How will rain affect a discs flight?

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Discussion Overview

The discussion centers on how rain affects the flight distance of a thrown disc, particularly in the context of disc golf. Participants explore the implications of rain on aerodynamics, lift, and drag, while considering various factors that may influence the outcome.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • One participant claims that rain would decrease the distance thrown by less than 1%, while others express skepticism about this estimate.
  • Another participant suggests that the volume and mass ratios of water to air and disc are likely less than 1%, implying that the effect may be minimal.
  • A participant notes that increased humidity from rain could reduce aerodynamic lift and drag due to the lower density of water vapor compared to air, but the net effect on range is uncertain.
  • It is mentioned that water droplets on the disc could disrupt aerodynamics, increasing drag and reducing lift, although they may not remain on the disc for long due to its motion.
  • Some participants reference designs in golf balls and airplane wings that utilize surface features to manage airflow, contrasting this with the random nature of water droplets on a disc.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the extent to which rain affects disc flight distance, with multiple competing views and uncertainties remaining regarding the various aerodynamic factors involved.

Contextual Notes

Participants acknowledge the complexity of estimating the effects of rain on disc flight, highlighting the need for further analysis of aerodynamic principles and the specific conditions of the throw.

mhammy
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How will rain affect a discs flight??

We're having an argument on how much rain will reduce the distance of a thrown disc. We have a "professional" disc golfer here who says that it would decrease his distance by less than 1 percent. The rest of us aren't buying it. So, assuming that there is no head or tail wind present and no outside friction sources other than the normal friction produced by the atmosphere, how much decrease in distance would one encounter while throwing a disc in the rain. Assume that it's a normal rain shower and not a torrential down pour, whatever normal is.
 
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Seems to me 1% isn't unreasonable. By volume, what is the ratio of water versus air in its flight? Surely less than 1%. By mass, what is the ratio of disc to accumulated rain? Surely less than 1%.

There are certainly many other factors to consider, I'm just ballparking orders of magnitude.
 


Water vapor is less dense than air (molecular weight of water = 18 compared with 28 for nitrogen and 32 for oxygen) so the aerodynamic lift and drag will both be reduced by the increased humidity that accompanies the rain. Which of those factors "wins" in terms of changing the range will depend how much the disk "flies" as it is thrown.

Any water droplets that remain on the disk will tend to mess up the aerodynamics, increase the drag and reduce the lift, but I guess they won't stay there for long because of the forward velocity and/or spin of the disk. @DaveC, this is not caused by the added mass of the water droplets, but the change in surface shape of the disk affecting the boundary layer of the air flow.

I don't know now to estimate the effect of these things on the range, though.
 


AlephZero said:
Any water droplets that remain on the disk will tend to mess up the aerodynamics, increase the drag and reduce the lift,
Hey, golf balls and some designs for airplane wings actually incorporate rows of bumps or divots in order to control the boundary layer and flow separation. :wink:
 


http://www.infoocean.info/avatar1.jpg I don't know now to estimate the effect of these things on the range, though.
 
Last edited by a moderator:


DaveC426913 said:
Hey, golf balls and some designs for airplane wings actually incorporate rows of bumps or divots in order to control the boundary layer and flow separation. :wink:

Yes, but the key word in that sentence is "design", not a random arrangement of random sized bumps.
 


laurent711 said:
http://www.infoocean.info/avatar1.jpg I don't know now to estimate the effect of these things on the range, though.

Your image isn't displaying for me (in Internet Explorer) - but "now" was a typo for "how".
 
Last edited by a moderator:


AlephZero said:
Yes, but the key word in that sentence is "design", not a random arrangement of random sized bumps.
I know. I was really reachin'...
 

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