Monday, August 31, 2020

Monday Mirth

It has proven impossible to stay on top of things well enough to have a post to write tonight, so as I try to do, a few things I've found or had emailed to me...

I know the feeling...

Herschel Walker referred to Donald Trump as a long time friend.  This is around when they met, when Herschel went to play for the USFL New Jersey Generals, which Trump owned, in 1984.  

There's a bright side to everything.  Can't make fun of his braces if they can't see them.  Of course, I have some land to sell to anyone who thinks kids will wear masks all day. 

That's all I ever find in my avocados, too! 

Sunday, August 30, 2020

One Out of Three Today

That's one out of three of the launches we expected.  Today was supposed to be dual launch of Falcon 9s from the Cape.  A Starlink launch this morning at 10:21 AM and the SAOCOM-1B satellite this evening at 7:18 PM EDT.  Over in Boca Chica, prototype SN6 was supposed to do a 150m hop today.  

When I checked in with SpaceX launches this morning, there was a notice that the weather yesterday interfered with prelaunch operations for the Starlink launch and it has been rescheduled for Tuesday morning, so the morning launch was off.  

As the day went by, I opened a tab on LabPadre where I've watched the majority of tests.  There was a mid-afternoon test where they got close to lighting the engine but aborted.  An apparent recycle that didn't involve sending crews to the pad and then nothing, so the hop was off.  

Luckily, the SAOCOM-1B launch went off without a hitch and it went as we had hoped for.  (That link is to the SpaceX mission video; here's some info on the SAOCOM-1B mission)  The launch trajectory went south, perhaps 10 degrees east of directly overhead, and then the booster returning to the Cape (Landing Zone 1) also went overhead and we were able to see the ~25 second long "entry burn" about a minute before landing.  

Going up on the left and coming down on the right.  Through the tens of Falcon 9 launches we've watched, this is only the second time I've seen this burn, and both the first time I've seen it in the daytime and the first time I've photographed it.  All this from my side yard. 

Due to the flight trajectory we got the launch sounds for a very long time, easily a solid six minutes, ending with the window-shaking sonic boom of the booster on return to the Cape.

We had rainy weather all afternoon but the clouds thinned just enough to catch part of the ascent and the last minute or so of the descent. 

Maybe 20 years ago, I heard a Space Shuttle launch manager say, "you have to get used to disappointment in this business" and that's still the truth.  We started out hoping to see three launches and consider ourselves lucky to have seen one as well as we did.  Next attempt at hopping SN6 will be tomorrow, 8 AM to 8 PM, CDT.  Next attempt at the Starlink launch will be Tuesday morning.  It's not like a long dry spell. 

Saturday, August 29, 2020

Let Me Be The First to Call Florida's Covid Outbreak Ending

With the disclaimer that I don't read enough other people to know if I'm the 900th to call it.  Probably not, though.  

I base this on a few numbers from the Florida state Department of Health.  I think the overall argument is easy to see.  Every single stat that I can get from the web site (and I'd like a lot more stats than I can get) is getting better.  This is the overall picture.  

Top left to bottom right: Emergency Department visits with influenza-like illness, then documented new cases.  Bottom left is Emergency Department visits with Covid-like illness and the bottom right is the Percent Positive for Laboratory Testing ("for" is a strange word there to me).  

Everything is getting better.  The ED Visits chart shows current numbers are under a third of what they were in early July.  New Cases are about the 35 or 40% of what they were.  

The time scale is different in the next plots, but the numbers are both moving in the right direction.  The two plots don't show the same sample; deaths seem to be from two weeks to months behind when a new case presents to the system, but the important characteristic is that deaths are declining rapidly.  

My county (Brevard) is in the lowest sixth of rates in the state, with a case rate of 1241 per 100,000, or 1.24%.  We haven't had a day with over 100 new cases since 8/8 and the last week has averaged 42 cases/day.  

The best read on this I've seen lately is one Irish posted several days ago - Lockdown Lunacy 3.0 - it's over on JB Handley's blog, but all the numbers in Florida are all pointed in the right direction.  Handley goes into Edgar Hope-Simpson's important work on influenza and seasonal patterns, which explain why the numbers in the northern tier of states were highest early in the year, and peaked later in the year in the southern tier.  The media made an enormous fuss over this trend, but it's what viruses do.  Irish biochemist Ivor Cummins gives a clear explanation of the seasonality in this short video.  Handley embeds the same video. 

Of course, lots has been learned in the last few months, both in our treatments of the virus and the knowledge of the virus itself.  Among the most interesting to me is the discovery that our T-cell immunity seems to be conveying immunity to this virus in most people.  That implies this coronavirus is genetically similar enough to other coronaviruses (mostly colds) we've been exposed to in our lifetimes.  That drastically drops the number of infections to achieve herd immunity to around the number of cases there have been.  The utter uselessness of the harsh lockdowns is interesting but not "new".  While that linked post is two months old, every study since then has reached the same conclusion.    

I also find it interesting that children apparently get the virus but don't spread it (more in Handley's post) and that so-called "super spreader" events have only occurred indoors.  One or two have occurred in events that had an indoor and outdoor component, but none are documented in outdoor events.  

Friday, August 28, 2020

NASA Just Snuck Out a Revised Cost Estimate on SLS

Ars Technica space reporter Eric Berger (and stick to space, would ya, Eric?) reports today that  NASA quietly upped the cost estimates on the Senate Space Launch System. 

"Already within my short time on the job, NASA is checking-off key milestones and marching swiftly toward Artemis I," wrote Kathy Lueders, who moved into the job after leading the Commercial Crew program. "That mission, the first uncrewed flight test of our powerful Space Launch System rocket and Orion spacecraft, is just a little more than a year away from launch."

Lueders next discussed preparations for a "Green Run" test of the SLS rocket's core stage this fall, possibly by the end of October. ...

After discussing this and other details, Lueders then rather casually let it slip that, "NASA also aligned the development costs for the SLS and Exploration Ground Systems programs through Artemis I and established new cost commitments." The new development cost for SLS rocket is $9.1 billion, she said, and its budget for the initial ground systems to support the mission is now $2.4 billion.

Back in 2017, the last re-plan said the costs would be $7.17 billion and the first launch would be "December 2019-June 2020."  As of now, the first flight is expected by November of 21.  At the best, that's a 17 month slip from 6/20 to 11/21.  SLS is the gift that just keeps on taking. 

It was only a few weeks ago when we found that each of the four main engines of the SLS would cost $146 Million a piece, or just shy of $600 million for the engines - not counting anything else on the rocket.  These are the same hardware design as the Space Shuttle Main Engines, designed as reusable engines.  At the end of each flight that $600 million will be tossed into the Atlantic.  As I pointed out in that May post, 

SpaceX has set a goal for the next version of the Raptor engine of $250 thousand.  The published thrust in a vacuum of the SSME is 512,000 lbs.  The stated thrust of the Raptor v2 is 250 tons, or 500,000 lbs. 

Not that a Raptor could directly replace an SSME.  It would require redesign of the system. 

What are the chances that the November '21 SLS flight will happen?  It's hard to know.  Certainly the major obstacle to be cleared is the "Green Run" test firing, but there have also been Covid-19 delays.  The Green Run, at Stennis Space Center in Mississippi, will be the first test of the entire hardware and "plumbing" system of SLS which will run the system for over eight minutes, the amount of time required for a mission.  

You might say, "What's the big deal?  These are Space Shuttle Main Engines; they're as well known as any engine that has ever flown, if not better.  All that SLS did was design in four instead of three and add some plumbing."  We can be sure both NASA and the contractors have simulated everything that can be simulated.  Unfortunately, that may not be enough.  As Berger points out:

Engineers familiar with testing large, complex systems for the first time say there is a low probability of a perfect test or a major structural failure. However, the highest probability is that NASA and Boeing discover some problems that will at least require several months to address before the core stage is deemed ready for launch.

It's not easy to correlate their simulation vs. reality experiences with the experiences I had in a completely different world.  I suspect the big picture is the same though: by this time, they've ruled out major failures that would blow up the booster on the test stand, but it may still be possible that they need to do design "tweaks" to get the system to work as desired.  If that "highest probability" outcome of having to do some redesign is what happens, the odds of a launch before the end of '21 drop to zero.  

SLS core on the test stand at Stennis Space Center.  NASA photo.


Thursday, August 27, 2020

Not Widely Reported - More Shots Fired Between Protesters and Property Owners

Hat Tip to the Blaze, I read that a group of BLM activists en route to Washington D.C. got into a disturbance with property owners in Bedford, Pennsylvania.  According to WTAE in Pittsburgh, the Pennsylvania State Police released the following statement. 

"The Pennsylvania State Police (PSP) Troop G Bedford station was contacted by a property owner on Monday, August 24 at 11:18 p.m. regarding a group of people in a private business parking lot. Troopers later learned the group was comprised of approximately 30 activists who are traveling on foot and in vehicles from Milwaukee, Wisconsin to Washington, D.C. At approximately 11:35 p.m. at the same location and before state police arrival, the property owners confronted the activists. The confrontation escalated, and gunshots were exchanged between the property owners and the activists.

"One of the activists was struck by birdshot from a shotgun. The man was treated and released from the Conemaugh Memorial Medical Center, 1086 Franklin Street Johnstown, Pennsylvania.

"A shotgun, shotgun shells, a semi-automatic pistol and 9mm casings were all recovered at the scene."

Note that was Monday night, so well in advance of the open conflict in Kenosha last night.  

As usual, it's not really known exactly what happened, and this story is particularly hard to figure out.  The WTAE article interviews representatives from the demonstrators, who (of course) act as if they're perfectly innocent choir boys and had nothing to do with causing trouble.

In a video posted early Tuesday morning to Facebook, marcher Tory Lowe said the group had parked to organize before they walked up an incline when a man emerged from a house and started shooting at them with a rifle, firing at least seven shots.

"He was like three feet away from us shooting and I told him there was a minister here," Lowe said in a video posted to Facebook.

Wait... firing seven shots from three feet away and nobody got hit?  That's strange.  Then the article goes on to say

It's important to note that in the video, the sound of a gunshot is heard before a person across the street emerges from their house and confronts the group walking down the road. You then can hear more gunshots, and at some point the people across the street can be heard saying something to the activists. In its first press release, state police said an argument happened and then gunshots were fired.

So the official story doesn't match the station's story and, as always, neither story may match the truth.  

The article at The Blaze goes into some other incidents before and after this incident.  They're a roving band of troublemakers crossing the country, from Milwaukee to DC.

Still, in light of the shooting I would say the evidence is that the "mostly peaceful protests" that have led to widespread property destruction as well as tremendous human suffering have gone to the next stage.  The Rubicon has been crossed and those people who are losing everything have started fighting back.  It's hard to imagine the Antifa/BLM side backing down at this point so I can only see it getting worse for the foreseeable future.

My blog brothers down at Gun Free Zone in Miami have linked to a Michael Bane blog post that seems to be worth reading.  I don't think I can add anything to his list except maybe to emphasize situational awareness, what your city is like, what your neighborhood and the next neighborhood over are like, from state level down to your neighbors.  Think about the things you've seen happening, like being harassed in a restaurant or having lights shined in your windows in the middle of the night, and decide how you're going to handle things.  Having a plan, any plan, puts you better off than the vast majority of the population.

By now, everyone has heard of this CNN story and seen the display.  “Fiery but mostly peaceful” sounds like it could describe a cremation.  A funeral pyre.

Wednesday, August 26, 2020

What Is That Strange Thing SpaceX is Building at Boca Chica?

That's a question that has come up a lot among the crowds who follow the various channels of updates from SpaceX watchers. calls them "Texas Tank Watchers" and sells merchandise with that on it. 

I've been watching this place for days, and don't really have a good feel for the positions of various things, but the construction can be seen on the far left in this view.

RGV Aerial photography, a guy who rents a Cessna 172 and pilot, then hangs out the window to take pictures gives this view from above.  

There's clearly a lot of rebar there, a pretty big hexagonal structure in the middle, and the rebar is forming large tubes inclined toward the center.   

Two sides quickly emerged in the debate: something related to hardware testing or a water tower to supply water for the launch deluge system.  To pick up the story from Teslarati:

As of almost two weeks ago, it was just shy of guaranteed that the concrete foundation SpaceX was working on would be wildly excessive for a water tower, turning it into a question of whether it would be a suborbital or orbital-class test stand for Starship.

Now, Musk has confirmed – somewhat surprisingly – that the foundation will ultimately support an “orbital launch mount” capable of hosting what will eventually be the largest and most powerful rocket ever built.

YouTube channel What About It? offers a rendering of one possible final result.  Looks plausible to me

With a diverter to help protect the reinforced concrete supports, since being hit with millions of pounds of thrust isn't good for concrete.  

A screen capture from RGV Aerial Photography might help you figure out the geometries of the different views. All annotations are mine.   

Back to Teslarati for some numbers

Barring additional changes, Super Heavy will be as tall as the entirety of a Falcon 9 or Falcon Heavy rocket – first stage, second stage, and payload fairing included. Powered by up to 31 Raptor engines, the Super Heavy booster will produce upwards of 72,000 kN (16,000,000 lbf) of thrust at liftoff – nine times the thrust of Falcon 9, triple the thrust of Falcon Heavy, and double the thrust of Saturn V (the most powerful liquid-fuel rocket ever to reach orbit). Combined with Starship, the full stack will weigh roughly 5000 metric tons (11 million lbs) fully fueled. For the purpose of static fire testing and final vehicle checks after ignition but before liftoff, a Super Heavy-class launch mount will need to withstand more than 7200 tons (~16 million lbf) of force.

Tuesday, August 25, 2020

Just How Wrong Was The Population Bomb?

Just short of two years ago, I wrote a piece on the 50th anniversary of The Population Bomb.  The 1968 best seller was different from your typical apocalyptic stories; it was supposed to be serious science by an actual scientist Paul Ehrlich.  As I said at the time:

Doomsday prophesy sells, and doomsday from someone with a handful of letters after their name (MS, PhD etc.) sells even better.  The future didn't turn out quite as dismally as Ehrlich suggested; he famously lost a bet where he picked a "basket of commodities" and bet that these five metals would go up in price in 10 years (1980 to 1990) - they declined in price an average of 57.6% while the  population increased.  Nevertheless, he influenced a generation or two of policy makers.

Ehrlich didn't just stop with a prediction that a basket of metals would be more expensive in ten years, he said there would be mass starvation in the 1970s and humanity would die off soon thereafter.  

Ehrlich prophesied that hundreds of millions would starve to death in the 1970s (and that 65 million of them would be Americans), that already-overpopulated India was doomed, and that most probably “England will not exist in the year 2000.”

In conclusion, Ehrlich warned that “sometime in the next 15 years, the end will come,” meaning “an utter breakdown of the capacity of the planet to support humanity.”

It's hard to be much more wrong than Ehrlich.  In contrast, University of Maryland economist Julian Simon published his book The Ultimate Resource in 1981.  He argued that humans were intelligent beings, capable of innovating their way out of shortages by many alternative means.  

I think the history of the intervening years has shown that Simon was closer to right.  Despite the adamant desires of environmental alarmists, there has been no mass extinctions of humans, nor have there been “hamburger wars” for food.  People have innovated our way out of scarcities. 

Marian L. Tupy is the editor of and a senior policy analyst at the Center for Global Liberty and Prosperity.  Together with Brigham Young University economics professor Gale Pooley, the two of them analyzed the two time periods, 1980 and 2017 (hat tip to FEE).  

In “The Simon Abundance Index: A New Way to Measure Availability of Resources,” we look at prices of 50 foundational commodities covering energy, food, materials, and metals. Our findings confirm Simon’s thesis. Between 1980 and 2017, the world’s population increased from 4.46 to 7.55 billion or 69 percent. Yet, resources have become substantially more abundant.  

It's almost as if each and every soul born in those 37 years came with some of the resources to support them.   Anybody who has witnessed (or given!) a birth or two can assure you none of the newborns come with supplies for all their needs, so that's not how it happened.  It came about by the diligent efforts of individuals around the globe creating human progress.

Ehrlich and Simon looked at inflation-adjusted prices of commodities. By our count, those fell by 36 percent. Taking that analysis a step further, we have come up with a “time-price” of commodities, which allows us to cost resources in terms of human labor. We find that relative to the average global hourly income, commodity prices fell by 64.7 percent between 1980 and 2017.

Second, the price elasticity of population (PEP) allows us to measure sensitivity of resource availability to population growth. We find that the time-price of commodities declined by 0.934 percent for every 1 percent increase in the world’s population. Put differently, over the last 37 years, every additional human being born on our planet appears to have made resources proportionately more plentiful for the rest of us.

Third, we develop the Simon Abundance Framework, which uses the PEP values to distinguish between different degrees of resource abundance, from decreasing abundance at the one end to super abundance at the other end. Considering that the time-price of commodities decreased at a faster proportional rate than population increased, we find that humanity is experiencing superabundance.

Finally, we create the Simon Abundance Index (SAI), which uses the time-price of commodities and change in global population to estimate overall resource abundance. The SAI represents the ratio of the change in population over the change in the time-price, times 100. It has a base year of 1980 and a base value of 100. Between 1980 and 2017, resource availability increased at a compounded annual growth rate of 4.32 percent. That means that the Earth was 379.6 percent more plentiful in 2017 than it was in 1980.  [Note: all bold added - SiG]

This post struck a chord with me because I've been reading Apocalypse Never by Michael Shellenberger.  Shellenberger was a celebrated environmentalist until he started saying the conventional green approach was hurting more than it helped.  For example, he started saying we couldn't possibly meet "green energy" needs without nuclear power.  In Apocalypse Never, he argues that the overreaction to climate change is causing damage, and while "climate change" might be a real problem, it's far from our biggest.  I'm only a quarter through the book and already in the first few chapters he's blown away some of the most common stories you hear, from the Amazon burning last year to plastic straws to the threats to gorillas in the Congo.  Time after time he shows how the first world's environmentalists are the problem.  I had intended to provide more detail in "book review" as I've done a few times, but I'll finish the book first. 

The myth of peak oil in one plot.  In 1980 we had only 27 years worth of oil left; 37 year later in 2017 instead of being without oil for a decade, we were down to only 46 years worth of oil left.  Say what?  One guy who has studied the Permian Basin in the Southwest US says it's totally reasonable to consider it a permanent source.  Essentially infinite.  Of course, what happened was that new techniques were developed to get oil out of the ground and that increased the amount that was recoverable.  All because the free market was allowed to function properly.


Monday, August 24, 2020

Starship SN6 Static Fires

SpaceX seems to be getting its processes down better at Boca Chica.  Earlier in the week (last Thursday?) they announced a road closure for a static fire test Sunday (yesterday).  Unlike SN5, which took several days with several aborts before they could achieve the static fire, yesterday they successfully static fired the Raptor engine for about four seconds

Thanks to new Blogger Editor, I can't even test that, like I used to, but it should start about 10 seconds before the ignition.  If that doesn't happen, you can advance it manually; the firing is it about 28:25.  Or see below.

The longer story is that they also had two aborts, followed by detanking the prototype and sending a team to the test pad to troubleshoot and fix the system. 

SpaceX’s first SN6 static fire test window – published by Cameron County in the form of road closure notices – was set for 8 am to 8 pm CDT (UTC-5), August 23rd a few days after the Starship’s cryo proof. The first test attempt began around 9:30 am but was aborted soon after as SpaceX employees returned to the launch pad to (presumably) troubleshoot. The second attempt began around 2:30 pm, leaving a little less than half the test window available.

Attempt #2 very nearly managed to extract a static fire, aborting possibly a second or less before Raptor ignition around 3:41 pm. Once again, SpaceX teams returned to the pad after Starship was detanked and safed, briefly inspecting the general location of the rocket’s Raptor engine before once again clearing the pad around 6:30 pm. At long last, Starship SN6 began a smooth and fast flow that culminated in the ignition of Raptor SN29 around 7:45 pm, just 15 minutes before the end of SpaceX’s test window.

I think it's fair to judge their progress by how fast they go through these tests, since the plan is take multiple launch hops for these prototypes.  This was the first scheduled day vs. for SN5 (my notes just say it fired successfully after several delays).  SN7.1 is another prototype to be destructively tested in the near future, and SN8 is going to be the next step closer to a full Starship prototype with nose cone and fins.  As for SN6, it's just getting started.  The scheduled date for its first hop test is Friday, with the next couple of days as potential backup days.

SN6’s first flight is expected to be an almost identical copy of Starship SN5’s highly successful August 4th debut, following the same 150m (~500 ft) parabolic trajectory. Filed before SN6’s August 23rd static fire, SpaceX has penciled in Friday, August 28th for Starship SN6’s own hop debut. Thanks to the fact that SpaceX was able to complete both SN6’s cryo proof and static fire on the first day of their respective test windows, August 28th is likely well within reach. Stay tuned for updates as Starship SN6’s hop debut schedule solidifies.

These are small steps along the path to a functional Starship prototype but they still feel historic.  It seems likely that we'll see a flight to about 12 miles up from one of the Starships within weeks (everything we've seen so far is just a prototype of the second stage).  It's possible we'll see the first prototype of the first stage, Starship Heavy, before the end of the year.  

Closer to home, we'll see the Argentine SAOCOM-1B satellite launch on Thursday evening at 7:19 EDT (2319 UTC).  I've written about this launch several times; it will be the first launch into a polar orbit from Cape Canaveral since 1960.  Finally, Saturday morning at 10:31, we should see another Falcon 9 launch the next batch of 60 Starlink satellites.  Those are the last launches with published dates at SpaceFlight Now.

Sunday, August 23, 2020

A Ham Radio Series 12 – Filters and Impedance Matching

 A few weeks ago when I talked about what I see as the fundamentals of RF engineering, I listed both of these and today I lump them together because they overlap so much in application.  An overworn saying in engineering is that “everything is a filter” in the sense that everything from a straight wire to any circuit you can imagine has an amplitude vs. frequency response that’s not flat (that is, the circuit doesn’t pass all frequencies equally).  Impedance matching circuits generally don’t have flat frequency response.  

Starting with the basics, filters are generally described with respect to the frequencies they pass rather than the ones they reject.  There are lowpass filters, highpass and bandpass filters.  The exception to that general rule are bandreject filters because it’s easier to describe what they’re rejecting rather than what they’re passing.   As their names imply, lowpass filters pass all frequencies below some critical frequency (usually called their cutoff); highpass filters pass all above their cutoff frequency, and bandpass filters pass a continuous group of frequencies around their design frequency while bandreject filters reject a continuous group of frequencies … .

There are many ways to make a lowpass filter, but as a conceptual aid, here’s a three element lowpass filter...

and here’s a three element highpass filter. 

Can you tell them apart at a glance?  A lowpass filter passes everything below some cutoff frequency.  Since DC is lower than any frequency, the lowpass should conduct DC and the coil in the series branch meets that requirement.  Likewise the highpass filter passes everything above some frequency which means it can’t pass DC, and the series capacitor blocks DC. 

Bandpass filters are more complex and come in different arrangements of parts (different topologies) depending on the percentage of the center frequency that they pass, often referred to as filter Q, defined as center frequency fo divided by bandwidth.  Usually written as 

Q = fo / BW 

If the value of Q is 10 or higher, filters are often designed as parallel resonant circuits coupled together.  A two element narrowband bandpass filter looks like this: 

The capacitors labeled Cm1 and Cm2 are impedance matching capacitors.  The designed (“native”) impedance of the filter is ordinarily nothing close to what you need and is typically quite a bit higher than your circuit.  The filter algorithm starts with the requirements for bandwidth and center frequency and you choose the inductor for the resonant circuits.   You’ll notice I called both coils L1 and both resonating caps C1; in two element filter like this, they’re typically identical.   The coupling capacitor, Ccpl, is ordinarily rather small, and I can’t recall one I designed where that wasn’t the smallest capacitor in the filter.   

If you’ve worked with cavity filters, they look like this schematically.

By contrast, if Q is less than 10 it’s considered a wide bandwidth BPF and the algorithms for design are different than the narrowband filter.  The wideband BPF is designed by first designing a lowpass filter and then resonating each of the elements in the filter. 

Filters have been designed differently over the years, and many methods remain.  In the early days of computer aided design, a new method called Modern Network Design came into being, in which everything can be designed from tables of prototype filters normalized to a cutoff frequency of 1 (radian per second, not cycle per second).  What the designer needs to do to select the filter type and complexity (how many parts it needs) and then convert the component values in the table to the frequency and impedance they need.  I started with that type of design and have stayed with it for my entire career.  It’s an extremely computerizable technique. 
Some of you might know that three element networks like the sample LPF and HPF above are sometimes called Pi networks, because the arrangement reminds people of the Greek letter Pi.  It’s also possible to implement these networks as a “T” network because it looks like... well, you know.  
Note that this is a lowpass because it has two series inductors and will pass DC.  The Pi and T forms are called duals of each other.

As a general rule, while there are two ways of designing the same lowpass filter, inductors tend to be bigger, more expensive and higher loss than capacitors, so the format I showed first is most commonly used.  That said, there can be other reasons to choose the T over the Pi; the most likely would be that you have the coil values you need for the T on hand while the value needed for the Pi would need to be ordered. 

It’s also possible to design a LPF that has only two elements; series coil, shunt capacitor.  That’s an L network, which we used in our definition of impedance matching and antenna tuners.  Although I didn’t mention it there, the Pi network is also used for impedance matching and having more parts extends the range of impedances it can tune.  

What if you want a filter to match between two impedances?  While the standard filter tables have different input and output impedances, you don’t have total control of the ratios.  It might be useful to know that any filter with an odd-number of elements can be made to match different input and output impedances by dividing it into two portions at the middle of middle element and denormalizing one end to new impedance. 

Saturday, August 22, 2020

California Killing Off Uber, Lyft Jobs Temporarily Halted

California Assembly Bill 5 from 2019, introduced here back in January, was carefully crafted to destroy freelance jobs and make them employees of the central company they work for.  It was said at the time that the target was those two gig economy leaders, Uber and Lyft, but my emphasis was for the unintended consequence of freelance writers.  What can I say?  I've had a handful of magazine articles published over the years, but never went fully freelance.  Which is saying I never went part time full time.

Both Uber and Lyft had announced they would be shutting down operations this week by midnight yesterday, but they won a temporary reprieve from the California Court of Appeal.  This gives them until October, less than six weeks, to put together a case that will allow them to continue their current employment arrangement.  If it's even possible to convince the state it was wrong in passing AB5. 

Uber and Lyft are under enormous pressure to fundamentally alter their business models in California, the state where both companies were founded and raised billions of dollars in venture capital. Uber and Lyft say drivers prefer the flexibility of working as freelancers, while labor unions and elected officials contend this deprives them of traditional benefits like health insurance and workers’ compensation. 

I don't doubt for a femtosecond that there are likely to be drivers who would prefer to be freelancers, and drive whenever they have some free time; or maybe need some extra income for something.  My gut feel, however, is that more drivers would prefer it to be more like a full time job, and the less actual work the better.  Something that required a bit less initiative.  I only know a couple of people who drive for Uber and in both cases it's "until something better comes along."

What I didn't know about the situation is that both Uber and Lyft are losing money.  They're nonprofit corporations, in everything but the all important tax status.  According to an article at the Foundation for Economic Education (FEE):

Their entire business model was based upon independent contracting, so providing full employee benefits is prohibitively expensive. Neither Uber nor Lyft actually make a profit, and converting their workforce to full-time employees would cost approximately $3,625 per driver in California. As reported by Quartz, “that’s enough to boost Uber’s annual operating loss by more than $500 million and Lyft’s by $290 million.”

Essentially, California legislators put these companies in an impossible position. A company can't lose money indefinitely.  Between the two of them, the companies employ 220,000 people in California alone (140,000 at Uber); if they lose the October court judgement, instead of making these 220,000 people employees with all benefits, they will make these people unemployed.  

I like to point out an acronym I came up with: TANSTAALWUC.  There Ain't No Such Thing As A Law Without Unintended Consequences.  The problem with invoking that is I don't think it's unintended.  The taxi driver unions got a law passed to kick competition out of the state.  It's fully intended.  

The “rest of the story” is that an October loss by Uber and Lyft might not end things. 

Uber and Lyft, along with DoorDash, were successful in getting a proposition on the state’s 2020 ballot that, if approved, would allow it to sidestep AB5 and continue classifying its drivers as independent contractors. The measure, Proposition 22, also stipulates that the companies provide more benefits to drivers, such as a minimum wage and access to health insurance. Unions and other pro-AB5 groups argue these benefits fall short of what drivers would be entitled to as employees.

In the gonzo, totally insane, illogical world of California, you never know what you'll find next.

(Kind of old but probably similar to today's situation - source)



Friday, August 21, 2020

Should NASA Send a SpaceX Dragon Capsule to the Moon?

That's not quite the title of a very worthwhile read from Ars Technica's Eric Berger this week.  His article is, “Could a Dragon spacecraft fly humans to the Moon? It’s complicated” and it's a long piece for Ars Technica but thoroughly worth the time to read.  

Think back three weeks to 8/2 as the Crew Dragon's Demo 2 mission is completing; this is where Berger begins.  

The landing came as NASA, at the direction of Vice President Mike Pence, is working urgently to return humans to the Moon by 2024. This is a herculean task for the agency’s administrator, Jim Bridenstine, who is balancing politics, funding, and technical hurdles to push NASA and its contractors forward.

Immediately after the splashdown and meeting the crew, Bridenstine plugged for the Artemis program, saying, “We have to make sure that another generation doesn’t miss this opportunity. Today was a great victory, but it was just a beginning. The Artemis Program is our sustainable return to the Moon.”  Bridenstine, under the direction of Vice President Pence, is driving toward a hard deadline of returning to the moon “to stay” by 2024 - or the end of the potential second Trump administration.  That's clearly part of the reasons for attacking this as a hard deadline; Moon or Bust.

The short answer to Eric Berger's question is that Crew Dragon could take a crew of three back to the moon with little modification, but it wasn't designed for that mission.  The emphasis appears to come from an op-ed published in the Washington Post on June 22nd, written by Robert Zubrin, founder of the Mars Society and president of Pioneer Astronautics, along with Homer Hickam, author of “Rocket Boys” (became the movie “October Sky,”) a retired NASA astronaut trainer, and spacecraft engineer.  Zubrin and Hickam argue essentially, why wait on the more expensive government vehicles when commercial solutions are already at hand?  They also come across as not being confident the Space Launch System and Orion capsule will be available in time for a 2024 mission.  I have to admit to leaning the same way. 

We recognize the hard work that NASA and its contractors have put forth on Orion/SLS, but they have simply been left behind by more nimble commercial companies. Dragon is not just cheaper than Orion; it is much better, because it is much lighter. The Dragon has a mass of 9.5 tons, compared to Orion’s 26.5 tons. Orion could have been designed lighter, but NASA has received so many conflicting directives from successive administrations — Orion was once required to fly to the asteroid belt! — it ended up with an elephant, not the racehorse it needed.

There are two big advantages to “running with what we got” - probably the biggest two advantages there can be:  money and time.  

The cost comparisons are extraordinary. According to an independent assessment by The Planetary Society, NASA has spent a total of $23.7 billion on development of the Orion spacecraft, which is designed to take up to four astronauts into deep space for 21 days. By comparison, through the Commercial Crew Program, NASA invested just $1.7 billion in Crew Dragon, which has now proven itself.

Then there are the launch vehicles. NASA is approaching a total investment of $20 billion in the Space Launch System rocket, which likely is still 18 months or longer from its first test flight. After this, the rocket is expected to cost at least $2 billion per launch. By contrast, SpaceX paid for the entirety of the Falcon Heavy’s development, and it would likely cost NASA between $150 and $200 million for lunar launch.

The Crew Dragon can carry four astronauts now - the next mission to the ISS will carry a crew of four.  The only issue is that the flight to the moon is longer than the uphill climb to the ISS - and it might be a bit crowded.  Additional storage space for consumables and other necessities (and probably some more elbowroom) are the changes that would have to be made for a version of the Dragon that could go to the moon.  According to an interview in the Ars article, SpaceX actually considered the design of alternate versions of the Dragon spacecraft: Gray Dragon and Red Dragon; both are named for the color of the world they would go to.  The plans might well exist now.

The Falcon Heavy might require tweaks to become man-rated as a booster, but NASA could workaround this by launching the Dragon on a Falcon 9, like they've just done and will do again soon, and rendezvous in space with a much heavier "other half" launched by the Falcon Heavy. 

Certainly, the politics of getting NASA to switch from the SLS/Orion to SpaceX/Dragon is a big deal, too.  Someone referred to the SLS as the Senate Launch System, in reference to Senator Richard Shelby (R) of Alabama and the Huntsville Space Center.  Senator Shelby has pretty much declared that humans must launch to the Moon inside the Orion spacecraft, on top of a Space Launch System rocket.  It's feasible that situations may overwhelm his control. 

Finally, there is the reality that the United States is borrowing heavily to dig itself out of the coronavirus crisis. At some point, belts will have to be tightened. If NASA could have a deep-space exploration program for $4 billion less a year by slashing Orion and the Space Launch System, some politicians may find that appealing.


I believe the vehicles they're comparing to here are the SLS Block 1B Crew and Block 2 Crew.

SpaceX does not have a lunar lander, at least not that I know of.  If they had one, they would have every part of a flight to land a couple of men on the moon Right Now.  I believe if they wanted to do it, they could land on the moon before 2024. 

Thursday, August 20, 2020

The Amazing Idiocy of the Post Office Conspiracy Theory

The year has kept up its feverish pace of every week handing me something that makes me shake my head and say, "what planet is this, anyway... and how did I get here?"  

This week it's the idea that Orange Man Bad is trying to shut down the Post Office (instead of trying to rescue it, which seems to be something that's actually going on).  The evidence?  Mail trucks break down while mailboxes get locked overnight in some places and swapped out of service in other places.  The first thing I saw posted somewhere was this tweet form Performing Monkey Jamie Lee Curtis (can't call her a singing or dancing monkey):


There's more than one example of stupid here.  The easiest one to poke fun at is her conclusion that because the driver of the red truck had a red hat with white letters, Trump's minions are engaged in an "outright attempt at stealing the election by denying access of the @USPS."  

I probably don't need to say that I don't know Ms. Curtis, but I'm going to say the evidence says she's a moron.  Thankfully, she didn't say that the guy was wearing a MAGA hat, but he was wearing a red hat with white letters, which must be the same thing.  It would apparently never cross her tiny little mind that a tow truck with a red cab might just use red as their company colors and the driver might be wearing a uniform with matching red hat.  It also appears that JLC apparently thinks that mail trucks are some sort of Alien technology that makes them the only freakin' vehicles on the road in this country that don't break down and need to be towed!!!  

Needless to say, JLC is not the only brain-damaged liberal in America.  This photo was also tweeted:

It blows my mind that there are grown-ass adults who don't realize that mailboxes might need routine maintenance.  It's like they believe mailboxes are the only things in the world made out of some miracle alloy that never rusts out or needs to be serviced.  It's alien technology again.  

These aren't isolated examples, they're everywhere.  In one case, New Jersey Representative Mikie Sherrill tweeted a similar picture which saw more than 5,600 retweets, and she only later noted they were being replaced by newer mailboxes (which is pretty visible if you actually look at the original photo).  I'm sure you've seen other pictures.

Let me stop to note that Rep. Sherrill says in her Twitter "about me" box that she's a former Navy pilot and former Prosecutor, which certainly implies she's a lawyer.  Nothing about that background particularly screams "moron" - and doesn't even say she's a Democrat.  I always wonder when I see something that idiotic from a politician if they're really that stupid or if they just believe the people following them are so stupid they'll fall for it.  

Anyway... there's lots going on here.  There's definitely an attempt to get people mad and outraged.  There's a layer that has to do with them really wanting access to millions of votes to control.  And there's a layer of union workers and Democrat politicians scratching each other's backs (as always).  Anyone who has worked in a union shop, especially a government union shop (cough, Kennedy Space Center contractors, cough) has seen situations where work just doesn't get done all week so they can come in and get it done for time and a half on Saturday.  The union and Democrats (but I repeat myself) don't like Trump's new Postmaster General appointee who's trying to unscrew the USPS.  If you want to read real background information there's the link up in the second paragraph, here's one to House Minority Leader Kevin McCarthy's article on Fox News.  Townhall's Kurt Schlicter writes that "The Post Office Conspiracy is First Class Stupidity."  Finally, Legal Insurrection asks, "Does Anyone Really Believe the Trump vs. USPS Hoax?"

Wednesday, August 19, 2020

A Minor Shop Update

I haven't updated this in a while, but my two valves are at the last two stages of fabrication.  To get to this stage from completing my test valve over two weeks ago, I needed to make two valve cages out of a bronze rod that I have and cut two new valves from drill rod (a piece of oil-hardening tool steel).  Shouldn't have taken as long as it did.

One valve standing up, one lying down in front of it, and two bars that work the chuck on my Sherline lathe in the background.  The cages are just sitting there, not bonded in any way - they slide on the valve stem.

There's a few steps left.  First, I have to put the valves into the stack up of pieces that make up the valve block assembly, put aside to wait for this back in July. 

See that hole on the right side of the block, top slice?  Once those are in place, that hole gets redrilled through the valve cage.  The slice on the bottom has the drill hole on the opposite side, for the exhaust pipe.  (Top valve is intake bottom is exhaust, BTW).  Then each valve will be spun against its cage with some lapping compound to make the valve fit that valve cage perfectly - they're literally made for each other.  

That uses the extra 1/4" diameter steel past the valve to twist the valve and push lightly into the bronze valve cage.  Some guys twist those valves in their fingers using the 1/4" stem as a handle; others have used a portable drill to power it.  

Once that's complete, I'll put the valve back in the lathe, cut off the excess material and then finish cut it to final length.  Then do the other valve.  The valve block will be put back together with gaskets between the slices. 

This has been a very slow stage, and that's primarily due to the small parts - the valve stems are 3/32" (0.094") diameter and everything has to be made precisely.  See the hole through the valve stems, near the small diameter ends?  That hole is 0.040" diameter, the smallest drill bit I have (#60).  Because of the sizes, none of the work holding accessories that I have will work.  I needed a piece that would hold the valve close to the top of the jaws in my vise, but it had to be thinner than the 3/32 stem.  It took over an hour to round up something of the right size in my scrap pile and cut it to size.  For most of what I work on, I can use a standard thickness parallel but those are too thick to hold the valve stem.  

Tuesday, August 18, 2020

Two Space Records - One We Watched, One We Read About

This morning, precisely on schedule, SpaceX Falcon 9 booster B1049 lifted off from Cape Canaveral Air Force Station Launch Complex 40 (also called "Slick-40").  We had a good view of the launch this morning as the clouds held off a bit longer than most mornings lately.

It one sense, it was a routine flight for SpaceX, the 10th Starlink mission carrying 58 Starlink satellites and three rideshare Skysat payloads from Earth observation company Planet.  In another sense, it was noteworthy: it was the record sixth launch and recovery of an orbital-class booster and since they're the only company doing that, undoubtedly the first time in human history.  It was also the 99th flight of a Falcon 9.  You can watch as much of the launch and booster recovery as you'd like here.

About 20 seconds after B1049 touched down on recovery drone OCISLY (Of Course I Still Love You), the smoke cleared well enough to grab a quick shot, with the booster almost centered on the SpaceX logo on the deck.  

The other record was set for the Raptor engine, the engine that will be used exclusively on their Starship and Starship Heavy vehicles.  

On August 17th, the SpaceX CEO unexpectedly released a photo of a Raptor test and a corresponding graph showing the engine’s chamber pressure, confirming that the company had successfully pushed the engine to record-breaking levels. Musk says that an unspecified Raptor – possibly serial number 39 (SN39) – briefly reached a main combustion chamber pressure of 330 bar (~4800 psi) during a controlled burn – and remained intact after shutdown.

Outside of subscale laboratory tests, the highest main combustion chamber known to full-scale, orbital-class rocketry was achieved by the Soviet Union in the 1980s with the RD-701 engine. Although the exceptionally unique engine was canceled before it could be used, it reportedly reached pressures of 290-300 bar in one mode of operation. Now, however, SpaceX and its Raptor engine appear to be the new world record holders – and by a huge margin.

In a world where small differences in performance are fought for, a 10% increase over the previously highest-ever recorded chamber pressure is certainly worth noting.  For comparison, the Rocketdyne F1 engine that powered the Saturn V had a chamber pressure of 70 bar.  The F1 engine was gigantic and used that 70 bar (1015 PSI) to achieve 1.52 Million pounds of thrust.  The Raptor is smaller and looking at half a million pounds of thrust.  That just means a vehicle needs three times as many Raptors as F1 engines.  The Saturn V had five F1 engines; Starship Heavy will have 30 Raptors (last I saw).

Considering the goals for the uses of the Raptor, the real design goals should emphasize reliability.  Starship is intended to go far beyond low Earth orbit, to the Moon or Mars.  The booster (Starship Heavy) returns for reuse, the upper stage (Starship) gets it into orbit then burns again to get onto the trans-Mars trajectory.  Starship itself has three Raptor engines.  There will probably be a burn or two along the way for trajectory correction.  At the worst case, seven or more months later, the engines burn again to brake it and either land or go into orbit around Mars.  Teslarati notes not being sure a single Raptor has burned for more than 90 seconds.  Whatever the longest burn time intended for the engine is, they should run it that long, and then life test one.  Would it be insane to put one in a thermal-vacuum chamber and leave it for seven months, like the satellites on the way to Mars now are experiencing, before restarting it?  Simply, combustion chamber pressure is wonderful but doesn't mean much if it takes too much life off the engine.  Engine longevity, burn duration limits, and reusability without rebuilding it seem to be the hard goals - hard in the sense of difficult to achieve and the sense of little or no room for compromise.  Design margin is a wonderful thing, so if they really need 300 bar and can get 330, that sounds good.  

Monday, August 17, 2020

The Cancel Mob Hits My Extended Backyard

I'm not a regular reader over at Legal Insurrection blog, but I happened to see a story today that caught my eye.  The Cancel Culture Mob has gone into attack mode over at the University of Central Florida.  UCF is on the east side of Orlando, and I'm guessing around 50 miles from me, but I've driven past it often enough  - and known enough people working part time on graduate degrees there - that I consider it part of my neighborhood.  I've never spent a minute on the campus. 

The story concerns Professor Charles Negy, a professor of psychology.  Professor Negy has been working at UCF since 1998 and earned tenure in 2001.  The story centers on the fact that a tenured professor of psychology said a couple of things that the Wokescolds objected to and they're determined to destroy him professionally and (because they typically do this) destroy him personally as well.  

One tweet, which no longer is available,said:

“If Afr. Americans as a group, had the same behavioral profile as Asian Americans (on average, performing the best academically, having the highest income, committing the lowest crime, etc.), would we still be proclaiming ‘systematic racism’ exists?”

A second tweet, also no longer available, said:

“Black privilege is real: Besides affirm. action, special scholarships and other set asides, being shielded from legitimate criticism is a privilege. But as a group, they’re missing out on much needed feedback.”

Neither of those strikes me as something that needs to be censored or something that's out of bounds for a professor of psychology to talk about.  They don't seem extreme nor do they advocate for any action; they're just observations of the world we all see.

Can't have observations from trained observers, can we? 

Rather than debate the merits or lack of merits in his opinions, a particularly aggressive attempt to get Negy fired ensued.

There was a petition with over 30,000 signatures, a Twitter hashtag was launched (#UCFFireHim) that trended, the student Senate passed a resolution, and there were protests on campus in which the President participated

And then it got worse, going into the usual pattern of the Woke. 

Students protested in front of his home, a clear act of intimidation we are seeing more and more frequently:

A protest Saturday in front of his home drew carfuls of students and prompted police protection, according to the professor.

“The cars drove by with a megaphone shouting ‘Black Lives Matter’ and ‘Negy must resign’ while blowing their horns nonstop,” Negy told The College Fix in an email Monday. “That went [on] for 30 minutes. That’s not ‘protesting.’ That’s bullying, harassment, and intimidation. That occurred after they had spent three hours on foot at the entrance of my neighborhood.”

He said several sheriffs were called out to protect his house.

UCF realized early on that they couldn't fire him outright for his Tweets, so they started soliciting his former students to find something he could be fired for.  Negy’s lawyer, Samantha Harris, describes what he has been through as an inquisition

UCF’s clarion call worked. Since June 4th, a litany (we don’t know the exact number, because they won’t say) of complaints has been lodged against Negy for his classroom pedagogy, for speech that allegedly occurred over a 15-year period from 2005 to 2020. The university charged Negy with discriminatory harassment on the basis of race, ethnicity, national origin, sexual orientation, religion, sex, gender identity/expression, and disability—it is worth noting here that Negy himself is both an ethnic and sexual minority—while providing him with only a handful of “examples” of his alleged wrongdoing. Negy begged for more information prior to his investigative interview so that he might prepare to defend himself, but UCF refused.

Ms. Harris goes on to say he was questioned and cross-examined for four hours one day and five hours another.  

I couldn't tell you what his ethnic minority status is, and it's hard to care less than I do, but the article points out that he's gay.  He's apparently in trouble for telling students it's easier to be gay in 2020 society than it was when he was their age.  To me, that sounds like one of those, "when I was your age I had to walk to school in the snow, uphill both ways" kind of stories.  Yet these delicate students can't stand hearing it and want to get the guy fired over it. I have a cloud of Looney Tunes-style question marks in the air over my head.  WTF?  Why is a story like that grounds to fire someone?  Why does everything have to be so serious?  I bet if the person who complained about that opinion talked to any other 60 year old gay they'd hear a similar story but then they couldn't think of themselves as such victims. 

The article is worth a read to get all the details of how this professor is being treated, but more than that, it's a template of how the Cancel Culture works.  They attack everywhere, as remorseless as a Great White Shark (that's ironic). 


Associate Professor of Psychology Charles Negy

Final words to Attorney Samantha Harris:

Cases like this are canaries in the coal mine: if a public university—a government agency—can treat someone this way for deviating from the university’s orthodoxy, and face no accountability for doing so, then what (and who) is next?

The answer, of course, is you and me. We are next. If decent people do not take a stand against these abuses, it’s not a matter of if the state-endorsed mob will come for us—it’s only a matter of when.


Sunday, August 16, 2020

A Ham Radio Series 11 – Transmission Lines – Part II

In this part, I want to take a look at transmission lines not as ways to get signals around your station, but as circuit elements.  They can be deliberately used as transmission lines or they can show up and surprise you.  Since nobody comes into your workshop and solders coax down when you’re not looking, let me go into how that could happen first.  

A transmission line doesn’t have to be two piece of wires in the shape of coaxial cable or twin-lead; any wire separated from ground forms a transmission line.  Probably the most common implementation of a transmission line is called a microstripline, but usually called microstrip, and the implementation is just a printed conductor line spaced the thickness of the printed wiring board above ground, like this:    

Doesn't that look like a simple double-sided PC board?  That's because that's all it is.  Just running a trace to some spot on the board for a ground connection makes that trace a transmission line. There are various ways to calculate what the width and height above ground need to be to get a desired impedance, or to calculate the impedance of lines you created accidentally. For a typical G-10 (usually FR-4) circuit board, 1/16” thick, the width of a 50 ohm line is about 110 mils (0.110”). Practically speaking, small differences in impedance don’t matter much so it’s not extremely sensitive to the width. 

I’ve used the antenna equation for the length in feet of a quarter wave monopole antenna, 234/f, many times.  The number is about 5% short of a quarter wave in free space because of what are called end effects – mostly extra capacitance at the end of the wire.  The actual number in free space (a vacuum, but virtually the same as in air) is just as easy to remember: 246/f.  Electrical length is longer with any dielectric (instead of the awkward to type here “epsilon”, I’ll use e), in particular divide the answer by the square root of the dielectric constant er.  For one of these G-10 PWBs, er is close to 4, so you divide the calculated length by 2. 

Any ground wire needs to be less than 1/20 of a wavelength long.  That number is close to 50/f to give the length in feet and 600/f to give the length in inches.  Let’s say you’re building a circuit for the 450 MHz band.  Any ground connection can’t be longer than 600/450 or 0.67 inches on FR-4 (600/450 = 1.333 in a vacuum, and divide by 2 for the er).  That’s over a half inch and it's really pretty easy to keep your traces shorter than that, but over the years, we’ve adopted the idea that the ground should be as close to the part as you can get.  

Let’s say you’re building something for 1300 MHz, a popular amateur allocation.  Grounds have to be within 0.230” to be within 1/20 wave.  What happens if the path to ground is longer?  The part starts losing its ground so the RF voltage begins to “float”.  At 1/8 wave long, a line shorted to ground at the end becomes a perfect inductor with reactance equal to the impedance of the transmission line.  In microstrip, deliberate microstrip or not, the skinnier the trace the higher the impedance (it’s not a simple relationship; half the width is not twice the impedance).  That means a narrow 1/8 wave line is a high impedance inductor to ground.  That’s not going to behave they way you want!

If the line is open (a “stub”), it becomes a perfect capacitor with reactance equal to the same impedance.  At 1300 MHz, an eighth wave is 0.567”. 

This why RF breadboards (prototypes) are built with a lot of ground everywhere, and tend to look like this more than neat little circuits with lots of wires at right angles to each other.



There’s a component circled in red.  That’s a 10 megohm resistor being used as point to solder a few parts to – a standoff.  The circuit is low impedance so virtually nothing flows in the resistor.  That’s an old trick, too.

If there’s any reason why RF design has gotten the nickname of “black magic”, this is probably where it comes from.  I’ve always told the new grads I mentored that if you think it’s black magic you’ll never be any good at it. 

Let’s say you have a way of stretching that line – a transmission line that’s open-circuited or shorted to ground – and you make it longer?  What does it look like as it gets longer?  


This is funky to read, but it’s saying that when the line is very short, it looks like a small capacitor if the end of the line is open or a small inductor if the end is shorted to ground.  As the line gets longer, those values increase until by the time you get to 1/8 wave long the cap or inductor reach the value of the impedance of the line.  As the lines get longer, you start to add reactance of the other kind.  The open line starts to add some capacitance and the short circuited line adds some inductance.  By the time you get lines ¼ wave long, the open circuited line becomes a series resonant circuit.  That means it’s an RF short circuit to ground that’s a DC open circuit.  The line that’s shorted to ground becomes a parallel resonant circuit which is a high impedance; it’s an RF open circuit but retains its DC short circuit.
If you could keep stretching this imaginary transmission line, you’d find that at 3/8 wave length, it behaves like 1/8 wave again with the opposite sense; that is, an open circuit line becomes an inductor and a short circuited line becomes a capacitor.  At ½ wave, it starts over again and behaves like the left side of that chart. 

Like antennas, transmission lines work the same on odd harmonics of the frequency you cut them for: 1/4 and 3/4 wave for example.  That means an antenna resonant on 7.100 MHz will be resonant on 21.3 MHz.  A 1/4 wave stub that shorts 7 MHz to ground will short 21 MHz to ground as well.  In practice, small imperfections in the way something is built that have negligible effects at the lower frequency can affect the higher frequency more because they become bigger fractions of a wavelength at the higher frequency.  

Always think of the size of components - including wires - in terms of a wavelength and how big the parts are. 

Saturday, August 15, 2020

Fighting Idiocy One Claim at a Time

As we hit 90 days of rioting in major American cities, one idea has stood out to me for its idiocy.  Peak idiocy was undoubtedly the looting in Chicago about a week ago, when a BLM activist said the looting was reparations.  

“I don’t care if somebody decides to loot a Gucci’s or a Macy’s or a Nike because that makes sure that that person eats. That makes sure that that person has clothes,” Ariel Atkins said at a rally outside the South Loop police station Monday, local outlets reported.

“That’s a reparation,” Atkins said. “Anything they want to take, take it because these businesses have insurance.”

Calling looting reparations is peak idiocy, but the other line in her statement is the one I want to focus on because we hear it all the time.  Looting is OK “... because these businesses have insurance.” All that does is hurt the small businesses, in this case likely black-owned businesses.  We've heard this line repeatedly since the rioting and looting started just as we've seen black small business owners getting beaten by BLM thugs or shouted down.  The looters' claim that those people are fine because those insurance fat cats will pay for the damage is just not true. 

“These were black-owned businesses, put together by people of color… and you came down here and destroyed it, and then you tried to use it in the name of Black Lives Matter,” Moses continued. “This won’t solve anything. This is all strictly for your glorification… you come through here and set fire to people’s livelihoods. Stop it now.”

Sympathizers also try to downplay riots with the supposed excuse that “businesses have insurance.” This is misleading, and not a miracle cure for the costs of lawless property destruction.

Not that it is a big distinction, but major retailers like a Walmart or Target may well have a policy that protects them from riots and looting to some degree, but most businesses don't.  Those companies that do have insurance are likely to have their rates go up (just as everyone experienced with their first car accident).  The businesses without insurance will probably be destroyed by the looting, and if they're not destroyed, paying to repair the damages is likely going to increase their costs too, which drives up their prices.  

This means no matter what, rioting results in higher costs for consumers, fewer jobs and lower wages for workers, and other steep costs that will hang over future generations.  Just as Detroit was ruined by the '67 riots (as were other hard-hit cities), all these cities will be destroyed by the riots of '20. 

I've long said a simple way to evaluate if someone knows anything about economics is to ask them about taxing businesses.  You can substitute the insurance here.  If someone advocates higher taxes on businesses, they're deluded.  They're asking to be taxed more themselves, they just don't know it.  Businesses collect taxes for the government and forward them, but those taxes are paid by the people buying the products or services.  Included in the price of every item in a store is this thing called overhead.  Every cost the business has: electricity, labor, building rent or mortgage, maintenance, the insurance being cited, and tax get added into their overhead.  

The person who advocates raising taxes on businesses probably believes the company is making tons of profit and sitting on it.  As reported here in January of '19, it's just not true. 

The public in general, but especially leftists, seem to have terribly inaccurate ideas about company profits.  The American Enterprise Institute published a study back in 2015 in which people were asked as a rough guess what percentage profit companies make.  The average response was 36%, which is only 5 times higher than reality.

According to this Yahoo!Finance database for 212 different industries, the average profit margin for the most recent quarter was 7.5% and the median profit margin was 6.5% (see chart above). Interestingly, there wasn’t a single industry out of 212 that had a profit margin as high as 36% in the most recent quarter. 

That January '19 post was really about how we know Medicare For All won't work because it's based on such bad assumptions.  It started with the observation that insurance companies aren't sucking down huge profits, either.  The top health insurers averaged 4.1 percent profit in 2017 (per Yahoo Finance). I find it hard to believe the business insurance industry would be very different from health insurance. 

So, No, Ariel Atkins.  Those companies aren't protected by insurance.  Claiming Black Lives Matter is clearly a lie because the black lives you're hurting by looting those business clearly don't matter to you.  Your justifications are pure bullshit.  You're not good or helpful or doing positive things in the remotest sense of the words.  You're simply a common street criminal.