Falcon cat

[davidpaul]

I'm replacing the .67 intro in my 41" falcon cat with a brushless setup and just want to know what you think about my motor etc.

leopard 5692 1340kv motor
6 cell lipo
180a turnigy esc
50mm 2 blade prop

[Meniscus]

Welcome to the forum!

It may be helpful to provide the pitch of the prop you are using. There could be a huge variance in speed, not to mention heat and current draw.

If your 50mm prop is say 1.4 pitch, then a safe estimate is around 45mph. I would say though to watch your temps. Typically in FE, when we test a hull with a given setup, we will put it on the water for 30 seconds and bring her back in. We then measure temperature and recharge the batteries. By measuring the amount of energy in mah that go back into the batteries and the time measured during the run, we can then make an estimate regarding Amp draw.

The thing to keep in mind for heavier hulls and higher current setups, try to only run the boat at full throttle. At partial throttle, it puts additional stress on the ESC which could cause failure.

Hope this helps. If you provide some more information, perhaps we can give you more feedback.

[davidpaul]

Thanks for that, yeah it is a 1.4 pitch prop.
The main reason I want to use that setup is because I have most of it "in stock"
The only thing I need to buy which is the motor as it's rather pricey I want to make sure it's the right one for my boat.
I have had experience with burnt esc's in another boat I have so I don't want to go there again.
The falcon is a light hull (in my view) would a smaller prop be a good idea say 44-48 mm 1.4 p.
40 MPH would be great to start with.
I have a smaller cat that is approaching the 50 MPH zone.

Thank you

[Meniscus]

Sounds good. I'm glad to hear that you will consider some smaller props and check the temps before propping up to the point where there is more risk of failure.

Another thought to consider is if you encounter big water or hopping on the water. This of course puts large spikes and loads on the electronics, consequently leading to failure, especially while turning a large prop.

Do you have a picture you can post of the cat?

[davidpaul]

[ATTACH]45681[/ATTACH]

I have been adding extra capacitors which seem to be helping avoiding an esc fire.

[Brushless55]

Thanks for that, yeah it is a 1.4 pitch prop.
The main reason I want to use that setup is because I have most of it "in stock"
The only thing I need to buy which is the motor as it's rather pricey I want to make sure it's the right one for my boat.
I have had experience with burnt esc's in another boat I have so I don't want to go there again.
The falcon is a light hull (in my view) would a smaller prop be a good idea say 44-48 mm 1.4 p.
40 MPH would be great to start with.
I have a smaller cat that is approaching the 50 MPH zone.

Thank you

I would start with the 50mm you have and see how it does
if you wanted more speed you should be able to prop up on that motor with no issues

[davidpaul]

My main concern had been my choice of motor SEC and volt's now I know they are all good I can order the motor.
I have a few props in the tool box so I can try different sizes.

Thanks

[Brushless55]

I'm really looking forward to your results with that motor on 6s with this size of a hull..

[davidpaul]

I'm really looking forward to your results with that motor on 6s with this size of a hull..

Do you think it's going to be good or bad ?

[Brushless55]

Do you think it's going to be good or bad ?

I'm very impressed by these big Leopards
I'm waiting for you to pull the throttle first

[lectriglide]

Reminder - Make sure to use a separate receiver pack to minimize the esc stress caused by internal BEC.

[davidpaul]

Reminder - Make sure to use a separate receiver pack to minimize the esc stress caused by internal BEC.

I've been using an external bec on the esc that I'm going to use on this project,should I still use a battery pack on the receiver ?

[Meniscus]

Since this hasn't been addressed yet, what lipos are you considering running with this setup? The concern I have is ensuring that they can deliver enough power for this setup. If you do not have enough power, it could possibly swell the lipos and cause a fire.

Let's say that you use a 6 cell lipo at 5000mah with a C rating of 30C continuous. If you take the C rating, multiply by mah and divide by 1000, you will get the continuous Amp rating the battery will handle. For this example, 6s1p (six cell lipo, no additional batteries wired in parallel), this would be 30 times 5000, divided by 1000 = 150Amps. To be on the safe side, you could run two packs in parallel to double the mah to 10,000, which would mean a constant of 300 Amps.

When running parallel packs, it also means there's less voltage sag under load. If any of this is confusion, you can try this link: http://www.offshoreelectrics.com/wiring.php

[Meniscus]

Just a quick note, when not using the BEC (powering the RX from the ESC) and running an external power pack or 4 AA batts, DISCONNECT THE RED WIRE FROM ESC going to the RX. Not doing so can cause many things to fry.

[Brushless55]

6s2p would be a good way to go