Top Secret Classified Flight Arrow

[Del the cat]

I had an idea for a novel arrow (doubtless been tried before) Small diameter shaft with long wooden vanes to both stabilise and stiffen it.
The vanes certainly stiffen the rear of the shaft, but how will it fly?
Well... the point travelled straight  , but the back end was going round in a circle! At the top of it's trajectory it flattened out and came down like a helicopter or Sycamore seed!
Very entertaining! I managed a massive 150 yards

On a more serious note, I used my best flight arrow (as shot from 90-110# warbows by my mate JT) as a reference and made an version based on that but with some hoped for improvements (based on my "stiffer at the rear theory"). I added a footing and tapered the front much more, The overall weight was down by 50 grains(375gn) The back was a whisker stiffer in spine, and the front a tad softer.
JT tried a couple of test shots and the improved version flew 18 yards further.
Obviously just 2 shots isn't a fair test, but it is encouraging.

The helicopter arrow does make me wonder I an actual flying/gliding arrow can be built.
Del

[Gimlis Ghost]

The Turks made arrows with two vanes curved in opposite directions for the purpose of changing direction in flight.
They used these against sappers and battering ram crews that were too close to the walls for them to shoot straight down at them.
The arrows when fired at a high elevation made loops, some looping inside to come straight down while others performed outside half loops to come zipping back towards the base of the wall.
Probably one in a hundred actually hit anyone but it could certainly be distracting. The men at the base of the wall would think someone had circled around behind them.

BTW
I just remembered reading of a ballista bolt fitted with wing like vanes to extend its range, though accuracy went out the window.

[bownarra]

How about a stiffer wood in the middle and lighter woods for the ends. Or just a light front end. There is a section in Saracen Archery about gliding arrows. It is something I always meant to play about with.

[avcase]

Del,
The biggest issue I have seen with attempts at making gliding arrows is similar to your experience.  It is very difficult to get an arrow that is generating substantial lift to travel in a straight line. They tend to veer off course so much that the overall distance is less than what can be obtained with a conventional aerodynamically stable arrow. But I haven’t completely written off the possibility that an arrow can generate some mild amounts of lift, or at least use aerodynamic drag to slow the decent, yet maintain travel along the intended direction.  It is just difficult to know for certain what happened with the arrow between the time it was launched and the time it entered the ground.

I do believe I may have had some success with this. When I test shoot my bows and arrows, I keep notes on the angle the arrow was launched, and the angle that the arrow entered the ground. I have some arrows that consistently enter the ground at a much shallower than expected angle, which implies that the arrow is descending at a positive angle of attack. So it is descending with the point high or nose up. These arrows also tend to penetrate the ground less, which implies they are striking the ground at a lower speed, which I would expect if some of the arrows energy is lost to drag, which could have produced some lift.

[willie]

I have some arrows that consistently enter the ground at a much shallower than expected angle, which implies that the arrow is descending at a positive angle of attack.

Hi Alan,
do these arrows differ from your other arrows by fletching or mass distribution? or?

[meanewood]

How about trying an arrow fitted with fletches at the front as well as the rear?

[PlanB]

If you're intending to have an arrow glide with added winglets froward, you are going to need to make sure that the center of gravity is well ahead of the center of lift, or expect craziness. And even if it could be properly balanced, your arrow is likely going to have greatly increased drag in initial stage, possibly shorter range therefore, and random accuracy.

I fly discus launched gliders (DLGs) - look them up on YT.

[simk]

interesting topic.
i'm not an expert - just occasionally doi'n free flight sports...
according to my understanding two things to be considered:
"lift" imho can only be generated....using a profiled "wing"....and only in a stable flight/not possible with a rotating projectile.
maybe i'm completly wrong.
cheers

[BowEd]

Dabble with this sport occasionally at Mo Jam gathering.No expert by any means.A very low height of 1/4" to 3/8" ,three inches long,straight fletch slightly off set for very slight rotation on the very best bare shaft tuned shafts on a paticular bow seem to work the best for me.

[Gimlis Ghost]

interesting topic.
i'm not an expert - just occasionally doi'n free flight sports...
according to my understanding two things to be considered:
"lift" imho can only be generated....using a profiled "wing"....and only in a stable flight/not possible with a rotating projectile.
maybe i'm completly wrong.
cheers

As far as arrows go you are basically correct. Though a arrow shaft with a smoothly tapered fore end and nock end can act as a lifting body according to some at least.

A round ball can generate lift if it spins backwards, sort of like English on a cue ball. That is the "Benoulli Effect". The amount of lift is tiny but it works well with low density air soft projectiles, they call it "Hop Up".

[avcase]

I have some arrows that consistently enter the ground at a much shallower than expected angle, which implies that the arrow is descending at a positive angle of attack.

Hi Alan,
do these arrows differ from your other arrows by fletching or mass distribution? or?

My best flight arrows tend to be on the edge of aerodynamic instability.  The center of gravity is usually close to the center of the arrow. But center of gravity is not the only significant point on the arrow. The center of pressure is equally as significant. On my arrows, the center of pressure is a short distance aft of the center of gravity.

I have put together some experiments to see if I can make some definitive progress in this area. For these experiments I have built a pneumatic arrow launcher and created a number of small and light arrows that I can easily change the center of mass, vane geometry, and vane position.  The arrows have a mass of only a couple grams, or about 30 grains, and are made from paper straws that have a hard polished cyanoacrylate glue finish to improve durability and help resist moisture. This helps keep the distances within 200 yards so I can run the experiments in a nearby field.

Most of my work so far is with qualifying the equipment. This started with a number of chronograph shots at different air pressures so that I have a good idea of the launch speeds. Over a 10 shot chronograph test, I rarely see 1fps variation for any given pressure and arrow mass. My plan is to shoot a group of six arrows at a time.  Four of the arrows will be adjusted for whatever variable I am studying (adjustments to center of gravity, vane geometry, etc.), and two arrows will be control arrows that never change. The control arrows will indicate if there are differences in atmospheric conditions, like wind from shot to shot.  On a perfectly calm day, I can consistently place the two control arrows in about a 1-yard radius circle at a distance of 130 yards away.  This means any differences in distance greater than this are probably driven by whatever variable that I might be interested in studying.

I have little doubt that a flight arrow can use drag perpendicular to the arrow shaft to slow its descent.  The big question is how to design this into the arrow so that it increases the distance the arrow travels. I am not quite to this point yet, but hope these experiments can help answer these questions. 

Alan   

[Del the cat]

V interesting post Alan.
Great to see thorough and methodical experimentation, in what is a very tricky/almost-impossible area.
Thanks for sharing
Del