Author Topic: Local conditions, drag and distance  (Read 6435 times)

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Online willie

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Re: Local conditions, drag and distance
« Reply #15 on: December 11, 2017, 11:14:44 pm »
Steve, increasing your sample size never hurts if experiments don't go as planned. your intuition just needs more information. ;)

Offline avcase

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Re: Local conditions, drag and distance
« Reply #16 on: December 12, 2017, 12:11:25 am »
There’s some really great info here. There is always something new to learn.  In the 1960’s and 1970’s, one popular theory was that it was best to shoot in very cool and still conditions. Flight shooting would commence early in the morning.

Here is a bit of an article from 1977 in the Freemont Argus newspaper. It was about George Alavekiu, who was preparing for the US Flight Nationals. George was describing the role the atmospheric conditions played in his first mile long shots.

>>>>>>>>>>>>>>>>>
George had hit a "weather window," as flight shooters call it. "At these speeds the air is practically solid, like water when you jump into it from a high place. If things are off just a little then your arrow will jump and roll and lose all its power to wind resistance." Looking for the "weather window", flight shooters every year converge on the Bonneville Salt Flats (where high-speed cars are tested) for the national flight tournament. The next one is scheduled for September. Before the shoot the arrows are registered. Actual shooting begins at dawn in order to take advantage of the still winds of early morning. Everything is important -- the temperature, the humidity, wind velocity and direction. Even shooting at higher elevations makes a difference because the air is less dense.”
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It is kind of funny that the article mentions the still winds at dawn as being the most desireable conditions.  There may be other reasons for this belief at the time. Perhaps it was because the bows simply held together better in colder temperatures.  Unfortunately, George never did make it to Bonneville that year.

A couple years ago I did some practice shooting at Bonneville during the winter and the temperatures were not that far above freezing. My distances seemed to be much worse than usual, although it was hard to know if it was influenced more by the temperature, or if it was due to the strong unpredictable winds that were blowing that day.

Alan

Offline avcase

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Re: Local conditions, drag and distance
« Reply #17 on: December 12, 2017, 12:39:06 am »
I am not sure how much arrow shaft drag can be exploited to get farther shots. It seems theoretically possible and I have made efforts to see if I can get something out of it with my footbow arrows. What I have observed is that these arrows land the softest. In contrast, my high forward balance arrows seem to punch a lot deeper hole in the ground and fall short.  My longest shots have been with the arrows where I have tried exploiting this concept of using shaft drag to keep the arrows in the air longer, but that may be due to a lot of other factors. I just haven’t been able to do enough shooting to draw any conclusions.

Alan

Offline joachimM

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Re: Local conditions, drag and distance
« Reply #18 on: December 12, 2017, 01:35:34 am »
   I notice that one of the problems we have is dealing with the lighter arrows around 200 grains or less. They come of the bow very fast but the slightest sideways motion kills the speed right out of the bow. Arrows around 300 grains from 50# bows can pretty regular hit the 300 mark but not good enough for records. I am moving my arrow weight up to about 250 or 260 this next year and see how it does.

Good info. The other day I tried shooting 25” 160 gr stiff carbon arrows that gave me 220 fps and I expected or rather hoped they would shoot more than 300 m. They didnt even make it halfway... but it was pretty windy weather though. I hadn’t expected the effect to be so dramatical!
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Offline Marc St Louis

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Re: Local conditions, drag and distance
« Reply #19 on: December 12, 2017, 05:02:27 am »
I tend to stay out of arrow discussions as it seems to me that there are too many variables to take into account to make a definitive conclusion.  That said I would be inclined to think that heavy moist air would be detrimental to distance shooting

Actually, moist air is beneficial, as it reduces drag. Counter-intuitive, but it's neatly explained here https://fogmountaintennis.wordpress.com/2014/06/05/atmospheric/ (under the heading "humidity")

So then shooting an arrow during a rainstorm should produce great distances  :)
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Offline joachimM

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Re: Local conditions, drag and distance
« Reply #20 on: December 12, 2017, 05:39:02 am »
except for the detrimental effects of extra drag by wind and rain itself  (-S

Actually, it's pretty difficult to combine all ideal conditions of humidity, temperature and wind.
in the early morning the humidity is high (closest to the dew point), but temperature is low. Wind speeds are often lowest in the morning, especially in summer, when winds rise in the afternoon due to convection of warm air, heated by the sun.

Overall, I can imagine that early summer mornings provide the best overall conditions to flight shoot.
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Offline Selfbowman

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Re: Local conditions, drag and distance
« Reply #21 on: December 12, 2017, 10:03:11 am »
Well I shot the same arrows and the same bow the other day that I shot at the flats last summer. I was disappointed to say the least . It was cold probably around 40 degrees  . My arrows flew 25 yds shorter than they did here or at the flats. No wind to speak of. Maybe cold air falls and hot air rises has more to do with it than we thank. .??? Arvin
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Offline Selfbowman

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Re: Local conditions, drag and distance
« Reply #22 on: December 12, 2017, 10:09:02 am »
I also think maybe that the water that comes off the flats in evaporation in the heat there makes the air more wet. Could be wrong about though. The water is shallow at the flats. Arvin
Well I'll say!!  Osage is king!!

Offline Badger

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Re: Local conditions, drag and distance
« Reply #23 on: December 12, 2017, 10:42:57 am »
  Arvin, I think rising thermal air currents help a lot.

Online willie

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Re: Local conditions, drag and distance
« Reply #24 on: December 12, 2017, 01:58:06 pm »
Quote
I am not sure how much arrow shaft drag can be exploited to get farther shots.
Alan, I know you covered some FOC principles in an earlier thread where gliding was discussed, but maybe there are thoughts for other possible exploits out there?  Have most of your efforts been limited to the  "If we can delay the decent, then the arrow might go further" concept?

Offline avcase

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Re: Local conditions, drag and distance
« Reply #25 on: December 13, 2017, 02:34:57 pm »
Quote
I am not sure how much arrow shaft drag can be exploited to get farther shots.
Alan, I know you covered some FOC principles in an earlier thread where gliding was discussed, but maybe there are thoughts for other possible exploits out there?  Have most of your efforts been limited to the  "If we can delay the decent, then the arrow might go further" concept?

Short answer is yes.  One of my biggest challenges at our Flight competitions is that some portion of the arrow remains above ground so it can be found and measured. A soft landing is pretty important, and it is even better if I can get a little extra distance in the process.

I do want to better understand the role of atmospheric conditions. I think this is useful. One of my current obsessions is trying to understand how Harry Drake shot an arrow over 2000 yards in 1971. It doesn’t seem possible given the equipment he was using, yet I do not doubt his distances were completely legitimate. My theory is that he was a master at knowing when and where to shoot in order to get as much help from the atmosphere as possible.  Another part of the mystery is that this record was set at a lower altitude location than Bonneville, and the recorded temperature was a very cool 59 degrees F.  The wind was noted as a gentle but steady off-angle tail wind of 5mph.

Alan



Offline DC

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Re: Local conditions, drag and distance
« Reply #26 on: December 13, 2017, 04:46:40 pm »

Short answer is yes.  One of my biggest challenges at our Flight competitions is that some portion of the arrow remains above ground so it can be found and measured. A soft landing is pretty important, and it is even better if I can get a little extra distance in the process.
A little aside for a sec. What would happen if you got a real soft landing. So the arrow hit flat and skipped along the surface. Does it not count in scoring?
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Offline avcase

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Re: Local conditions, drag and distance
« Reply #27 on: December 13, 2017, 06:37:50 pm »

A little aside for a sec. What would happen if you got a real soft landing. So the arrow hit flat and skipped along the surface. Does it not count in scoring?
[/quote]

According to the Flight rules: “An arrow that’s comes to rest in other than the usual position may be measured from the tip of the arrow if visible, or from the point which it enters any object other than the ground.”

In this case distance wouldn’t be measured to the point of the arrow where it came to rest. But this is where the acting judge may need to get involved.  For instance, if there was a chance some external forces act to continue to move the arrow after it has landed, such as high winds, or flash flooding, etc., then it will not be possible to score the arrow.

We have had rare instances where an arrow may have hit a rock below the surface and bounced out, but I am not aware of any time that this resulted in a much of an advantage.

I don’t think an arrow can descend at such a high angle of attack that it would land flat on the ground.  If it did, then there probably wouldn’t be enough forward motion to carry it forward very far. In fact, if this happened then the arrow will descend in a long slow spiral, and may end up traveling the wrong way by the time it hits the ground.  What usually happens is that the arrow picks up speed as it descends, and this moves the center of pressure further rearward, eventually forcing it into more alignment with the trajectory path before striking the ground. 

Alan

Online willie

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Re: Local conditions, drag and distance
« Reply #28 on: December 13, 2017, 10:47:11 pm »
Alan
Lots of light powder snow has been hanging in the branches of the spruce trees here. When a pilot friend stopped by, I commented how we hadn't had any wind for 2 weeks. He said it seemed unusual because just a few hundred feet up, it has been a steady headwind for days on end. His (airplane) trip home each afternoon is slowed, while he he looks out over a forest of undisturbed snowy trees. He observed that it seems like when the wind is the other way, the trees are swaying and the ride is bumpier.
Having worked on deck for many years, most of my observations about wind and waves were more about the waves, but I can say that all waves are not created equal. Sometimes sea conditions weren't near as poor as one would expect (for the given wind), and sometimes just the opposite. Could the same be true for the atmospheric side of the boundary? Are there vertical flows to be considered besides the of mentioned "thermal uplift"?

https://en.wikipedia.org/wiki/Secondary_flow#Wind_near_ground_level

« Last Edit: December 14, 2017, 12:20:48 am by willie »

Offline Badger

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Re: Local conditions, drag and distance
« Reply #29 on: December 13, 2017, 11:00:47 pm »
   Releasing balloons might give you some indications but I am not so sure what you would do to make adjustments for it.