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1/8 Scale rules question


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#1 Buddy Benedict

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Posted 24 March 2018 - 09:04 AM

Been reading up on the rules for 1/8 Scale and saw there is only 3 brands of motors that are legal to run. With all the different choices and price ranges of motors out there, why 3 brands? Wouldn't it be beneficial to the class if it was just a size limit like nitro has? That way racers could buy what they can afford and the class would grow.

 

Just my thoughts,

Buddy





#2 Mike Hughes

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Posted 24 March 2018 - 10:50 AM

I think most of it is to keep the cost down. There are some real expensive motor/controller combos out there. Which would not keep people away.

Mike




Edited by Mike Hughes, 24 March 2018 - 10:52 AM.


#3 raptor347

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Posted 24 March 2018 - 01:57 PM

Are you looking at current IMPBA rules or the NAMBA proposal?



#4 Buddy Benedict

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Posted 24 March 2018 - 04:16 PM

Looking at the current IMPBA rules.

 

 



#5 Hydro Junkie

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Posted 25 March 2018 - 06:21 PM

I know at R/C Unlimiteds, the FE rules allow:

1)  Only three motors(NEU 1527 1.5Y 850KV, HET Typhoon 700-98 840KV, Turnigy SK3-3994 850KV) 

2)  Speed controller capable of handling at least 130 amps and 8S battery packs

3)  Up to 8S packs but not to exceed 6000mAH.  Battery type restrictions are LiPo up to 4.2 volts per cell, LiHV up to 4.35 volts per cell, both types with discharge levels between 30 and 60C constant

4)  Props are limited to 57mm or smaller. 

IIRC, these limits were set to keep the playing field relatively even while keeping costs down.  It also limits the speeds the boats can attain since, unlike nitro or gas power, electric drive has full power at any RPM and requires no time to spool up.  Using these rules, the FE boats are also comparable with what the nitro scales hit in speeds on our courses.

Just a little trivia, NAMBA is looking at using the R/CU rules organization wide since they seem to work well.  If you want to read the full set of FE rules, they are located here:

http://docs.wixstati...3e080d97fbb.pdf


Edited by Hydro Junkie, 25 March 2018 - 06:22 PM.


#6 Mike Hughes

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Posted 26 March 2018 - 12:21 AM

The NAMBA rules proposal is to outlaw boats that dont run in Texas or Washington. These are the 2 areas that run the rules above. By voting for such rule, the rest of the boats will be illegal. If they want to run a limit class, then change the rule to add another spec rule. Not elimanate everyone else. Just my 2 cents. I voted NO.

Mike



#7 longballlumber

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Posted 26 March 2018 - 06:59 AM

Hi Buddy,

 

I will be the first to agree we need to take a look at this rule set and it’s on the
“too do” list.  At the time this was written, I think the intention was good.  It’s my understanding they were attempting to control the amount of available power for the 1/8 scale class.  Just a couple of notes:

 

  1. The NEU 1527 1.5Y is $310.00 at Offshore Electrics and is by far the most cost effective option of those listed in the rule book.
  2. There is a line in the rule book allowing the possibility of adding motors: “Any other brushless motor is subject to technical approval.”
  3. From a diameter and length standpoint of the motors that are listed; I would probably suggest the TP4070 would/could be a feasible option at $130.00
  4. I would be interested to hear what motors you think should be added?

 

 

At the end of the day; 1/8 Scale FE just isn’t that popular of a class.  IF you have enough boats in your local area; do what gets guys to the pond racing boats.  In the meantime keep us up to date what is working for your local area.

 

Later,

Mike Ball



#8 LohringMiller

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Posted 26 March 2018 - 09:36 AM

The current NAMBA two lap record holder runs those rules with the exception of the prop.  We ran a 1657.  I believe those rules are a good combination of performance and cost.  Full T power is overkill and allows boats like Joerg's 195 mph record holder with nearly 20 hp.  Performance is close to nitro boats with better reliability.  Limiting choices works well with the P limited classes and allows concentration on scale details, not electrical engineering.

 

Lohring Miller

 

Attached File  First NAMBA Nats 2012.jpg   192.92KB   13 downloads



#9 raptor347

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Posted 26 March 2018 - 11:02 AM

We were running a scorpion hk4035-800 outrunner  when that pic was taken.



#10 Hydro Junkie

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Posted 26 March 2018 - 01:51 PM

The current NAMBA two lap record holder runs those rules with the exception of the prop.  We ran a 1657.  I believe those rules are a good combination of performance and cost.  Full T power is overkill and allows boats like Joerg's 195 mph record holder with nearly 20 hp.  Performance is close to nitro boats with better reliability.  Limiting choices works well with the P limited classes and allows concentration on scale details, not electrical engineering.

 

Lohring Miller

 

attachicon.gifFirst NAMBA Nats 2012.jpg

Actually, a 1657 does fall within the rules as its a 57mm prop with a 1.6 pitch.  The raw numbers are 57X91



#11 RaceMechaniX

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Posted 26 March 2018 - 06:33 PM

I liked the proposal set forth for a new set of P-limited rules where by it was just a simple length and diameter of the motor.  Although this did not make it to the light of day to the national level, perhaps it would for FE Scale.  Using a can length limit and diameter is easy to tech.   You can add a prop diameter limit and capacity limit if necessary.

 

The Neu 1527 and TP4070 are very comparable motors performance wise and I would give the nod to TP on quality.  The Lehner 2280 is a step above both these motors if you can find the right 400A+ controller to drive it.  The Lehner would fair better if a prop limit were applied as they tend to be more efficient at higher RPM's compared to the 4-pole Neu, HET and TP motors. Although years of developing these hulls around nitro power have tailored them to certain props it seems.   

 

Although you could shoehorn 20hp into one of these hulls there is no way any FE 1/8 scale could use that kind of power.  At least none that I know of.  A reliable 7-8hp is easily doable with a decent motor/controller/batter combination and you don't need to break the bank to do it.  



#12 LohringMiller

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Posted 27 March 2018 - 08:02 AM

We were running a scorpion hk4035-800 outrunner  when that pic was taken.

I'm not sure where I got the idea that 55 mm was the suggested prop diameter in RCU.  It's true that we ran Scorpions first, but I converted to the Neu since the Scorpions weren't as durable and went up in price.  The HET motors are also a great choice.  I have no experience with the Turnigy.

 

The prop diameter, KV, and cell count are the real keys to equalizing performance.  The KV and cell count set the rpm.   The current draw at a given rpm and voltage is proportional to the first power of pitch and the fifth power of the diameter.  Playing with the pitch won't change the current a lot but will effect the efficiency and speed.  That's close to what happens in the P limited classes, but in those classes there is a temptation to push the current limits with bigger props.

 

Lohring Miller



#13 Buddy Benedict

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Posted 31 March 2018 - 02:29 PM

Haven't been able to get on here for a while. Thanks for all the comments. I don't see any use for limiting the brand of motors that are to be used. I personally think it should be a size limit and if you want to run a $500 motor with a $600 controller then so be it. On the other hand you can also use a $100 motor and $100 esc and still be legal. Looking at all the motors above, I think a can size of 40 X 100 with 8S power should work. 

 

Mr. Ball: There isn't much interest in FE here. There are a few of us that have P Spec Tunnels and anything else would have to run in an open class. My interest in the scale FE class is that I build a couple of 1/8 scales that would be easily converted to FE. By the end of summer I plan on having a FE version of my boats done and tested. Personally I wanted to test with a TP motor or a Turnigy motor. I can buy both of them for the price of one of the Legal IMPBA motors. 

 

Thanks.

Buddy



#14 Don Ferrette

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Posted 31 March 2018 - 06:50 PM

 I run FE 1/8th scales and have been looking at the motor situation for some time now. The can diameter length limit might be viable to open up motor options, still researching that as if we go down that road we should be thorough. The 8S limit on the other hand I find to be on the opposite end - a bad idea. This goes against the simple and basic equation of volts x amps = watts = horsepower. To create the needed horsepower to move any FE boat requires a certain amount of wattage. You have 2 choices to get there- more volts and less amps or more amps and less volts. More amperage is more heat and heat is the number one enemy of electronics. I have built and helped build numerous FE 1/8th scales and will go 10S every time as space permits (I have done 9S to save space to keep packs in the nose area but no lower). And the post someone made earlier that you'll fry ESCs easier on 10S just seems like an attempt to sway those who don't fully understand FE into backing the 8S limit. 1/8th scale is not a spec class and to infer otherwise because nitro scale is "limited" to .67 displacement is way off the mark as we can make more power by motor mods, higher nitro etc.



#15 LohringMiller

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Posted 01 April 2018 - 08:44 AM

I edited and condensed Darren Jordan's test series on the current and proposed P limited motors in the latest Propwash.  You can get an idea of what makes a good motor when you load them equally.  He advocates the can size rule for that class.  I would add that weight is also a good measurement.  If anyone wants to do something similar for the 8S motors, that would be instructive.  However, voltage, KV, and prop diameter will do a good job of equalizing performance.  You just need to check to see if the advertised KV is real.  The suitable motors will be discovered.  However, selecting several motors makes it easier to build a boat for those more interested in scale.  Motor choice has been very limited in the nitro classes and is getting worse. 

 

Lohring Miller