itsfishi

thanks man

ryan_t888

Better late then never

This should be easier.
In the boat section on the [link=http://radiocontrolinfo.com/calculations.html]RC Calculator[/link] page. There are several calculator apps for RC Electric boats and more.
Home Page is: [link=http://www.radiocontrolinfo.com]Radio Control Info[/link]

Excellent for determining if your power system fits in to the range you are aiming for, calculating prop pitch, calculating a rough first prop size value on a hull, and for determing an approximate speed of your RC built hull. Perfect if you have read over the info and now want to check over a possible power system combination.

Lots of info yet to add to the site.

Ryan

keithbradley

My Feedback: (38)

Interesting calculator and cool site. Ihave a few setups that seem to throw off most calculators, and they hit a little closer on your calculator. For instance...I have a 32" single motor cat that Irun a 1300kv motor on 8s with a m440. Your calculator puts me in the low 70's, where most others say around 50. The only thing that is off is the loaded prop RPM, but the other calcs are too...
Im going to run a few setups through it that Iknow the speed of and see what it says. It's nice to have another calculator to compare the others to!

ryan_t888

I'm interested in your findings. Let me know what you get and how it compares with actual. Please drop this information in to the RC calculator thread.

All my calculators are based on a database. It's extremely hard to get everything close. On some setups I'm too slow and others too quick. There's nothing I can really do to account for these extra parameters.

Also drop in your unloaded RPM's vs actual RPM's in to that RC calculator thread. This is one area that I need to update and would appreciate the feedback. I'm getting higher actual RPM's and would imagine you are to.

Thanks for the reply.

Edit: I'm getting around 50mph as well for your cat?

Ryan

Dan S

Keith,
I get the 48.5 mph for that setup?
what data did you enter to get low 70's

thanks,

Dan.

keithbradley

My Feedback: (38)

Ientered the right data...just looked at kmh instead of mph! whoops!

Dan S

lol Keith,
I saw that you mentioned that on your other thread.

its all good.

Dan.

BenNowak

Newbie here looking for advice. Last ran RC Buggies about 15 yrs ago and C/L Planes up to about 5 Yrs ago.

Confused on the whole LiPo & Brushless Motor thing. Building a couple hydroplanes (1:16 and 1:10 see the free plans at Astek Models http://www.astecmodels.co.uk/plans.htmfor an example) along with my brother & uncle to "Run for Fun" here on the lake. While these are striclty "Fast Fun" we want decent equipment WITHOUT going broke.

Cells:Thinking a 3 cell Parallel. Is that possible? Also, what is the 20C, 40C, etc. at the end of the rating? Any brands to stay away from or recommended?

Motor: This thing doesnt have to fly, but up on plane and GO would be nice. Does anyone make a fun grade motor? Again, not out to set records and spend tons of $$$. Looking at the Venom V500, local club (http://classicthunder.org/) mandates aScorpion HK3026-1210 but those seemt to have been discontinued. Is somewhere around 2000kV going to be ok or should I be looking at the 3000 & 4000 kV motors? What is the ballance between kV&Cells run? Lower kV&More cells?

Inrunner vs. Outrunner? All the new motors seem to be Outrunners. I have been told Inrunners REQUIRE water cooling where Outrunners don't. In a closed space, I would tend to want to run cooling as I need to plumb it for the ESC as well, so which would be better? Does it matter?

ESC: I have figured out the higher amps, the better and get one beyond what will be run (just to be safe and not burn it out). Like batteries, Any suggestions? Anything wrong with theHobby Wing "SeaKing" 60 or 90 Amp ESC or should I be looking at others for twice the price? OffshoreElectrics (http://www.offshoreelectrics.com/index.php) seems to have good prices and a good range of selections.

Now, How do I match all of these together and WHY doesnt anyone offer combo deal? [:@]

Thanks a load for all your help in advance.

ryan_t888

Start a thread with details on your hull.

Ryan

TerryTFL

Ryan,u are a nice guy.Thanks for your great info.As a  newbie at RC boat i have learnt a lot here

ryan_t888

Thank You

cubnpede82

I hope to be getting a Motley Crew or MG/Mystic soon, can anyone recommend props that would get close to stock speeds but give greater runtime? Also, any pros/cons of th AQ vs PB cats... tanks for all on RCU

Isaiah
shadymon1282 at yahoo dot com

gauicanada

My Feedback: (12)

I just redid a Super Hawaii and found my motor and ESC was too much for this hull, so I'm building a new one. My question is I have 4000mha 20c 3cell lypos and found them puffy and hot after 4 minutes of hard running, now my question is would the batteries do better if I wired them parallel?

ryan_t888

If you ran one 3s lipo, running 2 3s lipos in parallel will help the batteries. Make certain the lipo returns to its original state and when placed in parallel with another pack it is not in series.

coan

Hi Ryan

Im busy building a 1.2meter cat and im putting on two k&b 7.5 motors(converting to elec). Going for a scale look on it. Now from what i read so far and sort off understand is to run a motor under a 1000kv with 10 to 12s lipo. Please can you give some advice as i will be running two motors on such a big boat. The boat is home build so no real specs other than its 1.2 meter long really.  Would like to know what size elec motor and batteries should i get for each of the outboards?
Thanks in advance.
Coan

Brrapp

Good write-up for us noobs, thanx.

When talking about S and P on Lipos, are you talking about how the battery pack is configured, or talking about running packs in series or parallel?
My battery is a Turnigy 25-35C 2200mAh 3cell 11.1V but nowhere on it does it have an S or P rating.

*delete M i k e u p delete*

RatingS. Your 11.1 -3S. All lipos have a S behind the voltage. The 25-35C is the rating. The higher the C, will run cooler , the better the lipo will be. The lipo will be marked with voltage printed in smaller print. S series -P- parallel -your right.

Brrapp

Thanx Mike

Correct me if I'm wrong.

Each cell that makes up a Lipo battery is 3.7V. Therefor a 3S will be 3 X 3.7V = 11.1V and an 8S will be 8 X 3.7V = 29.6V. From there, each cell may be paralleled to give greater current while maintaining the same volts?

*delete M i k e u p delete*

Your spot on. parallel = volume in maHs2 x 5000maH = 10,000 maH series = 2 x 5000maH = 5000 volts.

Brrapp

OK So while I'm on a roll,

Hooking a 1400kV motor to a 3S will give a theoretical 15540rpm, but hooking the same motor to an 8S with give 41440rpm. Easy. But how do I work out the Amps?

*delete M i k e u p delete*

You know i don't worry about amps as my boats don't go above 4S lipos and run a T-120 esc in a 29" BBY mono with UL-1 motor a 440 Octura prop for sport. There's a formular and i don't want to give #'s out. May be Paul785 knows the #'s. Motor kv x volts ????? Ok, you mention 8S which to me signals HV and a 180 esc would fit the bill. I don't know if you have a boat or contemplating on buying one but a 29-31" mono is hard to beat. Motor wise, a 1800 x 4S + 440 Prop with a 3/16" flex and no trim tabs but twin turn fins. Center of gravity 28-30% of which depends on water conditions. Hope Paul chimes in with his vast knowledge. I really like to work with 22"- 26" monos to get the most out of them and really the 22" monos. Have a good day!

Brrapp

Just trying to reason why go for a 3S + 2970kV and not an 8S + 1100kV when the final RPM is the same, the difference must be torque or current or both. I would assume more Volts means more torque because the motor will pull as many amps as it wants, and at the top of this thread, a bigger (heavier) boat used a bigger (more S) battery.

ATM I have a Joysway Super Mono X, 'bout 15" and quite quick. I'm looking at something like a Small Bolt or similar but I want to know if and howI can upgrade before passing over the coin.





I get nervous without a spellcheck, I think I have CDO, it's like OCD but the letters are alpabetical like they should be.

*delete M i k e u p delete*

Now for one thing is weight of 8S is probably over 1 pound each and expense of 8s lipo can break the bank and the esc is on the high end of expense and servo has to be on high end of expense, to name a few.

danivida

Great thread. Thanks a lot for the interesting and helpful information.

Marcelo Campos

Hi Ryan. Very nice your post.

I am a rc drifter but i allways like boats.

So, i am choosing a model but i don't know what kind of boat is the best choice.

Looking at Hobbyking i found these two EP boats.

1 - Libero 675mm



2 - Sprint F3 Tunnel hull 630mm:



So wich one is the best choice for a guy that never run a boat?

Thanks.

Marcelo