How does rain affect mileage?

Rolling drag increases due to pushing aside the road water. There is a loss of momentum from rain that is accelerated to vehicle speed and drops off. The formerly smooth surface is now covered with less smooth water ripples, drops and imperfections. That is just the short list.

Bob Wilson

 

How about Rain

 

It can cost me as much as 50 W-hr per mile. Watts that I'm happy to spend to not have to ride my bike in the rain.

 

Yeah, but riding during a heavy rain is huge fun (seriously!), at least during the summer. It does make one appreciate a good waterproof pannier, however... especially when transporting a notebook to/from work.

 

Holy crap!! Had no idea, thanks for the link dogfriend.

Explains my 37 MPG the past tank and current one. Have had lots of rain/wet roads, even the ugly freezing rain! Add snow and below freezing temps and (relatively) short, hilly 15 minute commutes. Plus winter grip tires.

Even with an EBH. I know it's working, as the engine shuts off soon after the one minute 'warm-up' in the AM. But MPG is not any better, due to the weather and my terrain/time on the road (30 MPH to 40 MPH speeds).

 

is that a real palm program??? can i download it?


raindrop has a mass... and it has an acceleration

F= ma... now you have lots of little m and a.. but there are a lot going towards your car.. as you increase your speed ... you're increasing the rain's reaction...

 

It appears to be a real Palm program, but I don't know if you can download it or not. I found it on Hobbit's link page; Hobbit attributes the page to Wayne Brown.

Prius Palm Mileage Simulator

 

I have the (downloaded) application, but it currently is unavailable. After noticing the download links were missing from the site recently, I e-mailed Wayne to ask about them. He thinks the registration code was hacked into, and he took them down until he could figure it out. Meanwhile, he's pretty busy with stuff that, in his words, actually pays, so he doesn't know when they will be available again.

 

can i get a copy???

 

Not from me. I paid for the application and I'm sure that would be a licensing violation. Besides, he issues a registration code upon purchase that I think is good for only one machine.

 

On the other hand, it might slow down your speed so that you spend more time driving in the mpg "sweet spot."

 

Hi All,

Besides aero drag and rolling resistance, there is also conducted heat losses. In cold weather from the cabin, that the heater has to replace, and also from the radiator. I noticed a few mpg bump in wet weather when I started blocking my top grill openings. I think the top opening acts like a knife edge to guide the water right to the radiator, the hottest part of the radiator, which then gives up the most amount of heat.

 

Hi Dngrsone,

Heat flows from hot to cold. And the bigger the temperature difference the bigger the heat flow. So, a 180 F radiator will flow allot of heat into a 38 degree raindrop, and the more rain drops, the more heat will flow. Rain is allot more dense than air, and stays in contact with the radiator metal for a longer period, even to the point of evaporation. The heat of evaporation is dramatically more than the heat required to heat the water up to 185 F from 38 F.

It all adds up. I run the top grill block year round below 100 F.

 

In addition to energy losses at the front of the tire --squeegee action, perhaps some infinitesimal rising up a miniscule water hill pushed in front of the tire (At some point the rising would result in hydroplaning), I suspect that sideways horizontal splashing, and lifting/throwing of water behind the tire -- the reason we buy splash guards -- also represent a transfer of energy from the vehicle to rain water on, or formerly on, the road surface.

 

Yeah, I've read the info about blocking with pipe wrap and installing a engine block heater, but by the time I get off my a$$, it will be 105°F. I am sure that if I had an EBH, I would try to drive away without unplugging it in the first week. :doh: