what prop to use

[launchpad]

Hello Guys;

I am converting my miss vegas to bl, and need some advice.I will be installing a KD36-74-06XL 2800kv brushless motor,the esc is a scorpian 110amp commander v2 series,2x2s1p lipo batteries.I will be using the flex cable that is already there along with the rudder.Whay I need to know is,what prop would I use for this combo or can I use the prop that is already there.I will be water cooling the motor and the esc.Got to keep it cool....This is my second build,the first is done but no water test yet,been to busy and living on the west coast of british columbia we get alot of rain.Hopefully I can get it in the water before Xmas.
All your help will be greatly appreciated. AlPal

[egneg]

2800kv at 14.4 volts is over 40,000 rpm's - a real hot setup ... maybe too hot!

[launchpad]

Hello;
What would you recommend for the setup and also what prop to use. Thankyou
AlPal

[Fluid]

I would suggest a Feigao 10XL and an x445 prop to start. Also, what cells do you have - mAh capacity and "C" rating? Just saying 4S2P isn't too helpful as it is too easy to over-amp some packs.




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[Jimmy Sterling]

Hows about a 9XL spinning an x440/3, this setup will work well with an ETTI 150 amp speed controller that OSE sells. I think that this setup would be pulling close to 90 amps - 100 amps max, so as Fluid said we really need to know more info on the cells that you are planning to run.

BTW - how long is the Miss Vegas hull and what does it weigh approximately ?

[launchpad]

Hello;

First,I already have the motor that I mentioned,as for the batteries,they are 2s1p 5000mah lipo and thats times two.What can I hook up to the motor that I stated that I have,the kv is 2800 and a 6 turn bl.motor.I don't want to have to go buy another motor.

[AntronX]

Before you do run the boat for the first time, get Eagle Flight V3 data logger. Use that to check your full throttle full speed Amps. Start with Octura M435 3 blade prop. Running 45mm prop will burn your ESC up for sure. That's assuming you run 4S battery setup (two of your 2S packs in series). Do you plan to run stock hardware and prop shaft? At 4S your motor will spin at 41000 rpm unloaded - that's a hot setup. My vegas runs 42mm prop at 24000 rpm loaded and the boat does 45 mph. My motor is 1500 KV and my battery is 5S.

[launchpad]

Hi,

Yes I was planning on using the stock hardware but now I am not sure which way to go.I am new to the sport so could you tell me what you mean "that's a hot setup".When I see the comparison between your setup and then mine,looks like I could have some problems.41000 rpm compared to your 24000 rpm thats quite the spread.I know if you multiply the kv by the voltage that give you the rpm,am I correct? Can less voltage be used to bring the rpm down?Or should I get a different motor.
I really appreciate all the help I am getting.I have only been playing with boats for 10 months and I keep learning new things and the more you know the better you will be.

[egneg]

You could always run the batteries in parallel and drop the rpm's in half. Maybe start with a M545 or a detongued X645 and still have a good time with decent run times.

[AntronX]

20K rpm will be too slow, and running the prop that is too big will keep raising left sponson of your boat while it is running. We're talking about unloaded rpm, meaning running in the air, not in the water. In the water, it will run maybe at about 16K rpm. Mine ran pretty well with M435/3, feigao 8xl (2084 Kv) and 4S battery. Too hot, could mean either temperature of your electronics will be hot, too much rpm or just plain overkill for the job. I don't really know what exactly does "too hot" means, i just repeat what other people on the board say.

[DISAR]

IMO you have two choices:

1) Keep your batteries and buy a feigao 10XL as Fluid suggested and start with carbon propellers Graupner 40,42,45 diameter (they are cheap so you can see which one fits better). Once you decide which one is better you can buy the eqivalent Octura metal prop. Start from the smaller diameter first. (1668kv x 14.8=24,686 rpm)

2) Keep your motor and buy two 3s batteries to run in parallel (2800 x 11.1=31,080 rpm). Propellers same as above.

option 1 is cheaper.

[launchpad]

Hello;
Thankyou for all the suggestions,it looks like I have a decision to make.There are quite a few ways that I can go.Once I decide I will let you all know what I will be going with.
Thanks to all the guys who took the time to suggest the options I have.
AlPal
Will be in touch,if you do not hear from me before Xmas,I would like to wish everyone and there familys a very Merry Christmas

[D. Newland]

I raced a 6XL in N-2 Sport hydro a few years back. In a Viper.

2S2P batteries totaling 10,000 mah's. X646 2 blade Octura prop. Won the class, too. It was about a 90 amp setup.

It wasn't the fastest boat on the water that day but that didn't bother me any. it was certainly competitive.

If you already have the equipment, give it a shot. If you don't like it, then you can think about selling that motor and buying a 10XL and run it on 4S.

[launchpad]

Hello guys;
Well I have decided on which motor to use.I will use a feigao 8xl and 2x2s1p 4500mah lipos.Also a 100amp esc.One question;what prop would you suggest to use for this combo?

[Grimracer]

The boat will have allot to do with what prop you are going to use. The Vegas is an OK but not a great choice for a FE boat because the sponson AOA is so flat. Its going to use more power to make that boat go fast then the same boat with proper sponson AOA.

Grim