Studio711.com – Ben Martens

Launch Windows

We have been excitedly following the Artemis 1 mission as NASA prepares to send humans back to the moon. That coupled with all the SpaceX launches we’ve watched led Elijah to ask how launch windows are calculated. Instead of guessing at the rough idea, it seemed like a good opportunity to learn something.

For something like a trip to Mars, it seems more obvious why there would be a launch window. If the two planets are on opposite sides of the sun, the trip would take much longer than if the two planets are close together. JPL has page that explains this and here’s an animation from the Wikipedia entry for “launch window.” In this example, earth is blue, Mars is green, and the Mars lander “InSight” is purple. The timing of the launch is critical to get the correct trajectory to Mars and the launch window only opens every 26 months.

(Side note: InSight has been collecting data on Mars for four years and we’re within days/weeks of the mission ending. The solar panels have gotten so covered in dust over the years that it barely has enough power to even communicate with the orbiting satellites. You can read more about the end of life preparations on the NASA site.)

But what about launching to low earth orbit? It turns out there are a lot of factors which are listed in an article from Kennedy Space Center:

  • When meeting up with an object like the space station or aiming for launching a satellite in a specific spot, the timing is important for the same reasons as described above.
  • Atmospheric conditions (e.g. wind and temperature) can impact the performance of the rocket and how much fuel will be burned.
  • Launching a few minutes early/late can require extra fuel to adjust the trajectory. How much extra fuel is available when the other factors are taken into account?
  • Collision avoidance is included to give the rocket the best chance of reaching its goal without hitting any space debris.

All these factors (and more) need to be analyzed for all possible launch times within the window to ensure mission success. Loading more fuel on board might be one way to expand the launch window, but that can have other effects on the mission. Everything has to be balanced for success.

benmartens November 28, 2022 Science

Visited States

One of the main goals of this blog is to document my life. When I wrote the National Parks post a couple of weeks ago, it got me thinking that I should make a similar post about all the states that I’ve been to. LONG time readers might remember that I did this back in 2003, but I’ve added a few more since then.

The states are a little trickier because doesn’t it count a little different if I live in a state for 10 years versus stopping in a state for a 2 hour layover? I decided to break it down into four categories:

  1. I lived there. (Green)
  2. I visited there. In most cases this means I spent at least one night there, but in a couple days it just means I spent a full doing tourist activities and then slept across the border. (Purple)
  3. I drove through the state (Yellow)
  4. I stopped for a layover (Blue)

I was debating whether to include the “layover” category at all because it hardly seems like it should count, but it turns out that there aren’t many states in that category anyway.

By my count, I’ve been to 39 states + Washington DC if we ignore the layover states. Holler if you know of anything I’m missing on here!

If you want to make your own map like this, check out mapchart.net.

benmartens November 24, 2022 Travel

Xfinity Mobile – 16 Month Review

Time flies when you’re… saving money? It’s been 16 months since we ditched Verizon and went to Xfinity Mobile. As a quick recap, Xfinity Mobile uses the same cell network as Verizon but it’s cheaper and lets you easily switch your plan from month to month with no contract. Because it’s Xfinity and because the deal is so good, it feels like there should be a catch… but there’s not.

For the last 16 months, we’ve averaged $25.78/month total for our two lines. Not per line. Total. Granted we use a small bandwidth plan of 1GB shared between the two lines per month, but for our usage, that’s fine. In those months when we just use the 1GB, our bill is just under $20. We had one month where we bumped up to 3GB and another where we bumped up to both lines with unlimited data. If we had stayed with Verizon, and if Verizon hadn’t increased prices over that time (HAHAHA), we would have spent $78.50/month including my 20% employer discount. So we’ve saved $843.52 or over $50/month and our service has been the same.

To make it even better, the cost for the Xfinity Mobile plans has gone DOWN over time. It used to be $40/line/month for unlimited data but now it’s only $30/line/month. So if/when we change up to that again in the future, it will be an even easier decision and that’s getting cheap enough where I wonder if we should just use that all the time.

If you have Xfinity internet, give Xfinity Mobile a hard look. Unless they don’t support the phone you like, I can’t think of many reasons to not use them.

benmartens November 17, 2022 Commentary

Battery Backups

We don’t lose power a lot here anymore, but we have a lot of power flickers. Those rapid shifts in current can be bad for electronics, not to mention that it’s annoying when I’m in a meeting and my computer reboots because the power blipped a second. I started protecting my equipment with battery backups and now I have five of them spread around the house:

  1. My home theater is all on one. When the power goes out, my projector, Xbox, and sound system keep running for a while.
  2. Our home networking gear is all on a bigger unit than it needs to be. I can run our cable modem and WiFi for about 45 minutes. This is helpful not just for keeping the modem from resetting in a power blip, but it also lets me continue my work meetings for a while even if the power goes out.
  3. My main desktop machine and monitors are on one.
  4. Our downstairs TV is on one.
  5. The most recent addition was one for the 3D printer. We had a power blip in the middle of a long print and that meant I had to start all over.

These units give me a little piece of mind about protecting the units from changes in voltage but they’re also nice to smooth out the blips. What I really want is a whole-house system that smooths my power and provides some battery backup but those are not really targeted at home users yet. I expect that will change over time with all the research going into battery tech.

I have a mix of devices from CyberPower and APC, but most of them are either the big 900 watt units or the smaller 550-600 watt units. I like to put a Kill A Watt meter on whatever I’m going to buy the backup for to see how many watts I need and then I give it plenty of headroom (like 2-4x). There are calculators online that will help you translate all that into runtime, but like I said, in most cases I’m trying to protect against the 1-5 second outages so as long as I have a few minutes of runtime, that’s enough.

These battery backup devices only last a few years before the battery dies. The battery is a major component of the cost so in the past, I’ve usually replaced the whole unit to avoid frustration, but with five of them in the house, that’s a lot of extra unnecessary replacements. In the last power outage, I discovered that two of my devices had batteries that wouldn’t sustain the load anymore. I replaced one of the big 900w batteries and now the unit works great! The old batteries take some work to dispose of properly but I had that problem when I’d replace an entire unit anyway. I need to get better about remembering to periodically unplug each of these units from the wall while things are running to ensure that the battery is still good. Some of them do a self-test but it doesn’t seem to always catch bad batteries properly.

These units have other benefits too. When the power goes out for longer than a few seconds, I walk around turning most of the units off so save battery power. I can run lamps and charge phones for hours with them and I’ve even though about taking one of them camping when we’re off grid for a long time.

benmartens November 14, 2022 Gadgets

Ninjago Sword Prop

As we approached Halloween, we went through a lot of ideas for Elijah’s costume. Since we haven’t done trick-or-treating for the last couple of years, we decided to let him get an actual costume. He chose to be the green ninja from Lego Ninjago. I couldn’t resist making part of his costume so I set out to make a dragon sword to go with it.

I wouldn’t have gotten far if I hadn’t found an existing model, but luckily Thingiverse came through for me. I pulled that model into Fusion 360 and spent hours trying to figure out how to cut it nicely on the CNC machine without taking forever. I was able to apply a lot of learnings from my Luther Rose project.

The final product was carved out of a scrap 2×4 and I did it in two separate halves. If I had it to do over again, I think I would learn how to program in a cut that I can flip over halfway through because the seam between the two pieces was visible even in the finished product.

Once the pieces were glued together, I applied a few coats of a filler primer with sanding in between. The sanding took a long time with all the nooks and crannies. Thankfully, Elijah got interested in the project at this point and helped with the sanding.

We finished it off with a couple coats of high-quality gold paint. The final product looked amazing! It makes me want to do another one at the biggest scale that my CNC could handle…

benmartens November 10, 2022 Maker, Woodworking

Choosing An EV With Enough Range

Welcome to another Tesla Tuesday!

Range is a key factor when picking an EV. Until superchargers are as ubiquitous as today’s gas stations, EVs do require extra planning. So how much range do you need?

For normal daily use, the only factor to consider is whether you will comfortably make it home at the end of the day so it can charge overnight. I underestimated how much I would love knowing that my “tank” was full every single morning! On a road trip the range can impact how many stops you make along the way.

Just like in a gas car, your driving style can dramatically impact your range. We average around 250 Wh/mi (watt hours per miles) which means our 75KWh battery is good for 300miles. The EPA estimated range is 330 miles, but that number always seems to be high for all cars.

As the car gets older, the batteries are going to lose some effectiveness. There are lots of studies about this, but data suggests that we’ll lose 5% of our range after 50,000 miles and then another 5% by the time we hit 150,000-200,000 miles. At 50,000 miles, our range will be an estimated 285 miles of real-world driving.

Most current battery technologies do not like to be charged up to 100% or drained to 0% (though Tesla has some models that do like to be charged to 100%.) The Tesla manual suggests charging to 90% and not draining below 10% for regular use. This knocks our 285-mile range down to 228 miles.

It’s not just driving that will impact your range. The car is using battery all the time. Teslas all can record from four cameras around the car while they are parked, and your battery management system might be running various fans to heat or cool the battery. If your day involves a lot of sitting in parking lots, plan for another one mile of loss per hour. There’s also a feature called “Cabin Overheat Protection” which makes sure the temperature in your car never gets above 105. If you have that enabled on a sunny day, you’ll be losing battery to run the air conditioner. Let’s assume we’re parked in the hot sun at work all day and knock off another 15 miles. That brings our example down to 213miles.

Heating and cooling the passenger compartment can use a significant amount of energy too so you’ll want to build in some buffer for that as well.

We put about 75-85 miles per day on the car so ~200 miles of range is plenty. It gets charged up every night and we’re ready to go the next day. The only time I really think about range is when we’re taking a longer trip.

So why am I sharing all this? It may sound like I’m hating on EVs, but my goal is to encourage you to get the biggest battery you can get if you’re thinking about an EV. Even if you’re only planning to use it for your normal daily routine, take your normal daily mileage and double it. Use that number when you’re considering various vehicles. Assume you’re only going to comfortably get ~1/2 to 2/3 of the EPA rated range.

We don’t think about this as much with gas cars because it’s easier to stop and fill them randomly. But on the flip side, if current battery ranges are more than enough for almost everyone’s daily commute, would the market really going to pay for even bigger batteries? What’s the incentive for car companies to shove bigger batteries in the car when that’s already a huge part of the cost of the car? A better fix is getting people to realize that they have more than enough battery for daily use and getting the fast-charging network built out more for long trips. This whole post will probably feel silly in 20 years.

benmartens November 8, 2022 Electric Vehicles

National Park Passport

Did you know that you can get a passport book and collect stamps at the national parks? There are various options available at americasnationalparks.org and it seems like a neat idea that we might get for Elijah.

That got me thinking about all the national parks that I’ve been to. Thanks to Mom directly helping to create this list and for scanning in lots of old slides and photos that I used as references.

  • Shenandoah National Park (1989)
  • Gateway Arch National Park (1989)
  • Mammoth Cave National Park (1992)
  • Badlands National Park (1994)
  • Rocky Mountain National Park (1996)
  • Gettysburg National Park (1998)
  • Acadia National Park (1999)
  • Everglades National Park (2003)
  • Mount Rainier National Park (Many times starting in 2006)
  • Olympic National Park (2009)
  • North Cascades National Park (2010)

I’ll also include Indiana Dunes National Park, but I was there long before it became a national park in 2019.

The full list of “national parks” is huge because it includes landmarks, sites, trails, memorials, rivers, gardens, towers, islands, etc. I restricted the above list to anything with an official name that ends in “National Park”, but here are some other places I’ve been that don’t fall into that category:

  • Frederick Law Olmsted National Historic Site/Niagra Falls (1993)
  • Mount Rushmore National Memorial (1994)
  • Pictured Rocks National Lakeshore (1998)
  • I visited many different DC sites on two separate trips in 1998. One was with my school and the other was with my family.
  • Mount St. Helens National Volcanic Monument (Many times starting in 2007)

The trips before 2006 were family trips. Those trips started off in a tent and then eventually moved to a pop up camper. The camper felt so fancy because we had a dry place to hang out as a family when it rained and there was a fridge so we could avoid dealing with ice and coolers! (Thanks to Mom for apparently taking both pictures.)

benmartens November 3, 2022 Family, Outdoors, Travel

Optimal Efficiency In A Tesla

Welcome to another Tesla Tuesday!

When driving a car powered by a standard internal combustion engine, the speed that gives you the best fuel efficiency is somewhere shortly after the point where you can cruise in the highest gear. That’s generally around 40-45 miles. But electric vehicles don’t have gears, so what speed can I drive if I really want to get the most range?

The short answer is that somewhere around 25-30mph gives optimal range, but the full answer is more complicated.

Other than driving speed, one of the biggest factors is how much air conditioning or heating is being used. Heat in a traditional car is free except for the blower motor, but in an electric vehicle, you pay to generate both hot and cool air. It’s a battery load that varies with temperature, not speed. Other electric loads such as headlights and wipers along with things like tire inflation, elevation, wind, and extra weight can all play a part as well. Most tests are assuming that HVAC is not used and that all the other factors remain constant. Real world values will vary.

Tesla did a blog post back in 2008 about this topic with the original Roadster. Unfortunately the images don’t load for that post anymore. They have an updated post from 2012 when the Model S was coming out and that does have all the charts available.

Another chart that I found with an image search shows a similar curve for the newer Model 3.

A post on cleantechnica.com does a breakdown of how the Model S range varies with the outdoor temperature. They pulled a lot of real world data donated by owners to generate this chart. It shows how much range can be lost when it’s cold, mostly because of cabin heating. The falloff in cold weather performance is one clear area where EVs lag behind traditional vehicles, but if you go look at Norway (a place we’d all agree is generally “cold”), more than 80% of their new cars sold are EVs. The whole country is transitioning to it. So while this is something to keep in mind, it’s far from a blocker for adoption.

The curves in these charts are generally more interesting than the actual y-axis values because those values will depend on your specific model. And while the shape of these curves is pretty consistent across the Tesla lineup (except maybe the Model X which is huge), they’re no the same across brands. You’ll generally find that there aren’t many cars that sip their battery power more efficiently than Tesla. Their experience really pays off in that category.

A lot of this data is available because Tesla is collecting so much of it and it can be easily shared/collected for these studies. These same laws of physics apply to traditional cars too, but we’re a lot less conscious of it because we can’t see the data as easily. I’ve never heard anyone ask “How much range did you lose when you changed your rims?” or “How much range do you lose because you added running boards to your truck?” But with a Tesla, it’s relatively easy to measure all these impacts.

So now I have a car that’s fun to drive, cheap to operate, and spewing out huge amounts of data! Win win win!

benmartens November 1, 2022 Electric Vehicles

Getting Rid Of Junk Mail

Like most of you, we get lots of junk mail. It’s kind of absurd. It all just goes straight in the recycling and aside from wasting my time, it feels like a waste of resources too. I’ve used Catalog Choice in the past to try and stop some catalogs. (I never kept track of the ones I tried to stop so I don’t know if it worked.) Now I’m trying six months of Paper Karma. I’ve been throwing junk mail into a box for a couple months so that I can make good use of my subscription time for the service.

The way the app works is that for every piece of junk mail you get, you scan it with your phone as a quick way to search for the sender and then they take care of contacting the company to try and get you removed from their mailing list. They have direct access to the recipient lists for quite a few companies, but for others, they have to take slower methods of notification that may or may not work. I scanned in the whole pile shown in the image and probably about half of them have a “success” status already which means that I shouldn’t continue to receive those mailings. It’s not a guarantee, but even if it cuts my junk mail in half, I’ll be happy.

benmartens October 27, 2022 Commentary

United States Fully Electric Vehicle Sales

Welcome to another Tesla Tuesday!

In the last three months, one in every 26 cars sold in the United States was a Tesla.

Staggering! In the third quarter of 2022, 6.1% of all US auto sales were full electric vehicles with about two thirds of those being Teslas and most of the Teslas are either the Model Y or the Model 3. With the way things are going now, it is looking like the fourth quarter will end with Tesla will be one of the top 10 auto brands by quarterly sales in the United States. They’re growing very rapidly while traditional auto maker sales are still roughly flat.

Electric vehicles are very common in my area. I pulled up to a stoplight the other day driving our Model Y and of the six cars waiting at the light with me (all going the same way, not spread around the intersection), FIVE of them were Teslas. Ford is coming on strong too and looks to be in solid possession of second place. I know that I’m living in a bubble of EVs so while the percentage of EVs being sold is huge out here, I didn’t expect it to average out to 6.1% for the whole country.

There’s a long way to go as the country shifts to EVs, but it’s awesome seeing so many people choosing this on their own and not being forced into it by legislation. EVs might not be for everyone yet, but they’ve certainly earned serious consideration in every car purchasing decision.

benmartens October 25, 2022 Electric Vehicles