Prop selection for 32" Mono

[dmanning]

Yeah they are rated at 6- 16 cells NiMH and 2-6lixx I have checked with the manufacturer and found that there is a 110℃ thermal shutdown and a voltage regulator for 18volts and over when using ESC's with a BEC. As mine is an opto series there is no safty voltage shutdown. it will just run a little hotter. The manufacturer states the max voltage is 24volts. 18 Nimh cells is still bellow this limit.
So the ESC isnt the problem and the motor is super smooth but I have noticed that when I spin the prop by hand the magnets dont feel strong like in my walkera 380 2500kv brushless.

[astecme]

Hahaha you are finicky arnt you.

You asked for help - if you don't want it say so....

Boats are finicky on set up. The motor you have should unload. No load RPM should be 39000rpm - it does not sound like that. With 25% slip the boat should be running at 75.046 mph with the prop you say is on it. So something is not right!!

28% may indeed be correct for the boat bearing in mind the angled shaft but 30% is the default start point so stick the c of g there and see if it porpoises. My guess is the motor is not what it is said to be.

[dmanning]

75MPH??? I think your forgetting loss in RPM due to load.

When I throw all my boat details into FE calc It gives me a max speed of 37mph with my current prop.
No load rpm is 41,220.45 but loaded rpm is 19,822.69.

Yeah I was also thinking the motor might not be a 540 9xl, the company I got it off is kinda dodgy. Maybe its really a lower KV

The kinda help i wanted was from people who had experience with simillar setups, and I have gotten great advise from people.

[andym]

I run a triton on 9xl 5s lipo and with a x448cf prop see over 50mph regular on the gps. Something sounds wrong with your set up.

[dmanning]

I agree somthing is wrong, I suspect its the batteries.
I am running 18 cells 3300Mah NiMH that are only rated at 12C.
As im running them in series I have high volts but only 3300mah capacity and at 12C thats only 40 amps max discharge rate. When the motor and ESC are trying to pull over 80 amps from the Batteries, they just cant keep up.
I should really run the batteries in parrallel or get some Lipos, but that means alot more money. So for the moment I will try the cheap way out by selecting the right prop.

I had amazing results with my smaller boat, a 23 inch shallow V. I was running 12 cells with a 380L 2500kv motor. I tried it with a 30mm 1.6 pitch prop and a 35 mm 1.4 pitch prop. The 30mm prop would just sit and cavitate, and the 35mm prop would only get it up to like 18Mph. When I put a 35mm 1.2pitch cupped prop on it, the boat took off. With the right prop and no other changes the boat will now do 32mph.

[dmanning]

Well I ended up buying 3 props.

g2305 - Graupner 47mm 1.6 pitch carbon fibre prop
g2327 - Graupner 42mm 1.6 pitch carbon fibre race prop
g2299 - Graupner 42mm 1.4 pitch carbon fibre 3 blade prop

All three props hadvery different results and all were much much better than my current props.

The G2305 has alot larger bladed than my current 48mm prop due to the 1.6 pitch, and as everyone said it was way to large, and quickly overheated the ESC.

The 3 blade g2299 was great, if you hit the power hard from a stand still the whole boat launches itself out of the water instantly. Fantastic acceleration. Top speed was aprox 38mph.

But the real winner was the G2327 42mm carbon s series. This prop has a very different blade shape from the rest of the props I have. It worked great with 18cells, aprox top speed calculated from the video footage was 46mph.

I am very happy with these results, good props make the world of difference.

[dmanning]

Here is the final video of the boat doing its thing with the new G2327 42mm carbon s series prop and running on 18 cells. Let me know what you all think

http://media.putfile.com/Brushless-Cyclone-18cells-16pitch-prop

[saleens7]

i think its pretty fast....looks like your doing 35+ish....seems to handle very well too...
EDIT: wait i just read the post with the speeds...46mph?!? looks slower than it really is....how big is this hull?

[Mich. Maniac]

I just noticed this one. cool to see. This hull just wont ride the way it should at higher speeds. If you go fast enough it will just blow over. Also you will just have to power it to high speeds, twins or a huge lehner.

[dmanning]

Yeah in this vid its not doing 46mph its doing about 40 - 42, the hull is 33 inches long and 36 with running hardware. It seems to be going slower since I have greased the drive shaft. I put a heap of grease in there to stop water getting thru. But i think its having a drag effect.

[DISAR]

I have the same boat called "Bluestreak" from Kyosho. I converted it to electric from nitro by putting esc and motor from SV 27 but suddenly stops maybe from overcurrent. I will put the same motor as yours with 12cells first. Have you tried it with 12 cells? What prop? I also have a problem with the banging up & down at medium speeds and tottally lifting up at high speeds, what do you recommend? Thanks.

[dmanning]

I have tried it with 12 cells and it runs very cool, but not as fast as I would like.
A good 42mm prop works well with 12 - 18 cells.

The issue with the bouncing at medium - high speeds may be because your center of gravity is too close to the transom and/or the base of the boat has too much flex. To get around these issues I re-enforced the transom and base with mitreboard and filled the nose of the boat with expandable canned foam. It makes the boat a little nose heavy, but also makes the hull very very rigid.
As a result the boat runs very flat.

As an added bonus if my boat does flip it has so much foam in it, it will not sink.
I evan tested it without the electronics and threw it in our pool upside down with some old batteries in it to match the weight. Every time it just rolls back up the right way. Dosn't evan get any water inside.

[DISAR]

Thanks!! I have reinforced transom and bottom (midships to aft) with epoxy and carbon now I will put the foam to the nose.