Handyman:

With your TT 61s on the Twin-Air 45 you are going to need three blade props to load the engines properly due to tip clearance.

Counter rotating three blade prop sets, in 61 sizes, are available only from J&Z/Zinger/Zingali that I have found, and they run about $70 for the set. You also need a custom spinner for the reversed engine, the spinner set from Tru-Turn with the adapter nuts will add another $100 to the cost. And before any of this, you have to get a reverse rotation crankshaft for one of the engines and install it. And then if you nick a prop blade, well, the conventional rotation prop only cost $22, so hope that's the one you damaged.

Unless your insanity approaches mine (I spend the money) it's not worth it.

On your set-up the MAS or J&Z/Zinger/Zingali three blade composite 12x6 props should work fine, and you can use the Du-Bro plastic three blade spinners. $25 for two props and two spinners. And if you decide to go to 12x8 the reverse set is another $70, the normal set is another $14.

So you decide. While counter rotation will not double the cost of the plane, it will go a long way in that direction.

It does look good when the engines are stopped.

Bill.