chuffpdx
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Re: Air Speed Indicator

Fri Jun 04, 2010 3:01 pm

Bicster wrote:Nissan needs to drop some new info fast, before we all go insane.
Aye, I thought it was just me. :D

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Nubo
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Re: Air Speed Indicator

Fri Jun 04, 2010 10:30 pm

Bicster wrote:Nissan needs to drop some new info fast, before we all go insane.
Haha! I suppose you're right! :)
I noticed you're still working with polymers.

Rat
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Re: Air Speed Indicator

Sun Jun 06, 2010 10:06 pm

I think an air speed indicator is a pretty silly idea since the only thing it is useful for is to tell you your power consumption, and there is already a gauge that does that. Even if you knew the air speed, that would only make a difference if it was high and steady in one direction, and you were driving a long distance in one direction more or less with or against the wind (not orthogonal), in which case you probably already know the prevailing wind direction. If you want one, though, have at it, but I would be astounded if Nissan puts one in. Having said that, it does make a difference in some cases, as I found out by personal experience. When my wife and I drove from the Bay Area to Santa Barbara down 101 a few years ago in her Acura TSX I kept a close eye on the mileage indicator and was able to keep it just over 30 MPG. Coming back in the same car, driving style (no rush), and route I couldn't. It stayed at about 28.5 max. The difference is that prevailing winds along the California coast come from the NW (tail wind going out, head wind coming back). For most of us most of the time, though, we are turning so often and the winds are shifting so often that it all averages out anyway.
2011 SL down to 9 capacity bars
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Nubo
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Re: Air Speed Indicator

Mon Jun 07, 2010 2:36 pm

Rat wrote:I think an air speed indicator is a pretty silly idea since the only thing it is useful for is to tell you your power consumption, and there is already a gauge that does that. Even if you knew the air speed, that would only make a difference if it was high and steady in one direction, and you were driving a long distance in one direction more or less with or against the wind (not orthogonal), in which case you probably already know the prevailing wind direction. If you want one, though, have at it, but I would be astounded if Nissan puts one in. Having said that, it does make a difference in some cases, as I found out by personal experience. When my wife and I drove from the Bay Area to Santa Barbara down 101 a few years ago in her Acura TSX I kept a close eye on the mileage indicator and was able to keep it just over 30 MPG. Coming back in the same car, driving style (no rush), and route I couldn't. It stayed at about 28.5 max. The difference is that prevailing winds along the California coast come from the NW (tail wind going out, head wind coming back). For most of us most of the time, though, we are turning so often and the winds are shifting so often that it all averages out anyway.
It's just those type of highway cruise scenarios where maximizing range could be most important. Consider an EV will be more affected than an ICE, due to its inherent efficiency. ICE already wastes a lot of energy, so the impact of adverse winds is a smaller percentage of the total. See the charts presented elsewhere for range vs speed for EVs. ICE cars are influenced, but nowhere near to that degree.

Wind does not have to be direct in line of travel to have an influence. As a cyclist, I'm keenly aware of the difference that even a quartering wind can make. And I spent a week in May getting pushed southward by those wonderful coastal CA winds! :)

In terms of information, yes you do have power consumption, although from pictures of the display, the resolution of that information may be less than ideal. On the other hand, people tend to drive at a set speed. Knowing the nature of the wind influence would help to choose a better speed in a rational manner rather than reacting to increased power consumption whose cause (and therefore mitigation) may not be immediately apparent.

But the one thing I didn't think about is that, while planes are almost always traveling more or less directly into the relative wind, cars are not -- as you point out. What that means for my airspeed indicator fantasy is that the pitot tube would not be accurate for side winds. :oops:

Guess I can make due with a bit of string taped to the nose. :lol:
I noticed you're still working with polymers.

BrendanDolan
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Re: Air Speed Indicator

Mon Jun 07, 2010 3:28 pm

Nubo wrote:
But the one thing I didn't think about is that, while planes are almost always traveling more or less directly into the relative wind, cars are not -- as you point out. What that means for my airspeed indicator fantasy is that the pitot tube would not be accurate for side winds. :oops:

Guess I can make due with a bit of string taped to the nose. :lol:
To be fair, an airplane on has a 1 in 360 chance of flying "directly" into the wind. Depending on your route of flight, it's common to never have a tailwind or a headwind. Only time you are generally going to have a headwind is on take off and landing. Everything else is fair game.
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AndyH
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Re: Air Speed Indicator

Mon Jun 07, 2010 4:35 pm

BrendanDolan wrote:To be fair, an airplane on has a 1 in 360 chance of flying "directly" into the wind. Depending on your route of flight, it's common to never have a tailwind or a headwind. Only time you are generally going to have a headwind is on take off and landing. Everything else is fair game.
And there's no guarantee that we'll have a headwind even during takeoff and landing - unless we're using a huge chunk of pavement, a beautiful grassy aerodrome, or an aircraft carrier. ;)

Wind affects all vehicles regardless of what turns the wheels - so does cold weather. We don't notice the affect of the wind or cold as much in an ICE because most are seriously over-powered.

Since aero drag is probably the most significant user of power above 45mph, an airspeed input would allow a driver to decrease their road speed in a headwind to reduce energy use, and increase their road speed if they want to take advantage of a tailwind.

Geeky but useful for efficiency nuts. :D

palmermd
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Re: Air Speed Indicator

Mon Jun 07, 2010 4:45 pm

AndyH wrote:Since aero drag is probably the most significant user of power above 45mph, an airspeed input would allow a driver to decrease their road speed in a headwind to reduce energy use, and increase their road speed if they want to take advantage of a tailwind.

Geeky but useful for efficiency nuts. :D
Why again to we need the airspeed indicator? We already have a speedometer and an amp-meter. If you are drawing more than normal amperage at a given road speed, then slow down because your either going uphill or there is a headwind. Inclinometer would probably be less expensive to implement and be more accurate. It might even be built into the car already. I just don't see what is gained by adding this instrument.

ps 1/360 chance of being within 1 degree of a perfect headwind...you have a 50/50 chance of being within 180 degrees of a perfect headwind.
Michael

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KeiJidosha
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Re: Air Speed Indicator

Mon Jun 07, 2010 5:11 pm

Interesting discussion. I just finished a round trip from LA to San Francisco with beginning and ending locations at ~200’ elevation. Prevailing winds were 280@15G29 on the way up and 270@12 coming back. I added up used state of charge and difference was 7 % higher going North with a slower average speed.

The other thing to consider is elevation. Even with tail wind southbound on San Marcos pass into Santa Barbara, I was down to 5% remaining at the top of the pass. Back up to 15% 10 miles later in Santa Barbara. I found elevation costs me 4-5% /1000 feet of elevation. I’ll be interested to see if elevation is part of LEAF navigation system. Lakeview Terrace to Mount Wilson is only 30 miles, but it’s 5,000 vertical feet. Highland to Big Bear is 35 miles and 6,000 vertical feet. Suggest Quick Charger at Hwy 18 and 210 for the skiers.
- 2009 BMW MINI E > 2013 Honda Fit EV > 2017 Chevy Bolt EV
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AndyH
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Re: Air Speed Indicator

Mon Jun 07, 2010 6:08 pm

palmermd wrote:Why again to we need the airspeed indicator? We already have a speedometer and an amp-meter. If you are drawing more than normal amperage at a given road speed, then slow down because your either going uphill or there is a headwind. Inclinometer would probably be less expensive to implement and be more accurate. It might even be built into the car already. I just don't see what is gained by adding this instrument.
Certainly - 'need' it's not. :) The inclinometer can go to sleep when driving in Kansas. ;)

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planet4ever
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Re: Air Speed Indicator

Mon Jun 07, 2010 7:22 pm

BrendanDolan wrote:
Nubo wrote:
But the one thing I didn't think about is that, while planes are almost always traveling more or less directly into the relative wind, cars are not -- as you point out.
To be fair, an airplane on has a 1 in 360 chance of flying "directly" into the wind. Depending on your route of flight, it's common to never have a tailwind or a headwind. Only time you are generally going to have a headwind is on take off and landing. Everything else is fair game.
Gee, Brendon, what Nubo said sounded right to me. I don't know much about wing aerodynamics, but I had the impression a plane would be in danger of crashing if there wasn't a net airflow from front to rear. In fact if your ground speed is 100 MPH and there is a 90 degree crosswind of 50 MPH, wouldn't you be flying only 30 degrees off from directly into the effective wind? I'd call that "more or less directly into the relative wind."
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

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