Clarifications to the GT12 Rules

[mark christopher]

Originally Posted by LongRat

The huge current and therefore significant voltage sag seen in 1S only compounds the problem,

im not sure where you are getting your "workings" from but your way out...

for example the core 1s system is a 45 amp speedo, now that means it can only pass 45 amps from the lipo to the motor, and the motor is not drawing enough to pop speedo's

i get the feeling your just anti 1s

what 2s lipo do you use and from what class did your gear come from prior to gt?

[mark christopher]

Originally Posted by keenbutkrap

little jonny goes to his local modelshop and ask what have you got not many will say mardave as for cost a 1/10 buggy ready to run is less than a mardave kit and can be run anywhere gt12 is now a racers class not a beginners

so why are clubs thriving and gt class is the biggest grower indoors?

[LongRat]

Well put points, but electrical loads affect the whole car (motor, ESC, battery), whereas mechanicals only affect the motor. So I stand by my opinion that 1S puts higher loads on the car's power system. I'm currently making a finned aluminium pod floor for a GT10 car to get rid of more heat for this very reason - to allow bigger gearing in 1S without blowing up the motor. I never said 1S would be a cell-killer, or motor-killer. But it WILL load these components to a higher level.

[mark christopher]

Originally Posted by LongRat

Well put points, but electrical loads affect the whole car (motor, ESC, battery), whereas mechanicals only affect the motor. So I stand by my opinion that 1S puts higher loads on the car's power system. I'm currently making a finned aluminium pod floor for a GT10 car to get rid of more heat for this very reason - to allow bigger gearing in 1S without blowing up the motor. I never said 1S would be a cell-killer, or motor-killer. But it WILL load these components to a higher level.

well i disagree with your opinion then

[LongRat]

Mark, we do disagree, I have stated my opinions so we can leave it at that. This is something we do agree on!

My workings come from this:
1S and 2S cars lap a track at a similar pace. They therefore are producing similar power levels. 1S car does so at half the supply voltage, so must draw about twice the current to achieve this. Resistive losses scale as the square of the current, this is where the extra heat comes from. Your 45A speedo will not restrict the current flow to 45A. It might just overheat if the continuous draw exceeds this value though. Instantaneous spikes of somewhat over 100A are very likely. Modern cells can take this, but of course the 1S system NEEDS to be heavily loaded up (geared) to get any performance out of it so it isn't doing the battery any favours. In an era where people are so conscious of battery safety, this appears to be a strange move.

I use Loong-Max 2300 2S batteries in a solid machined case that I manufacture and sell. Prior to GT12 I raced touring, before that I raced GT10 (as a 2 cell). I also race off road 2wd occasionally and have 1/10 SC truck and several nitros. I have been involved in RC for 15 years and been manufacturing components for 5 years. I had one of the first brushless drive systems for RC cars in the UK in January 2000.
I am indeed strongly anti 1S. That's my history, cheers.

DAVE

[f888fhw]

Originally Posted by mark christopher

easy, keep running it at thier club at club level and buy 1s if they wish to go to a national...

But i cant, if you remove the 21.5 / 2s from the club guide lines / rules the club will not let me run, and i will have to spend £150 / 180 to carry on running at the club......

The club is only going to run the brca rules to the letter. No mention of 21.5 = a big waste of my money and having to spend more....

[LongRat]

I guess you could slap your stuff on Ebay immediately before anyone realises it isn't legal and buy some 1 cell stuff...

[Dave Dodd]

Originally Posted by f888fhw

But i cant, if you remove the 21.5 / 2s from the club guide lines / rules the club will not let me run, and i will have to spend £150 / 180 to carry on running at the club......

The club is only going to run the brca rules to the letter. No mention of 21.5 = a big waste of my money and having to spend more....

personnally i think that would be a bad move for your club, upsetting a lot of members

btw if your using saddles, they are legal to use, the servo u have may be okay too, so its a new esc & motor which could be got for £100 or less..
your esc may handle 1s ? you never know...

[Dave Treacy]

Interesting discussions but I'm not sure anyone has considered the motor wind in the calculations.

For "compable speeds" assuming similar gearing a 21.5T motor is wizzing around at about 60% more RPM that the 13.5. This generates more heat and surely draws more current?

[Paul B]

Originally Posted by SlowOne

The 21.5 class has become redundant. It was there because there were too few 1S-ready speed controllers at a fair price. With the new Mardave and Schumacher controllers now available for only £15 more than a good booster on its own, there is no reason to use 2S. Obviously clubs can do what they want, but for Nationals it is a redundant rule and will be removed

I am a little confused by this statement. The 21.5 class being redundant is not my experience at a number of clubs locally, far from it in fact. Whilst it may be the case at national events, it may not necessarily reflect the national club scene. There does not appear to have been any caveat in rules that stated 21.5 would be removed if not taken up at national events.

I find it reassuring that clubs adopt BRCA National rules for the classes they run locally and assumed that the BRCA considered this point when setting (or amending) class rules.

IMO removing this particular section would devalue its currently popular following at a number of club run events and championships. It may even damage what is a growing class that is encouraging new and returning racers.

The general theme of removing previous rule guides, especially recently published items such as this, may also devalue future rules set by the BRCA and I fear, goes against a number of the associations core objectives.

Paul

[LongRat]

Paul - couldn't agree more.

Dave:

If the speeds and gearing are similar, then the motor RPM must be also. The calculations bear this out, using typical motor values:

13.5 motor @ 3300kv, at 3.7V = 12210 RPM
21.5 motor @ 1600kv, at 7.4V = 11840 RPM

So the motors indeed rev to similar speeds. However current draw has nothing to do with RPM in a motor, only torque. While all motors have an RPM/V coeffient known as kv, they also have a torque per amp coefficient called kT which is rarely discussed.

[mark christopher]

Originally Posted by Dave Treacy

Interesting discussions but I'm not sure anyone has considered the motor wind in the calculations.

For "compable speeds" assuming similar gearing a 21.5T motor is wizzing around at about 60% more RPM that the 13.5. This generates more heat and surely draws more current?

spot on dave....

[mark christopher]

Originally Posted by LongRat

Mark, we do disagree, I have stated my opinions so we can leave it at that. This is something we do agree on!


I use Loong-Max 2300 2S batteries in a solid machined case that I manufacture and sell. Prior to GT12 I raced touring, before that I raced GT10 (as a 2 cell). I also race off road 2wd occasionally and have 1/10 SC truck and several nitros. I have been involved in RC for 15 years and been manufacturing components for 5 years. I had one of the first brushless drive systems for RC cars in the UK in January 2000.
I am indeed strongly anti 1S. That's my history, cheers.

DAVE

Ah it makes sence

well i have no "interest" in what class im pushing, my lipo sponsor can supply me 1s or 2s stubby
i have racer elec TC, buggy,f1,12th and sc, 8th off road ic, 10th, 8th off road ic, won nationals and been racing/involded in rc for 30 years. i was one of the first to use lipo power in 4x4 buggies (pre production soft case trackpower) been an active brca section comittee member and a scribe for a uk mag for many years, i believe in the best package for the best classes, giving the racer the best fun. oh and i read rules fully...
thats my history, cheers.

[mark christopher]

Originally Posted by f888fhw

But i cant, if you remove the 21.5 / 2s from the club guide lines / rules the club will not let me run, and i will have to spend £150 / 180 to carry on running at the club......

The club is only going to run the brca rules to the letter. No mention of 21.5 = a big waste of my money and having to spend more....

thats an issue your club needs to decide, the rules they are following are guide lines only...

[mark christopher]

Originally Posted by Paul B

I am a little confused by this statement. The 21.5 class being redundant is not my experience at a number of clubs locally, far from it in fact. Whilst it may be the case at national events, it may not necessarily reflect the national club scene. There does not appear to have been any caveat in rules that stated 21.5 would be removed if not taken up at national events.

I find it reassuring that clubs adopt BRCA National rules for the classes they run locally and assumed that the BRCA considered this point when setting (or amending) class rules.

IMO removing this particular section would devalue its currently popular following at a number of club run events and championships. It may even damage what is a growing class that is encouraging new and returning racers.

The general theme of removing previous rule guides, especially recently published items such as this, may also devalue future rules set by the BRCA and I fear, goes against a number of the associations core objectives.

Paul

just have national rules, i fail to see your point, the elec off road section do not publish different rules for clubs to use, nor do many other sections, clubs simply follow the sections brca rules unless they decide not too

[terry.sc]

Originally Posted by f888fhw

Not when your club is going to make you buy new gear, because 2s is being removed from the rules! Im not interested at running at nationals, but dont want to buy new gear just to run at the club.
Please keep a small note in the rules to allow the use of 2s at club level. If this.was not in the rules it would have not been a very difficult decision for me to justify entering this class.

As has been pointed out several times above, what your club decides to do is entirely down to the club and has nothing to do with the BRCA rules. If your club want to run 2S then there is no one stopping them doing so, there isn't going to be anyone from the BRCA committee coming down to check what rules you are running to as the BRCA has no control over what clubs do.

If you are unhappy with what your club is going to do, the people to speak to are your own club members and committee, complaining on here or to the BRCA committee isn't going to make any difference to what your club does.
If there is a group of you who are currently running 2S and want to keep running them then the club must be pretty stupid if they could be turning away current members purely because they aren't capable of managing their own rules and have to adopt what the BRCA run. If everyone else at the club is happy to move to 1S only, then whether the BRCA includes 2S rules in an appendix or not isn't going to make any difference to stopping your club moving to 1S only.

[terry.sc]

Originally Posted by RogerM

Oh dear, SOMETHING needs to happen as since the beggining of GT12 I've wanted to race this class, especially at my local club. However in order for me, and many many many many others I suspect, to take the plunge there needs to be a very clearly stated set of totally unambegious rules.

This is crazy! Please for your own sake, and that of the clubs, sort this mess out! I currently would rather do a 100 mile round trip to race a different class than go to a club less than 4 miles from my house to run GT12 as I KNOW whatever I buy will be the wrong damn thing in a few months time.

The class looks great fun, should be super close racing ... please don't kill it!!

Am I missing something here? Surely the simple way to find out what you need to run at your local club is to go down there and ask them what they run. Why are you making a 100 mile round trip to avoid them because you don't know what rules they run to? The BRCA rules might have no bearing on what they run, the only way to find out what classes they run is to go and ask them.

The BRCA rules for sanctioned national meetings have always been for 1S 13.5. The rules have also always stated the 21.5T appendix was there as a framework for clubs if they want to run 2S.

[Paul B]

I was led to believe that the BRCA set class rules and guidelines to promote the sport and encourage competition. I therefore questioned how removing a previously published guide that had, in part, contributed to the formation of what is becoming a popular class, achieves this.
Paul

[terry.sc]

Originally Posted by RogerM

That is the problem Mark, I'mmmissing informed, little Johnny who wants to start racing is alsommisinformed & his dad thinks "stuff this, a play station is easier" & yet another junior racer is lost forever.
Mardave's have always been a great place to start racing... until now it seem . :-(

Little Johnny who wants to start racing will only be misinformed if he is misinformed by his local club.

No one I have ever known in all my years running a club has decided to start racing and first found out about the BRCA and then bought all his equipment based on the rules for the class he fancies having a go at. Every new racer I have ever known has started by going to his local club and asking questions, and any decent club will tell them what the basics are they need to get them going, not what they must buy to be competitive.

As for new racers buying equipment that isn't BRCA legal, I would say at least 90% of brand new racers will have illegal equipment. RTR touring cars and buggies come with Mabuchi 540 motors, first brushless systems being Hobbywing sensorless systems - cheap but not BRCA legal. Cheap nimh cells that came with the car, again not BRCA legal.
Any decent club shouldn't care what electrics are in a beginners car, the whole point is just to get them started and take things from there.

[terry.sc]

Originally Posted by LongRat

PLEASE, TC is a very poor example for this. Not when the rules state that cars should be a reasonable replica of a road going vehicle yet homologated bodies incude many that are openly not even trying to be a model of a real car. This is why so many people regard touring as boring, same thing happened to Pro-10, almost killed 1/12th... It shouldn't happen to GT12 too. While the concept may be ok on paper, running heat after heat of Ascaris gets old. Reminds me of the Dodge Stratus.. and now the Mazda 6. I might slap a huge wing on the back and a carbon splitter and run mine as a Ford Escort GT.

No class has ever died out or been avoided because the body wasn't scale. Pro10 did not die out because of the bodies used, nor did 1/12th numbers drop because of the non scale bodies. If you believe that why did 1/12th pick up again with even less scale bodies. The people who say touring cars are boring would still see it as boring if they had accurate scale bodies as they would then be running with slower motors.

There is a reason there were heat after heat of Stratus and Mazda 6, those were the bodies that worked best. Look at WorldGT, there is a body list of around 20 bodies of various makes, yet everyone uses the Protoform Sophia because that handles the best. That's why you see everyone running an Ascari.

If you want to open the body rules at national level then do what everyone else does and put in a proposal for the AGM, complaining about it on forums isn't going to change the rules. If the majority of racers vote for an open rule then you can run what you want, although it's highly likely you would then end up with a class of GT racers being full of Mazdaspeeds.