42" Cat build

[Blackjack-sven]

Want to make a very fast cat. The hull is the Genesis from Hobby King and runs great with its stock setup (knock on wood), but I want to get as much speed out of her as possible. My buddy has been egging me on in regards to a race and I just broke down and ordered a 1600kv motor, 80HV esc, and two 5s1p 4000mah 50c batteries (series). I also have the intention of running an Octura m430 prop.

Does anyone see problems with this setup?

Criticisim is welcome but don't bother with rants and raves cause I know it may all go wrong.

[RandyatBBY]

Want to make a very fast cat. The hull is the Genesis from Hobby King and runs great with its stock setup (knock on wood), but I want to get as much speed out of her as possible. My buddy has been egging me on in regards to a race and I just broke down and ordered a 1600kv motor, 80HV esc, and two 5s1p 4000mah 50c batteries (series). I also have the intention of running an Octura m430 prop.

Does anyone see problems with this setup?

Criticisim is welcome but don't bother with rants and raves cause I know it may all go wrong.

We need a little more info on the motor. How many poles and size?

I feel ya about the Criticisim is welcome but don't bother with rants and raves

[tiqueman]

I ran the Leopard 1600KV using an M440 on 6S and it pulled 110A max. So Id think the 80A would handle it. I could have run a lot more prop on it but was happy w/ cold temperatures and my Amp draw. A 430 seems like it would be a very small prop though. In my mind, Id think maybe a higher amp rated esc may give you more head room and things to do, ie 6S. But again, Im not familiar w/ how the HV controllers handle amp draw.. Id think the same as a LV.

Also, if Im reading it correctly you already have the hull, but if not, dont be suprised when it shows up 36" long and not 42.

[Fluid]

I won't rant, but there is LOT wrong with your plans. I will try to help.

First, a 30mm prop will never move this hull to any reasonable speed. This boat requires a larger thrust cone.

Second, you cannot run a 1600 Kv motor on 10S. That is nearly 60,000 rpm - totally worthless.

Third, an 80 amp controller is seldom suitable for 10S FE setups, especially in larger boats.

The first thing you need to do is decide what you want the boat to do. Simply throwing power at it will not meet your goals but will empty your wallet.

- what speed do you want?
- What run time is acceptable?
- how much $$$ are you willing to spend?

Unfortunately you should have asked for guidance here first, before ordering those inappropriate components. Until you do some real planning you will only waste your $$$ without the satisfaction of a fast, reliable boat. Tell us your goals and then we can be of REAL help.



.

[tiqueman]

Yeah I definitley missed the (series) part. Thats not a recommended set up at all..... 5S2P will be decent, but 10S, as Fluid stated is a very bad idea.

[Blackjack-sven]

k well its a hk motor, so pole wise I have no Idea but believe it to be a 4 pole motor. if I run a 5s2p batt system what would I need to hit the 80mph mark?

What is the rpm range I want to keep the motor in? I'm only looking for 4-5 min run times and I dont mind if the electronics are warm to very warm after the run.

[Jacked1]

If it is this motor..
http://www.hobbyking.com/hobbyking/s...idProduct=4937
or any of the heli motors that are 1600kv that they sell you won't come close to that speed.

And you should try to keep under 40,000rpm with any motor unless you are willing to change the bearings a lot and if it is the KB-45 then keep under 30,000 and change the bearings from the start.

[tiqueman]

80mph w/ 18.5 volts would take one heck of an esc. I think its quite unrealistic. Youd pull more than 300A on a ?? motor and probably not even be at 70mph. I feel you need to re-think this entire set up or, go twins if you want that kind of speed and keep easier on your components.

Rpm range for your application I think would be in the mid 30k range, but would get you know where near 80 on 5S and a 1600KV motor.

Maybe a 240A HV, a Neu - low KV motor, and 10S? Then, is that hull going to handle it, Id say no. I had one, it didnt like any prop larger than a 42mm before it would almost torque roll itself over. Twins would help the torque issue.

[siberianhusky]

About 1500$ later and learning how to set up a boat then you might be getting close 80!
Thats a pretty lofty goal for somebody with no experience!
There is a lot more than just power required to get a boat to those speeds.
Take a look a Neu or Castle motors, thats more the quality you need.
That esc will not do it by a long shot. Also your looking at one or two passes at those speeds not 4+ minutes!
Seriously drop your goal by about 30-40mph and start learning from there, it will cost you far far less in the long run.
I'm also not sure if that hull would survive a crack up at those speeds, try tossing it out a car window at 80, thats about what hitting the water will be like!
Take a look at the MHZ hulls they are strong and known to go fast. The Skater or Danger zone are nice 290-430$ for the bare hull. Skater is 39", Danger Zone 43".

[Blackjack-sven]

@ Jacked1. yes it is that exact motor.

So what if I ran twin 1600kv motors, 5s2p, with 80amp esc's???

[tiqueman]

Still not enough esc. I run a 45" HPR cat, twin Castle 1520s, on 6S each side, non modded 447s I run almost 80. Im using Ettis 150 esc and they are not going to last long. I have not yet logged it to see what amperage Im pulling but they come in pretty wamr after a 2 min run.

My twin HOTR runs Feigao 10XLs, which are in the 1600kv ballpark, that boat ran 70 and pulled 90A per side. I used 120A controllers in it and also ran 6S

[Blackjack-sven]

@Tiqueman. I dont have that kind of money kicking around which is why im staying in the hobbyking market.

this is the esc thats on its way over.

http://www.hobbyking.com/hobbyking/s...idProduct=8945

[tiqueman]

Dont take this as being a smat a$$, but then your not going to hit 80mph. There are less expensive ways to do it, but you will still have hundreds and hundreds into it. And, in my opinion, thats not the hull to do it in. Youd need to reinforce the heck out of it and even at that, it doesnot corner well at anything above 40, so your strictly to a SAW boat, almost stopping to turn around at each end. If thats what your looking for, thats fine, just letting you know.

Mudl did a less expensive build w/ his and reached 80. Theres also a couple other members who have done it, I believe using Scorpion outrunners and Turnigy 180 escs?

I "budget built" my twin HOTR and still had over $700 in it.

[Blackjack-sven]

700 for the whole shibang I can deal with. 700 for just esc's on the other hand.....no thank you

[tiqueman]

Mind you that was w/ me doing A LOT of custom work, making parts etc and I had some things to put in it. Etti 150s go for 150, so your 3 into it for controllers, T-180s are $80, so 160 in controllers. I believe OSE and Fightercat both have the Seaking (same as Turnigy) for competitive prices and cheaper shipping. Bill34207 is running a pair of the 180s on a twin set up in a 60" twin cat, big neu motors and running 6S2P per side. Its a 22+ pound beast and runs mid/ upper 60s. He had to add cap banks, just lettn you know they may handle the demand of what you want to do for low cost.