Dual 40mm counter rotating prop thruster pod


#1



Ion, thank you for the belt design idea posting.

Prototype of dual 40mm counter rotating thruster pod concept design.
3D printable! Some design refinements still need to be made.
This is in test phase sending to Open ROV for thruster evaluation.

Mark


#2

Hi Mark:

I like your design :-) Thanks for your appreciation.

For more efficient power transmision,,,,,,

Have you checked "http://www.technobotsonline.com/" and "http://sdp-si.com/Catalogs.htm"? Making a search for Timing Pulleys and timing belts ?

Regards


#3

Cannot update the tables ¡¡

Check them in the following post


#4

Hope this can help.

596-Poleasdecorrea.xlsm (150 KB)

#5

Ion,

I did check your suggested sites thanks.
For this build I was able to obtain parts from the local electronics recycle center and salvage yards.
I am using 1mm timing belts so I can achieve reverse rotation without much loss in the power train.
The belts are low cost from SPI $2.00ea. 1mm timing pulleys are harder to find so far electronics gold mine has small DC motors for $1.00 with desired pulleys. When they come in I can verify and post. Old inkjet printers are a good supply of parts (pulley)but not all recyclers keep them. Will post design after verifying part suppliers.

Thanks,

Mark


#6

Test data by Laughlin at Open ROV HQ


#7



#8

Hi Mark:

Nice builds. I see you've fitted three blades supporting the ducts upstream the propellers, working as an intake stator.

Have you tested a "twisted" version of those stator blades ? A counter rotating pre-swirl, would increase the propeller efficiency (post swirl -wake- minimization) , at the same time that would .. let's say, homogenize the perturbed incoming flow.

I also see the ducts section is cylindrical. That allows for tip vortex minimization but, I think, it does not help too much for thrust. May be a Kort type duct, together with the stator swirl blades could help more.

Would have to make some numbers. Many times the scale of the ROV results into odd results.

Are those the standard Graupner propellers ?

About the graphs: If I've understood them, looks you've got a lot better "astern" efficiency.

regards


#9

Ion,

I have not tried twisted version of stator blades yet. If you have a number for twist that would be great. The printer is down for repair at the moment.

Robbe Plastic Propeller ROB1466-67 Type = Right 40mm

Robbe Plastic Propeller ROB1466-67 Type = Left 40mm

Gear ratio 2.25 to 1


Thanks,

Mark


#10

Hi Mark.

OK, as it usually happens to me, I didn't realized you've already posted the gear RPM ratio.

As from the graphics, it seems that your dual arrangement doubles the expected thrust from the normal two 65mm propellers.

May you confirm it ?

Regards