Heat and sight marks

[bimble]

Sorry, it's the whole scientist thingy. Why test only one thing when you can check several and then not have to do it again later on.

Afterall, you know that if they simply prove that it isn't the archer wearing down we'll be asking them to find out what it is!!!

[Tropicalshot]

as some one who shoots in Tropical far north qld Aus, i can say from my experience that during our monsoon season ( summer) the higher the humidity the lower the arrow drops over a set distance. as we are comming into our winter, still a pleasant 28deg C i am finding the arrow hitting higher beacause of the low humidity, even though our temp ranges from 36 Deg C with 90% + humidity during cetain summer days, to an average of 27deg C with between 30 & 50% hunidity during the day(sometimes lower) during winter, we leave our bows out in the sun(50deg C + direct) or shade if we can get it. i am finding no effects of bow performance, only me getting more tired in the more humid days, the only thing we have to watch out for is leaving our bow set up in a car as the temp here soars and can delaminate the limbs,( have seen this done)

[Watch_Man]

Maybe this Sunday for testing. We have our County Windsor and this all depends on if I shoot or not. I'm involved with a few other things including the scoring so I may withdraw from the shooting. We are going to try and take the Hooter Shooter along ayway for 'The Meggy' and one or two others to see.

As I am sure you will appreciate there will be many other things going on. My plan is to set it up on part of our EFAA field course located at the back end of the target field. This will keep it out of the way while still allowing me to shoot a set of arrows every hour. I am going to see if I can set it at 80yds, depends on clearance from the target side.

As Wendy is in the competition we will be using either one of her Mathews Apex 7's or more likely, the 38 Ultra rather than one of her UltraEite's. Still proposing to use an X10, Navi FMJ and either a Nano Pro or XR. We have our little weather station for pressure and temperature.

We will do our best to make this happen on Sunday, I also want to combine it with some testing we are doing with the FOB's v Vanes so it could be an interesting day.

Now lets just check the weather forecast......

[RGrahamSmith]

As an ex-physics teacher, I'll say this -

I also have noted arrow drop after a while shooting in warm weather, but have always put it down to my own drop in performance. However, seeing that the suggested reasons here sound likely candidates as well, I would, say that experiment should be interesting. Since there are so many variables, and a good scientist always changes only one at a time, it will be difficult! I'd imagine that the main things to test are:

1. effect of temperature on limb material - surely heat softens most materials, leading to less strength in the limbs (this is my "prime suspect")
2. effect of heat on string tension
3. effect of air density (less at higher temperatures) - though as suggested, this ought to allow arrows to fly faster, if anything.
4. effect of heat on the archer - the most difficult to quantify, as it will have many variables in itself! Still, the use of a constant anchor point and a clicker should (?) take the archer out of the equation...

I don't think temperature effect on the arrow itself is likely to be significant, but of course the type of arrow used would have to be the same throughout testing, or it's not a "fair test".

A mechanical device won't be able to test all of these, surely..

I look forward with interest to the outcome of any experiments that are done. Looks like the basis of an M.Eng. for someone (That's like a PhD for engineers)

Graham

[archery_mum]

While we were shooting the County Windsor yesterday, watch_man carried out the tests with the Hooter Shooter. He started at 9am and shot every hour till 5pm. I know he is hoping to try and get the results done today. We have a large white sheet in our front room at the moment with lots of pen marks on. He also took our little weather station and recorded temperature and pressure each time.

[Watch_Man]

I will try and get them sorted today if I can. It was interesting and I never expected to actually see much change. The arrows and bow were left out as if they were being shot. I used the same 4 arrows for each test:

X7
Navigator FMJ
X10
Nano XR

To establish if the Hooter Shooter was recording accurately I also shot a Nano Pro twice straight after each other and they went in the same hole. I did this at the start, mid way and at the end. despite some wind they did go in the same hole. From that I assume that the vertical variation must be due to external factors.

[bimble]

Ooooo, I am looking forward to this. This is why I like science, the ability to do experiments.

Now if only all disagreements on AIUK could be sorted out this way!!!

[Watch_Man]

Here are the results of the Icelandic Jury.... oops not Eurovision yet

The testing was carried out during the Lincolnshire County Windsor on the 11th of May - the hottest day of the year so far as it turns out. The hooter shooter was set up in the field area at the back of the target line and was visible at all times. The arrows were fired as near to each hour as possible as it was done during arrow collection. This was +/-5 mins each time. The Barometer/thermometer was placed at the base of the hooter shooter and everything was left setup as if it was on the equipment line. The arrows were laid flat in the lid of an arrow bax so should have received the same amount of heat exposure. I was not the only one to shoot the Hooter shooter during the test - 4 arrows per hour can take its toll so I let some of the other AIUK members at the shoot have a go.

The temperatures/pressures/humidity were as follows:

9am 20 1022 55%

10am 23 1021 49%
11am 29 1022 41%
12am 31 1021 30%
1pm 30.5 1021 31%
2pm 40 1021 22%
3pm 33 1021 31%
4pm 31 1021 49%

The arrow shot at 9am was deemed as being point zero and all other arrows were recorded as a minus or plus in mm from the previous arrow fired. So all measurements are in relation to the previous arrow. I tried to be as accurate as I could but there were several groups of very close or overlapping holes.

So as an example the X7 dropped by 8.73mm between 9am and 10am but between 12 and 1pm it went up 24.84mm from its position at 12pm.



This test was carried out during a normal shoot and not under any kind of scientific conditions. The only reading I have concern over is the X10 one showing the arrow fall by -49.83 between 12 and 1pm. There is no obvious explanation and that is where the hole was. I only wonder if perhaps I nocked the arrow upside down although I tried to be as careful as I could each time. However both carbon outer arrows fell during this hour where the two aluminium out ones went higher.

[Watch_Man]

Originally Posted by sp220

I am quite impressed with the results:

But - Only the density of the air should have any real affect on the flight of the arrows.

All the variables you have - the temp, the pressure and the humidity, vary the density..

So to find a correlation on the results, you should work out the true density of the air at each time interval, and then plot the + - margin for each arrow at each time interval against the true density.

I say true density because (as you may have read) more humidity means LOWER air density (which seems the wrong way around - I thought the same thing), but thats life.

So, while good, I dont think you are seeing what is giving you this spread untill you fully work out the density at each level (as it may be rising and falling just like the spread of arrows)

PS: the graph would perhaps be more technically correct if it were plotted as a scatter diagram than a line graph - it will be easier to show a trend - and that way you can use different icons or points for each arrow type. You should also remove time as a factor - its not impportant, and you have it plotted, but it is not a variable in the experiment.

The current lines you have on the graph dont show the truth of what is happening, because you have plotted the variation against time - which makes the graph appear as though the arrow speed varies with time (which has given you very sharp peeks and dips), and makes the arrows look very erratic.

For best results:

plot a scatter diagram - along bottom x axis have the density - along side y axis have + - displacement in mm

and have a different symbol for each point for the different shafts - excell will do it automatically

This will give you a correlation as to what is happening, and you will see a good result - it should be quite clear I think

If you are unsure, I am willing to have a go at it if you like

Hi Sam

yes, please have a go this information is there for anyone who wants to use it or make any sense of it. I think you are probably better equiped to do this than I am

[ChakaZulu]

Originally Posted by sp220

Only the density of the air should have any real affect on the flight of the arrows.
The current lines you have on the graph dont show the truth of what is happening, because you have plotted the variation against time - which makes the graph appear as though the arrow speed varies with time (which has given you very sharp peeks and dips), and makes the arrows look very erratic.

Broadly speaking that's right, but it occurs to me that time could have an effect if the cause of the difference is the temperature of the equipment rather than the air temperature/density. Speaking off the top of my head and without experimentation, I should think that the limb temperature would rise over time (obviously up to a limit).

And I assume that there was no wind during this experiment? You may have mentioned it and I just missed it.