Water Rocket Forum

How much does your 2 liter bottle weigh? I weighed some of mine and they weigh 46 to 48 grams and hold 9 to 10 bar max before exploding. This might help with why our bottles hold different pressures. If others could do the same it would be interesting to see the results.

reno1 wrote:How much does your 2 liter bottle weigh? I weighed some of mine and they weigh 46 to 48 grams and hold 9 to 10 bar max before exploding. This might help with why our bottles hold different pressures. If others could do the same it would be interesting to see the results.

I know this is off topic, but I saw some Mountain Dew bottles the other day with a new logo on them. It said MTN DEW. I see Pepsi recently changed their circle doohickey thing too.

These are all UK bottles, a random mixture, in no particular order...

Pepsi - 2L: 42g

Sprite, Coke, Coke (Zero), Co-Op Lemonade, Happy Shopper Lemonade - 2L: 44g

Coke, Diet Coke - 1.25L: 42g

Silver Spring Soda Water - 1L: 28g

ASDA Soda Water - 1L: 36g

House of Commons Sparkling Mineral Water - 500ml: 34g


It occurs to me that knowing the dimensions of the bottles would help to determine the surface area and hence a relative bottle wall thickness (proportional to the max. pressure?)

So I'll see if I can find time to put up some more measurements later.

Spaceman Spiff wrote:

reno1 wrote:How much does your 2 liter bottle weigh? I weighed some of mine and they weigh 46 to 48 grams and hold 9 to 10 bar max before exploding. This might help with why our bottles hold different pressures. If others could do the same it would be interesting to see the results.

I know this is off topic, but I saw some Mountain Dew bottles the other day with a new logo on them. It said MTN DEW. I see Pepsi recently changed their circle doohickey thing too.

Yes. The changed their name to Mtn Dew.

Hi,

Swiss 2L Sprite: 46.9g
Swiss 2L Coca-Cola: 46.8g

Both are good to about 10 bar (when not spliced).

Regards
Soren

I can weigh some bottles but I want to know what we are measuring. Do I have to take the sticker off the bottle and the cap too? What about the ring around the neck that remains from the cap when it is removed?

Tim Chen wrote:I can weigh some bottles but I want to know what we are measuring. Do I have to take the sticker off the bottle and the cap too? What about the ring around the neck that remains from the cap when it is removed?

Hi Tim, I weighed all my bottles bare, just the bottle itself. Also removed all glue. Thanks in advance for your input and good luck with school.

Tim Chen wrote:I can weigh some bottles but I want to know what we are measuring. Do I have to take the sticker off the bottle and the cap too? What about the ring around the neck that remains from the cap when it is removed?

Well I left the labels and rings on. However, I just weighed ten neck rings together: they came in at 4g (or 1/8 oz) the lot, at the resolution of my kitchen scales. Call it 0.5g apiece, so about 1% of the bottle weight. I'm pretty sure the labels weighed even less.

To be honest, at my level of sophistication there are much bigger sources of error than that. I usually assume I've got a minimum of 5% wrong either way on any measurement.

2 liter PET bottles have reduced in weight over the years. From http://www.petresin.org/news_didyouknow.asp --
"A 2-liter PET bottle that weighed 68 grams in 1980 now weighs as little as 42 grams."

2L bottles also used to have a ridge around their middle, like this one: http://www.aircommandrockets.com/labs/p ... 00_001.htm
You can't find these anymore in the United States. In Asia or Europe you can still find some.

The ridge was great for preventing the bottle from buckling in flight. The new 2-liter bottles are nearly useless for water rocketry now. The walls are so thin and flexible that the vacuum formed inside the bottle when the pressure is exhausted at high speed causes the rocket body to buckle.

-Alex