P Limited Hydro IMPBA.

[Paul Renna]

Gentlemen

Hope this isn't too stupid a question.

What about limiting the prop?
One of the great lessons I learned is the prop is a major source of performance improvement
As I understand it, you can have all the horsepower you want but if you are running the wrong prop it doesn't help very much

Back in the day in RC cars, we used to have "Hand out" motors for the stock classes. Perhaps "Hand out" props may be an option.

If everyone was running an X440 for example wouldn't that limit the affect of high performance motors, big ESC's and big batteries??

Paul

 

[T.S.Davis]

No two of them are the same. Even if they are cast on the same day. Even if the same guy balances, sharpens, and hardens them.

 

[HTV Boats]

Gentlemen

Hope this isn't too stupid a question.

What about limiting the prop?
One of the great lessons I learned is the prop is a major source of performance improvement
As I understand it, you can have all the horsepower you want but if you are running the wrong prop it doesn't help very much

Back in the day in RC cars, we used to have "Hand out" motors for the stock classes. Perhaps "Hand out" props may be an option.

If everyone was running an X440 for example wouldn't that limit the affect of high performance motors, big ESC's and big batteries??

Paul

Paul,
The problem I see with a specified prop is that will start a S**T storm opening up a can you don't want. Certain hulls perform better with certain props and it also takes away another element of setup. We don't need IROC.
NAMBA rules are working and if you just have to be different call it P-Lite. (crap). The class deserves record status. Racers join, participate and work at events so they deserve every right other racers have. 36X60 is pretty much accepted already and that gets back to not complicating things. A voltmeter and caliper and done.
Mic

 

[MarkScott]

Sounds like the IMPBA BOD is the same BOD that was there when the outboards showed up.. Who'd want to run those boats? So there are 4 rules for IMPBA Outboards, more for Stock B, but it's all KISS.

Just an idea to toss out for IMPBA P-LTD rules, hull length. 30" seems to be the norm for most hulls(?). Leave P at 34". 34".

 

[RaceMechaniX]

And what if I proposed variable length limits based on the number of poles? So 6 pole motors are limited to 56mm, 4 poles limited to 60mm and 2 pole motors limited to 64mm. Motor with higher pole counts are disallowed.

Changing the length limit for P-Lite down to 30" would wipe out 90% of the boats except for tunnels.

 

[HTV Boats]

Sounds like the IMPBA BOD is the same BOD that was there when the outboards showed up.. Who'd want to run those boats? So there are 4 rules for IMPBA Outboards, more for Stock B, but it's all KISS.

Just an idea to toss out for IMPBA P-LTD rules, hull length. 30" seems to be the norm for most hulls(?). Leave P at 34". 34".

Mark,
As Tyler states 30" eliminates a lot of hulls and will result in less seaworthy boats. One of the reasons FE Tunnels lag behind others in growth.
Yes the same attitude that pooh poohed sport/stock outboards is alive and well. Outboards in their day brought a lot of members into racing. How many times have I heard the condescending I started in OB Tunnels. We brought the big numbers to racing and Sport never could set a record or get a US-1. That is one reason I feel P/L needs to be in the book officially. Gets old being a second class (no pun) citizen.
Mic

Tyler much respect but don't open up a length discussion. (tear down inspections). After years we have had a majority settle in at 60mm enough that one national organization adopted it officially. 3660 is a limit do we need more than that? Is it not working? Give it a few years and address changes that are really needed.

 

[RaceMechaniX]

I am challenging the motor length topic because there is not parity by simply specifying a length and diameter. This is also to highlight why the BOD may be having a difficult time adopting the rules.

 

[HTV Boats]

I am challenging the motor length topic because there is not parity by simply specifying a length and diameter. This is also to highlight why the BOD may be having a difficult time adopting the rules.

Tyler,
I have seen this discussion ebb and flow for years. Length seems to be the last block. Under 60mm limits manufactured options. I was at one time in favor of 62 but would rather concede to 60mm and align things nationally. There is no perfect parity unless you control motor, esc, battery and total weight. I would like to see several manufactured options and a simple post race inspection. It's out there and being run now. Pick a number and don't overthink it.
Battery capacity would make sense if you want a real limit. Then the discussion goes to MA rating and over under rating. Right now the rule books has 10000 and 12000ma limits but no way other than trusting the sticker, is there an inspection process.
Mic

Most of the BOD have no FE experience or opinion and defer to others. I would love to see a poll of actual FE racers on the subject.

 

[T.S.Davis]

Most of the BOD have no FE experience or opinion and defer to others. I would love to see a poll of actual FE racers on the subject.

That's kinda how NAMBA does it. Let the racers decide. The BOD looks for conflicts and syntax errors. Then has the members decide.

In IMPBA you have to get passed the BOD before the racers are allowed to even consider it. Most don't know that IMPBA has had limited proposed to them multiple times. That's because they never got passed the BOD. In theory, having the BOD approve a proposal first should work perfectly. The members elect representatives. Those reps are supposed to...well......represent. They convey the desires of their district members to the organization. It's not weird. If the gang that proposed it are the only FE club in your district and you don't even contact them.....are ya? Are you representing them? I know. "No time. It's a hobby. Directors are volunteers. Put up of shut up" I get all that. The BOD takes it's direction from the guys in the meeting. If any of them are adamently against a proposal the racers end up with no say.

It's really not worth the energy Mic. It's also not that big of a deal either. Just run NAMBA. Much less stressful.

 

[LohringMiller]

As I've posted many times, to get displacement like limits for electric power, you need to limit voltage and current either directly or indirectly. Voltage is easier by limiting the cell count for a particular battery chemistry. That has encouraged a search for the best battery with no rule changes for years. Current is harder. There are power measuring circuits that FAI aircraft use. The motor, as was pointed out was the fuse in the past that limited current to around 100 amps. If you want to push for the highest current you can run through a given motot the size rules work. Adding a weight limit would work even better.

The easiest current limiter to measure is propeller diameter. That encourages propeller development while keeping the smoke in on the electric components. It works for the 1/8 scale classes. Propeller development pushed our full size electric hydro from 75 mph to over 100 mph. It brought the old P limited classes running the UL-1 motor up to and beyond 3.5 nitro performance. It would be fun to see what pitch to diameter ratios and cups would be best at converting watts to thrust when you have unlimited rpm choices. Currently, IC powered models' speeds are rpm limited.

Lohring Miller

 

[Mark Bullard]

I can test a range of what you call P and P limited motors and come up with numbers that would work for any motor of that size. Now I would say that the motors all be the same pole numbers and close to the same KV. The test is not that hard but this is what you would need to have a limited class. The test would also pick up the rewinds. Once the numbers are set up for the motors any new brand motors can be tested to see if they meet the specs. These specs should be used for record trial boat motors also.

 

[Isaac Lathrop]

Pardon my ignorance on the subject. As a newbe to FE. and RC boats in general. I find the limited classes to be the most popular and very competitive in our area. Due to three rules. Over all length, motor size and voltage. I couldn't afford to run all the classes I do, if they were not in the limited class. I go to races to run boats not socialize. So when a race is posted and there is only 2 classes that I can run, it's not worth the time or expense. To travel, stay in a hotel, time away from the work. To drive in circles 6 times over two days. If they go by the 36x60 rule.

Isaac

 

[J.J. Horvath]

Weighing batteries? Current fuses? Length limits by motor poles? So those who write the rules want this kinda of precision to make everything even, while also saying they are ok with having found the custom rewinds pull 1.5x more current than the motors that were the previous p-limited standard and what others are using. Can’t see how this makes sense.

Limited hasn’t run its course, the racers who think it has run its course, may have run their course. Membership must be flourishing with the organizations that they want to eliminate a stepping stone of sport boaters turning into boat racers; which is P-limited classes. I am newer to boats and started racing because the power system of my RTR boat fit P-limited, and the competition is somewhat “even” to learn the ropes. So where does a new racer start if the class is eliminated? Rip everything out, spend hundreds to fit “P” class? Will that happen often?

Will that new racer then have a good experience when he finds out he needs to buy a custom rewound motor from another racer to take the top podium spot? Will that racer make him the same custom motor as he is running in his boat? I’d rather have the new guy improve his driving or boat setup in the class that is supposed to be very even power wise..

Take some advice from Mic, he hosts great FE races with even competition and attracts racers from all over. The top podium spots change regularly, which is a good sign.

I also race the people rewinding and see a large contrast. Less entries and racers including myself, are leaving the class because it’s obvious you need to rewind motors or a rule change is needed.

Let the racers figure out the best setup combos for the class, and feel it can be simpler than these solutions being discussed. Allow options, but keep the motors “limited” by the manufacturing process, not ones knowledge of brushless motor theory and rewinding.

In general the rules should be simple like this, and should make it even enough to keep the essence of the class:

- 34” hull length limit

- 3660 motor can limit, with no internal modifications or rewinding. Any KV

- 4S voltage (10k mah max, prob don’t need that much but don’t want to eliminate a new guy who bought large packs) no HV

- Any ESC
- Any prop

 

[RaceMechaniX]

Hello JJ,

I definitely agree that there is a performance disparity between what used to be a limited motor and the rewound motors. This was on clear display at the recent Spring Nationals in Atlanta where the P-Ltd boats were running speeds just below the full blown P-boats. I do believe the performance parity would be better if rewinding was disallowed, however this throws Don under the bus and it would prevent anyone from building their own motors. A similar situation occurred in IMPBA when Mathew Waldon came up with his own cast cylinder which met the IMPBA definition of a production one piece cast cylinder head. That engine should have been legal in what was then LS27, but it was pushed into the open XLS27 class running against QD's and disk motors. I don't recall the final outcome, but it sent a clear message that innovation leading to a performance edge was discouraged.

I have discussed the current limiter with fellow racers and it is a solid performance equalizer however how many racers are willing to pay $75 per boat for a device to race in a limited class? And there is always the possibility of cheating a current limiter, so do we need to make these a swappable device to discourage cheating? Neu has an F5D limiter in case anyone is interested in testing one: Neu Motors F5D current limiter

 

[donaldhuff]

"The easiest current limiter to measure is propeller diameter. That encourages propeller development "

SO, it's ok to do propeller development, but doing the same for the motor is somehow cheating????

 

[Mark Bullard]

Very simple. Battery limit, number of poles limit, and KV limit. With approved torque limits. Now how do you check the torque limit. That is the magic number. You put a fixed DC voltage on two wires to lock the motor in a pole position. By using a very small torque wrench with a dial that will read newton meters, you will have to have a coupling of some type to connect the torque wrench to the motor shaft. Hold the motor to where it will not move you then turn the wrench to make the motor pole to the next position. This will move the needle in the dial to a newton meter reading. This is how we check brushless motors in my shop to make sure the rotor magnets are still up to there torque levels. By doing this it is like putting the motor in a dyno. By testing different brand motors with the same poles and KV you can come up with good torque numbers for the class. This will work for all record trials and protest. And for anyone running a rewind will show up every time with no question.
This is also a good test for all motors that racers use in their boats. You test the motor when it is new, record the number and you can check over time to make sure your rotor magnets are still good. When magnets start to lose pull you will lose torque.

Now people wonder why I don't run FE. I don't like playing with things I work on every day. LOL

 

[LeeWininger]

Have a battery question. 4s-10kMah. Does that mean a total capacity of 10k, ie 2-5k packs, or each pack has a limit of 10k?

 

[J.J. Horvath]

So a simple solution is available and was done in a gas class before.. Keep limited to production motors and then in full P, allow rewinds, because that is the next step up and states “Any motor”.

Under the current rules it is not cheating, just think it’s counter productive to the class and what the class is about.

Don’t get me wrong, I am rewinding as well now because that was made the standard. So I am throwing myself under the bus, but even though I can do it, others can’t and think it should be changed to better the class

 

[Samuel Hagan JR]

Have a battery question. 4s-10kMah. Does that mean a total capacity of 10k, ie 2-5k packs, or each pack has a limit of 10k?

2 5Kmah Packs equals 10kmah

 

[HTV Boats]

10000ma is 2 5000ma packs in parallel.

As for "stock" motors in theory great. It does create a nightmare for inspection. If gas races actually tore down and inspected after races the class would die. Or many would not race that day.
Right now "limited" has simple easily enforced linear rules. 34 inches- 3660 and 4S -10000ma. If you make 1 watt motors into 2+ watts you need to feed them. Cut to 5000ma and big power rewinds won't make 6 laps. If you engineer efficiency good for you.
Now how do you enforce 10000ma? Stickers? No procedure in the book there. Batteries come in various lengths and widths and no industry standards . Weight is a better indication for power. Try 600grams and see what you can buy. You will find quality 5000ma packs and 6000-7000ma under that weight but they will be low C ratings and junk you would not run. At some point with larger boats being built 10000 and 12000 ma batts will need some real tech criteria,
Mic