# Cold temps might rob power



## dgui (Jan 12, 2010)

Cold temps seem to have a significant effect on bands and tubes. Is anyone else out there that have noticed this. Yesterday morning I was shooting at 24 degrees and as some of you know sometimes you just have to shoot.


----------



## Melchior (Dec 27, 2009)

Yes, the temperature has a significant effect on the performance of rubber. Especially with tubular rubber, 
but flatbands suffer as well.


----------



## ZDP-189 (Mar 14, 2010)

http://slingshotforum.com/blog/11/entry-403-effect-of-temperature-on-rubber/


----------



## Jacktrevally (Feb 14, 2011)

The Young's modulus of a rubber material increases as the temp rises, this is an effect not shown by any other materials. I.e the stiffness increases with Temperature.

As a rubber is stretch it is heated, if it is stretch 'quickly' the temperature rises due to the transfer of mechanical energy to the rubber.

So my question I've been asking is if you stretch a band slowly and releases immediately will it perform better than a rubber strech quickly and released after being held stretched?


----------



## ZDP-189 (Mar 14, 2010)

Release quickly.

It is an adiabatic process and does not require time for heat to soak into the bands. OTOH, you will lose crosslinks and connections to filler particles, so hysteresis will increase.


----------



## crazymike (May 8, 2011)

Well I had a few 31 degee days Did notice a big change in TBG flatband, so I went and shot out of my car window. Winter is near.


----------



## treefork (Feb 1, 2010)

I have found that the tb gold flats perform well in cold temps. I like to hike through the woods sniping random targets at all distances i will place the sling inside my warm coat occasionally when not takin shots. I have come to enjoy shooting in the winter months.


----------



## Northerner (Nov 9, 2010)

I just finished testing some TBG for temperature sensitivity. The cut was *3/4" x 11/16" x 7 3/8". *With a 30" draw I was getting 200-203 fps with 3/8" steel ammo. After 20 minutes in the freezer, the bands tested at 191 fps for the first shot and then 194, 195, 199 fps. After 6 hours in the freezer, the bands shot 185, 189, 191, 194 fps. The low 185 fps reading could have been a slightly short draw but I'm not sure. I seem to be loosing about 6% with very cold bands. As was mentioned, keeping the slingshot inside a coat would be a good idea when hunting in the winter.

Cheers,
Northerner


----------



## Charles (Aug 26, 2010)

Thanks so much for posting your experimental results. I am surprised the loss is not greater.

In this regard, Joerg's latest video is very appropriate:






Cheers ....... Charles


----------



## Jacktrevally (Feb 14, 2011)

Thanks for the results Northerner. Your tests are muchly appreciated.


----------



## JasonP (Jan 4, 2012)

having studied basic engineering this effect came as no surprise to me, what did surprise me however was our ability as sling shooters to detect subtle variations in slingshot performance


----------



## Rayshot (Feb 1, 2010)

I am not a physics guy but am fascinated with the created laws of physics, so here is something that I don't quite get regarding something Jorge said.

He mentions that the bands are storing or gaining heat "energy" from stretching. And that the *"heat energy" is what gives* or adds the extra oomph, speed in a shot if done while the bands are warm.

My Question; Is the heat the energy, or is the bands being warmed, affecting their ability to contract quicker. Maybe not the best comparison but like muscles, warm or muscles cold. Or like liquids such as molasses and honey when warm they flow better than when cold.

If you are in the know please keep it simple as you can, I am not looking for a lengthy essay.


----------



## JasonP (Jan 4, 2012)

I'm not sure if I fully understand your question Rayshot but I think you have misunderstood the process, keeping in mind that energy can neither be created nor destroyed; only change from one form to another. When bands are drawn out some of the kinetic energy you input is converted into thermal energy, upon release this thermal energy is converted back into kinetic energy. The longer you hold out the bands in a drawn position the more thermal energy they release (to the environment) meaning that when you shoot, there is less energy available to be converted into kinetic energy resulting in a weaker shot.

Also, the properties of elastics do change with temperature. Put simply when you first draw the bands you notice the relatively high draw weight, if you wait a few seconds you find your shot steadies and your hands shake less, this is because the draw weight has decreased (usually around 10-15%) and although this may help your shots accuracy it decreases the force acting on the projectile and therefore decreases its final velocity.

Please note that I am no expert in the field and am looking for many of the same answers you are.

Ps. Sorry if this kind of turned into the essay you asked us to avoid... hope this helped


----------



## NaturalFork (Jan 21, 2010)

I shot in sub zero temps recently with thera black and 107s. They both had performance decreases but not as much as I would have thought. Both were still pretty shootable.


----------



## Northerner (Nov 9, 2010)

I did another "cold temperature test". This time I put the slingshot outside at a temperature of +3F. After 40 minutes I brought it inside and shot within 30 seconds. The first shot with 3/8" steel was 186 fps, then 194, 195, 198, 199. Prior to the test the bands were shooting 199 fps at room temp. I lost about 6 1/2% this time.

I wonder if thicker bands or tubes would lose more power. The thin .030" TBG doesn't seem too band in the cold.

Cheers,
Northerner


----------



## Charles (Aug 26, 2010)

It seems from your experiments that the cold weather effect, while significant, is not quite as bad as I had imagined. Thanks for continuing your experiments.

Cheers ..... Charles


----------



## crapshot (May 3, 2011)

shooting cold weather will check temp specs on line of elastic im using latex gum or linatex


----------

