I'm currently scratch building a 100 inch four engined model and would like to fit 3 bladed contra rotating props (10 x 5 ) . I'm looking for a supplier and hope forum members might be able to help . I live in Spain . Thanks in advance for any suggested suppliers .
There should be props that size available, but I have no idea of suppliers for Spain.
Easy to get here... I have some.
It is likely you'll have to get glow style props. I find the selection for electric 3-blade is not as good, especially in reverse pitch props.
If all else fails, there is a method for cutting 2 blade props to make 3 blade, then glue a plywood plate on each side of the hub to lock it together. Its successful for glow models and electrics don't impose the same loads so it should be fine. This gets unsightly for the props on a WWII bomber due to no spinner to hide the assembly. Hiding the hub in a spinner its a good solution.
I think you mean counter rotating props.
Contra rotating are two props rotating in opposite directions on the same axis as in the Avro Shackleton.
I managed to get some 9x5 counter rotating electric 3 blade through ebay from China and it was that prop size that actually set the final size of the plane!