Heat and sight marks

[archer_thom]

Reading the thread on shooting in the dark reminded me of a paranoia that was rampant in Switzerland a few years back. The theory went that as your limbs heat up, they become less efficent. The evidence? As the temperature rose, arrows were dropping low; this was during the 2003 heatwave so the temperatures were around 5 degrees hight than we normally get. It's worth pointing out that this was not a panic among the top archers, but in my area we tend not to see them much.

Tests were done, records were kept, and there was a clear correlation between temperature and dropping arrows. It was considered odd that my black Border limbs didn't lose as much height as some white and silver limbs, but such doubts were dispelled by the assertion that they are simply good limbs...

A few weeks later (towards the end ofthe heatwave) I was on a national training course on the west coast of France, where temeratures were regularly reaching 40C. (It got so bad that we shot at dawn and dusk). The effect was worse than ever here, so I asked the head coach about it...

"Oh yes" he said,

"That's heat fatigue in the archer".

Have if you saw that one coming.

[Niall]

Isn't it something to do with air density? Hot air is less dense and it is more difficult to generate lift. I think that in aviation,planes need a longer take-off run in hot weather than they do in cold weather.

[sambow]

Originally Posted by Niall

Isn't it something to do with air density? Hot air is less dense and it is more difficult to generate lift. I think that in aviation,planes need a longer take-off run in hot weather than they do in cold weather.

I have always found the opposite. When shooting (compound) late in the summer as the night draws in my arrows consistently start to drop when shooting in excess of 60M. I always put this down to me tireing and dropping my arm, but I was informed by a top archer shooting alongside me that as the air gets colder the arrows will drop and sight marks need to be adjusted.

Regarding the airplane example. I served an apprenticeship at Rolls Royce aerospace (albeit many moons ago!) My understanding of the longer runway example you give was not to do with lift on the wings but the efficiency of the engine. Jet engines run more efficient and generate more thrust with a cold charge of air than with a warm charge of air.

Coming back to the arrow. I would expect that dense air would give greater friction around the surface of the aiir than less dense air, hence slowing it down. I would imagine that an arrow shot in a total vacuum would travel faster than one shot in dense air (this is only a gut feel so I would appreciate any views on this)

[Flying Whale]

Maybe we can get Watchman and Archery_Mum to use their hooter shooter to unequivocally answer whether there is an effect on either the bow (limb material reacting to temperature), or the atmospheric effects, rather than effects on the archer.

Once that is decided then we can speculate as much as we like as to whether it is air density etc...

[sambow]

Originally Posted by Flying Whale

Maybe we can get Watchman and Archery_Mum to use their hooter shooter to unequivocally answer whether there is an effect on either the bow (limb material reacting to temperature), or the atmospheric effects, rather than effects on the archer.

Once that is decided then we can speculate as much as we like as to whether it is air density etc...

They've got a hooter shooter! Wicked!!

That would be a great idea if they could do it. If they choose a warm day with a clear sky and no noticable wind and shot at about 6pm than repeat at 8pm the temperature should really drop by them. Even better shoot every half hour and record the temperature and plot vertical movement. That should give a good indication of what is going on. (It would be also interesting to see how compound and recurve compare)

[geoffretired]

Is it the bow? Is it the air? Could a bow be kept cool, using ice pack, sand shot on a hot day? Could it then be allowed to warm up and be shot while the outside temperature was the same?
If the archer was shooting from some shade, archer fatigue could be almost eliminated,yes?

[not dead yet]

what does the hooter shooter do exactly. please

other than shoot 1440

[sambow]

Originally Posted by not dead yet

what does the hooter shooter do exactly. please

other than shoot 1440

My understanding is it is a mechanical jig which simulates a shot. Because it is a mechanical jig variation from shot to shot is minimal (unlike humans shooting). So you can use it to experiment on equipment, hence when you make any changes you can see the effect of the changes without worrying "was it the change I made or did I do something ever so slightly different that time". Personally I would love one and could spend hours of fun, but they are hellish expensive!

[wingate_52]

Wooden longbows tend to "weaken and lose cast" in hot weather.

[archery_mum]

Sounds like an interesting test. I just asked watch_man and he thought it would be a good excuse for a picnic

I would suggest that the test be done at 70m and with X10's (carbon/aluminium) Navigator FMJ's (Aluminium out) and Nano Pro's (all carbon) as I would like to see the effect of heat on each arrow type. I also think I can get all three on a boss at 70m without having to adjust the hooter shooter between arrows.

It would need to be a warm still (ish) day when I haven't got a competition or anything else on. Fortunately we have 24/7 access to our club field.

I think you guys need to get a plan together about how the test should be run, agree on time gaps - say every hour, do we start before noon and let it run through the hottest part of the day?

What about the bow itself, does it need to be shaded with an umbrella as it would have to remain in the hooter shooter. And the arrows, do we store them in a quiver and just leave them on so they accumulate heat as they would do through a competition?

I'm sure we could get a couple of club members to help out if they have time (well volunteered english_archer )

Keep coming with ideas so we can at least agree on what we are testing and then once everything is specified we can just wait for a good day.