more motor ?????

[hammertime]

is there much difference between the 12L and 8XL........ if so what will i see in performance..... i know the difference in size and kv but other than that will i see a difference at the prop in my catamaran.... or speed heat etc

[saleens7]

the XL will have more tourque....so you could run a larger prop...

[Fluid]

The XL will also run smoother and cooler. I have ditched all my smaller 2-pole motors and gone with XL sizes exclusively. I was suprised how well the 8XL ran on 8 cells with an x645, but it is very fast on 12/4S with an m440 or x637. Like Saleens said you will be able to spin more prop at the same rpm, which means more acceleration and more speed. The 3-ounce weight difference is so minor - especially with a 12/4S setup - that you'll never notice.


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[hammertime]

will i see a huge difference in speed from an 8xl from my quannum im running now....in the cat..... on 14 cells..... its a 6 pole motor at 1350 kv.... i was also thinkin about running twins in it as well..... winter project or end of summer...... or do you think i should stick with a single..... i think 2 motors and 24 cells wouldnt be much different cuz of the weight.... or am i wrong..... my major issue is lack of room.... its the bandit cat and it is a very shallow hull..... i have seen videos of this boat with twins and it screamed at 124 kph....dont know what that is in mph... but they were also from germany and im guessing they had some redic power in it and money.... im just gettin board with the speed its at right now i want more more more

[Fluid]

Hammer, IIRC the fast Bandit S in Germany ran twin motors/ESCs/drives on 18 cells; 124 kmh = 77 mph. It is neat, but I would stick with a single motor unless you just like the idea of twins.

You will see much higher speeds with the 8XL versus your Quannum - the main reason will be the higher Kv of the 8XL. The 8XL will run okay on 14 cells, but personally I'd stick to 12. You will not need the extra voltage to get high speeds; I know from the experience of a club member's Bandit S that you can get close to 50 mph with the 8XL and 12 cells in oval trim. Set up for SAW you can top 55 with the right setup.


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[hammertime]

thats what im lookin for...... what would be a good prop and esc..... i want to run this as a saw boat

[hammertime]

will my 70a esc be ok or do i need more muscle

[part time]

if u are going for a saw boat get the hydra 120 . 70 amps and 14 cells only gats u 1176 watts max. and the 8xl is rated for 84 amps so u would be able to make 235 more watts or about 1/3hp with room to spare to push the motor.

[hammertime]

ok see i dont know how all that stuff works..... i didnt realize i could get more power like that.... sounds good

[part time]

volts x amps=watts u can run the feigaos up to 50000 rpms. so if we divide that by 2084 we get 23.99. so that means 20 cells or 24v unloaded. 24vx84amps=2016watts so almost twice the power thats not factoring in the rmp drop when u load the motor or pushing the amp rating. these number are at 100% efficiency

[Jeepers]

DEFINATLY use a bigger esc, if you over prop you can kill a 70 amp esc quickly, I found that out the hard way today, I was testing my dads 70 hacker on my 8xl(he said he couldnt get it set up properly) so i stuck it in my hydro and ran 45 second s smoked it, actually burned a hole in my boat :mad: I even proped down from what I normaly run! I usually use a cc125 in my hydro. dang now I owe my dad 200 bucks:(

[Fluid]

Most folks do not realize that if they want a true SAW boat, they cannot run for more than about 30 seconds before bringing the boat in. Actually, most record-holders only make two passes and bring the boat in - or it may thermal on the third pass.

With the 8XL you can make a semi-SAW boat. In other words, you can prop it so that it will hit a relatively high speed but you won't run it for more than 30-60 seconds. Believe me, you do not want a true SAW boat if you are on a budget, because you WILL burn stuff up! Been there, done that, got the magic smoke stink.

You can use your 70 amp controller to carefully work up your speed, but you will probably not be able to top 50 with it. Actually, right now a very good but inexpensive ESC is sold by United Hobbies - the OEMRC Sentilon100A HV 2-12S Speed Controller is in reality a Hacker 99 that was made by the manufacturer in China on a "third shift". Let your conscience be your guide when buying Chinese electronics, but at under $100 this is a good controller. A couple guys in the club have them and they have worked well so far. I would put a small computer fan on the heat sink, but otherwsise they are ready to go.

Prop-wise with the 8XL and 12 good cells, start with an x440 or x442 and get the cat trimmed, then step up to an x640 or x642. Be careful as you test, use a stop watch and time your runs, keeping them under 45 seconds total and checking heat and speed each time. You may find that as you go up in prop size the speed will rise, then fall. Go back to the prop that gave the highest speed and trim the boat. The fastest attitude is with the bow high, running on the last 3-6" of the sponsons - but this risks a blowover. But, that's what SAW-type running is all about - pushing the envelope. :cool:

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[hammertime]

well what i do is just fast passes back and forth.... im not going to be acctually running saws..... i dont run an oval..... just fast passes back and forth..... thanks for all the info..... what about running a brass pipe over the heat sink.... thats what i do in my hammer on the proboat esc..... works good.... and i already have a s/b 440/3 perfect for my first try with the 8xl

[part time]

then what u might want to do is get a tranny. then u can do your fast passes or run it normal all with the same boat. just with a quick gear change.

[hammertime]

im not sure i want to mess with gears..... not a bad idea though.....

[part time]

not really much to mess with u could set it to where u only need 2 pinions. 1 for 1:1 (saw) and one for normal driving. that away if u were out at the pond and some guy with a nitro started talking smack u throw on the saw pinion.

[Fluid]

.... and i already have a s/b 440/3 perfect for my first try with the 8xl

No, not perfect. A three-bladed prop is not the same as a two-bladed prop. The 3-blade loads the motor much more - in this case it may give slower speeds because it will not allow the motor to turn up high enough. If you insist on using the x440/3, limit run times because heat might be an issue. :eek:

IMO 3-bladed props do not belong on most FE boats. They can work for special applications, but this is not one of those. They are harder to balance, have limited sizes available, load the motor a lot.....not many positives to them. :cool:



.

[ReddyWatts]

I usually use some 1/8 hobby grade plywood under the controller/motor and 1/16 balsa wood under the batteries to prevent any damage to the hull, if something burns up. It has proven to be a good heat insulator from any catastrophic events. It also adds strength to the hull for the horsepower the brushless motors are generating these days. Its cheaper and safer than working with the carbon fiber.

Fluid, I know you are not a fan of the 3 bladed props, but have you tried the Y537/3? It is becoming one of my favorite. I put it on a direct drive, 14XL with 24 sport cells and it is running in the 40's using only 50 amps. FECalc says it should be running in the 50's. There is no need to water cool anything. I had a high school kid say " that is the most amazing thing he has ever seen". You know how hard it is to impress a kid these days. ha

I am running it in the supercat right now, but will be moving the setup to the mean machine shortly. I want to see if I can get it close to its potential.

[Fluid]

That little y537 does not have enough pitch to get you to 50 mph with your current setup. Your temperatures are so low because the prop is not loading the motor enough to generate enough power to get you there. For more speed you need more pitch - I'd recommend an x642 as a rough guess. That prop has sufficient blade area to drive either of your cats, and enough pitch to get you close to 50. As always with a new prop, watch your temps. FECalc is a nice tool to help you get in the ballpark but it does not always predict performance very closely - too many variables.

You have to load the motor to produce power, but it is a balance between heat, power/speed, and run time. For example I didn't water cool my 50+ mph P Sport Hydro, but I only ran it in heats lasting less than 70 seconds. The real limit is the NiMH pack temperature, since that cannot be cooled. LiPos would help there. ;)

The y537/3 is an okay sport prop and if it works for you that's fine. But it fits nothing I run. :cool:

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[ReddyWatts]

Fluid, I know this is an unconventional setup, but the temps are 120F on the controller, motor and batteries. I am running it on some cheap tenergy 3300 batteries. This setup is pushing a 34 inch hull. It will probably add 4-5 mph on some good cells. It is running in the 40's now. I tried it on the X440 and X442 props but this one is faster. Here is a link to a video of its performance, taken at the end of the run. It had already slowed down some, but check it out.

http://www.rcflix.com/photopost/showphoto.php?photo=2693&cat=500&ppuser=3055

[hammertime]

so a 2 bladed prop would be a better choice for this setup..... also fluid what hardware are those guys using...... i need some better stuff ........ thank you so much for all the help anything else would be great.... i want to do this right the first time

[Fluid]

The x440 has less effective pitch than the y537, so of course it is slower. You need more pitch to go faster. How are you measuring your speed changes - GPS or radar? How long are you running to get up to 120F?

I'm just trying to help you go faster. You don't have to take my advice......


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[ReddyWatts]

I am using a gps for speed and a watts up meter for load. I ran out a full charge on 3300 batteries. I did not time it.

[hammertime]

fluid i havnt tried anything yet..... you sound like you know what your talkin about and i value any knolege i can soak in...... i dont really know a lot about this stuff.... i know enough to get by...... would the speedmaster strut be ok to use

[hammertime]

you as well reddy

[Fluid]

so a 2 bladed prop would be a better choice for this setup..... also fluid what hardware are those guys using...... i need some better stuff ........

I believe a 2-bladed prop is your best bet. Realize that you could go even faster with a hotter motor like a 7XL - but your run time will be shorter and things will get hotter faster. For sport running with some speed running thrown in it is difficult to beat the 8XL for versatility.

On a hull that size I liked to use the Fuller's Next Generation Mono package - I think Steve used to sell it. Another option is the Fuller's Crumbgrabber setup. Don't worry about it being listed as 6-8 cell hardware - it was used on the 12-cell rigger that made a 98 mph pass in LA last year.

My Mean Machine has the SpeedMaster 21 strut and Mono rudder; it runs low 40s with a very conservative 10XL and 4S1P/TPX3300 setup. I'm not certain if that hardware will even fit on the Bandit transom.

There is always more than one way to skin a cat (no pun intended). I do not pretend to know everything there is to know, but I do have the fastest 12- and 18-cell cats in the US, with the record plaques to prove it. I have helped other guys go nearly 70 mph with their cats, but not everyone can go there. You have to be willing to sacrifice your boat if you want to exceed 50-60 mph as a crash at those speesd can destroy the boat. I know, I lost my favorite. :(
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[hammertime]

yea they dont give ya much room for options but i def need some new stuff for sure..... i cant even ajust my strut right now..... is this the speed control you mentioned earlier

https://www.unitedhobbies.com/UNITEDHOBBIES/store/comersus_viewItem.asp?idProduct=3728

[Fluid]

Hammer: no it is this one:

https://www.unitedhobbies.com/UNITEDHOBBIES/store/comersus_viewItem.asp?idProduct=4691


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[hammertime]

perfect thank you...... im ordering that thing at the end of the week!!

[hammertime]

i measured it out.... there is enough room for the strut and a sv rudder..... unless there would be a better rudder to use

[hammertime]

thats a bummer you lost your favorite cat...... maybe i should just send you this thing and pay you to make it a beast lol..... i think you have got me on the right track here..... it will be a slow process (low funds) but i think in about 2 months it will be there

[ReddyWatts]

Fluid, I am trying to build a fast (high 40's) reliable boat that runs cool (50 amps)and has a long run time on a budget. That is why I like the 14XL. If I put this setup in my mean machine and get different batteries, hopefully I will reach my goal. Thanks for your suggestions. I will try the other props, next payday. Also planning on getting a neu motor for the supercat, I really like the way it handles. Which motor do you suggest?

Reddy

[part time]

hammertime there is also the twisted liquid racing hardware for the thundercat its only 50 for the strut and rudder

[ReddyWatts]

http://www.rcflix.com/photopost/showphoto.php?photo=2694&cat=500&ppuser=3055

[RMZDADDY]

Reddywatts, I'm sure you can accomplish your goal, I have my MM running 45.7mph with a 12xl geared 1.26:1 on 24 cells using an X642. That's turning 31771 no load rpm at the prop. If I had to do over, I would have used the 14xl direct and got over 34000 at the prop. With the current setup I'm averaging 52 amps with a peak of 72. I've thought about going to a larger prop (my initial goal was 50mph) and I still may, but that might defeat the purpose of having a reliable sport setup.

[Jeepers]

[QUOTE=ReddyWatts;4880]I usually use some 1/8 hobby grade plywood under the controller/motor and 1/16 balsa wood under the batteries to prevent any damage to the hull, if something burns up. It has proven to be a good heat insulator from any catastrophic events. It also adds strength to the hull for the horsepower the brushless motors are generating these days. Its cheaper and safer than working with the carbon fiber.


:( my esc was mounted on wood it burnt a hole on the top of the boat as it flipped when I turned left to get it closer to shore when I heard the boat give out:(

]

[ReddyWatts]

A hole in the top of the boat? I have not had that one happen yet. Was it velcroed to the wood?

It is nice to be able to open the hatch and find everything at 120F. I was runnning a 10XL last year and it was all around 140F @ 70 amps with less run time. I still have some tuning and props to try on this one, but I am very satisfied with it so far on a 77 amp controller.

[hammertime]

http://www.offshoreelectrics.com/proddetail.php?prod=oct-oc6str-130a

would this hardware work ok on my cat

[ReddyWatts]

I like to pull the flex cable after each days run, so the cable does not rust and bind. It is a pain, if the rudder is inline with the prop shaft.

[steveo]

hey what was the cell count on the m-1 cat in the video

[ReddyWatts]

24 cheap sport cells from tenergy. It will run a lot faster with some good batts.

77 amp - 30 cell Jeti controller, Y537/3 prop, 50 amps, 120F on all components. I only water cooled the 14XL motor. I do not like the Jeti opto 77 controller. You can build a mean machine like it for under $500. That boat setup would have cost $800, 1 1/2 years ago. The only brushless parts available at that time were for competition racing. It just keeps getting better, faster and more reliable.