Flight Arrows

I've been fiddling about trying to make up a couple of decent flight arrows for my refurbished 70# longbow.
It has a very fat grip due to a big knot hole there which doesn't help.
Tricky chaps flight arrows, as you want to get maximum energy into the arrow which implies stiff spine and keep it there which implies low drag fletchings. You also want it to straighten up as quick as possible which maybe implies a weak spine.
Anyhow when I made the flight arrow for the 100# Elm bow I found that my regular 35-40 spined shafts actually gave a good result, with the arrow hitting the target straight on at 10 yards. I'm experimenting with various shafts, fletchings etc to try and get decent arrow.
I was using my little lathe to turn down some old field points. I'd stuck one onto an off cut of arrow shaft to give it some internal support whilst turning it down. When I came to remove the point from the shaft I heated it with a blow lamp, it got hot, the glue melted and the hot gasses inside popped the end off like a bullet, I heard it hit the wall and rattle on the floor. Could I find it?
I ended up tidying and cleaning that end of the garage, I found it eventually in the last area I tidied. Mind it did be a favour as I've chucked out a load of scrap, also made a little wire loop under the bow support block on my tiller rig so I can hang up the scale.
Here's a pic showing how various arrows are striking the target at 10 yards (looking down on them), all shot from the same 70# bow at 28". The lower arrow is pretty much straight and has the biggest fletchings. Out of interest I was aiming at the big scrap of paper, which maybe contradicts my idea that underspined arrows don't shoot right, or maybe I have learned to aim slightly left all the time and they are actually flying true.
Anyhow the real point is, one is always learning and having to modify ones beliefs. I have no problem with that at all, I try not to be dogmatic and I try to be open to new ideas assuming they are backed up with solid experience and not just the usual "I've read that..." from an "armchair expert".
Draw your own conclusions from the pic!

Maybe that sounds a bit arsey! I would welcome any comments on flight arrows if you have any experience of 'em. There was a time when flight archers were a very secretive bunch, hopefully we are all a little freeer with information these days.

Update on Needle bow:- I heat treated the belly and it was a reasonable weight, just so narrow that it would try and bend sideways. I shortened it to gain stability and the draw weight was pretty high, it was never going to really be of any use and I'd only really glued it up as a distraction whilst waiting to fly off to Tennessee. I eventually just drew it to destruction, it split along a growth ring the whole length of the top limb which was a little weaker than the lower. I didn't shed any tears over that one!