Prop table pleeeeaaaasssseeeeee. !!!!

[rcboatmanwithkids2880]

Hi Guy's ,

Just wondering if anybody has put a table together which enables best use of props given a certain application , I understand there are many variables , including hull type cell counts etc.

Just would like to see a " Prop Guru " put a conclusive chart together in database form , such as what has been developed for BL Motors with Cell Counts !!!!

At the moment I am trying to find the best prop for my current outboard tunnel project that is 6S powered ???

Living in hope of a Prop Chart ,
Brad
Oz

[LarrysDrifter]

Maybe give us some details on your hull and set up info and someone here can help?

[rcboatmanwithkids2880]

Hi Larry ,

My tunnel project is a Dumas Hotshot .45 , that is 36 X 15 inches wide & weighing 3.5kg fully set up with 6S battery . Was thinking of a 3 blade , though with what I have read recently on this site is that 3 blade props cause top end speed to be lost to a degree due to the increased blade rotation. ....

Also , with my boat being an O/B , would the drive require a pushing type prop , rather than a lifting type prop ????

Have used an Octura X642 in the past with much success with my Aparitions sport set up ....

Any advice would be most appreciated ....
Brad ,
Oz

[LarrysDrifter]

Whats the kv?

[Make-a-Wake]

I refer back to this every now and then.....................


Choosing the right prop for an application is the hardest selection. Too large of a prop will certainly destroy electrical components. Too little of a prop will not get the boat on plane. It's not voltage that destroys motors, it is current and maximum rotational velocity that destroys motors. Current is controlled by the load placed on the motor.

It is recommended to seek advice if one does not know what a conservative prop would be for their specific application. Every combination is different!

Knowing which prop would work best for a hull, comes mostly from experience.

2 cell LiPo 6 cell NiMh – 30mm - 40mm Diameter
4 cell LiPo 12 cell NiMh – 37mm - 46mm Diameter
6 cell LiPo 18 cell NiMh – 40mm - 52mm Diameter
8 cell LiPo 24 Cell NiMh – 45mm – 55mm Diameter
10 cell LiPo 30 cell NiMh + - 48mm+ Diameter

It is extremely important to understand this chart is very basic, and the best or most conservative prop for any given combination may very well be out of this range.

A larger prop increases load. Increased Load will result in an increased current draw. A smaller prop will decrease current draw. Higher prop pitch will increase current draw, a lower prop pitch will decrease current draw.

Larger Props may create stability issues, make it difficult in corners and create torque steer. An advantage to using a larger prop at slower speeds is thrust. Acceleration on plane will be much greater. Efficiency is also higher for larger props as there is less possible slippage.

Smaller props may have higher levels of slippage, slower acceleration out of the hole but have several advantages. They are typically more stable handle well in corners, and don’t veer the hull of course under hard acceleration. (torque steer)

Advantages: 2 Blade vs. 3 Blade when diameter and pitch are equal.

2 Blade
- Higher Top Speed
- Less Load on motor
- Motor will turn higher RPM’s

3 Blade
- Higher thrust / Faster Acceleration
- Increased Stability and cornering
- Higher Lift Characteristics

OCTURA PROP GUIDE

12 Best used for submerged drive Setups. Low Pitch Larger diameter.
X4 are low lift general purpose props
M4 is similar to X4 but with the tongues removed to unload the prop
Y are similar to X series but have 10% more pitch
X5 are similar to X4 with medium lift and more pitch
X6 similar to X4 and X5 with medium-high lift
14 are medium-high lift commonly used for hydros
16 are high lift props for riggers and hydro's
17 are the highest lift prop for riggers and hydros
P7 are similar to 17 series but more rake and slightly less lift
19 are high lift for riggers and hydro's
V9 are moderate lift and high puitch suitable for riggers, hydros and SAW racing
20 are moderatley high lift with high pitch suitable for riggers and hydros
21 are high lift for riggers and hydro's
22 are high lift, highest pitch surface drive only good straight line speed

PRATHER PROP GUIDE

All general Purpose Props with Pitch ratio’s near 1.5 ranging from 1.5 to 1.6

Prop #-DiameterPitch
215-40.6mm-63.5mm
220-43.7mm-66mm
225-46.7mm-71.1mm
230-48.2mm-76.2mm
235-50.8mm-81.3mm
240-53.8mm-83.8mm
245-57.1mm-88.9mm
250-58.4mm-91.4mm
255-61mm-96.5mm

[rcboatmanwithkids2880]

Hi Make a Wake ,

Thanks mate , Great information required by a lot of people in our hobby. !!!!

Brad ,
Oz

[rcboatmanwithkids2880]

With my tunnel project , the kv rating is 1340 - 4 pole on 6S set - up ....

[LarrysDrifter]

Id try an X440/3 or an X442 to start. Work your way from there.

[rcboatmanwithkids2880]

Ok , Much Appreciation ....

Brad
Oz

[millzee]

thanks for the write up and charts, I'm posting this so I can find it when I need it, thanks again.

[jasoncyclone]

Thanks Make A Wake. That has tons of great info! I am going to print it, and I don't ever print stuff anymore!

[battlefury]

thanks for sharing, this is great stuff on prop infos

[Fluid]

Id try an X440/3 or an X442 to start.

'Way too small for a 90 cm/6S boat, even with the budget Keda motor. Start with an x/m445 as a minimum diameter, this hull was designed for a 7.5 nitro engine and 50-52mm props (as per the designer, my friend Jerry Dunlap). Check motor/ESC temps often as you dial it in, although boat setup/running attitude will have a lot to do with running efficiency. Keep the CG back and don't run the prop too deep - I'd start with the centerline of the prop 8 mm above the sponson bottoms and angled up at the prop end about 1-2 degrees. Good luck, that's a great looking hull!



,

[rcboatmanwithkids2880]

Hi Fluid ,
Thanks for the advice on props & thanks for the compliments regarding my build , it didn't turn out too bad & it"s almost complete. !!! . Have given it a few coats of clear that looks great & added separate brass intake for cooling Motor & ESC , which look crude , though fitting with being a wooden hull ( new pics soon ) . The Dumas is an old design ( IMHO Jerry Dunlap Rocks ) , though I believe it to be an efficient one with its lines & angles being favorable for racing in all varied water conditions . Will be raced with Model Boat Club Of New South Wales in Sydney ( MBCOFNSW.COM ) around August - September 2012



Make A Wake ,

You have certainly helped a lot of guy"s out with this latest knowledgable posting of yours , seems there should be less threads created in " Prop Talk " now. - " Onya Mate ". ......
Brad
Oz

[Make-a-Wake]

Make A Wake ,

You have certainly helped a lot of guy"s out with this latest knowledgable posting of yours , seems there should be less threads created in " Prop Talk " now. - " Onya Mate ". ......
Brad
Oz

You're welcome, I'm not sure who created it, but it has been a "sticky" on RCU for several years posted by Ryan, he may have made it, when i was a noob especially i would refer to it so i wouldnt blow so much stuff up................still created my share of smoke however..............just not as much with the info.

Here's the complete thread, includes voltages, hull sizes, motor sizes.......etc..........etc.............

http://www.rcuniverse.com/forum/m_9069147/tm.htm