PDA

View Full Version : Best prop question????



TINY
10-17-2011, 04:57 AM
Probably been asked a thousand times but im after outright speed, the 55" arrow shark cat doesn't turn real good..

Motors are 2 x leopard 4082 1600kv

2 x swordfish 200amp esc

2x 6s 35 to 75c

sharts are running opposed but could be changed if needed..

Cheers justin

sanyijr
10-18-2011, 02:00 PM
Tiny,

Not-so-Tiny setup. Sorry, out of my relm of knowledge.... But I am curious to see suggestions.

Sean

TINY
10-18-2011, 02:21 PM
Been given suggesstions of x447 and 450 3blade but they look so small for motor?? And big boat....Just want it to go real fast and turn when i cant see it....lol

Boaterguy
10-18-2011, 03:10 PM
let me Change my post to please the general community.
on alot of twin cat build threads, I see people talking about which is better, inwards or outwards.
try changing it and see if it helps.

LarrysDrifter
10-18-2011, 03:15 PM
Boaterguy, what set up do you have in your twin drive cat? What is the rotation of the drives? Do you give your bad and misleading information based on what you read or your experience?

Fluid
10-18-2011, 03:40 PM
How fast do you want to go? What are the details of your packs (1P or 2P, brand, capacity, "C" rating)? How much does the boat weigh? Those motors and ESCs will only take so much abuse, especially with low performance packs. In "theory" the x447s would probably max out near 55 mph, but I suspect they are too small for a 55" hull. To go much faster you'll need bigger diameter and more pitch (and thus more amps) but the motors, packs and ESCs may not be up for it. With top-end components I'd run x457s but they'd likely melt yours.

Turning has a lot to do with the rudder used. The brand of rudder, how much is below the bottom of the sponsons, and a photo or two of the transom area would help us to diagnose.


.

TINY
10-18-2011, 06:26 PM
How fast? as fast as possible... c rating is 35 to 75 as stated.. Capacity is 5000mah Turnigy nanotech.. motor is 4 pole.. does any of that help.. Its a 55' glass cat with 2 batts 2 200amp esc 2 motors and alloy hardware.. also a couple of pool noodles.. 1 or 2p? (what does that mean)

Will the motors handle 12s and high volt esc's?? thought the 4082 1600's were pretty good?
Cheers



How fast do you want to go? What are the details of your packs (1P or 2P, brand, capacity, "C" rating)? How much does the boat weigh? Those motors and ESCs will only take so much abuse, especially with low performance packs. In "theory" the x447s would probably max out near 55 mph, but I suspect they are too small for a 55" hull. To go much faster you'll need bigger diameter and more pitch (and thus more amps) but the motors, packs and ESCs may not be up for it. With top-end components I'd run x457s but they'd likely melt yours.

Turning has a lot to do with the rudder used. The brand of rudder, how much is below the bottom of the sponsons, and a photo or two of the transom area would help us to diagnose.


.

tiqueman
10-18-2011, 07:52 PM
Oh my.. we have a lot to talk about. No, a 1600kv motor cannot take 12s. Thats over 70,000 rpm. 1P is the set up most ready to runs use and what most people sport boat with. It for example is a 4S pack. or (2) 2s packs series to 4S would be 4S1P. 2P is parallel set ups. 4S2P would be (2) 4S packs wired in parallel to give you the same 14.8V output.. but your mah doubles.

From experience I have a 45" cat doing mid 70s on 1600KV castles (roughly 4085ish i think) Castle 1520s, and turning 447s. That was running 6S1P per side. The cat you have obviously is 10" longer and much more stout, but I dont see why 60 would be a problem. and turn 447s.

Oh and leopards are pretty good, but even a NEU will let go and toast at 70k rpm.

And one more thing. Every hull is different when it comes to "in" vs "out" rotation of props. I have two hulls that it doesnt really seem to matter that much on. My HPR runs WAY better with them spinning out. Another guy whos in the club has and expresscraft MTI and it also likes out. He just built a DF twin cat and it was all over the place while spinning out, hw changed them to in and its a totally different controllable boat. So testing is all you can do. Try both and see which is better.

TINY
10-19-2011, 12:03 AM
Ok i run 2 6spacks (1p) I thought it was kv mutiplied by cells but it sounds like kv multiplied by cell voltage.? is that correct.. Makes sense now.. 35k was my target rpm So if i went up to 5 series leopard and 600-800kv ish i could run bigger and better props with a higher speed at 12s??

tiqueman
10-19-2011, 12:12 AM
2 6s packs together for 1P would be 12S or 44.4 volts.

Yes KV is multiplied by final voltage for your unloaded rpm value. And yes again, your still spinning the same rpm, but your amp draw would go down and able you to swing a larger prop. therefore, a bit faster. Your on the right track now.

6BOOST
10-19-2011, 08:55 AM
Are you distinctly set on on running twins? I know most people like twins on big cats, but for your goals, a single 2028 castle, fightercat 16s/200a speedy and 12s would net you 60+mph for probably less cost and a hell of a lot less hassle, 50+" mono's have gone over 70mph with one of these one 12s. Not trying to move the goalposts for you, but when your knowledge is limited the K.I.S.S principal imo would net your more enjoyment for less hassle till you get a handle on it all and with the same outright speed. I don't know if you already have speedy's, but your battery packs can still be used:)

6BOOST

TINY
10-19-2011, 09:46 AM
Thanks for your reply's guys and your right I'm new to elecs and used to hate elec and nitro? I raced a TS 30.5 carbon baja that cost me a fortune.. It wasn't untill I saw a mates e revo done up that I grew a respect for electrics.. I've had fast 1:1 cars bikes and boats so I'm happy to pursue the smaller scale stuff. My goal is 80 mph with a big cat. Not interested in oval racing or similar.. Just outright speed!! I just need the combo and I can order and assemble. I'm not being cocky guy's but when you spend over 8k on a buggy then two or three on a boat suits me fine since I now live near alot of lakes and have a new respect for boats...
Cheers justin

6BOOST
10-19-2011, 10:22 AM
To run 80mph in a 55" cat your going to need much more then 4082's imo, at least to do it more than once lol. There is a few motor options, single NEU2230, twin 5698 or TP power 5660 or twin castle 2028. Ultimately the first 3 will cost similar money as the money saved on batteries, speed controllers and drives on the single, will cost you extra on the higher quality 2230, the twin 2028's will be a little more expensive, as the motors are about $100 each more expensive than the other twins.

If you want a reliable 80mph, then you can double your estimation by the time you have it in the water, for that sort of money if you don have the hull already maybe consider going down to a 32-41" cat with something like a NEU 1527 which Steve has on special here in the store atm and 80mph might be possible within your budget.

6BOOST

TINY
10-19-2011, 02:51 PM
I've got everything already but will need bigger speedy's and motors.. If i was going to run twin castle 2230 or 2028's the what sort of props should i be getting made up..

All drive line is installed, dual stinger etc etc

Fluid
10-19-2011, 05:09 PM
An 80 mph cat just 32" long is not for everyone. It will not run that fast on anything but reasonably smooth water, and run time will be short. Believe me, I know better than anyone else.

A club member made a 44" HPR cat go into the 80s (on GPS) with twin 1527 Neus and 10S2P/5000 mAh. He still needed reasonably smooth water but it worked well for him. The guy was an experienced FE builder though, and I do not recommend any new FE boater start with a 55" boat!! :scared: :crying: :Praying:

If the OP really wants a 55" 80 mph twin cat it will cost him. The old addage is true: Speed, low cost, reliability - pick any two. Even then you will not be able to run that fast in very rough water, and amp draw will be high if you use the 80 mph capability. The Castle 2280 does not have the Kv needed for 80 mph on 10S. I doubt that the smaller Neu 1527s will work in a 55" boat, 2230s are a better choice with Kvs around 1000. Then ESCs - Schulze 40-160s are the gold standard, but based on what I have seen with my Castle HydraICE controllers the HV version may work well....whenever it comes back on the market.

Your packs are marginal at best. I have seen Turnigy packs burst into flame (literally!) after two minutes run time in a 42" mono running 55 mph on 10S. It is tough for some new boaters to grasp, but ALL the power in an FE boat is in the packs. Period. Better motors just stress the pack harder. The better the pack quality, the faster the 10S boat. Inadequate packs will not only slow the boat down and risk a fire, they can and will take out an ESC due to high ripple currents.

I wish you luck, just go slowly and plan on making the first trip to the pond a learning experience. Go slowly even though you will be very excited. Don't bring along a crowd. Don't plan on reaching 80 mph, put on smaller props and aim for 50s or 60s. Run for no more than one minute, then bring it in to check temps. Send it out for another minute, then check again. This is tedious but it can save you from making a very costly mistake. You'll thank me.


.

6BOOST
10-19-2011, 06:16 PM
Just to clarify I didn't say to use 1527's in the 55" cat;) But Fluid speaks the truth and knows his sh1t, heed his advise well:)

TINY
10-20-2011, 07:12 AM
An 80 mph cat just 32" long is not for everyone. It will not run that fast on anything but reasonably smooth water, and run time will be short. Believe me, I know better than anyone else.

A club member made a 44" HPR cat go into the 80s (on GPS) with twin 1527 Neus and 10S2P/5000 mAh. He still needed reasonably smooth water but it worked well for him. The guy was an experienced FE builder though, and I do not recommend any new FE boater start with a 55" boat!! :scared: :crying: :Praying:

If the OP really wants a 55" 80 mph twin cat it will cost him. The old addage is true: Speed, low cost, reliability - pick any two. Even then you will not be able to run that fast in very rough water, and amp draw will be high if you use the 80 mph capability. The Castle 2280 does not have the Kv needed for 80 mph on 10S. I doubt that the smaller Neu 1527s will work in a 55" boat, 2230s are a better choice with Kvs around 1000. Then ESCs - Schulze 40-160s are the gold standard, but based on what I have seen with my Castle HydraICE controllers the HV version may work well....whenever it comes back on the market.

Your packs are marginal at best. I have seen Turnigy packs burst into flame (literally!) after two minutes run time in a 42" mono running 55 mph on 10S. It is tough for some new boaters to grasp, but ALL the power in an FE boat is in the packs. Period. Better motors just stress the pack harder. The better the pack quality, the faster the 10S boat. Inadequate packs will not only slow the boat down and risk a fire, they can and will take out an ESC due to high ripple currents.

I wish you luck, just go slowly and plan on making the first trip to the pond a learning experience. Go slowly even though you will be very excited. Don't bring along a crowd. Don't plan on reaching 80 mph, put on smaller props and aim for 50s or 60s. Run for no more than one minute, then bring it in to check temps. Send it out for another minute, then check again. This is tedious but it can save you from making a very costly mistake. You'll thank me.


.
\

Thankyou for your reply, ive heard from a couple of members here in oz that you know your stuff...

That being said i have an upgraded apparation, several planes, over the top 1/5th scale baja's and a couple of 1;1 toy's..( petrol that is..lol)

All i want to know is what i need to do to get that figure and if it can't be done then so be it... My baja can do 80 mph and it weighs 12 kilo's with a single 30.5cc 2stroke engine from trevor simpson.

Maybe i should be looking at combustion rather than electric???

Everyone tells me elec is the way to go but from all the comments it sounds like i'm asking for the limits of FE in my first year??? Why not a 55" cat more room for bigger components and stability i would have thought? If Turnigy nanotech's are junk i'll spend the extra 50 dollars per pack.. no biggy? But on many threads you guy's rave about turnigy???
I run on fresh water dams that you can see your reflection in... eg not the ocean and built for drinking water so no fossil fuel craft allowed.. not even ripples unless you throw a stone....

If my ski boat can do 100mph and weighs over a tonne why is it so hard to get something with a power to weight ratio 1000's of times better go slower... What am i missing???

Sounds like 12s is the biggest, i have got the best absolute balance charger and 28 volt power supply so now biggest esc, smoothest drive, lightest weight and optimum prop for best motor...

Is it a secret that no one tells you or do i keep blowing s..t up untill i find the combo??

To work out your theoretical times in drag racing you just use a simple graph that shows weight,power gear ratio = 1/4 mile time.. less human error..

Thats what im trying to find out... My figure is 80mph the cat is 55" and if some one could tell me what to bolt into it i'd be very gratefull..

Thanks in advance..

6BOOST
10-20-2011, 07:54 AM
Tiny your goal of 80mph is not hard at all, providing you have plenty of money, and as far as blowing sh1t up, that is why everyone is telling you it's harder than it seems as a lack of first hand experience can lead to failures. Also your budget of $2-$3000 is another problem, as the components needed to reliably sustain this speed are not cheap, your talking Lehner, NEU and higher quality motors, one thing I disagree with Fluid on is the castle 2028, it has propelled similar size hulls in single form to over 70mph, but I think you'd be pushing it hard to do it and without a lot of experience with setup. If you go to a NEU2230 for instance, there is $1650 in motors straight up, plus shipping to Australia, then you have a minimum of 10-12s/5000mah packs, nanotechs are fine but just expect to have some with dead cells, some puff easily, basically buy double what you need just in case, good quality packs are more like quadruple the price not $50 extra.

So as previously stated, you can build a nice, good quality boat with long run times that hauls ass, something that will do 60-70mph between $2000 to $4000, but start going much over that and the quality and price required jumps quite dramatically. out of interest where in Australia do you live? I'm in SE QLD.

6BOOST

egneg
10-20-2011, 08:37 AM
Tiny I sent you a PM

TINY
10-20-2011, 08:56 AM
Cheers guy's i don't want to sound like a d..k but i run my own buisness, and have some cash money to play with.... My fg monster truck on NOS is on utube..... 3k/6k not that bigger issue.. trevs reed motor cost me 2k.....

The deal with my wife is im allowed to spend my extra dough on toy's rather than grog....lol I picked the 55" cat cause it looks cool... running around in circles doesn't do any thing for me but the buzz of riding my bike at 300kph or doing 90kph around a hairpinn turn gets my blood flowing.. Got no kids and a great/puts up with wife...

I may be naieve hence the questions but i will persist untill i get the the result i'm after.... I have even bought a zodiac and tricked up a mina cotta elec outboard on 24volt lithion... cost me over a grand as a recovery boat so i can run on these dams... even heated up the prop to give it some more pitch... My edge trimmer has a rear dominator rc pipe..lol

I have been bitten buy the boat bug and dont want to take the stairs..... Elevator to the top is how i roll... just wish i knew what friggen button to press.. You boys keep these combo's close to your chest dont you..

ps im at mooloolaba..
cheers justin

6BOOST
10-20-2011, 09:39 AM
It's more that everyone will have a different formula and also interpretation of how to achieve the goal you have set as to why you get so varied a response, and I assume no one person wants to say here, you need these components, they I'll work, as no one formula is the right one.The best place to start would be YouTube, there is countless video's of FE cats on there and most list the components used inhe video details. Lehner Motor has some sweet video's in the video section of various boats, and lists their speeds and components used as well. Next step would be to pm some of the more notable forum member, and when you find someone you trust, stick to that one persons advise until you get comfortable making your own decisions, listening to 10 different people is often the cause of more headaches than cures;)

Good luck with the project,

6BOOST

TINY
10-24-2011, 12:33 AM
Cheers mate, people keep yalking about 2 or 3k, that was a naieve guess some time ago.. I have everything and now i have a pro over here in oz that will talk black and white.... I guess im gonna end up withn the worlds fastet apparation if i have to redo the lot... lol

Looking forward to his custom paint.. he doesn't know it yet but i'm giving him no restrictions or ideas.... It's like christmas... might spike his morning tea...lol

Chrisg81983
01-05-2012, 12:09 AM
I am glad u fround a real pro. There are more pro's, and record holders than you know over here who are all full of knowledge. I am eager to see some videos of your maiden run.
Good luck
Chris

Leonard
09-18-2012, 09:54 AM
ihi. i have just started in the HV FE boating. some help would be Greate. i bought the TP5660 800kv and swordfish plus 300A Esc. running in a DF67MkII 42"..My problem is that i am not sure on what size prop o start with. i want to run it on 10s or 12s. tested it on 9s with a x455 prop. not to Greate for the money spent so far.

any suggestions pls

thank you
Leonard