Fletching IMHO must be a right or a left helitcal for better broadhead controlled flight. Straight fletching does not give you enoughflight control after the first 3 yards to over compensate the over steer the fixed blade broadheads planing.

And I'm of the opinion that Thunderheads are very hard to get consitant flight out of them. I took them off and put two other types of fixed blades on and got quick results for accuracy. I won't use a thunderhead after that exercise in futility.