mike_o

True top speed (GPS / accurate measurement)

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Top speed remains a controversial issue and seems subject to all sorts of exaggerations. I just bought new, small GPS to rid my car of my bulky (motorbike type) Zumo device. The nice little newcomer has immediately been put to good use clocking some of my Tamiyas.

So I suggest we open a new thread (this) where we can post the true, measured top speed of various Tamiyas in various trims. In order to keep the thread clean, I suggest we limit comments and discussions to a minimum, and just post our findings along with relevant information. Something like:

Model name and top speed

Motor

Gearing/wheel size/roll distance per revolution

Bearing type

ESC

Battery

Measurent device (GPS/Speed Gun/Watch)

Comments/photo

Did I miss anything?

I'll go first:

Thunder Blitz: 18km/h

380 motor (stock)

Stock gearing (13.65:1 = 1,73cm/rev)

Fully Ball raced

TEU-101

7,2v NiMh

Garmin Nuvi 1240

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Thunder Blitz 480 RWD: 37km/h

Graupner Speed 480 Race motor

15T pinion (8,19:1 = 2,81cm/rev)

Fully Ball raced

LRP AI Runner Plus Reverse

7,4v LiPo

Garmin Nuvi 1240

RWD only !

rc_juli_2011001.jpg

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u do realize that "gps" only measures lateral velocity

if your car fell off a cliff... it'll reach terminal velocity but gps reads zero B)

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u do realize that "gps" only measures lateral velocity

if your car fell off a cliff... it'll reach terminal velocity but gps reads zero B)

Remember kids. When assessing the top speed of your car, only drive it on a flat surface, and never up the side of a 90 degree wall, or you may distort the readings!

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u not a fan of the "wall corner" on buggy tracks then? B)

just noticed OP mikeo is using a Boy Racer

Wonder what's the fastest anyone can get one of these up to... :D

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Rising Fighter

Stock ESC

540 Silver Can

7.2V / 3000 NIMH Cells

16.4mph

This was only a couple of runs old at the time, and it hadn't even had ball races fitted at the time..

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Re-re Lunchbox, 70mph

No battery at all

...in the trunk of my wife's Mitsubishi...

B)

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u do realize that "gps" only measures lateral velocity

if your car fell off a cliff... it'll reach terminal velocity but gps reads zero B)

Why can't it measure vertical velocity?

It's basically plotting the intersection of a set of spheres, which by their nature are 3-dimensional, and calculating speeds based on changes in the position. A vertical change is the same as a horizontal one to the system.

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Why can't it measure vertical velocity?

It's basically plotting the intersection of a set of spheres, which by their nature are 3-dimensional, and calculating speeds based on changes in the position. A vertical change is the same as a horizontal one to the system.

It is the relative difference in distance between the satellites it is using to determine position. Seen from earth, the horizontal difference between satellites is great, but the vertical difference is small. So it is harder to be exact.

When we use a GPS on our boat on the sea, it often believes we are +/- 10-20m from sea level. Tides here are rarely over 0.5m. However, the GPS can show us almost the exact position of the GPS in the boat when we're next to the pier. About +/- 1-2m

So GPS is less accurate vertically, which also means less accurate when measuring vertical speed.

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I'm more than happy to strap my iphone to a chassis, but exactly how big a distance do you have to travel to get an accurate reading, given mot devices will have a measurement/data interpreation/data reporting cycle time.

I'm thinking i'd need at least a 50m stretch of tarmac, which at 25Km/h is only 7 seconds at max speed and i'll guess that most sat nav type devices update every 5 or 10 seconds ??

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GPS accuracy depends mostly on the:- number and positioning of the satelites and how close the atmosherics actually are compared to the assumed atmospheric model used and if the system administrator (US DOD) wants any added inaccuracy!!

Remember speed = distance / time

velocity = displacement / time

speed = velocity only in a perfectly straight line.

MK1 rough rider

7.2 nicd (old)

540 stock

14 km/h (dry)

stig -not available.

PS Vonez. Three satelites is the minimum for GPS computation of lat and long. The current new generation passenger jets (A380, B777 etc) have extreamly accurate GPS backup of barometric altitude indications.

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Fair enough but my point is what is a sensible measurement time, given sat nav devices don't report every second ?

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I did a series of very short runs, like 10 meters, resetting the GPS max in between every one. The recorded max was consistent within 1 km/h. I think 25-30 meters would be enough, given the car reaches top speed in a small fraction of that distance.

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Are the iPhone GPS readings accurate?

I'll get my wife to DL the app if they are.

Although when I mentioned it last week, she wasn't too keen on me strapping her phone to my RC cars and belting up and down the street. <_<

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Dont quote me, however, modern digital signal mobile phones, (iphone) positioning uses GPRS, the data signal sent from each cell tower is encripted with a semi-random code which gives each tower signal an "identity". The clock in your phone which is also updated by the information from the "Cell" is then able to compare the time taken for the signal to reach your phone by comparison of the time it recieves the semi-random code to the time it was sent. This time difference can be converted to distance (Range). Get three or more cells and you get three of more distances from the respective cell towers, and so where the three arcs intersect is where your phone is. However, if your phone is moving then the "GPS app" compares where your phone was to where it is and so gives you an velocity. Again accuracy will depend on the geometry and number of cell towers in range, and how quickly this data is processed by the app. For my money, a side-by-side test of GPS phone app Vs radar gun Vs lazer start / finish chrongraph would be a good project?????????????? Or perhaps this would be one best left for myth-busters??

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Durga

3S LiPo

7700kV Mamba Max

117 km/h

Measured with a Garmin Etrex

Jesus - that will be hard to beat :-)

Back to earth:

m03b002.jpg

M-03M Suzuki Swift : 30km/h (varying from 28-31 on 4 different runs)

Stock 20T pinion

RS540-SH stock silver can

TEU-101

4000mAh LRP NiMh

Fully ball raced

Garmin Nuvi 1240

IMG_0057.jpg

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So I tried reducing weight om the M-03M. Downgraded to a class 380 motor and a 77gr 1500mAh LiPo, stripped the receiver, and removed the battery holder parts. Total running weight now down to 977gr!!!

IMG_0426.jpg

Note the wheels spinning :-)

IMG_0427.jpg

So slim.

I didn't have a 16T or 18T 0.6M pinion at hand, but I could fit a 19T to try it out. Expectedly, the car's handling has become more nimble, but acceleration is not impressive. At low speed, it still spins the wheels, but there is no high-speed acceleration. Top speed has gone down very little, and I think a lower gearing will not nessescarily lower the top speed much. I have ordered a 16T pinion to see what it will do. It wouldn't surprise me if the 380-lightweight version is as fast on the track as the 540-motored stock version.

M-03M Suzuki Swift : 27km/h

19T pinion

Graupner Speed 400 (=Mabuchi RS380-SH)

TEU-101

7,4V 1500mAh LiPo

Fully ball raced

Garmin Nuvi 1240

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DT-02 Desert Gator (/Super Fighter G): 33km/h

17T pinion

Tamiya Sport Tuned 540 motor

TEU-101

7,4V 2200mAh 25C LiPo

Fully ball raced, ball diff

Garmin Nuvi 1240

DT02002.jpg

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My Avante 2011:

63km/u

Setup: 8.5T transpeed brushless sensored motor with Hobbywing Xerun 60A esc

25c 4000mah 2s 7.4V lipo

19t pinion (made by Kawada)

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F2001 Ferrari AWD 84 MPH

Novak 5.5L (light) Sensored Brushless Motor

Stock 20t pinion, Stock 55t spur gear, Stock (glued) Tamiya Type A (hard) Tires

Stock kit supplied bearings

Mamba Max Pro ESC w/Smartsense

Turnigy 30c 7.2v 2s Lipo (8.4 v actual)

Cell Phone GPS

Comments; 84 MPH. This was the maiden run on July 29th, 2011. Run was made in a massive and flat parking lot. Outside temp was a blistering 98 degrees (f). Believe it or not, even at this speed the car was just strolling along. The F201 Ferrari is the perfect chassis for high speed. I think the semi scale aero of this F1 chassis actually works at extreme speed. The type A hard tires were selected to go easy on the drivetrain for the maiden outing. Speed was limited due to the the minimal braking profile program on the esc and resulting limit on stopping area at end of run. Braking profile is being reprogrammed for next run. Plans to use Type B sticky tires and certified radar gun for an official 100 mph plus run this weekend. Should be a piece of cake. PS, the little Michael Schumaker looked right at home in the cockpit.

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F2001 Ferrari AWD 84 MPH

Holy **** - that's 135km/h... :unsure:

Here is a more modest input: F103: 39 kh/m

rc_aug1_2011002.jpg

Tamiya F103: 39 km/h ( 25mph)

Graupner 500 BB VZ (not that much faster than a silver can, but more torque)

LRP Digital Runner Plus ESC

7,4v 3000mAh LiPo

Garmin Nuvi 1240

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Had a replty from a non-member named Trevor Miczinsky. Anyone ever heard of this guy? Told me an F201 has a fragile gearbox that can't handle this kind of power. Also told me I do some great paintwork and builds on vintage stuff, but that I'm a liar. Hmmmm. Hey Trevor. Come to Knoxville, bend over, and let me give you an "actual" 84 mph F201 enema! Yes, my main interest is with the oldies. Yes, I am known for my building and painting skills. I'd like to add that I'm a speed junky and I'm building some incredible lipo/brushless stuff that will blow your mind. PS Trevor, when the Surgeon is trying to get Michael Schumacker out of your keister, please tell him to be careful with my pretty paint job.....

F2001 Ferrari AWD 84 MPH

Novak 5.5L (light) Sensored Brushless Motor

Stock 20t pinion, Stock 55t spur gear, Stock (glued) Tamiya Type A (hard) Tires

Stock kit supplied bearings

Mamba Max Pro ESC w/Smartsense

Turnigy 30c 7.2v 2s Lipo (8.4 v actual)

Cell Phone GPS

Comments; 84 MPH. This was the maiden run on July 29th, 2011. Run was made in a massive and flat parking lot. Outside temp was a blistering 98 degrees (f). Believe it or not, even at this speed the car was just strolling along. The F201 Ferrari is the perfect chassis for high speed. I think the semi scale aero of this F1 chassis actually works at extreme speed. The type A hard tires were selected to go easy on the drivetrain for the maiden outing. Speed was limited due to the the minimal braking profile program on the esc and resulting limit on stopping area at end of run. Braking profile is being reprogrammed for next run. Plans to use Type B sticky tires and certified radar gun for an official 100 mph plus run this weekend. Should be a piece of cake. PS, the little Michael Schumaker looked right at home in the cockpit.

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Tamiya TA03F Subaru WRC (HPI Ford GT Body) - 133km/h by GPS, 135km/h by radar.

Castle CM36S 5700Kv Motor

Castle MambaMax ESC

14T pinion 0.6mod - Tourer wheels 30mm rear/26mm front - RWD only (motor in rear)

VXB metal shield bearings

4S Lipo (2 IP4000 25C packs in series)

Mobile phone GPS, Police issue radar gun

HPI RS4 Evo3 (Lamborghini Gallardo body) - 127km/h by GPS, 128km/h by radar.

OS Max 18CV-R Engine with OS Tuned pipe

2 Speed - Tourer wheels 30mm rear/26mm front - 4WD

VXB metal shield bearings

30% Nitro

Mobile phone GPS, Police issue radar gun

Test strip of tarmac was the main street of town. Big thanks to the local copper for taking an hour out of his sunday afternoon.

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DF-03 Dark Impact : 30km/h (peak of 31)

Stock 26T pinion

RS540-SH stock silver can

LRP Digital Runner Plus

7,4v, 4000mAh LiPo

Fully ball raced

Garmin Nuvi 1240

It seems that a 540 silver can in a 4WD ball raced chassis will do around 30km/h...

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