Anyone Ever Measured Their Buggy Speed..?

[BUNGCHIDDI]

I know I should just be happy bashing and not worry about how fast this & that but im just curious has anyone measured the speed of their buggies..?

Now obvuiously the brushless people out there will win every time...so im curious to know if any of you have measured your brushed speed & what set-up where you using at the time.

My old HS2 restoration with ballrace, 12T corally & 1900mAh battery was doing about 50meters in 4 secs....if my math is correct thats ~45kmh/28mph....does this seem right..? Looking to see what the rest of you are getting for your various set-ups.

[loaded]

Brushless won't necessarily be quicker, there are a lot of quick motors out there. Brushless is easier to maintain though. People talk a huge amount of rubbish about the speeds of their buggies, frankly I can't believe the claims made by many, especially on eBay. I have heard comments about stock Hornets going 40 kmph, when 10 to 15 is more like it. It is very difficult to judge the speed of something so small, the smaller it is, the faster it appears to go (hence why the 959 looks ridiculously fast in stock form, notwithstanding the stock Technigold).

There are a couple of ways to accurately measure the speed of a buggy, a radar gun is one way to measure it. Radar guns are illegal in some countries, so be careful before going out and buying one on eBay. Some are inaccurate. Perhaps the best way to measure the speed is over a measured distance. Say 100 metres, with a start to get a run up to top speed. Then measure the time taken. the shorter the distance you use, the more inaccurate it will be. Someone had better measure with the stopwatch rather than the driver. Then calculate for MPH/KPH using simple maths. This is a free method, without getting out complex equipment like radar guns.

Be precise though, 4 seconds could be 3.5 or 4.8 (examples only) which would wildly affect the actual speed. The faster the buggy, the longer the distance you should measure to make it accurate. Did you measure by counting, or someone with a stopwatch? 45 KMPH is correct caluculation though for that time over that distance (again, distance estimated, or exact?)

Paul.

[Gruntfuggly]

Just to add to Paul's suggestion - if you're timing manually (eg, using a stopwatch, etc.) do it several times and average the results...

[wolfdogstinkus]

Run past a speed camera with your wifes number plate taped on the roof!

[BUNGCHIDDI]

Got my son to measure out the 50m distance on the street....yes true...100m would have been better. Timing was done using a stop watch....also i made a mistake..i didnt allow time for run up speed - so it may have been slightly quicker....i started from stationary

Visually start the stop watch at word GO.....then stop as it crosses 50m.....i know its fairly inaccurate but it gives some idea of speed....so id say 45kph...could be +/-8kph.

I know what you mean about ppls claims on speed....way over the top - im simply trying to gage if im in the right ball park or not for some simple hop-ups ive made.

Then i was going to compare tghe same gear in my new DF03 to see if it moves any faster givin the simpler more efficient drive train in the DF03....just need to get the gearing ration right first tho.

[loaded]

I must admit it sounds a little on the fast side, especially if you didn't have a run up, but feasible. I am not saying I don't believe! The average is a good idea.

Keep well,

P.

[TA-Mark]

This spreadsheet shows what to expect in the name of speed at maximum from a buggy. And the standard setup (really only does about 25-27km/h).

Green indicates 'good' ratios. Electrics temps will increase as the you get closer to the 'red' end of the gearing scale.

It does not take into account the Kv of the motor under load (Stated motor ratings are unloaded), drag through the driveline and bearings, wheel slip on the road, or the grade of running area. So you could expect 4-5km/h less than what is calculated by the number of rpm x the circumference of the wheel.

This topic of thread would be one of the worst topics for the old 'my buggy goes this much faster...or my buggy does some unbelievable speed'... Hope this thread doesn't turn into one of them.

[loaded]

HI Mark, how did the race meet go? I couldn't get a ticket, unfortunately :-D

Are these completely theoretical speeds? A standard DF03 going 25Kmph? I remember people talking about hornets (standard ones) doing 40 kmph before! The truth is most fit people can outrun most electric buggies (I am not talking about hopped up, nitro, brushless and brushed low wind motors etc).

Paul.

[TA-Mark]

Race meet was great, can't wait for the next one. I know it's not fair but I won every race I was in

Not so much theoretical as they are mathematical speeds. I can beat the standard buggys in a foot race, against the kids the buggys win. I do the 100m in 12.5sec. I'm probably being a bit generous to the 540 silvercan giving it 17,000rpm. If I change that field to 16,500rpm it changes the speed to 28.8km/h.

I also worked out spreadsheets for the DF-01, DF-02 and TL-01b buggys to compare (and to see what I'd need to fit in them to run brushless). With the setups that I have in each of the buggys atm (There's 1 of each chassis type here in 27T class) they are all the same speed, 27T class is very tight racing, no one gets to pass on a straight. They all come out to 28km/h-30km/h in the spreadsheet for the setups running, so I'd say it's pretty accurate.

To make a hornet/grasshopper do 40km/h you would need some serious rpm bolted to it... and some real front suspension to keep it in a straight line to get it there. I would estimate mine at 35-40km/h with the 5700kv in it, using a VLB pinion to get the ratio right for high rpm brushless. I've done high speed passes down the tarmac with it, but it was so nervous even with all my suspension mods. It's not as fast as the DF-03 with the 4600kv anyway.

One that has always struck me is the big blatant 44MPH on the side of the HPI Savage box... there's no way that great lump will get to 70km/h... maybe down a big hill with a tail wind.

[BUNGCHIDDI]

wasnt really the intention of the thread....as i say just wanted to know where my buggy was operating in relation to others out there, ive never raced or even seen another other than my own.

based on your spreadsheet...im doing roughly around the same speed as a 4600MM with 20T/85T....with a 26T/78T set up (with 12t motor)....making mine ~40kph.

Ive ordered the 23T pinion and sticking on the 85T spur.....whilst the top end speed is good the accelaration is poor.....85T spur is a tight fit, but then again maybe the smaller pinion might help when it arrives.

Cheers.

[TA-Mark]

The spreadsheet is really for the DF-03 chassis. To compare a different chassis to it you would need to compare the FDR (Final Diff Ratio) column. You would also need to know the operating RPM of the motor. I would expect The Hotshot II to be geared a lot taller than a DF-03. I don't think the Hotshot wheels are 85mm diam either.

I know my Fox is quicker in a staight line than the modern 4WD buggys, all in standard kit trim with the same ESC and battery.

I could throw the figures into the spreadsheet if you know the motor max rpm and FDR for the Hotshot II (or for any other chassis).

[BUNGCHIDDI]

The speed of the DF03 with the HS2's gear in there looks to be the same.....at top speed but as i said the DF03 has poor accelaration, so i'll retest with the new gear ratios to see if it moves any faster, Terry had spoken about lower pinion/higher spur can release more power from the motor, or allow it to get to higher power bands...

Cant find any info on my motor...got it from Ebay...with some help in here i was able to take it apart and find a small hand written 12t on one of the rotor segments.....does this make it a 12t motor..? its a corally modified 300..., no other markings on it anywhere - so I dont have a clue what RPM its running at. It seems way faster than my sport tuned motor, just by the frequency of the spin...higher pitch. Its running off an RV11 ESC without issues so its not lower than 11t ...i would imagine.

I didnt want this thread to sound all......mines can go this fast bla bla bla...was interested given my lack of experience. The spreadsheet is a good idea, cant read the red sections but it looks as though some electric buggies with the right gear can really shift..!!!

Cheers.

[blakeatron]

Measuring speed is hard - we normally strap a gps thing to the car and blast about! Dont know the name of the gizmo we use as its not mine, sorry

My quickest car is my savage flux running on twin 3c li-po's, got 58mph on grass fully standard except spektrum radio gear;

Speed is overated - as I couldnt do anything with my flux, now turned the power down via the castle link kit! It was pulling wheelies at over 30mph and still managed to backflip at over 10

[terry.sc]

Yes it's a 12 turn motor, Corally, like most performance motor manufacturers, do just write on the armature what the wind is.

I have had the speed of my buggy measured at the end of the straight at my club one night, someone brought a radar gun down and he measured the speed. Specification was Kyosho Lazer with 14 turn motor, and coming out of a tight hairpin bend, so more or stationary, it reached 23mph/37kph at the end of a 12m straight. If I'm running outdoors though I go up 6 teeth on the pinion as I don't need to gear it down for acceleration.

[loaded]

I am a little wary of GPS speed measuring, the GPS in my car doesn't pick up which road I am on sometimes in London (gets the one parallel) so if it can be so inaccurate with big scale cars, what about smaller ones?

Anyway, the gadget you want is this:

Dodgy Chinese GPS tracker/speed measurer

P.

[cubsfan2009]

Here's a good link to calculate the top speed of any car. My DF03 with CC 4600kv comes in at about 34mph with tire ballooning, and I think that is plenty fast. A 5700kv would be to fast for most situations.

http://scriptasylum.com/rc_speed/index.html

[Lemming]

I've tried a Venom Speed Meter in the past on my Novak SS5800 Top Force...

It recorded a top speed (on the ground) of 35mph. Top speed air running was some 42mph - amazing what resistance the road provides (plus wind resistance of course).

Problem is that it isn't the most precise system in the world. You have to take several measurements (roll-out etc) and input it into the device. It all comes down to measurements and accuracy, so god knows exactly how accurate it is.

E-Maxx is supposed to do about 30mph but the Traxxas forums measured stock ones as about 27mph. I think often the acceleration can make people think it is faster than i really is. E-Maxx seems quicker in normal conditions than the Top Force, but that's purely acceleration.

Personal thoughts as always

Steve

[TA-Mark]

Here's a good link to calculate the top speed of any car. My DF03 with CC 4600kv comes in at about 34mph with tire ballooning, and I think that is plenty fast. A 5700kv would be to fast for most situations.

http://scriptasylum.com/rc_speed/index.html

What internal ratio did you use to get that, cause I can't get that figure. Mainshaft to axle is 3.0555556:1. By my spreadsheet (which will be doing the same calculation as that website) to get 34mph you must be using 26/82 gearing, or you have larger than normal tyres.

I went back to 4600Kv from the 5700Kv in my buggys because the laptimes are faster with the slower motor. Less wheelspin and more drive out of corners. You are still full speed by 2/3rd straight. It's only 1 sec a lap faster, but that's enough.

It recorded a top speed (on the ground) of 35mph. Top speed air running was some 42mph - amazing what resistance the road provides (plus wind resistance of course).

35mph from the 5800Kv would be very close to what it was really doing. By my guess (and my DF-01 page of the spreadsheet) you were using 16/74 or 17/74 to get it. I reckoned my Blazing Star with the 5700Kv, 17/74 gearing was getting 60km/h (38mph) when I used to run it like that (and before I did any maths on their speeds). The CC-01 tyres are a touch taller than the 82mm diam Top Force spikes and are great for tarmac speed runs.

Gunna get one of the guys here to drive the 44mph Savage while I drive the DF-03 and we are are going to have straight line race. I know my DF-03 is doing ~50km/h. If the Savage doesn't beat it we'll know that the big white letters on the box are just a sales pitch.

[cubsfan2009]

I plugged in the following:

internal ratio = 2.94 (from Tamiya website)

Trans ratio = 1 (not positive on this one)

Spur = 82

pinion = 23

Volts = 7.4

KV = 4600

Tire = 3.25"

Ballooning = .125" (best guess)

Result = 33.82 mph w/ballooning; 31.4 mph w/o ballooning

I don't think the chart accounts for ballooning which is hard to judge.

[TA-Mark]

Trans ratio is not 1:1. There's 22 teeth on the counter gear and 18 teeth on the mainshaft gear, making the total 3.0555556:1 between mainshaft and axle. Compare the FDR's to what is in the manuals, they workout right with 3.06:1.

55T diff gear / 22T counter gear = 2.5:1

22T counter gear / 18T mainshaft gear = 1:222':1

2.5 x 1.222' = 3.055555556

That's the same setup I have in my MS, 23/82 with the 4600Kv on 2s Li-Po (7.2v Ni-MH occasionally).

No, I didn't allow for ballooning of the tyres, There is practically none from 85mm (3.35") CC-01 tyres or from the Tamiya High Density Spike tyres. I didn't allow for drag or the real Kv under load either.