how does temperature effect disc flight?

[money 21]

how does temperature effect disc flight?

[Dag]

Shivering messes with my aim and sweat plays hell with a clean release...

There was a thread on this mebbe last winter.

[inthedrift]

I think there was a thread...

My experience is that my discs do not seem to glide as well in really cold temperatures, although stability seems to be relatively unaffected. It's always an adjustment once the snow is on the ground for those of us who brave the winter to continue playing. I'm going through that adjustment presently as we now have several inches of snow on the ground. The questionable footing messes with my timing a lot, it'll take a few weeks before I'm feeling the winter groove

[swel304]

Air density is up so more drag/less glide which can hurt distance and make the disc seem to fly more overstable. Or at least this is what I seem to remember people saying all the other winters that this topic has come up.

[JHern]

Air density affects disc flight. All forces on the disc scale with density times the square of air speed. If density drops, as it does when hot and humid, or at high elevations, then you have to throw the disc faster to get the same forces (lift, drag, & turn).

I just threw discs in Salt Lake City this past week (4500' elevation, ~40˚F) as well as at home (sea level, ~70˚F). While the cooler air will increase density, the higher elevation decreases density...elevation was the stronger effect, and the over all density was lower.

[ashley]

Air density affects disc flight. All forces on the disc scale with density times the square of air speed. If density drops, as it does when hot and humid, or at high elevations, then you have to throw the disc faster to get the same forces (lift, drag, & turn).

I just threw discs in Salt Lake City this past week (4500' elevation, ~40˚F) as well as at home (sea level, ~70˚F). While the cooler air will increase density, the higher elevation decreases density...elevation was the stronger effect, and the over all density was lower.

I have read this several times, and I don't understand what you are trying to say. Are you saying you threw farther at 4500/40 or at sea level/70?

[swel304]

Air density affects disc flight. All forces on the disc scale with density times the square of air speed. If density drops, as it does when hot and humid, or at high elevations, then you have to throw the disc faster to get the same forces (lift, drag, & turn).

I just threw discs in Salt Lake City this past week (4500' elevation, ~40˚F) as well as at home (sea level, ~70˚F). While the cooler air will increase density, the higher elevation decreases density...elevation was the stronger effect, and the over all density was lower.

I have read this several times, and I don't understand what you are trying to say. Are you saying you threw farther at 4500/40 or at sea level/70?

I am pretty sure he is saying that even with the 40 degree temp the high elevation still caused the density to be lower than sea level@70degrees. i.e. it was easier to throw for distance in the higher elevation.

Science aside I personally believe that the distance people loose during the winter is more to do with stiff joints, cold hands, and additional clothing bulk. The less you wear the stiffer you get from cold, the more you wear the harder it is to move. When its really cold I start out bulky and remove layers when I feel close to breaking a sweat. When I warm up like this the cold air density only seems to take a minimal amount off my max D drives, like maybe 5-10 feet. With the bulky clothes on or cold muscles it takes more like 50+feet off. I have nothing to back this up other than my own experiences but it has always seemed to be a fairly consistent measure for my own cold weather game.

[mark12b]

I have read this several times, and I don't understand what you are trying to say. Are you saying you threw farther at 4500/40 or at sea level/70?

Depends on how you throw. Thick, heavy air like you get at sea level or when it's cold will be better for hyper flips, whereas if you're in thin air the disc will fly better with a more direct line. I live at sea level and when I throw in thinner air, the distance is pretty much the same, but I have a harder time shaping lines.

[kern9787]

Simplified version:

Colder air = denser air

Significant rise in elevation above sea level = significantly less dense air

Denser air = more drag = more lift (glide) and more high speed turn

Less dense air = less drage = less lift, less turn, but faster.

So in more dense air (colder, or lower elevation) shots will be slower, but have more glide and fly less stable. In less dense air, shots are faster, but with less glide and more high speed stability. Two different kinds of shots are favored, but one isn't necessarily longer than the other.

[Sean40474]

I'm glad we got folks like you around JHern, I didn't pay much attention in physics lol.....too much higher level math. I was fine till I got to trig and calc.

[JHern]

I'm glad we got folks like you around JHern, I didn't pay much attention in physics lol.....too much higher level math. I was fine till I got to trig and calc.

Aw, shucks!

The density dependence of the aerodynamical forces acting on a disc comes from Bernoulli's principle. The motion of an object through a fluid (i.e., air) gives rise to pressure gradients; pressure gradient forces are responsible for drag, lift, and turn. All of these forces scale proportionally to the change in pressure induced by the motion of the object through the fluid. From experience, we know that these forces increase as the air speed (speed of an object relative to air) is increased. The fluid density times the square of the speed of motion divided by two is called the kinetic pressure. By Bernoulli's principle, the sum of the kinetic pressure and actual pressure are supposed to stay constant along a streamline if the viscosity of the fluid is negligibly small. This means that the pressure along a streamline changes from its ambient value away from the object to a different pressure just adjacent to the object, because the relative speed of the air goes to zero at the edge of the object (the air next to the surface is stuck to it). Therefore the pressure change next to the object changes as the kinetic pressure changes, density times air speed squared divided by two.

Anyways, air density models exist, where you can dial in temperature, humidity, altitude, etc. (equation of state of air). Just so you know, the forces all scale with density, it is the relevant variable.

Also, the drag increases with increased density, but so does the lift. For a straight and level flight, the disc flies pretty much the same distance at different densities, but the duration of the flight changes.

Discs will turn over easier at higher density because the torque (arising from the pressure gradient acting off-center) also scales with density times air speed squared divided by two.