Thread: Velocity Loss From Summer to Winter.

Originally Posted by Bremic

Listed here, although currently shows as out of stock. Does give you price indication.

Oehler 35P 3 Screen Chronograph w/ Printer - oehler, 35p, screen, chronograph, printer - Serious Shooters

I am glad they are out of stock at that price.

Originally Posted by R93

Jeez guys we are getting into principles of flight here as far as aerofoil designs and lift. I havnt studied any of that stuff for over a decade. In saying that you are right to the best of my knowledge Sneeze.
The idea is to create high pressure under the aerofoil and low pressure at the top. Therefore creating lift. Most rotor blades are symetrical however and change the angle of attack by applying pitch.
As far as a projectiles resistence thru "air" I am not sure on the measured effects, but do see a difference from a low pressure day to a high pressure day in my calcs for said range. It can be a bit and enough to miss at range if not taken into consideration.

Hi 'R93'.. Hows it going...It wasnt worried so much about 'Principles of Flight" I sat that exam as well but 30 odd years ago. I am not worried about angle of attack or aerofoil design. It was your reference to helicopter blades, engines and density altitudes in relation to the loss of 90 FPS that had me thinking that your were refering to the bullets path through the air and the Army lecture on the effects of the viscosity of the gas on bullet and shell performance.

Originally Posted by Chicken

My oehler is still affected by light particularly this time of the year with the sun being so low. It went friggin nuts yesterday being triggered Constantly, by goodness knows what. I'm hoping it was just static. Prior to this it has worked flawlessly for two years

Take the orange diffuses off when this starts to happen in low light

So in conclusion I think its safe to say to James that without any doubt at all his velocity loss has nothing to do with a helicopter









Hope that helps.

Originally Posted by R93

I am glad they are out of stock at that price.

My goodness that is expensive...........

Originally Posted by Kiwi Greg

Take the orange diffuses off when this starts to happen in low light

Cheers Kiwi Greg I shall give it a try.

Originally Posted by sneeze

So in conclusion I think its safe to say to James that without any doubt at all his velocity loss has nothing to do with a helicopter


Hope that helps.

Glad we cleared that one up

Originally Posted by Scribe

Hi 'R93'.. Hows it going...It wasnt worried so much about 'Principles of Flight" I sat that exam as well but 30 odd years ago. I am not worried about angle of attack or aerofoil design. It was your reference to helicopter blades, engines and density altitudes in relation to the loss of 90 FPS that had me thinking that your were refering to the bullets path through the air and the Army lecture on the effects of the viscosity of the gas on bullet and shell performance.

I know where your coming from Scribe. IMHO air density has more effect on internal and external ballistics than most give credit.

'James' you and 'sneeze' might be clear on why there is a 90fps drop in bullet speed between summer and winter but I am damned if it is clear to me yet.

Originally Posted by Scribe

'James' you and 'sneeze' might be clear on why there is a 90fps drop in bullet speed between summer and winter but I am damned if it is clear to me yet.

Its the chemical reaction thing. Powders can react(burn) faster(or slower) depending on temp. Usually hotter means faster but not always due to some retardant coatings etc.
Its like a jar full of drain cleaner and a cup of cold water = clean drain, substitute cold for boiling water and you will have a clean ceiling instead.

For any given day, change the pressure and not the temp and there is a requirement to add or subtract elevation. It may be insignificant but it is there, so it is a variable.

If you're still there James and haven't committed suicide with all the advice you're been given

Here's another tip. Pop your bullets down your Y-fronts or in your pocket and keep them at 37.5 *C all year round. Just be aware that if you get the flu it might push the temp up to 39*C

Scribe put simply the ambient temp makes the powder warmer or cooler. Warm powder will burn faster than cold powder creating more pressure which intern creates more velocity.There are plenty of variables involving powder types,double base vs single base, burn rates,etc, I personally think barrel and chamber temp has an impact as well but its not something Iv given a lot of thought to. Some people (including myself) carry their ammo in a pocket close to the skin to try and keep it close to body temp in cold conditions, it helps.

Originally Posted by Im2lazy

If you're still there James and haven't committed suicide with all the advice you're been given
:

Hmmm bit condescending but you might be right. James I was wrong about the helicopter, apparently your going to need something really high to jump off.

Originally Posted by sneeze

Scribe put simply the ambient temp makes the powder warmer or cooler. Warm powder will burn faster than cold powder creating more pressure which intern creates more velocity.There are plenty of variables involving powder types,double base vs single base, burn rates,etc, I personally think barrel and chamber temp has an impact as well but its not something Iv given a lot of thought to. Some people (including myself) carry their ammo in a pocket close to the skin to try and keep it close to body temp in cold conditions, it helps.

Well there you go now, I know what you were talking about. All the time I was thinking outside the rifle, air density, viscosity, moisture and so on and so on. If you guys go on stretching the ranges onwards and outwards you will have to calculate earths rotation into your figures like they do with the long range artillery. Just kidding.

Thanks for that information.