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Old 07-12-2006, 02:54 AM   #166
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Less capacity, less cells, all for the same goal: less Watt.

Less capacity = less Amp draw = less Watt
Less cells = less Votage = less Watt

But in reality, you need to tell me how you gonna archive less capacity? It's easy to say "let's use 2000mAh batt", but who is manufacture it? We now have AA in 2100+mAh, AAA in 1100+mAh. How you can do Sub-C with 2000mAh? You are basically asking batt manufacture to go back 10years (is it?) and produce something that no one is using anymore. This is not gonna happen.

The only practical way to archive less capacity is using smaller cell, like AA cell. This means different weight, different dimension with Sub-C cell. Chassis need to be redesign for smaller cell. This is the same with using 4cells Sub-C. And you have to remember, if you using smaller cell on 1/10 touring, means you will have 2 different cell type for 1/10 touring and 1/12 pan, this is bad for people, seller, manufature.


From my point of view, the only practical way to archive less Watt is less cells, and to consider the future, 4cells is the only solution IMO.
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Old 07-12-2006, 03:07 AM   #167
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Quote:
Originally Posted by johnbull
What is the single uncommon denominator. Cars remained the same, speedos got more reliable, motors remained the same. Just an increase in battery limit.

If you're going to do anything at all, just limit it to 3000mah maximum and keep it there for 10 years.
Exactly what I have been saying

Oscar has echoed my previous comments... battery technology has increased far quicker than the motor or esc manufacturers can keep up with.

Having less-restrictive motor rules may allow some of that technology difference to be regained, or it may do nothing at all.

Limiting the capacity of the cells will produced the desired results (heck, 3300's and 9 turn motors aren't that slow).

The problem is.... how do you convince the cell manufacturers (and racers) to turn back the clock on technology..... or is it already too late to do that?
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Old 07-12-2006, 03:10 AM   #168
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Quote:
Originally Posted by semper
But the 2wd offroad WC was supposedly won with 5 cells connected and a 14t motor...
5 cells and a 12 turn. 2nd place was a 14 turn @ 6 cells.

My thoughts:

* Oscar is right. Today's cells contain too much energy for the poor ESC's and motors to handle. Brushed==> motor suffers. Brushless ==> ESC suffers. Badly!
540 motors were fine for SC1700's. With 4200's, 540 is just too small...

* 4 or 5 cells works. These guys are ahead of us: http://www.rcracechat.com/vb/forumdisplay.php?f=294

* There's always going to be one weak link! If it's not the cells or motor, then it's the tires. And that weak link is going to have to be replaced often, and it's going to be expensive. That's racing. Stop whining.

* Excess Power is the best equalizer. DerekB understands this.

* If a vehicle is not overpowered, it's not fun.

I think there is a way out. I'm pretty sure it's possible to alter the rules for B/L motors a little, to make them more powerful. That way, they don't have to do 70.000 RPM (ESC switching like a motherf***er!) to make equivalent-to-brushed power.
B/L rules are too restrictive, that's the problem.
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Old 07-12-2006, 03:14 AM   #169
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Quote:
Originally Posted by elvo
I think there is a way out. I'm pretty sure it's possible to alter the rules for B/L motors a little, to make them more powerful. That way, they don't have to do 70.000 RPM (ESC switching like a motherf***er!) to make equivalent-to-brushed power.
B/L rules are too restrictive, that's the problem.
But then people would still make them do 70k rpm and they would make WAY more power than a brushed, so we would be back to square one.
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Old 07-12-2006, 03:18 AM   #170
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Do I understand this right ..... we have two problems:

1. Component overheating leading to DNF's
2. Cars being too fast, incidents leading to DNF's

Can I summarise this as electrical components, chassis components and driver abilities raced to, and increasingly, beyond, their limits?

Isn't this what elite level racing is all about? Whether its 1:1 cars, motoGp, rc cars, or for that matter triathlons or the Tour De France?

When was the last time nobody retired in a F1 race due to mechanical failure? When was the last time no rider went over in MotoGp (risking a fair bit more than we rc drivers BTW)? Or nobody in Le Tour bonked going up L'Alpe Duez? Or slipped in an Olympic hurdle event?

If we legislate to the effect that nobody suffers failures, then are we discriminating against certain drivers who have a knack (which is just a pathetic word for "skill") of driving, setup or engineering such that they DO finish races?

I don't see how the "too fast, too many crashes" argument stacks up either. I mean if the car is too fast and you crash too much and someone else doesn't well then surely he deserves to beat you? And for driving hacks like me, well that's what 19T, Stock and 540 classes are for.

DNF's are one of the prime drivers in performance improvement - engineering stuff that previously broke so that it doesn't next time. Training / practising so that previous mistakes are eliminated or reduced? Isn't this one of the primary thrusts of all sport in general?

I don't race at Worlds level and never will, but from my lowly position it seems like there are plenty of classes of racing to cater for most abilities and equipment levels. I guess I just haven't understood what's so broken about the current situation.

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Old 07-12-2006, 03:39 AM   #171
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If we really moving to 4cells, I would suggest we let the 4cells and 6cells both legal for a while, similar to what we have no on 2WD/4WD IFMAR rule.

So it would be something like:
4WD, 6cells, 1500g / 4WD, 4cells, 1350g
are both legal.

However, this might be ok for mod, but for 19T or stock this would be problem bcz 4cells need less T motor to be competitive with 6cells.

So maybe, it can be like:

For mod: 4WD, 6cells, 1500g / 4WD, 4cells, 1350g
For advance: 4WD, 6cells, 19T, 1500g / 4WD, 4cells, 11T, 1350g
For stock: 4WD, 6cells, 27T, 1500g / 4WD, 4cells, 19T, 1350g

I dont know if 4cells would be competitive against 6cells in advance and stock div, but I'm quite sure mod is ok as you can go 4T or 5T to get 4cell competivive enough.
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Old 07-12-2006, 03:42 AM   #172
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Oscar, thanks for the clarrification on exactly what your letter was about. It makes a lot more sense than a lot of what was said previously!

Heat build up IS a growing problem for the modified class, but not for the 27T and 19T, or their equivalents around the world. But, controlling it is never going to be as simple as reducing the number of cells, this is just too simplistic an approach. You cannot restrict anything when you don't control the controlling factor! Cells will continue to develop and more manufacturers will come to the market, just as they are now. There is a veritable explosion of cell manufacturers in China.......

The cell manufacturers WILL continue to improve their technology come what may, the competition between them will drive that, and at the current rate, even if you elected to reduce it to 5 cells today, it will probably be less than 12 months before you are facing the same problem all over again!!!

The only solution is to introduce controls external to the current component package that will either reduce the heat build up from one or more of it's existing sources - as per Oscars suggestion about using a mechanical brake instead of the motor - but this has other implications, and/or the introduction of an electrical restrictor into the circuit that will limit the power to what ever is deemed suitable.

Using the external limiter to restict the total energy available (like total fuel quantity) to me provides the most cost effective flexible approach to the heat problem and the mosty reliable in terms of implimentation and cost.......

So Terry, get Clive to look at an external, inline, current/voltage restrictor that is small, simple to install, reliable, cheap to produce and flexible to be changed as required, you have a world wide market at your feet just crying out for it apparently..................good luck if you choose to accept this mission.....
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Old 07-12-2006, 03:45 AM   #173
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Quote:
Originally Posted by fathead
But then people would still make them do 70k rpm and they would make WAY more power than a brushed, so we would be back to square one.
We'd be in square one WITH MORE POWER ON OUR HANDS!
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Old 07-12-2006, 04:09 AM   #174
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WOW.

Lost of info, with lots of idea's. One thing people have to reallise is that the battery manu. will not slow down on there technology R/D. As most of these guy's don't just make cell for us. There main customers are the "power tools" market. All contrator want a cordless drill or what not. to last longer on a single charge.

The cell reduction is an intreging idea, I'm actully going to try, running a 5 cell this weekend at our throphy race. I don't race mod. So I will try it in 19turn(Chris is you read this. Shhh ). in one of my qualifiers. If I get disqualified do to under wait for the one heat. Who, cares I'm curious and willing to try it out. I'm actully going to try it with 3300's too. my new 4200 haven't arrived. I will let you guy's know what happened.

I know so far this year I've seen 6 stock and about 10 19turn go up in smoke. (one guy did 3 in one day, to agressive profile on his esc.) I mean guys a willing to risk going over board on the gearing it to the roof and they know the consaqueces(okay can't spell right now 3 am)
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Old 07-12-2006, 04:17 AM   #175
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I think the issue is not if we are ok today (which we more or less are...) but more what happens if the technology keeps on growing exponentially. The real issue at the moment is that the tech curve between batteries and electronics do not match at all... where will we be in 3 years is i think what is really at stake.

- Limiting the battery capacity is a good idea, at the express condition this does not turn it into a battery war: In other words dont limit the battery capacity and at the same time switch to 7 minutes mains !

- We used to have 12Turns limit on ifmar, Brushless arrival pretty much killed the idea...could we spec brushless to a given limit in order to "cap" motor power again ?

- Oscar suggests allowing air holes in the bodies, which i think is SO needed and so useful... and also easy to implement overnight.
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Old 07-12-2006, 04:21 AM   #176
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Having raced model cars for 11+ years and over that time raced both on and off road,I do see the need for cars to be slowed down.

I quit off road quite a few years ago for many reasons. Many of the clubs I attended raced modified and I suffered from many high speed accidents,snapping my chassis on one occasion. It seemed if you wanted to do well you have to have a fast,well set up car.

It all turned into a money game,and I wasn't game for playing it.

I feel over the years now i'm racing stock 27 on road I feel happy with the power.

Not many off road clubs raced stock years ago,maybe thats changed now but its one factor that might have kept me with off road. Call off road a bad memory,but on road is where i'll be for the forseeable future. No jumps to worry about on road and the 27 stock motor provides all the power I need. If I get better at dealing with the speed i'll consider modified. I don't need the pressure of driving at a silly speed for 5 minutes,i'll race at my level with a motor that i'm pushing the limits of,not the other way round where theres an open mod ruling in force.
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Old 07-12-2006, 05:09 AM   #177
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A simple and fast solution to the heat problem would allow for cut outs in the body! For example the side windows and rear window!
I will go to the track tomorrow and test this and meassure the temp. difference and also try to look at the laptimes if there are any changes to handling etc.

Another solution like ttso mentioned is to go to smaller cells like the Sanyo HR-4/5SCU and GP200SCH. This cells have the same diameter, but are only 34mm in height. (2000mAh) Bolts right into current car designs and if we at the same time lower the weight rule to lets say 1400gr. we would put less stress on our tires as well.
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Old 07-12-2006, 05:33 AM   #178
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Quote:
Originally Posted by Eirik
A simple and fast solution to the heat problem would allow for cut outs in the body! For example the side windows and rear window!
I will go to the track tomorrow and test this and meassure the temp. difference and also try to look at the laptimes if there are any changes to handling etc.

Another solution like ttso mentioned is to go to smaller cells like the Sanyo HR-4/5SCU and GP200SCH. This cells have the same diameter, but are only 34mm in height. (2000mAh) Bolts right into current car designs and if we at the same time lower the weight rule to lets say 1400gr. we would put less stress on our tires as well.
If we do move to 4/5C cell, I think in no time we will see 3000mAh 4/5C cell. 4/5C cell is basically not in developing cycle right now as the need for such cell isn't much.

Remember, AA is 2100mAh already and still growing. I really dont think using any cell bigger than AA would help to limite the capacity. But by using AA or smaller than AA size battery, chassis re-design is must have. And still run into the same problem where the touring and pan can't share the battery.

An air intake is good idea, but I don't think this will solve the problem of too many Watt. At the end you will still run into Watt problem just like CPU did in pass 5years. It would be a good temp solution, but not for the long term.

Mech-brake will change entire chassis design into something else, and it still run into Watt problem in very short time. When you freeup some energy for brake, you will only turn those energy into something like accelaration.


Btw, for those "stock won't smoke" people. I myself smoke at least 3 stock motor in race due to aggressive driving with too powerful battery. And everytime the major race happen, I can see at least 1 dude smoke his stock motor in every main. My theory: if you never smoke your motor, you are still far away from the limite...
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Old 07-12-2006, 05:53 AM   #179
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I've followed this entire thread and I attended the IFMAR metting in Italy and there are a few points that I think are being overlooked that everyone needs to at least recognize and think about before they make a quick judgement:

#1 - Impossible to limit the capacity of the batteries - We (the racing world) are a small market when it comes to the global usage of these cells. The drive for the battery manufactures is to create a better cell to sell and promote their company - I think a capacity cap would kill their interest in our part of their respective markets. Also, everyone is forgetting the hardest thing - How do you check or regulate battery capacity?? Are you going to have 150 matchers at a big race checking to make sure people's battery packs aren't too good?? Seriously, think of the logistics here.....

#2 - Many comments I see also include increasing lenght of race time from 5 minutes. Another logistic you have to look at is for the large event organizer all the way down to the local track. Running the hobby shop and track here, I am against this. Why??? Simple... We race 3 quals and a main on Sundays - usually 10 heats with 6-7 being TC. Adding 1 minute to each race adds 30 minutes to our day - Not bad right?? For a track owner that is more time at the track, more cost and more wear and tear on the facility. Now, add that 1 minute to a race like the IIC, Cleveland, Snowbirds or even the IFMAR WC... That means less rounds of qualifying/practice or less entries - this means less money for the race organizers, tracks and hobby shops - You know, the places that are on the front lines trying to promote and help our hobby grow.....

#3 - Let's see...... 1/12 went to 4-cell only because of speed, drivability and cost.... Oval went to 4-cell only because of speed, drivability and cost.... Off-road is now running 5 cells for more drivability.... Anyone notice a trend??...... I'm going to test here with 6,5,4 cells hopefully this week and I'll give a little info on what I find....

#4 - There was another part of the IFMAR meeting that delt with the magnet rules for brushed and brushless. As was discussed at the meeting, simply changing the magnet materials used would increase the power of the motors around 20%, while increasing durability (brushless rotors exploding) as well as increasing the effiency which would reduce motor and esc heat. It was also mentioned that due to the global market use of this magnet in other applications, it's actually cheaper in price than what we currently use now..... I'm not a motor guy so I'm not 100% on this one but it sounds like a no brainer to me.... More power, more reliable, more effiecent, cheaper.... Maybe use this in conjunction with a 5-cell or 4-cell pack and we have no difference in speed with a huge reduction in heat and much more reliable system.... I think this would give both areas (brushed and brushless) a new avenue to develope their product further for the future.

#5 - Weight - A reduction in the weight of the cars also would go a long way. I've seen posts about actually adding weight to the cars but this to me is crazy!! A heavier car will impact harder breaking more parts, a heavier car will put more strain and load on the tires, suspension components and especially the drivetrain components. Even with all the fans and extra heat sinks we all used on our cars at the WC, we all still had to add weight (I added 70grams to my car). Now, think of each time you accelerate and brake a heavier car - more heat - I know at the WC I used the brakes a minimum of 7 times per lap (I don't use drag brake).

#6 - There are some creative ideas out there to try and help the heat problem. The idea for a mechanical brake is a good one to reduce heat but adding another servo and more working/moving parts to these already tightly packed cars may be tough and complicated to get everything set and working right. Allowing some regulated cooling holes in the bodies would be great and I don't think it would hurt the looks of the cars at all - I'm going to test with some body cut-outs to see if and how much of a difference it can make. This is a sort of random idea I just thought about, if people are worried about loosing the speed due to the reduction of cells, then why not a 2-speed? This way you can gear to have good bottom, good top end. In the end, the reduction of cells would have less heat, 2-speed would give us the speeds back as well as reduce the strain we put on the motors to deliver the power off the corner and the super high revs on the straight that are what eventually kills the motors (rotors explode, arms come out of balance).... Just a random though as I'm sitting here next to my nitro cars....

No matter what the different opinions or views I think it is great everyone can put in their .02 and it's creating an interest. The sanctioning bodies that we run under need to be progressive in adapting the rules for the future growth and health of the hobby. I think IFMAR's attempt to get everyone to the MFG meeting in Italy and to get everyone talking and interested in testing to solve the problems of the future has been a sucessful one. The discussions have started, the testing is underway and I'm sure the positive solutions will be found to the future health of the hobby and industry.
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Old 07-12-2006, 06:33 AM   #180
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Applause Mr. Cyril well said dude!!

Hmm, we have lots of discussions on this topic in Germany as well.....
First of all I wonder why barely someone talks about car parts and tyre wear.....

We all have to understand that most of the RC producers live from the "normal" racers. Its not all about the "Pro" driver....
Within the last year motorpower and voltage have increased big time, not only getting motors to melt, as well as speedos, also the cars and tyres have come to their limits.

I think its not very funny for a modified club racer when he melts his rear belt or diff within 4-5 rounds.
Also tires have come to a certain limit, tyre wear has gotten imense....
At some races people win, because they have the money to buy another set of new tyres!!

We all do not want this sport become a sport of the rich, do we??
Most people here have given op Mod due to the costs in particular, as for example in our region we had 60 people in Mod 2 years ago, now we have barely 20.

Ok, this is an Ifmar thread, not an local thread, sorry......
Barry, I can not understand why a limit of capacity should be the solution??
You can run a 7 or 8 turn even with 3000 maH, its not a capacity problem. Its a voltage problem, that causes the heat not the capacity!!
I am sure there would be a 3000 mAH with 1,28 than....
For example, good 3300's had 1,17 to 1,18, if you look at good 4200 SHV's, damn thats 1,23 or 1,24!! This all within one year of progress.....

Further on guys, come on, how will somebody control all this at the big races, its almost impossible......
I think the best solution is to limit the amount of cells.....
The japanese federation has found a good solution for that, and I think it could be a good solution for the US, Europe and so on as well....

Tyre wear, heat, car wear, speedo, all solved in one step, I think.
In combination with that it also will be important not to go from Sorex 36 to Sorex 24 for example, that would be totally weird.

If the rules stays like this, the class will die, but thats only my 10 cents on this topic.
Maybe even more people will go back to 12scale than...

Have fun guys,
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