R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 07-13-2006, 09:01 PM   #331
Tech Elite
 
W.E.D.Jim's Avatar
 
Join Date: Oct 2001
Location: Kissimmee,Fl.
Posts: 4,927
Trader Rating: 17 (95%+)
Send a message via AIM to W.E.D.Jim
Default

The 12th scale racers are using 4 cells and are getting all their laps and no more radio problems then normal...I think?

One thing is for sure, some testing is in order, since speculation is useless, except for entertainment.



Side subject; I wouldn't blame the RS200 for spectator deaths in Rally, maybe standing next to the track is a factor? I wonder how many deaths there would be in US racing organizations if people could stand at the edge of the track during the races, regardless of the technology in the cars?

Kind of like saying meat grinders should be safer because people keep sticking their hands in them and having them mutalated due to their poor design.

LOL, Jim
__________________
www.wedjim.com ...Reopening soon. I'm still painting, just not with 40+ bodies waiting. :)
www.prolineracing.com
www.HarleyDavidson.com
"Nothing but the best!"
W.E.D.Jim is offline   Reply With Quote
Old 07-13-2006, 09:15 PM   #332
Tech Elite
 
WheelNut's Avatar
 
Join Date: Jan 2003
Location: Edmonton, Ab
Posts: 3,210
Trader Rating: 5 (100%+)
Send a message via MSN to WheelNut
Default

Also consider the future with technologies like this in your TC. http://forums.radiocontrolzone.com/s...d.php?t=222362
__________________
•Brad Comis
WheelNut is offline   Reply With Quote
Old 07-13-2006, 09:24 PM   #333
Tech Regular
 
Join Date: Oct 2005
Posts: 306
Default

Quote:
Originally Posted by Smoking motor..
Reasons why Touring cars are faster.

1. Chassis design has enabled the the cars to be better balanced and thus have a much higher cornering speed.

2. Supension geometry has now come to an ideal geometry most TC supension has a very simlar pivot dimension and roll center adjustment range this make the car very easy to drive at speed so they don't handle like a shed.

3.Tyre technolgy allow the tyre to run hotter for longer and produce more grip than ever before more grip more corner speed.

4. drive train effiency has improve to a point where it there bettween 1 and 2% loss due to belt wrap or the friction of the bevel gears.

5. bodie shell have become aerodynamic effiecent rather than realistic therefore the downforce and low drag has increased top speed and grip

6. Battery voltage has increase incapacity over the last two years.

The question is what do you change as slowing them down isn't really going to make them slower.

For anyone information about real classes such a group b rallying and c-class racing it was the organisers that killed it off as the got scared of the risk being too high rather than the driver and manufacture plus the rs200 was very underdevelope when it killed those spectators.
IMO the concern is not to reduce speed instead simply how to avoid the overgrowth of battery progress overtaken esc+motor combo progress and simply killed them,

sorry, slightly off topic,
1. I believe rs200 is not underdeveloped, its overdeveloped like others group B.. if you remember those big upfront and rear spoiler of group B beast, that tell you how difficult getting traction with such power
2. the reason of group B banning is after several fatal accident related to other group B cars not only due to rs200 accident alone > 1st. rs200 in portugal that you mention, 2. toivoinen (Lancia S4), 3. attilio bettegea (lancia 037), those all fatal accident..
Faiz is offline   Reply With Quote
Old 07-13-2006, 09:39 PM   #334
Tech Master
 
Jeff Brown's Avatar
 
Join Date: Nov 2003
Location: Orlando, FL
Posts: 1,913
Default

Quote:
Originally Posted by Rick Hohwart
Ok so I am not going to go re-read the entire thread.

So please link to the posts that show MANUFACTURERS comparisons of:

Run time
Brush life
Top speeds
Lap times
Motor temps
ESC temps
Receiver battery requirements

Please show me.
Actually, this was tested several years ago with Reedy. The debate was what it is today about cells and the speeds.

Mike Reedy had some Team Drivers test Touring Cars with 4 cells on foam tires. Even back then we were still running 7 or 8 turns with 6 cells, probably around 2002 or 2003. So some tested and dropped to 6 turns with 4 cell packs. They were about .3 to .5 tenths of a second slower a lap. Not a major drop. The motors finished better, the cars were easier to manage and drive for the race.

If you think that dropping from 6 cells to 4 cells decreases runtime you are mistaken. It is easier to make runtime with fewer cells which was the driving force of 12th scale switching to 4 cell only worldwide.

Jeff
__________________
SXT Traction Compounds | www.TractionCompound.com
Jeff Brown is offline   Reply With Quote
Old 07-13-2006, 09:59 PM   #335
Tech Master
 
Jeff Brown's Avatar
 
Join Date: Nov 2003
Location: Orlando, FL
Posts: 1,913
Default

Quote:
Originally Posted by DerekB
Here's something to think about.


Going up in voltage reduces amp draw. So if we went to higher voltage and used lower tuen motors that resulted in similar performance to the lower turn 6-cell in theory we should have the runtime, reduced stress, and speed.

I guess I'll have to set up some test and see what happens.
Interesting. When I run a motor at 2 volts it pulls say 4 amps. Then I run the same motor at 5 volts and it pulls 12 amps. Please explain.

Jeff
__________________
SXT Traction Compounds | www.TractionCompound.com

Last edited by Jeff Brown; 07-13-2006 at 10:51 PM.
Jeff Brown is offline   Reply With Quote
Old 07-13-2006, 10:33 PM   #336
Tech Fanatic
 
ttso's Avatar
 
Join Date: May 2004
Posts: 900
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by Rick Hohwart
Ok so I am not going to go re-read the entire thread.

So please link to the posts that show MANUFACTURERS comparisons of:

Run time
Brush life
Top speeds
Lap times
Motor temps
ESC temps
Receiver battery requirements

Please show me.
I don't have number but this is what I can tell you by seeing my friend's car.

Runtime, no problem for 5mins
Laptime, about 0.3~0.5sec slower per lap in 13sec track
Motor, 6x2T
Brush life, make it at least 2times longer if you compare with 6T in 6cells, maybe 3times longer
Temp: wayyyy cooler than 6cells
Batt: IB4200
RX batt is needed for safty, as I dont know if it's ok to run without RX batt
Car weight: 1340~1350g

I'm going to test 4cells 19T vs 6cells 23T once I have time, so I might able to give you more number. But like I said, you need to drive/see the car in person to understand 4cells touring.
ttso is offline   Reply With Quote
Old 07-13-2006, 10:34 PM   #337
Tech Master
 
Join Date: Aug 2001
Location: Australia
Posts: 1,010
Trader Rating: 55 (100%+)
Default

Quote:
Originally Posted by tones
just thought i'd share what i found in testing at a local race meet tonight..

track is indoor asphalt ~10-11 seccond lap.

motor used was 7x1, 12° timing for 6 cell, 18° for 4 cell (didn't play with spring tensions - MR 3.8).

dropping to 4 cells reduced motor temp by ~25°C.

lap times were around 0.1 - 0.3 secconds per lap slower.

less blackening on edge of comm from arcing and in gernal looked _alot_ better.

gearing up a few teeth with 4 cell gave best results, if taken too far lap times slowed.
a little more information...
equipment used was ko 302f, ko vfs-1 comp, ko 2413.
no rx pack was used.
amb personal didn't miss any laps in any of my runs.
dont recall experiencing any problems with the servo.

camera doesn't seem to like the close ups so cant post photos, but the brushes from the motor used for the 4 cell runs have only a very slight change in color towards the face of the brush. quite impressed with that after 8 or so runs on it without a rebuild, some of which in practice well exceeded 5 minutes.

plan to continue testing on different tracks as soon as possible.

Last edited by tones; 07-13-2006 at 11:07 PM.
tones is offline   Reply With Quote
Old 07-13-2006, 11:13 PM   #338
Tech Elite
 
2-Bad's Avatar
 
Join Date: Jan 2003
Location: Australia
Posts: 2,725
Trader Rating: 24 (100%+)
Default

Quote:
Originally Posted by Jeff Brown
Interesting. When I run a motor at 2 volts it pulls say 4 amps. Then I run the same motor at 5 volts and it pulls 12 amps. Please explain.

Jeff
Jeff,
No explanation needed... you are right.... more Voltage to a motor = more RPM, more current, more temp, more brush burn....
__________________
Yokomo * G Force * Sanwa * SMC * ProSpec
2-Bad is offline   Reply With Quote
Old 07-13-2006, 11:31 PM   #339
Tech Addict
 
eforer's Avatar
 
Join Date: Sep 2004
Location: Rhode Island
Posts: 607
Send a message via AIM to eforer
Default

Power (Watts) = Volts X Amps

to achieve the same power with less voltage:

Shebango! Amps go up.

I guess thats the argument for why more current is consumed with 4 cells. That said, if one uses the same motor in a comparison between 4 and 6 cell, less voltage will result in less power and less current.
__________________
Speed Merchant/Corally USA/Specialized RC/Team Kwik/Tekin/Sweep/Parma PSE/Team Pickles Performance

Last edited by eforer; 07-14-2006 at 12:50 AM.
eforer is offline   Reply With Quote
Old 07-14-2006, 01:30 AM   #340
Tech Fanatic
 
Join Date: Aug 2004
Location: UK
Posts: 902
Trader Rating: 3 (100%+)
Default

Quote:
Originally Posted by W.E.D.Jim
The 12th scale racers are using 4 cells and are getting all their laps and no more radio problems then normal...I think?
Yes but 1/12 are lighter cars and they race for 8 minutes, so there is less volt drop under hard acceleration and less load. Problems will show up more often with 4 cell TC especially with Mod motors. Some ESC's may have problems with 'power-fail' voltages (ie won't work well on 4 cells) and running without a RX batt means servos will operate slower. Also lap counting problems with PT's will happen more often. These are all things to consider, as ttso says it will be safer to run with a RX batt, without one you may have more trouble.
Terry_S is offline   Reply With Quote
Old 07-14-2006, 01:56 AM   #341
Tech Fanatic
 
Join Date: Aug 2004
Location: UK
Posts: 902
Trader Rating: 3 (100%+)
Default

Quote:
Originally Posted by TryHard
I personally am in the camp of the end user is the biggest problem. By it's very nature any competitive sport is going to have people pushing equipment to it's limit for an edge...
Maybe it can be helped by equipment manufactuers upping there game in some areas, but really, it is still on the end user.
Thankfully, I'm in the equipment camp that I know has some of the best specs out there (Hi Terry ). At a recent national over here in the uk, track temps were in the 50C's... no problems with overheating.

Ed
Hi Ed, glad you're going well even in the 50C's heat!
Terry_S is offline   Reply With Quote
Old 07-14-2006, 03:49 AM   #342
Tech Rookie
 
Join Date: May 2006
Posts: 2
Default

Quote:
Originally Posted by ttso
I don't have number but this is what I can tell you by seeing my friend's car.

Runtime, no problem for 5mins
Laptime, about 0.3~0.5sec slower per lap in 13sec track
Motor, 6x2T
Brush life, make it at least 2times longer if you compare with 6T in 6cells, maybe 3times longer
Temp: wayyyy cooler than 6cells
Batt: IB4200
RX batt is needed for safty, as I dont know if it's ok to run without RX batt
Car weight: 1340~1350g

I'm going to test 4cells 19T vs 6cells 23T once I have time, so I might able to give you more number. But like I said, you need to drive/see the car in person to understand 4cells touring.
The motor that ttso’s friend used was special designed for 4cells running, not the typical 6T motor with 6cells on market.
So just as eforer said,
Power (Watts) = Volts X Amps
to achieve the same power with less voltage:
The 4cells motor we are using is draw more Amp. than a 6cells motor. Typical figure is 10-15Amp. @ 2V, 6Tx2.
The speed, may not fast but at least equal when compared to those 6cells modified touring with 8/9T motor in 8 mins racing.
The running time sure no problem for 5 mins, even 7+mins without Rx battery.
One thing I want to mention is: people using 6cells 6T or 7T 5mins compare to 4cell 6T even 5T, the speed of 6cells sure to WIN, it is no doubt.
BUT please be noted that in Japan or Hong Kong. We are talking about 4 cells modified compare to 6ells modified in 8mins racing; it is no doubt both of them are in same speed.
Recycle is offline   Reply With Quote
Old 07-14-2006, 03:56 AM   #343
Tech Regular
 
Join Date: Feb 2004
Location: Netherlands
Posts: 286
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by eforer
Power (Watts) = Volts X Amps

to achieve the same power with less voltage:

Shebango! Amps go up.

I guess thats the argument for why more current is consumed with 4 cells. That said, if one uses the same motor in a comparison between 4 and 6 cell, less voltage will result in less power and less current.
I am not an electronics expert, but I think you've got that backwards. Power is indeed a formula of the Volts times the Amp draw. But the Amp draw is defined by another formula, namely Volts = Amps x Resistance. If the volts go down and resistance stays the same then Amps go down too. The result is less power (volts x amps).

As someone argued when you remove two cells you remove some resistance and as can be seem from the formula, if volts stay the same and resistance is reduced the amps go up. This is actually already part of todays problems as the current crop of cells have half the resistance we had about three years ago...

Quote:
Originally Posted by Josh Cyrul
tonyv - Actually, we probably wouldn't change gearing. Example - If I drove really hard on the brakes and throttle I had about 750mah left after a run. If I drove just to reduce the wheel spin off the corner (still heavy braking) I came back with about 1100mah. I think all we would do would be a slight timing/spring adjustment and we have 2000mah+ left to make that 8 minutes
Josh - Point well made. I think laptimes would be no more than 0.2s a lap slower if that on most tracks.

Quote:
Originally Posted by Oscar Jansen
You can see it different: We have less cells, but same weight = more load (A) on motors/batteries/speedo. If we would have less weight we would accelerate faster, but arrive with higher top speeds, and than we have to brake harder = more heat (remember, the tyres stop us to go faster through the corner)

We have to decrease also average Amps.... and this you can only do this with: runtime....

So, 4 cell-6m could be an answer...
Oscar, that is the direction I am leaning towards too. We will need multiple changes to address the heat related issues. And then there are other problems such as the driveability aspect. Sure, it should become too easy, but it shouldn't become so hard that there are only 20 or 30 people in the world that can control the cars either. Combining a cell reduction with an increased race length will help with that too. However even then I think there also needs to be a discussion on the technologies that will be allowed such as for instance the types of magnet allowed. 4 cell + 6 mins is something I would be ok with but do you think that it will be enough to make a long term impression on these problems?

Switching to the driveability considerations for a second, one of the reasons it is more difficult now than in the past is the sheer torque we run with. This results in major abrupt weight transfers in the car when going on and off throttle. The top drivers are able to control that, but most of us have trouble with that. This is especially the case in today's point and shoot style of driving caused by the fact that we don't have any runtime problems anymore and therefore basically are running 5 minute sprint races.

Reducing the voltage will reduce the torque and increasing the race length will, as Josh pointed out, result in running less timing and softer springs when running brushed motors. All this reduces the torque and thus the torque effects.
__________________
Tony Vredenberg
tonyv is offline   Reply With Quote
Old 07-14-2006, 06:02 AM   #344
Tech Regular
 
Sanabria's Avatar
 
Join Date: Oct 2005
Location: On turn 13.
Posts: 255
Default

Quote:
Originally Posted by tonyv
I am not an electronics expert, but I think you've got that backwards. Power is indeed a formula of the Volts times the Amp draw. But the Amp draw is defined by another formula, namely Volts = Amps x Resistance. If the volts go down and resistance stays the same then Amps go down too. The result is less power (volts x amps).
Actually, eforer is correct. The ammount of current that the motor draws is a function of load, which is predicated by the cars weight and the final gear ratio. Current is load, which is what the motor demands to move the weight. This is something that some seem not to understand.
For example, lets say 100W are required to move X ammount of weight and you have a 10V source. (For simplicities sake, lets pretend that the motors efficiency is 100%) That motor will demand 10A. Lets now reduce the source to 5V. It still takes 100W to move the weight, so now the motor will demand 20A. When you factor in the efficiency (or lack of) of permanent magnet DC motors, it starts going down hill.
Sanabria is offline   Reply With Quote
Old 07-14-2006, 07:25 AM   #345
Tech Regular
 
Join Date: Feb 2004
Location: somewhere in the north of england
Posts: 347
Default

Quote:
Originally Posted by Faiz
IMO the concern is not to reduce speed instead simply how to avoid the overgrowth of battery progress overtaken esc+motor combo progress and simply killed them,

sorry, slightly off topic,
1. I believe rs200 is not underdeveloped, its overdeveloped like others group B.. if you remember those big upfront and rear spoiler of group B beast, that tell you how difficult getting traction with such power
2. the reason of group B banning is after several fatal accident related to other group B cars not only due to rs200 accident alone > 1st. rs200 in portugal that you mention, 2. toivoinen (Lancia S4), 3. attilio bettegea (lancia 037), those all fatal accident..

Yeah I know First off all the rs200 had a massive turbolag problem and a floppy chassis i know this from talking to guy that raced them in rally cross. This made them really hard to drive and the turbolag would catch you out that why 8 spectators bore the brunt off it the other cars went past the spectator no problem. The Lancia the went down the cliff killing the drivers let just say the the fuel the were using init wasn't 85 octane petrol it was a blend of avgas and some other combustant it was reffered to as rocket fuel and aluminium tank weren't exactly safe for storing it in, in the event of an accident compare to mordern kevlar fia approved tanks. There are a lot a thing about the cars run that unless you know people that have race and delveloped them since '86 you won't know about. Like the 6r4 4wd system was nowhere near developed to cope with 500 bhp of the 3.2 v6. A mate had to spend 30 grand on getting thing like that sorted out to race it. Shame he sold he said it scared the s*** out of him going down brands hatch straight it was doing 140 mph and had more to go and this is a rally car .
Smoking motor.. is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
2006 Ifmar 1/12th & 1/10th Istc Electric On-road World Championships – Danny Teh Malaysian R/C Racers 1 02-16-2005 10:38 AM
2006 Ifmar 1/12th & 1/10th Istc Electric On-road World Championships phlim Singapore R/C Racers 3 02-16-2005 09:52 AM
2004 IFMAR ISTC & 1/12th On Road Worlds at Full Throttle Speedway AdrianM Electric On-Road 2162 12-29-2004 04:09 AM
2004 IFMAR 1/12th and 1/10th ISTC ELECTRIC TRACK WORLD CHAMPINSHIPS Marcos.J Electric On-Road 55 02-10-2004 09:05 AM
2003 Ifmar ISTC 1/10 on road???? Wilfred Electric On-Road 2 09-01-2003 05:39 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 04:06 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net