RCGaryK

iTrader: (3)

Thank Goodness! Like someone else said, going to 4-cell helped save Oval and revive 1/12th scale and it's about time someone tried this in sedans! It's past time, and I can't wait to run 4-cell 19T!

mpetrich

Adrian, Kufman knows his stuff. I will wait to read his reply/take on this but I would not just dismiss it as an EE not fully understanding. Anyways, IMHO, the switch to 4 cells will be moot in the not to distant future as an above post stated, 2 cell LiPo will become the norm and each racing class will be divided up by the Kv rating of the brushless motor.

Interesting to see what happens......

Thanks,
Matt

Jaybo

3 cell, actually :P

but cause they're obviously lipo and not nimh, they're classified differently... and there's still the 4.8v limit

a good question will be though... if i have 4 cells of 1.205v.. will that make my pack illegal for 4.8v limits?

AdrianM

iTrader: (4)

No doubt about that. I know a lot of ME's and EE that are geniuses about "their stuff" but really can't really apply what they know to "this stuff" becuase they don't work on "this stuff" for a living. They work on much more important stuff

For example. We had some of the best automotive suspension engineers from McLaren in the UK consult with our engineers at Schumacher UK. What was the result...nothing. Nothing they suggested worked in our application. The dynamics of an R/C car are different than a real car. There is no butt in the seat of an R/C car, our cars accelerate harder than a top fuel dragster, corner harder than an F1 car, etc.

The problems with kufman's comments on the old thread revolved around real world wattage output and efficiency of our motors. He assumed racers would run hotter winds and gear up so amp draw would get higher than we are running now so wattage output would be similar and motor life would be as bad or worse. It was pointed out to me that this is impossible since our motors will never approach current wattage outputs at lower voltages due to inherit limitations of their construction.

Kufman was absolutely correct in theory but it just wasn't so in real world application.

EddieO

iTrader: (6)

When I first started racing, we had a guy who started coming in to buy craft stuff for his wife......one day he popped out back to watch us race....

Turns out, he was an engineer at Boeing......he was one of the top guys who designed the 747, 767, etc (he still actually works there).

He asked us why we were running little wings on our buggies and such....and of course, we told them we had to or the car would not handle correctly....

We then got a 25 minute theory on why it would not work or even have an effect on something that small.....there was no rationalizing with this guy who had been designing planes for 20 years.....it was like talking to a wall.

So finally.....we had him drive a car around.....with the wing on....

Then, we took the wing off and let him drive.......which of course the car nose dived over every jump......

He was stumped......so he went in and bought a kit with everything.....and spent a whole year trying to prove the cars could work just as good without a wing.....he never did.....but he would always maintain it broke the laws of aerodynamics or whatever....

At that point, while engineers are smart people, I never quite bought everything they said when it comes to RC.....

And as for the 4 cell discharging different than a 6.....it does. It has something to do with the voltage or some crap. I got to listen to it multiple times.......why, I dunno. Maybe Issac from Axxis will pop on here and explain it....

Later EddieO

Ben.C

I'm for it...

4 cells means 2 less cells to buy=Cost Cut
Less wear on motors=Cost Cut
Less wear on tires=Cost Cut
less waer on parts=Cost Cut

Anyway,you can still use 5 or 6 turn motors to compansate for the loss of voltage.(Not much but better than nothing,you guys get what I mean)

Conclusion,I think reducing 2 cells is a good thing for thenormal racer as it reduces cost.Formula 1's running 2.4 litre engines from now on till who knows when??(Was 3 litres last 10 years or so)...

I would like to see what do the Pros and sponsored drivers think...?

ttso

iTrader: (1)

Yes minimum weight for 4WD dropped to 1350g from 1500g. Other changes including wing-size and location, not really big deal compare with 4cells and 1350g.

Ben.C

Agreed....The major change in rules will effect how cars are designed nest time. Drive trains will be lighten to get back the rip being loss from 4 cells etc....

iblumberg

In the short run, this switch may cost a bit. As noted, it will likely require new chassis designs (well, there goes another $400+ for the new chassis).

On top of that, we will probably need new servos designed to work at the reduced voltages. The KO2123 FET servo that I run for example will likely be slow as molassas on a cold day running at 4.8v when it is designed for 7.2v.

Oh well, who ever said progress was cheap?

Ira

ttso

iTrader: (1)

I did some drawing with Kyosho belt proto to see possible 4cell layout for side motor belt.

You would still able to use current servo with 4cells since BEC would convert power to 6V anyway.

Ben.C

I feel that the servo should be on the other side...As the 4 cells are still heavier than the motor.Where the lighter esc and rx can be with the batteries.

gee-dub

iTrader: (1)

for the comment of 4 cell saving oval, where? out here in cali paved/carpet oval is about as dead as...dead (you can count the number of year round track programs on 1 hand give or take). the SW tour is still going thanks to joe myers dedication, and some new 4-tracks series rotating between 4 tracks. i don't know though, maybe it is a east coast thing.

i would think in the stock/19t going down in cell count would increase useable horsepower, which in turn would make battery voltage/IR that much more important (kind of the opposite theory of offroad where just about anyone can overpower an offroad track for 5 mins). mod on the other hand will definately be dropping cell count and gearing to the moon to compensate. i do not think, with the exception of a few tracks with incredible traction and/or banking, that 4c is going to make a huge difference on motor/arm/brush longevity. top guys will still be cutting/rebuilding every run.

as far as 2/3 the price, yes and no. you must consider that racers who share packs between other popular forms of 1/10 ep racing now have to buy additional packs. plus i think we will see matchers bumping prices a bit on the 4c a bit more than 2/3 the price of 6c, just like 1c is more expensive than 1/6 a 6c typically.

rangulo

Wow!!! That is great they are switching to 4 cells.. I personally witnessed Adrian driving his car with a 4 cell 19turn and in my opinion was faster but needed a little work to free it up throught the corners.. The 6 cell stock guys had a lot of rip and most times could only use it in the straights.. There is only so much power the tires will allow you to put down in the corners and with the 4 cell 19t Adrian was able to put power down more efficiently in the corners than the 6 cell stock guys and allowed him to keep up with less motor and tire wear...

By the way has anybody seen a Lipo pack in an airplane blow up when they crash.. Its nasty dangerous stuff.. I hope they come up with a system to seal the batteries from explosion.... I know I personally would blow up a few packs with the spectacular crashes I have done in the past..

AdrianM

iTrader: (4)

The lastest stuff is much better. The only way to cause a fire is to grossly over charge them...but that can happen with any battery.

rangulo

I was just talking about the high impact of a crash.. Some of the guys who race gas have them for their receiver packs and when they crash...PISSPISSSPISSSPISSPISSS....Thats what they sound like... Melts there plastic holders.. THey are great advantage seeing how they weigh 60 grams less then a standard nitro receiver pack....