Copy block to, let's say, the right side of the block that the prop is on.
shift the block on the right all the way into the original.
shift the second block forward until you can attach the second prop to it.
And then you have a contra-rotating prop. I don't know if it works with the bigger engines, but I know it works with the smallest prop type and it takes a 7,000 pound plane to literally just less than 700 mph in less than 45 seconds.
Also, use fuel tanks. This drinks a lot of fuel. You've been warned.
@MEERKAT978 Don't know if it works on mobile, seeing as I use PC. That said, you're perfectly welcome to try it out.
I like to use fuselage blocks for this.
And then you have a contra-rotating prop. I don't know if it works with the bigger engines, but I know it works with the smallest prop type and it takes a 7,000 pound plane to literally just less than 700 mph in less than 45 seconds.
Also, use fuel tanks. This drinks a lot of fuel. You've been warned.