SoCal LEAF & EV Gathering, Y7 - Finished - 19 Aug 2017

[GRA]

Because they find they do not "need" it, and the rinky-dink part sits unused.
Much better that way than to invest the R&D required for a spiffy part that is expensive and then rarely bought and even less often used.

Seems like it would work the other way, for a rinky-dink afterthought - most people would only choose to buy it after finding they need it, whereas a retracting sunshade would most likely be built-into the car. It's not as if Tesla doens't bundle unwanted options with desired ones: having to pay $5k for A/P just to get ACC being a case in point.

That makes it much worse -- force everybody to pay for a part that few care about.

Sure it's worse assuming that it can't be added afterwards, but that's exactly what every automaker (including Tesla) does, to boost their profit margin. The ideal would be to offer it and every other option a la carte.

[tbleakne]

Good turnout and conversation at EV Breakfast yesterday, Aug 5. In addition to all the discussion about Model 3, there was quite a bit of interest in the Eclipse Mon Aug 21. Jason is going to OR, Sparky, Mark Z, and myself are going to ID. May we all have good clear weather, clouds not allowed.

At the previous breakfast, talking about the eclipse, some opinion was expressed that the Earth's axial rotation was the dominant factor in the speed that the Moon's shadow moves across the country. I was skeptical, so I put on my physicist's hat. My calculations are rough, taking some approximations to keep math simple and avoid 3D vectors which are hard to visualize:

R, lunar orbital radius = .238 10^6 miles
2 Pi R, orbital circumference, = 1.50 10^6 miles

We choose a reference frame centered on the Earth-Moon system, so we can ignore their common motion about the sun, which is almost 100 10^6 miles/hr relative to the Sun. One Lunar month, new Full Moon to next Full Moon, is called the Synodic Period.

T = (Lunar Synodic Period = 29.5 days) * (30 * 24 = 720 hrs/mo) = 708 hrs
Lunar contribution to shadow speed = 2 Pi R/T = 2,120 mi/hr.

Earth rotational speed at Equator = 24.5 10^3 miles/24 hrs = 1,037 mph.

If we look down on the system at Eclipse from above the North pole, we see the Sun, Moon and Earth all in a line, with both the Moon's orbital motion and the Earth's rotation counterclockwise. Note, at this time, the Earth's spin and Moon's motion are in the same approximate direction, so the Earth's spin reduces the speed at which the Moon's shadow moves across the surface. We apply some correction factors to both speeds:

Because the Earth is farther from the Sun than the Moon at a New Moon, the speed of the Lunar shadow is amplified by the ratio of their distances (in 10^6 miles):
(98 + .25)/98 but we can ignore this.

The local latitude determines how far one is away from the Earth's axis, and hence how much speed you have from the spin. It does not affect the Lunar speed. Latitude(Rexburg, ID) = 44 deg,
Cos(44 deg) = .72

Finally, there is the local time of day. If the sun is not directly overhead, the shadow will be elongated by its projection on the surface, an enlargement of 1/Cos(angle from zenith). The speed of the shadow along the surface will be affected by east-west tilt, but not north-south tilt.

In Idaho, Eclipse Totality is at 11:30 am MDT, 10:30 MST, 1.5 hrs before Noon.
Cos( 360 * (1.5/24) = 22 deg ) = .92
This factor reduces the spin speed while amplifying the lunar speed.

Putting these all together, we have:

Net speed of shadow measured along Earth's surface =
Moon's contribution - Earth spin contribution
= (2,120/Cos(22)) - (1,037 * Cos(44) * Cos(22)) =

2304 - 687 = 1620 mph

Again, this is only approximate, since the angles interact somewhat, but it gives the idea.

[GRA]

I thought I had a tendency to go OT, but enjoyed the explanation!

[GRA]

Deleted duplicate post.

[garygid]

We had 15 bodies attending at the Golden Corral, with lots of good conversations.
Some people arrive around 8, others mid morning.

If anyone has difficulty with transportation, please let us know, and we can try
to find some ride-sharing arrangement that might be useful.

Our next Gathering is on the 19th of August, at the Hometown Buffet on 17th
in Santa Ana.

[garygid]

Note: This coming Aug 19th, the HTB Gathering will be the last in our 7th
year of Gatherings. Three weeks later, skipping the holiday weekend on
September 2nd, we begin our 8th year of Gatherings on Sep 9th at the GC.

[TonyWilliams]

You don't have to skip Sep 2 to get your EV fix!!!

Our Grand Opening of operations in California will be Saturday, 2 Sept 2017 from 12 noon to 4pm.

Rain or shine!!!

Bring your Electric Vehicle (EV) and a printed copy of the Eventbrite ticket (linked below) to be entered to win hourly drawings.

Please park EVs only in the alley behind our shop. Gasoline powered cars, please park in front.

Live music, beer and food on site. This event is in conjunction with Stumblefoot Brewing Co. and EV West.

Quick Charge Power LLC
1780-104 La Costa Meadows Drive
San Marcos, CA 92078

760-798-0342
844-EV-PARTS

https://www.eventbrite.com/e/grand-open ... 6888481441

Thanks,

Tony Williams

[TonyWilliams]

We are up to 75 registered. Food, booze, music, and EVs

https://www.eventbrite.com/e/grand-open ... exshreclip