The first step is to spend the time to get a near perfect tune with the bow/arrow combination. With a good tune you can fly most any broadhead with much smaller fletch and a slight offset to the feather. 4" feathers will work fine when set up right. The big performance killer is a poorly tuned bow/arrow and using huge feathers with a large amount of helical to get the shaft to come out of the bow straight. Making a flu flu out of a broadheaded arrow is a poor way to tune for perfect arrow flight and will give a speed robbing rainbow trajectory every time. So tune well, smaller fletch, little offset and meat in the freezer....warf
I have a burner, but use "the little choppers" alot, no mess and they don't burn the shaft. For $5 more you can have the exact shape and size you want custom made.
Right now I am using the 4" shield cut, but my all time favorite shape is one that I came up with. It is basically a shield with the corner rounded off a tad, I call it a ParaShield. I will try and post some pics of it soon, has a real classic look to it.
I agree, tuning is the key... I used 5" shield with quite a bit of helical on them for years, but I never liked 'em high-profile... lower is less drag and less noise. I used them not because I didn't have the arrow tuned well, they just looked cool!
A 4" parabolic is plenty in providing great arrow flight, even with broadheads like Bob said. Slight offset with straight or helical provide best over-all performance IMO. Arrow gets off a rest or shelf better with just a slight offset... more problemic when fletching is wrapped half-way around the shaft, for me anyways. I like 3 - 4" slight offset helical clamped parabolic these days.
Low profile Parabolic is best for speed but a higher profile will give you better steering of the arrow. Keep the ammount of helix on the fletch to a minimum as this affects down range speed.
The best combination i have come up with is a Low profile 3.5 inch parabolic fletch with 1.5 of degrees of helix. Help this along with a pile that is at least 100 grain (more if possible). and you will have an arrow that will follow the pile without to much deviation and not be affected too much by cross winds. This of course is a setup designed for IFAA shooting, where shots are made up to 80 yards. For IBO distances (25yds approx) i would imagine a larger parabolic fletch is necessary to straighten up the arrow quicker.
Parabolics are as good as anything but I like the way bananas look and work.I chop them 5' and with a shorter profile so I don't get the noise of the higher feathers and they work good for me.If I shot a lot of targets 4" parabolics are great.jmo