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All Forums >> RC Cars, Buggies, Trucks, Tanks and more >> RC Car General Discussions >> How to find Speed?
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How to find Speed? - 7/21/2008 9:34:27 PM   
TRXRUSTLER


 

Posts: 39
Joined: 7/10/2008
From: Port Charlotte, FL, USA
Status: offline 		I was wondering how fast my Rustler went, but I don't have a radar gun so I don't know any other way to find out...................Thanks.
       Post #: 1

RE: How to find Speed? - 7/21/2008 9:45:11 PM   
guver


 

Posts: 8967
Joined: 3/7/2003
From: LaGrange, OH, USA
Status: online 		You can time it (distance/time) or maybe plug you numbers into here http://www.scriptasylum.com/rc_speed/_top_speed.html

OR post your specs and someone can guess really close.

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RE: How to find Speed? - 7/21/2008 11:43:59 PM   
elf232



Posts: 106
Joined: 6/28/2008
From: Baltimore, MD, USA
Status: offline 		Just set up a 40 yard run on a parking lot and do the math.


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RE: How to find Speed? - 7/22/2008 12:34:09 AM   
TheIronMaiden


 

Posts: 24
Joined: 5/25/2008
From: Dallas, TX, USA
Status: offline 		some gps units can measure speed, if you have one of those you could strap it to your car and see how fast it goes.

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RE: How to find Speed? - 7/22/2008 12:59:11 AM   
sloppyG


 

Posts: 2172
Joined: 12/10/2006
From: , MB, CANADA
Status: offline 		distance/time= speed

just make sure to get your units correct

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RE: How to find Speed? - 7/25/2008 7:53:53 PM   
nissanlove


 

Posts: 51
Joined: 7/23/2008
From: , FL, USA
Status: offline 		is it inches/seconds?

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RE: How to find Speed? - 7/25/2008 8:29:20 PM   
calvino


 

Posts: 6302
Joined: 4/17/2007
From: Thousand Oaks, CA, USA
Status: online
quote:

ORIGINAL: nissanlove

is it inches/seconds?

that would work to

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RE: How to find Speed? - 7/25/2008 9:21:19 PM   
dsales



Posts: 524
Joined: 8/14/2005
From: London, UNITED KINGDOM
Status: offline
quote:

ORIGINAL: calvino


quote:

ORIGINAL: nissanlove

is it inches/seconds?

that would work to


are you sure about that?

The official units are:

Speed = m/s (metres/second)

Distace = m (metres)

Time = s (seconds)

ahh, it was the 1st thing i learned in physics...

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RE: How to find Speed? - 7/26/2008 5:22:25 AM   
SAVAGEJIM



Posts: 4658
Joined: 7/6/2005
From: behind my 'puter, USA
Status: offline
quote:

ORIGINAL: dsales


quote:

ORIGINAL: calvino


quote:

ORIGINAL: nissanlove

is it inches/seconds?

that would work to


are you sure about that?

The official units are:

Speed = m/s (metres/second)

Distace = m (metres)

Time = s (seconds)

ahh, it was the 1st thing i learned in physics...


In the US, we use the British Imperial system (feet, seconds, pound mass). Funny, we dont call it the British Imperial system, we now wrongly call it the "Standard" or "American Standard" system, even though the foot was actually based off of old England's King Henry the 1st (or at least the legend goes). So, it is very funny that the British now use the Napoleonic SI instead of their own British Imperial system. Again, more historical irony, King Lewis (Louis en Francias ) the 16th who made metric system the standard French measurement was killed. The French Republic kept the system, and due to Napoleon's influence, the metric system became the SI and was sperad all over Europe.

Personally, I prefer to calculate most things in SI, speed, as in this discussion, becomes very easy to convert from Km/hr from m/s and so forth. I can even do it mentally without the aid of a pencil & paper. In the British Imperial system, it is much harder, converting from ft/s to mi/hr is much harder. There are 12 stupid inches in a foot (Why cannot it be TEN inches per foot?). King Henry ole #1 should have had his foot cut off by the toes! Then, feet would be much more easier to work with because there would be 10inches to a Henry foot! Worse, there are 5280 surveyed feet in a statute mile! They should have made a concept of a kilo foot, or at least a kilo yard. That way converting from ft/s to mi/hr would be much easier.

Sorry for the rant, this is my beef with the British Imperial system when calculating speeds. I like to do things mentally, but because of the Brit Imp system not being divisible by ten, I have to resort to a calculator, spreadsheet, etc when converting ft/s to mi/hr (or even yd/s to mi/hr)

< Message edited by SAVAGEJIM -- 7/26/2008 5:26:31 AM >

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RE: How to find Speed? - 7/26/2008 5:23:18 AM   
JATO TO THE MAXX


 

Posts: 110
Joined: 11/7/2007
From: Garner, IA, USA
Status: offline 		Or you could just buy the Venom Speed Meter

http://www.venom-group.com/itemdesc.asp?ic=VEN%2D0615

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RE: How to find Speed? - 7/26/2008 8:34:12 AM   
Gex_61



Posts: 1677
Joined: 10/29/2005
From: Bakersfield, CA, USA
Status: offline 		Do it without ever turning your car on.

http://www.teamassociated.com/racerhub/techhelp/marc/JScripttable.html
http://www.teamassociated.com/racerhub/techhelp/marc/gearform.html

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RE: How to find Speed? - 7/26/2008 9:40:10 PM   
SAVAGEJIM



Posts: 4658
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From: behind my 'puter, USA
Status: offline
quote:

ORIGINAL: JATO TO THE MAXX

Or you could just buy the Venom Speed Meter

http://www.venom-group.com/itemdesc.asp?ic=VEN%2D0615


I have one of those, I used it on my R40. Nifty gadget to see how fast a car goes on a straight, but it unfortunately only adds unwanted weight on the track.

My only problems I have with this Speedo is getting the oll-out corect. Then, as the foam on the tires wear down, doing another roll-out to account for the reduced wheel's diameter.

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RE: How to find Speed? - 7/26/2008 9:44:49 PM   
SAVAGEJIM



Posts: 4658
Joined: 7/6/2005
From: behind my 'puter, USA
Status: offline
quote:

ORIGINAL: Gex_61

Do it without ever turning your car on.

http://www.teamassociated.com/racerhub/techhelp/marc/JScripttable.html
http://www.teamassociated.com/racerhub/techhelp/marc/gearform.html


Those are very nifty, and I use those very same formulae on an Excel spreadsheet. The only problem with that is the part of the RPM. You really dont know if your car will turn those RPMs unless you actually do some field testing. For example, an engine is advertised to reach 42000RPM (and virtually all RC advertisers are lying snakes). Put high gears on the engine and run that car on the street, wnd you will discover very quickly that the engine simply does not have the torque @ 42000RPM to turn those gears. The engine might reach 35000RP max on those high gears, so the calculated speed at 42000RPM on high gears is moot.

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RE: How to find Speed? - 7/26/2008 11:29:46 PM   
sloppyG


 

Posts: 2172
Joined: 12/10/2006
From: , MB, CANADA
Status: offline
quote:

ORIGINAL: nissanlove

is it inches/seconds?



it's whatever you want

you have to convert from whatever distance you time (say 50-100 feet) to miles, and convert the time into hours

you'll get something like (random here) 30 feet/second, figure out how many feet/hour, then convert the feet to miles/hour

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       Post #: 14

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