I have some four inch Trueflight flu-flu feathers that I'm going to use. I plan on using six feathers per shaft. Should I fletch them straight, offset, or helical?

most of the flu-flus i have seen have been straight fletched.  that's all i have ever shot. i guess it depends on the distance - reach you think you might need.

Maybe put three on and shoot first to see how they work for you.  I myself find that 6 slows the arrow down so much it doesn't do anything (if shooting at game).  Of course, for practice or for the kids, maybe 6 is the right number.
CHuckC

i use 4x4" right helical myself. works good for me hunting uplands, waterfowl, rabbits, and pesky squirrels.

Depends on how far you plan to shoot. Straight fletch will go the longest distance, probably 50 to 60 yards. The more offset or helical you put in the less distance they will travel.

I use six Fletch but only make each one two inches long and they work very well for me!

3 straight works best for aerial shots IMHO.  I've got some of the straight six's and they are much slower.

I use 4 feathers @ 4" long each and fletch right helical. They fly about 80-90 yards out of my 49# Kanati.

I wouldn't go with six fletch, but if I did I would go straight fletch.

I do 4-5" helical and they go about 100 yards with plenty of oomph at 30 to bring down game.

What Pat said.  More feather = shorter distance.  More helical = shorter distance.

Arrow weight makes a big difference--heavier will go further.

Helical is also noisier, although I don't know that it makes a difference with flu-flu's.  They are noisy anyway.

Other than aerial shots at birds, they are useless for hunting for me.  Rabbits and squirrels just duck or dodge them.  Remember, they are conditioned to avoid hawks and owls swooping down on them--much quieter, and probably as fast as a slow flu-flu.  Your results may vary.

I think it really comes down to what you will use them for.

I have Flu Flu's (all helical) from 3,4, and 6 feathers, each.  

Some 4 inch and some 5.25 inch's.

Some with blunts ands some with judo's.

I mainly shoot stumps and patches of weeds with them so not using them for hunting.

Any flu flu is a good flu flu.  If shooting into the air / tree for game, I'd have more feathers to slow that arrow down.

What is your bow and arrow setup and what do you plan on doing with the flu flus?  Flu flus are more fun when matched to your setup and chosen activity.

I prefer 3 4" helical fletch on my flu-flu's.  I used to shoot 6 fletch flu flu's out of my compound -- no need for 6 fletch out of a recurve, unless you just think it looks cool.  That would slow the arrow down to the point of really changing point of aim past 10 yards.  

I shoot 3 fletch helical so I can get more arrows fletched with less arrows and they seem to shoot well, but slow down plenty quick enough for aerial shots.

ARROW WEIGHT IS VERY IMPORTANT!!!!! I fleched some of my daughters 1916s the same as my 2219s........they stopped in midair and dropped about 20 yds from the bow, just short of the arial targets we were shooting at. She wasnt having any fun.............

I agree with everyone above. I usually fletch several styles of flu flu's for different situations. 3 X 4" or 3 X 5" for aerial shots at fast moving game birds or shots at squirrels in high oak trees. Spiral flu flu's for aerial target practice. And I carry 4 X 4" fletch for close shots at squirrels in trees.

I have a 21 arrow memorial shoot every year to honor my dad.  I used 4  4" straight fletched 1916's for this honor.  These were my dads hunting arrows.  I put a flag out in a field as a point to shoot towards and had to put the flag out 50 or 60 yards and some arrows overshot that target.  I wished I would have used 6   4" straight fletch arrows to cut the travel distance down.

I guess it depends on what you are going to do with the arrows.