ambient temperature: something I never would have guessed

[bob_ninja]

Titan,
You are talking about bike engines using fuel injection. Mine is an older model using a carburetor. As far as I know carburetors don't have air sesonsors and don't adjust fule intake for air temp/density. That is why I am guessing that denser air increases oxygen intake while fuel intake remains the same - carburetor is dumb

 

[mechtech]

oilyriser - Something isn't adding up. You are correct about humid air being less dense than dry air [H2O=18, O2=32, in molecular weights].
Maybe the source of the bullet drop info is mis informed, or got it backwards, or a misprint.

 

[Bryanccfshr]

I can assure you that the round does not travel as far in more humid air. This is not anectdotal my "cousin said" jibberish or internet sourcing, it is what I and every other Marines who have performed long range shooting have been taught and experienced. This is common knowledge personally experienced and logged in data books. Try not to take offense when simple arithmatic does not explain art. There are articles written by wanna be physics gurus who say the opposite of what I stated. I have my doubts about their range time to prove there theories

.
The Rule stands as truth.. much like the mystery of 5w20 providing good used oil analysis (not really a mystery when you get below the surface) .. it may not be intuitive but you can't argue with the results in the field.

I will give that the air being thicker when humid is a simple explanation(although false) to help shooters remember to adjust for humidity.

 

[Titan]

bob_ninja wrote: You are talking about bike engines using fuel injection. Mine is an older model using a carburetor. As far as I know carburetors don't have air sesonsors and don't adjust fule intake for air temp/density. That is why I am guessing that denser air increases oxygen intake while fuel intake remains the same - carburetor is dumb "

I see your point...makes sense to me!

 

[Gary Allan]

oilyriser - Something isn't adding up. You are correct about humid air being less dense than dry air [H2O=18, O2=32, in molecular weights].
Maybe the source of the bullet drop info is mis informed, or got it backwards, or a misprint.


Help me out here on this semi stratospheric (and atmostpheric) debate here. Is there an assertion that air that is at 100% humidity @ (fill in the temp) is lighter then 0% humidity air under the same conditions? That is, 100% saturated vapor is lighter then that having no water in it at all??

How does the spacing of the aforementioned molecules alter this? One would think that one cubic foot of condensed H20 would surely be more dense then 1 cubic foot of zero moisture air (yes, I'm being funny) ..the common sense rationale (which is surely able to be flawed when dealing wiht the properties of water ..etc.) is that it would resemble a para amotization chart ..or entropy table much like the difference between 212F water and 212 saturated vapor.

Or are all of you guys in concert bring up some horrific discussion about di-hydrogen-monoxide and having fun with the plebes???

but anyway, before you brought up molecular weight comparisons ..I would have thought just hitting the individual (or however many) vapor packets would create some type of collision situation for the projectile.

So a water molecule has less mass then an Oxygen-Nitrogen mixture. Who would of thought

So to increase fuel economy ..perhaps they should install sprinkler systems on the highways. At least in the summer. The vapor added to the air over the road way should decrease air drag and increase fuel economy.

Oh woe is the life of the physics and chemistry challenged

[ March 16, 2006, 07:17 AM: Message edited by: Gary Allan ]

 

[oilyriser]

Planting trees near highways will add moisture and reduce wind. It'll also cut down on whiteouts in cold winter areas that have this problem. Lots of money can be saved.

The bullet observation is fascinating. The bullet does work when it compresses the air in front of it. Some of that is recovered as the air slides past and behind. But if some of the work is lost as water condenses on the front of the slug, you don't get as much of a push from behind. It probably doesn't work on cars, though, since they go too slow.

 

[Bryanccfshr]

Trees are an outstanding resource for roadsides/highways. Another benefit is they absorb some sound and emissions. They would also keep the roads cooler resulting in less surface degradation.