Texas: Speed limit 100 mph

[aerohead]

My jaunts out to west Texas have led to an observation.
(1) It's really windy there (i.e. wind farms).
(2) The posted speed limit is 75-mph.
On any given day,traffic may be driving 75-mph into a 25-mph headwind.
Below is a road load horsepower I extrapolated for a 1991 Honda Accord sedan.
It's a little womper-jawed but the data in accurate.( I could use a drafting table)

If you look at,say,the horsepower required at 100-km/hr vs 100-mph,you get an idea of the energy penalty from the geometric growth of aerodynamic drag (the area in yellow).
If we can legally drive in 100-mph air,we might want to reconsider the importance of body shape.Especially when you see American Quarter Horse Association Members pulling their horse trailers,with hay bales on the roof, at 100-mph.

[Frank Lee]

Especially when you see American Quarter Horse Association Members pulling their horse trailers,with hay bales on the roof, at 100-mph.

I drafted one of those ALL the way across North Dakota on a V-Max heading home from the Sturgis Rally. We were FLYING. I would never have gone that fast otherwise!

[wdb]

But diesel makes it all okay!

[ChazInMT]

Yeah, and remember that you get there faster, so you aren't driving as long....so it all works out even, you might be getting 10MPG instead of 15MPG but you are only driving for 2 hours instead of 3. So, yeah. Make sure you load the hay bales on the back of the trailer too, where it's easier to reach, because once they're up there on the roof, you'll get the same mileage wherever they go.

[redpoint5]

I actually believed the fallacy of everything working out equally by driving faster when I was younger.

I also believed the fallacy that it is more efficient to keep a house warm all day even when it isn't occupied than to turn the thermostat down when it isn't occupied. The misconception being that more fuel is required to bring the house up from such a cold temperature compared to the little amount of fuel required to maintain temperature.

Shortly after I held those incorrect beliefs, I took 9th grade physics.

[kach22i]

Originally Posted by redpoint5

I actually believed the fallacy of everything working out equally by driving faster when I was younger.

I also believed the fallacy that it is more efficient to keep a house warm all day even when it isn't occupied than to turn the thermostat down when it isn't occupied. The misconception being that more fuel is required to bring the house up from such a cold temperature compared to the little amount of fuel required to maintain temperature.

Shortly after I held those incorrect beliefs, I took 9th grade physics.

Don't go discounting all of your early intuitive misconceptions, there is always more to the picture.

Thermal Mass is the key phrase here. Associated terms: passive solar, earth-shelter, adobe, radiant heat etc..........are all expressions or examples of this in action.

Your comfort level is determined by more than air temperature. The rate at which energy leaves and or enters your body greatly determines how cool or how warm we feel.

I have an older house with thick/mass lath and plaster walls and if I let all that mass heat up (including furniture etc..), the A/C which I have at my disposal cannot catch up to the thermal flywheel already in motion - I'm screwed if I don't leave the A/C on all day on the hottest of days.

Think of the energy required to stop all that mass of a tractor trailer once it's moving, it's a different kind of energy but a much better visual to work with and it gets us back to our topic.

In Aeroheads example I think a safe conclusion is to avoid driving on windy days, at least into head winds. One action could be just to slow down on windy days, and I think the safest drivers already do this out of an sense of self preservation.

As for the hay-bail guys, I'm not in their world and suppose that I really would not understand.

[Frank Lee]

Nice thing about a flexible schedule is I've been known to wait for favorable wind direction before embarking on a long trip if the wind is really strong, and it often is here. Or simply wait for sunset at which time the winds often calm down. Other nice things about driving overnight are less traffic and less need for a/c.

I'll also adjust cruise speed to wind direction, slowing even more for strong headwinds and taking advantage of "free speed" for tailwinds, and big hills.

[basjoos]

Install an airspeed indicator and drive according to air speed rather than ground speed. For a given air speed, your ground speed will be lower in headwinds and higher in tailwinds. It also lets you find the best location to be in when drafting.

[ennored]

Originally Posted by basjoos

Install an airspeed indicator...

I've lightly looked at various anemometers and DIY wind speed/direction setups. Never found anything I thought was robust/elegant (simple yet effective) enough.

Did you actually do it?

(Love to know my airspeed on the motorhome, it's a huge part of my fuel consumption. Watching grass, trees, and flags helps, but doesn't quantify it.)

[aerohead]

Originally Posted by ennored

I've lightly looked at various anemometers and DIY wind speed/direction setups. Never found anything I thought was robust/elegant (simple yet effective) enough.

Did you actually do it?

(Love to know my airspeed on the motorhome, it's a huge part of my fuel consumption. Watching grass, trees, and flags helps, but doesn't quantify it.)

Here is a link to Aircraft Spruce and Specialty's airspeed indicator with MPH face plate.https://www.google.com/search?q=dwye...U5ZfMqyfsfM%3A
Along with a Pitot tube,you'd be able to register your airspeed up to 12-degrees of yaw (crosswind).
Dwyer makes a wind-seeking pickup head,that 'follows' the air.