap.

:woohoo: Five years at IU weren't totally wasted:woohoo:

Roger----- how long in real ft is your track? If we know that, we can come up with an approximate time. Also why are you saying 1/72nd scale?


Because TJETS are somewhere between 1/72 and 1/76 scale

Roger Corrie

Roger I think you are a touch low. The track is .186 scale miles. It takes 5.376 laps to make a mile. To do 120 mph you need 1 mile every 30 seconds. Divide 30 seconds by 5.376 laps and you get 5.58 seconds per lap.

:woohoo: Five years at IU weren't totally wasted:woohoo:

Now all I have to do is crank the volatge down till I get close time wise. Then I will know where I want to run my next mail-in race at voltage wise. Having all kinds of crazy ideas

If you turn down the voltage from the norm then how will those that don't have the ability to adjust the voltage on their home track tune their cars?

Roger-- from the info given I'm guessing your track is 13 1/2 ft per lap. If that is true your lap should be 5.6 sec to match the 120mph.

Roger it sounds like your track is close to mine in length, a 1/5th mile. We will run on 9 volts sometimes to slow them down, we have run on 6 volts too but that seems too slow. But I have never seen anything that can do 120 on a 1/5th mile, I think the fastest thing I've seen at the Thunderbowl in Tulare is about 70 mph average per lap. I like the G-Jet powerpack because even with 6 volts the power to all 4 lanes with T-Jets is smooth.

I've never bought into the "scale speed" thing because time does not scale with the physical dimensions of the cars, and human reaction and perception is based on real time. When you watch the video from an onboard camera on a race car, especially a Formula 1 car running on a road course, the driver's perception of the track, required anticipatory actions, reactions, and driver input is incredibly fast, much more akin to what you as a human must handle when driving a race prepared HO magnet car.

The fact that the HO car is 1:64 scale does not change your brain's perception of the real world situation that you are dealing with in real time, because the time does not scale. There are mathematical models for defining the equivalent aerodynamic and hydrodynamic forces exerted on scale aircraft and ship models that are a fraction of the size of their real world counterparts, and these formulas are critical to the design and validation of new aircraft and ship designs. I could potentially see these being used to figure out the equivalent speed of perhaps a 1:24 wing car if you could measure the forces exerted on it, if indeed the formulas are actually usable down to models of that size. There are lower limits.

But the fact remains that scaling down the physical dimensions does not change the time and human element, which is the reason the "scale speed" ratings of 1000+ scale mph are rather meaningless in the overly simplified context in which they are presented. While the seemingly hyper velocity ratings of scale race cars may sound unrealistic on paper, when it comes to the actual race action and driver reaction reaction times required to negotiate the race course, the speeds are not far off the mark in terms of racing realism, especially when you consider all of the other unique variables, like being able to see the whole track from a birds eye view. Where the best equivalent realism falls is hard to say, but it is clearly not simply a matter of scaling down the real velocity of the cars to achieve equivalent lap times if you are looking to provide realistically equivalent racing action for 1:1 human drivers, assuming that's what you are hoping to achieve. If you are looking to make a movie where the cars are traveling at an equivalent velocity in-scale, then what you are proposing (tweaking voltage to achieve lap times) is reasonable, but it's not as realistic from a racing perspective.

I would simply pick a fixed voltage that everyone can design, test, and tune their cars against, especially if you are doing some sort of proxy race. Just my 2 cents worth of opinion.

Try entering your numbers in these

http://www.mcr5.org/NMRA/articals/speed.htm


http://www.nhsouth.com/crafts/workbench/ssc.htm

Jeez ladies!

Do I have to do everything???

http://i44.photobucket.com/albums/f30/modelmurdering/DSC05690.jpg

http://i44.photobucket.com/albums/f30/modelmurdering/DSC05689.jpg

http://i44.photobucket.com/albums/f30/modelmurdering/DSC05688.jpg

Why fo ya gotta make stuff so hard? :rolleyes:

I dont quite have all the bugs worked out of this. Could somebody send me a large zip strap please. I originally fingered we could adapt the PTO from an AFX cop car to drive it, but then the read out would be vertical. :p

Umm, where's the oil pressure and tach? Maybe some bondo to blend it in a little smoother?

Jeez Bill!! That car's got some miles on it!!!! :eek: You wouldn't happen to have any video of that behemouth, would ya??? :rolleyes: It does look kinda top heavy!! :lol:

:p:p:p:p:p:p:p

:eek::woohoo::D ROFLMAO!! @Bill...

Trust the brilliant mind of Bill Hall to invent a whole new catagory of HO Racing! :woohoo:

Bill, are those scale miles or actual miles?

At my track we have 6 lanes, of which we use the inside 5. This is an oval mind you but powered by an 18-22 v. aurora power pack 1 pack per lane. The lane lengths vary from 23.75 feet for lane 1 to 27 feet for lane 5 and with slottrak computer scoring will get you a lap with a stock t-jet with silicons of about 3 seconds. This was equal to a scale mph of 350. Our A/FX mag will do a lap of 2.2-2.5 and equate to about 450 mph. This is on lane two (just tested for your viewing pleasure) and power supply is increased as you move out, slowest on lane one to most on lane 5. Tomy 440's do about 600 mph (whew) if you can follow them for more than a lap.

Hi everyone,

I have been thinking about scale speeds....

Roger Corrie

See, now, thats where you went wrong, right there :)

Holy crap Bill, I'm glad I wasn't drinking a soda, you'd owe me a new keyboard and monitor dude.........