Here's one to chew over. It is POSSIBLE (and, actually easy) to have a heavier arrow that shoots as flat, or even flatter than a lighter weight arrow! And that is when both are fired with the same launching force.
I just returned from doing a presentation at the ATA show. I was really pleased with how well the presentation went over with everyone attending – and even many who didn’t attend, but who heard about it from those who did attend. The trip was somewhat of an ordeal. On the way up I was only able to drive about 3 hours a day before becoming too exhausted to continue. By the time I headed back I was able to drive seven hours a day, so it looks like the after-effects of the radiation treatments are finally beginning to wear off a bit.
At any rate, I had a little demonstration in the presentation that I'd set up to show folks the effect on arrow flight that EFOC makes. It was a short, rubber tipped arrow with a movable rubber weight. By sliding the weight up or down on the shaft I could shoot the arrow at 6%, 11% and 24% FOC, without the mass of the arrow changing.
I pre-selected and marked the positions for the rubber weight for those specific amounts of FOC. Only a few compound shooters use over 6% FOC, and most use less than 6%. A typical traditional wood shaft with most commonly used broadheads show about 11% FOC. 24% FOC was with the weight as far forward on the shaft as I could slide it.
By using the same launching force and shooting angle on each shot I could demonstrate how much arrow energy is CONSERVED by using EFOC, and also demonstrate that front-weighted EFOC arrow DO NOT nose dive - indeed, they fly both flatter and farther than an arrow OF EQUAL MASS but with a lower amount of FOC. (Just as O.L. has repeatedly proven with his record-setting flight arrows.)
The small shaft was unfletched and, of course, the flight at 6% FOC was TERRIBLE, and it flew about half the length of the lecture hall. At 11% FOC it flew somewhat better, and traveled a bit over 60% of the length of the lecture hall. At 24% FOC the flight was great, and the small arrow HIT THE WALL at the far end of the lecture hall with a resounding thump! You could actually hear the collective gasp of the folks in the audience.
That simple demonstration became the talk of the entire convention - even among folks who hadn't attended, but who heard about it from those who had attended. During the balance of the day of the presentation and the next day I had a number of compound shooters tell me that they had changed to EFOC arrow and, to their amazement, had discovered that the EFOC arrows, though heavier than thier ususal, lower FOC arrows, were shooting flatter at long range. This they each had discovered because they were expecting to have to move thier sight pins DOWN (aim higher) with their new, heavier arrows, but ended up having to moving their sight pins UP (aim lower)!
Based on the information from several of the compound shooters who appeared to have done more extensive investigation of EFOC on their arrows it appears that the 'break even point' was around 150 to 175 grains of increase in total arrow mass. That is; when changing from a low FOC (which was usually around 5%-6%) to EFOC around 24%-25% they each had found that an increase in arrow weight for the EFOC setup of about 150-175 grains resulted in the SAME SIGHT SETTINGS (same point of impact) at 20, 30 and 40 yards as they had been getting with their 'customary arrows'.
This would make an interesting investigation with a shooting machine! After the ATA presentation, there is one thing I know for sure; we're beginning to make real inroads into the bowhunting public (FINALLY!.
)
Ed
Topic: arrow physics 2 (Read 5125 times)
