Calculate gearing changes based on windspeed?

  • Thread starter Kometes
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In summary, the conversation is about a person looking for equations to calculate gearing changes based on wind speed and a fixed engine output in a race car. They discuss the potential impact of a head wind on top speed and the possibility of adjusting the final gear ratio to compensate. However, there is a concern about potential negative effects on corner exit performance.
  • #1
Kometes
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Hi All,

I'm looking for a set of equations to allow me to calculate gearing changes based on a known tail/head wind speed, anyone got any starting points? 4 speed transmission and a fixed engine output.

Cheers,
 
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  • #2
In what context? Road car, racing, etc? The changing of actual ratios in the box or shift points?
 
  • #3
Race car and changing the actual ratios. For example, car has w,x,y,z gear ratios in so that the engine is hitting the limiter at the end of a straight, if it then gets a 5km/h head wind I'd like to be able to work out how many teeth I'd need to go down on the final gear (z).
 
  • #4
Since you're mainly fighting aero drag but hopefully still accelerating (depending on the class and track), your potential top speed will be down by about the same amount as the head wind. Knock off half the percentage difference (200 km/h vs 195 km/h for example) and start with that.

Personally, I'd be careful about changing final drive ratios to compensate for somewhat unreliable wind conditions at the risk of messing up corner exit performance at other places on the track. Unless you have extremely long straights, you might end up being slower.
 
  • #5
Thanks for the reply Mender. It'd mainly be for top gear and there's few corners where you're maxed out in top gear so it should be fine.
 
  • #6
Sounds like you're talking about changing the ratio of fourth gear and not the final drive ratio (diff), right? If so, ignore my comment!
 

1. How do you calculate gearing changes based on windspeed?

To calculate gearing changes based on windspeed, you will need to know the windspeed in miles per hour (mph) and the desired gear ratio. Then, use the formula (mph / gear ratio) x 60 = rotations per minute (rpm). This will give you the target rpm for the given windspeed and gear ratio.

2. Why is it important to adjust gearing based on windspeed?

Adjusting gearing based on windspeed is important because wind resistance can significantly affect the performance and efficiency of a machine or vehicle. By changing the gear ratio to match the windspeed, the machine can maintain a consistent rpm and operate efficiently.

3. What factors should be considered when calculating gearing changes based on windspeed?

When calculating gearing changes based on windspeed, factors such as the weight and aerodynamics of the machine, the terrain, and the desired speed should be taken into account. These factors will affect the amount of resistance and the required rpm for optimal performance.

4. Can you use the same gear ratio for all windspeeds?

No, the gear ratio should be adjusted according to the windspeed. If the windspeed increases, the gear ratio should be decreased to maintain the target rpm. Similarly, if the windspeed decreases, the gear ratio should be increased.

5. How often should gearing changes be made based on windspeed?

The frequency of gearing changes based on windspeed will vary depending on the specific machine and conditions. However, it is recommended to regularly monitor windspeed and adjust the gearing as needed to ensure optimal performance.

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