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cheapest way to know the top speed of my rc

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cheapest way to know the top speed of my rc

Old 01-24-2015, 07:13 AM
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krokodyl
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Default cheapest way to know the top speed of my rc

Hello everyone i was wondering if there is any device that i could put on my rc truck and know the top speed for like $20? Thanks for any help.
Old 01-24-2015, 07:47 AM
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collector1231
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Go to a private or street in a neighborhood, have a friend drive at whatever speed you want them to, and once the RC car is about the same speed as the real car, you have your answer.
Old 01-24-2015, 07:55 AM
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krokodyl
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you see the problem with that is that is that I cant do it on the street because on pavement my monster truck goes out of control, it starts doing spins and would probably hit the car. And i don't know anyone who would want to go at realy high speeds on the grass, besides theres no large enough grass area were real cars are aloud. Any other ideas? I dont want to spend $100 on a radar gun.

Last edited by krokodyl; 01-24-2015 at 07:57 AM. Reason: spelling mistakes
Old 01-24-2015, 08:46 AM
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Neverlost1
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Do you own a GPS? Strap it to your truck and check the "trip" display. It will show your top speed..
Old 01-24-2015, 10:12 AM
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krokodyl
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I dont own a gps but will be considering buying a cheap gps unit. Thanks guys
Old 01-24-2015, 11:14 AM
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GPS won't be very accurate but it will give you an idea.
A bit more expensive but more accurate. http://www.eagletreesystems.com/inde...&product_id=63
Old 01-24-2015, 03:14 PM
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Some reports say GPS units will report driving speeds with errors down to about 0.1 to 0.5 MPH.
krock, maybe you would want to go "old school" and use a stopwatch and time how long your truck goes between two lines? Use this link http://www.csgnetwork.com/csgtsd.html to help you.
Old 01-24-2015, 05:38 PM
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krokodyl
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I think a gps unit is still more exact because if my truck is speeding torward me i wont be able to press the button on the stopwatch at the correct time, besides this gives you the average speed not the top speed. Also my camera doesn't have milaseconds, only seconds so filming it then looking at it in slo mo would be extremly inexact.
Old 01-24-2015, 05:51 PM
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A GPS is the way to do it.... The are defiantly accurate enough for what u are planing... The more satellites it's connects with the more accurate it is. If u want to do it for cheap...... Look for a secondhand android smart phone with a unbuilt GPS..... Something like a 3 year old Samsung Galaxy mini...

Another option is a hot wheels radar gun, they are more accurate that u would think, but they are very popular with electronic enthusiasts so even secondhand they can be expensive and hard to find.
Old 01-24-2015, 05:53 PM
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Forgot to mention.... Some of the smart phones have accelerometers built in... There are apps that use that and the GPS than can give u 0-100 times, max speed, and Max g forces among other things
Old 01-25-2015, 04:21 AM
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Draw two lines in the grass, 1/4 mile apart, clock your car from one to the other, then multiply x 4. Its free.
Old 01-25-2015, 05:54 AM
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u could use a GPS to measure out the quarter mile....
Old 01-25-2015, 06:45 PM
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cumquat
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this wont tell you the actual top speed, but it's free and will tell you the maximum theoretical speed http://scriptasylum.com/rc_speed/top_speed.html
Old 01-26-2015, 05:30 AM
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Anthoop
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A company called Venom used to make a speedo that consisted of a magnet/pick up and a electronics box...that was cheap but you had to calibrate it properly for it to be accurate....I tested mine whilst sat in a real car and driving the RC alongside. (so it was as accurate as the real car speedo).
http://i162.photobucket.com/albums/t...p/DSC00651.jpg

The cheapest/free way to get an idea of the speed is (as already said,) measure a distance and time how long it takes to cover the distance. You could also get a theoretical idea by calculating the gear ratio and measuring the circumference of the tyres, along with the maximum engine/motor rpm (again as already said).

Last edited by Anthoop; 01-26-2015 at 05:34 AM.
Old 01-26-2015, 07:04 AM
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Is it the cheapest??.... Just to rock the boat and offer a different perspective

The cost of the measuring device to measure the distance for the speed trap and something to measure the time it takes might cost more than a second hand smartphone with unbuilt GPS and accelermoter.

I guess if u have everything allready it wouldent cost a dime. I know builders tape measures can get expensive when looking at brand names and I'd hate to thing how expensive one of those big long ones are....

I honestly think, generally speaking it's more common for the average house hold to have at least 1 smart phone, and in a lot of hose holds 1 per person.... I'm sure statistics would reflect but it's safe to say that smart phones are more common than long tape measures and stop watches.

so generally speaking, I would say for the average joe it would be cheaper for them to use there smart phone as a speed measuring device.
Its just unfortunate that the OP is one of the few with out one.

where I live....In Australia, there is more mobile phones in use than there are people

check out this for more info on phones
http://en.m.wikipedia.org/wiki/List_..._phones_in_use


there are a few options to try... It's really up to the OP on what's going to be the cheapest.... If he is really good with online sale sites he might be able to pick up a older smart phone for next to nothing...
Or who knows, there might be a local store that has all the bits needed to measure, time and build a speed trap
Old 01-26-2015, 08:15 AM
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Measure out 110 feet on the ground. Have a friend with a stop watch stand by one line. You stand by the other. Take a running start with the truck at either line. If you start at his line he hits run on the stop watch when it crosses the line...You yell stop when it crosses your line. Or you yell start when it crosses your line and he hits stop when it crosses his going the other way. Make several runs. Multiply each of the run times by 48, Total them up and take an average.
Old 01-27-2015, 09:03 AM
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Anthoop
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Originally Posted by phmaximus View Post
Is it the cheapest??....
Yes it is because you do not need any tools or equipment at all if it really came down to it. For example, you could count a hundred salmon lengths (if you had a salmon (sarcasm alert)) and count the time to travel the distance, from that you can calculate how fast it is travelling in salmons/hour! :P If you know how long the salmon is then you can convert the salmons/hr to something more familiar.

Being more realistic- you do not need to measure the distance in total, if you only have a 5m measure then lay it end to end a number of times.....or just use your plates of meat (feet).
Old 01-28-2015, 04:38 AM
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So ur saying... Even tho the average joe has a phone/GPS in there pocket it's cheaper to set up a speed trap??
how can it be cheaper than free??? Wouldent the average joe just use there phone?

Soeed trap
Stuff that... Sounds like a lot of work...for a crappy result.

fact is u do need tools....
u need a measuring device
timing device and ideally something to mark out a start and finish

i get the sarcasm but it's floored, sure u could measure it in salmon lengths but that's not a standard measurement and there is no standard lenght for a salmon.... So the end result, if u want to convert fish per hour to mph ur still need to measure it.... It's just the same as asking how long is a peice of string.... If I said my car travels 1 peice of string every hour, is that a fast car? Or a really long peice of string?

Ok correct me if I'm wrong but...Im no expert
if ur running around the 60mph 100kmh and over u really need to use at least 1/8 of a mile otherwise it won't be very accurate...
so that's about 200m..... Are u seriously suggesting that u would measure 200m with a 5m tape measure??? I wouldent, no way.....imagine trying to do that yourself with no one to hold the end
And seriously, to get the vehicle up to speed before the trap u are going to need some room to get a run up... I think the average joe is going to struggle effectively controlling there rc car from those kinds of distances.

I guess what im saying,,, no matter what, u are going to need a measuring device... Otherwise how do u measure the distance or time?
and some of the methods like using ur feet is just ridiculous. That would be so inaccurate it's not even worth doing it.
I say if u are going to put the effort into making a speed trap do it right, otherwise it's a wast of time with poor results.

and saying that,,, I think u will find a old smart phone is cheaper that a time and distance measuring device....

obviously the OP is a child/minor, I'm very doubtful they would have the skills and recourses to be able to pull of a successful accurate speed trap... I think they would have more luck using a family members phone or real car to measure it...
Old 01-28-2015, 04:42 AM
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See I have no idea what's the minimum distance to accurately measure speeds in certain ranges... I can only assume the longer the better... 110 feet sounds a little small, but like I said before I'm no expert, I'm just guessing from logic
Old 01-28-2015, 07:06 AM
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Drag strips use a 66ft long speed trap before the finish line to calculate the mph. But that's also a computerized timing system not a stop watch.

Edit: I have tried using speed apps on my iPhone to calibrate aftermarket speedometers in 1:1 cars and found it difficult. I don't know whether it's satellite or tower based gps but there was a lag in the displayed speed in some locations vs other locations probably due to reception. Something to keep in mind

Last edited by Maj_Overdrive; 01-28-2015 at 07:18 AM.
Old 01-28-2015, 11:14 AM
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Anthoop
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Originally Posted by phmaximus View Post
So ur saying... Even tho the average joe has a phone/GPS in there pocket it's cheaper to set up a speed trap??
how can it be cheaper than free??? Wouldent the average joe just use there phone? .
I am cutting it down to the above...
The person who is/was asking stated they do not own a smart phone nor any kind of GPS device....(and if we are honest they are looking for an idea of the speed...)

I agree that if you have access to one of those devices then just download the doodah...strap it on... and away you go!
If you know how long your shoes are and can do some pacing (toe to heel (straightish)) then you can define a distance...easy to mark and time a distance....in fact free really. :P
Old 01-28-2015, 09:51 PM
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True true. I wonder how the OP went?
Old 02-02-2015, 10:36 PM
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Go to a private or street in a neighborhood, have a friend drive at whatever speed you want them to, and once the RC car is about the same speed as the real car, you have your answer.
Old 02-03-2015, 04:29 PM
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krokodyl
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Already mentioned i cant do that!!!!!!!!!!!!!!!!!!!

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