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Old 05-17-2014, 11:40 PM   #946
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Originally Posted by RedBullFiXX View Post
Rear are hex hub
Front are unique size as well
O i see, so I guess it wouldn't fit then.

Thanks mate
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Old 05-18-2014, 07:40 AM   #947
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Do the scale bodies handle ok? It would be neat to try racing with one.
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Old 05-18-2014, 07:46 AM   #948
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The squared relationship is most accurate for low-power, high-turn-count motors. Plenty of other things creep in to change the relationship as power levels increase. One biggie is the internal resistance of the battery. I'm guessing that the Novak results include this, and probably maintained the same battery resistance for all tests, which is not the situation we have. The 2s-LiPo-in-a-1s-case that I linked to earlier would have four times the internal resistance as a 1s with the same energy density (since the cells would be connected in parallel internally, rather than in series).

The Novak numbers indicate a factor of 2.76 difference in power between 21.5T and 10.5T motors, but only a factor of 1.79 between 10.5T and 5.5T motors. One could probably come up with a pretty good estimate of the internal resistance of the battery they used if the motor resistances were known.
Yeah I don’t know how Novak powered their dyno, it just notes 7.2V.

I looked at a couple of the dyno graphs in the brushless dyno thread as a reality check on the Novak data, they suggested the difference in power relative to turns is even less dramatic. The same poster had a 17.5 at 167W, a 3.5 at 524W, unless I overlooked some significant difference in test method, which is certainly possible. A little over 3.1 times the power with 1/5 the turns.

What factors are considered in the inverse square prediction?

My first approximation wag includes these for the halving of turns case:
- Current roughly doubles due to the wire resistance and winding inductance cut in half
- RPM doubles (Novak and other’s Kv data matches this very well)
- Field strength for a given current is halved with less winds

2 x 2 x ½ = 2. Or a simple inverse relationship. I’ve attached a chart of the Novak data with a 1/T curve fit for reference, which appears to match reasonably well.
Attached Thumbnails
The future of 1/12 scale-motor-power-vs-turns.png  
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Old 05-18-2014, 07:49 AM   #949
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http://m.youtube.com/watch?feature=e...&v=lHO1krwqFS4

http://m.youtube.com/watch?feature=e...&v=SjFcz7BdezM

Kyosho plasma LM with 30.5 motor
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Old 05-18-2014, 09:42 AM   #950
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hey ed is that 2 cell 30 turn?
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Old 05-18-2014, 09:52 AM   #951
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My question is...why would that be a hit on a 1/12th pan car chassis when it isn't on the myriad of other chassis that can already run that style of body?
classes we run are
13.5 sedan
21.5 scale sedan
21.5 rubber tire F1

Lots of people seem to like the speed and close racing of the F1 cars but are turned off by open wheel racing. We almost had enough interest in the speed passion 2wd lemans cars to start a class but in the end people decided the foams were just too much of a headache.
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Old 05-18-2014, 11:25 AM   #952
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Speed and close racing have little to do with the chassis and more to do with the driver and motors used. F1 does tend to be a bit cleaner because most drivers who race F1 realize you have to be more careful when you are wheel to wheel with an open wheel car. Take away that open wheel and you take away the extra caution that leads to the close racing. That said if you were close to having a LMP class based on the SP1 LMP chassis...there's no reason why you couldn't run the F1 rubber tires on that car. The chassis is nearly the same as the SP1 F1 car.
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Old 05-18-2014, 04:10 PM   #953
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In the UK we have recently (last 2 years or so) introduced/formed a class we call 'GT12'. It's essentially a simplified 1/12 pan car class - simple chassis/suspension, 13.5 1S, foam tyres, GT bodies and a price limit of £100 ($150) on a rolling chassis kit.

There are currently 2 main chassis manufacturers - Schumacher (Supastox) and Mardave (AC12), with at least 1 other (Zen-Racing) about to release a car.

Until now the bodies have been made by a couple of small UK firms (as it's a UK only class), but one of the big players in the global bodyshell market is soon to release a body to fit the cars.

Modifications/upgrades are limited to stop it getting too out of control. It's still developing but has exploded at club level here and we offer 30 places at our 1/12 nationals, which were all full with reserves last season.

In many ways it's the perfect entry level class, but also one which is accessible for small clubs and racers on a tight budget. Lots of guys use second hand 1/12 LiPos and electrics, plus the tyres and bodies last ages.

The future of 1/12 scale rests with the people we can get into the class, and GT12 provides the perfect 'foot in the door'.

http://www.rcnews.net/wp-content/upl...ype-F-Body.jpg
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Old 05-18-2014, 11:34 PM   #954
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Originally Posted by TCS_FUN View Post
hey ed is that 2 cell 30 turn?
Yes, they are using two cell lipo. One cell would be way to slow.
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Old 05-18-2014, 11:57 PM   #955
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The GT bodies I think are only a draw because of the lack of really good looking, scale looking prototype bodies and LMP bodies. Scale is what people are looking for in new classes. Look at the new classes that have come about recently: Stadium trucks (yes off-road), VTA, RC GT, the resurgence of F1, and even to some extent...WGT. Yes WGT isn't as scale as the other classes listed...but it is more so than the wedge style pan car bodies, and that combined with a spec tire that works made that class work. Now I'm not a big fan of GT bodies for pan cars because they already run them in other classes. Why run the same thing just on another style of chassis? To me that makes no sense. Each class should be unique. That's also why I was for 2 cell 380 motors in 1/12h. The smaller motor could reduce the pod size and make it much easier to bring bodies closer to scale. Just think how much further you can lower the body over the rear pod with a smaller motor and how that can lead to more scale bodies. Of course to go along with that it would need to be mandated that the wing be a separate, bolt on piece and not molded in.

That's just my thoughts...
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Old 05-19-2014, 02:12 AM   #956
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Lots of good points here guys!

Mark, that Supastox class looks excellent!

Agree to some degree as to spec/stock racing. IMO it should also have an upper age limit = for YOUNG beginners. They won't ruin a class in the same was as a grown man with a thick wallet

Back to the main topic of the tread - the future of 1:12 scale: I really do think we could improve the cars, but we need to test with higher voltage and smaller motors!

Those who did - how to they feel compared to a "legal" car? And are they faster?
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Old 05-19-2014, 07:56 AM   #957
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1) I'd love it if we could return to running realistic looking body shells.......and if there were a couple of sources for decal sets that would facilitate the replication of one's favorite LMP style racecar.

2) It would also be great if we ran tires that would last more than a couple of runs. Perhaps spec foams (or even rubber tires) could be the answer. The purple stripe lilacs do seem to work very well for the WGTs, so why not try to find a comparable combo that would work equally well on the 1/12th scale class? For me, the biggest drawback to running 1/12th scale these days has become the need to bring a couple of different tire options to each event and especially the need to true them all way way down in order to be competetive. The tire bill has become unreasonable. I can run my WGT at a very high level on just a single set of spec tires for each event, and that one set will usually remain usable for several more subsequent race days. By contrast, I'll usually use up at least 2 (and sometimes 3) sets of tires during a typical 1/12th scale race day........not to mention the need to carry multiple sets of a couple of different tire compounds...... just in case my usual tire choice isn't working so well on a given weekend. IMO, the tire bill has become the biggest downside to 1/12th scale racing. A spec tire (even if it were a rubber one) could go a long way towards reducing the cost of tires. This is not to mention that nobody enjoys spending inordinate amounts of time at the tire truing station. I'd suggest a durable and peel resistant foam tire that would come at a raceable size right out out of the package, perhaps in combination with a minimum tire size rule (to discourage tire truing).
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Old 05-19-2014, 08:02 AM   #958
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1) I'd love it if we could return to running realistic looking body shells.......and if there were a couple of sources for decal sets that would facilitate the replication of one's favorite LMP style racecar.

2) It would also be great if we ran tires that would last more than a couple of runs. Perhaps spec foams (or even rubber tires) could be the answer. The purple stripe lilacs do seem to work very well for the WGTs, so why not try to find a comparable combo that would work equally well on the 1/12th scale class? For me, the biggest drawback to running 1/12th scale these days has become the need to bring a couple of different tire options to each event and especially the need to true them all way way down in order to be competetive. The tire bill has become unreasonable. I can run my WGT at a very high level on just a single set of spec tires for each event, and that one set will usually remain usable for several more subsequent race days. By contrast, I'll usually use up at least 2 (and sometimes 3) sets of tires during a typical 1/12th scale race day........not to mention the need to carry multiple sets of a couple of different tire compounds...... just in case my usual tire choice isn't working so well on a given weekend. IMO, the tire bill has become the biggest downside to 1/12th scale racing. A spec tire (even if it were a rubber one) could go a long way towards reducing the cost of tires. This is not to mention that nobody enjoys spending inordinate amounts of time at the tire truing station. I'd suggest a durable and peel resistant foam tire that would come at a raceable size right out out of the package, perhaps in combination with a minimum tire size rule (to discourage tire truing).
I rarely use more than a single set of 12th scale tires for a full day of practice + club race the next day
And always the same compunds
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Old 05-19-2014, 08:36 AM   #959
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I rarely use more than a single set of 12th scale tires for a full day of practice + club race the next day
And always the same compunds
Similar experience. Fronts seem to last forever for me. Rears I might burn through a set in a day but that is practice+3 quals and a main. I run grey or greylow rears and unless I'm spending a lot of time on the boards the rears wear nice and even and do not chunk.
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Old 05-19-2014, 08:50 AM   #960
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Originally Posted by Dave H View Post
Yeah I don’t know how Novak powered their dyno, it just notes 7.2V.

I looked at a couple of the dyno graphs in the brushless dyno thread as a reality check on the Novak data, they suggested the difference in power relative to turns is even less dramatic. The same poster had a 17.5 at 167W, a 3.5 at 524W, unless I overlooked some significant difference in test method, which is certainly possible. A little over 3.1 times the power with 1/5 the turns.

What factors are considered in the inverse square prediction?

My first approximation wag includes these for the halving of turns case:
- Current roughly doubles due to the wire resistance and winding inductance cut in half
- RPM doubles (Novak and other’s Kv data matches this very well)
- Field strength for a given current is halved with less winds

2 x 2 x ½ = 2. Or a simple inverse relationship. I’ve attached a chart of the Novak data with a 1/T curve fit for reference, which appears to match reasonably well.
Hi Dave,

I have opened a thread to continue our discussion, since most of the guys here have little interest in it, and it's sort of tangential to this thread. Here's a link to the new thread:

http://www.rctech.net/forum/radio-el...urn-count.html
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