Wednesday, March 31, 2021

Surprise Bill in Florida House; Second Amendment Preservation Act

I learned today that this week a new bill has been submitted to the Criminal Justice & Public Safety Subcommittee in the Florida House of Representatives.  HB1205 is a "2nd Amendment Preservation Act" much like the laws passed in other states.  The full text of the bill (pdf) is online.  The bill was introduced by Kaylee Tuck, a young representative from south central Florida; district 55 which covers parts of Okeechobee County just north of the Lake. 

I don't know what the chances are for bills this time in the session, but I'll go ahead and email everyone on the committee anyway asking they pass the bill and send it to the full House.  My representative isn't on this committee but he's a Rino and a shining example of the problem with Term Limits - people who have been in office get name recognition, so when they limit out of one office, they run for the one down the hall or on the other side of the capital and move over there.  Still a lifetime career politician just with varying titles.  

The forum where I found out about HB1205 had this video by a channel called Guns&Gadgets describing the bill and going through some of it page by page.  It's a 10 page bill; the first four are "Whereas" statements and the last five are the actual rules.  It seems like a good bill to me. 

Tuesday, March 30, 2021

Starship SN11 Discovers a New Failure Mode

Unfortunately, we don't know what it is just yet.  All we know for sure is what little we've been able to see with our own eyes.  SN11 lifted off from Boca Chica at 8:00 AM CDT, into a dense fog.  SpaceX's video stream, which included the usual photography from cameras around the ship, showed a seemingly normal ascent to 10km (6.2 miles), cutting off engines one at a time while climbing, until it hovered at altitude for a few seconds.  The descent looked normal (although they were losing video regularly) until the engines started up.  This was the last frame update from the vehicle.  As you can see, the mission time was 5:49.  This is 10 to 15 seconds before landing.  

This SpaceX mission video is part of a (much) longer video Everyday Astronaut posted that was live streamed this morning.  I've queued up the video to start around 38 seconds before ignition and liftoff.   Really of note is that there seems to be an explosion coinciding with the ignition moment in the picture above.  He has video of chunks of SN11 falling to the ground and is visibly worried about his cameras, set up where the chunks are falling.   Late this afternoon, Elon tweeted a reply to him saying, "Barely a scratch. :) Back on the stand soon! Will report conclusions as soon as we know them."

Did it explode due to something going on at this instant, or did the FTS (Flight Termination System) detect something so far from normal that it blew the craft?  Wish I could answer that.

I don't think it was the FTS deciding it had to destroy the vehicle.  The FTS system terminates a flight if it goes well off course or shows strong evidence of not being in control.  That takes time and everything was looking pretty normal until it didn't.  This looks to me like an engine explosion, from the things I can see.

As that second to last tweet says, SN15 is a few days away from the test stands to test "hundreds of design improvements" in all aspects of design.  Somewhere in the next couple of weeks, Booster BN1 will be brought to a different test stand for its testing.  In observing how quickly they were pushing to get SN11 ready to fly, I'd been thinking it was almost a formality to get SN11 out of the way and get onto testing 15, but learn as much as possible from 11 while you can.

Monday, March 29, 2021

The Flight of the Smellicopter

An interesting article popped up today in Electronic Design's email news, about navigating micro drones by using a sense of smell. Navigating a drone or some equipment using smell has a lot of practical uses; the obvious one would be looking for a gas leak in a place with natural gas utilities, but there are others, such as the way bloodhounds have long been used for tracking people by scent. What about a missing child? What about environmental hazards, chemical leaks, and other industrial accidents?

The problem with using smell to navigate is that while we do have things that function as synthetic noses, they aren't very good.  (Where's my drummer?  They just don't smell good. (rim shot))  That's why a team led by Ph.D. candidate Melanie Anderson at the University of Washington thought they'd use the smell-sensing antennas of a Manduca sexta moth to produce a drone that they call the Smellicopter.
Why a moth antenna? In addition to sensing wind and vibrations, these fast-responding, highly sensitive transducers capture olfactory information that the insect uses to find food and mates. A sensed odor induces a complex series of chemical reactions, culminating in an “action potential” that propagates down the antenna to the brain of the insect. An electroantennogram (EAG) measures the aggregate electrical activity of the olfactory neurons in an antenna by measuring the voltage drop across the antenna.

“Nature really blows our human-made odor sensors out of the water,” said lead author Melanie Anderson, a UW doctoral student in mechanical engineering. “By using an actual moth antenna with Smellicopter, we’re able to get the best of both worlds: the sensitivity of a biological organism on a robotic platform where we can control its motion.”

That point was amplified by co-author Thomas Daniel, a UW professor of biology who co-supervises Anderson’s doctoral research. He added, “Cells in a moth antenna amplify chemical signals. The moths do it really efficiently—one scent molecule can trigger lots of cellular responses, and that’s the trick. This process is super-efficient, specific, and fast.”

If you hear of the University of Washington being attacked, I wouldn't be surprised if Ms. Anderson's lab at UW were to be set upon by the animal rights people because she's plucking the antennas off live moths for this experiment.  In this photo, the antenna is the little round loop on forward (left) end of the drone.  The moths are put into a refrigerator to anesthetize them before the antenna is plucked off, but there's only two antennae per moth so the moths are either regenerating the antenna or they're sacrificing the moths. 

All that aside the way they handle the signals from the moth is plain old analog electronics.  They measure the output of the antennas. Output was between 10 µV and 1 mV in response to stimuli, so they set the gain to 1,000 after some experimentation. The moth's antenna output impedance was high, though, between 500k and 750k ohms (500 and 750,000 ohms), and the system picked up electrical noise too easily.  That was easily solved with an active filter and more amplification - the output stage has a gain of 11. 

The drone pictured with the modification for using the moth antennae is a commercial/open source model called the Crazyflie 2 Nanodrone.  Without the antenna sensor (another EAG, or ElectroAntennoGram) it weighs 23 grams.  Once outfitted for their experiments and characterizations, it can fly up to seven minutes on its 250 mAH battery. 

It's an interesting article, digging into how the biology department told the mechanical engineers how the moths work their way upwind to the source of a smell, as well as digging into the details of how the engineers have made the drone work.  Biomimetic designs, literally life-copying designs, are becoming a big thing (as was always expected) and this a good look at how it's going on. 

Sunday, March 28, 2021

Oh the Precious Goal in Life to Be A Victim

There was a story this week, toward the bottom of the news where it belongs, about a dude who considers himself a woman, but hasn't actually had the surgery that matters the most, yet.  You know, the surgery Rush used to call the Chopadickoffofme.  When poor dude goes through the TSA checks to get on an airplane, they always find this anomaly between his legs and need to resolve it.  Dude has gone screaming to any camera and microphone that he can find to scream to about (I suppose) how unfair it is that the scanners can't read his mind and learn how he identifies.  The story on the Blaze says that model and content creator Rosalynne Montoya recently shared an experience with social media users and insisted that TSA is transphobic.  
"Can we talk about how horrible it is to travel while being transgender sometimes?" Montoya asked in the now-viral video, which has been seen by at least 18 million people at the time of this reporting. "I always have immense anxiety leading up to going through security. And this means that I totally recognize the privilege of having all of my documents correct. So, the gender marker on my license, for example, says 'female.'"

"But, going through the scanner, there's a male scanner and a female scanner in the TSA checkpoint," Montoya continued. "And, looking at me, you know, I look like a woman and I am a woman. So, that's great. I love having systemic privilege when I feel unsafe, which is in an airport. But, going through the scanner, I always have an 'anomaly' between my legs that sets off the alarm.
Pardon me if I get your pronouns wrong, but the TSA isn't transphobic; they're bomb-phobic. 

He/she/xe/xshe (whatever) tells the sad story about always having the anomaly between his legs if he goes through the scanners as a woman and has an anomaly in his chest if he goes through as a man.  Apparently he was committed enough to get breast implants, so augmented, but not committed enough to get subtracted from. 

The story is also covered at PJ Media, who got in contact with TSA and reprints much of the way they address the situation. 

I have a simpler example.  Back two days before New Years Day of Y2K, Mrs. Graybeard and I were hit by a pickup truck while riding our bikes.  She had several stainless rods inserted in her back; we call it a pound but don't really know what it weighed.  As a result, she was given a card by her doctor to hand to the TSA.  It states she has implants that will show up on their scanners.  We've taken at least a dozen trips in the intervening years and Every Single Time she goes through the scanners, they stop her for more thorough investigation.  Every Single Time we've asked the TSA about the cards they say (in effect) "nice cards, but we have to be sure."  Essentially, anyone could print up cards like that. 

And that's what's going on with Rosalynne Montoya.  Anybody could say they're a trans woman and have a pound of explosives between their legs.  Once the anomaly shows up, they have to prove it's safe.  They're responding to the risk, not the person. 

Saturday, March 27, 2021

A Ham Radio Series 23 - Introduction to Power Supplies

One thing that every radio and virtually every accessory needs is power.  In some cases, especially handheld portables, the power is supplied by batteries; in many other cases the power is obtained from the AC power lines.  Typically 120V 60 Hz in the US and 220V 50 Hz in much of the rest of the world.  If you're operating a 100W output power transceiver that may run on 12V and take 20 Amps on peaks a few percent of the operating time, for example, that can be run off a deep cycle 12V battery, like the marine or RV batteries or it can be run on a line-operated power supply.

I want to take a short dive into line-operated power supplies.  The details of building one vary with the requirements, but they're well within the range of things amateur builders can design, build and get running.  For low power supplies, say the 1 to 2 amp supplies that you might be familiar with for little things around your house, there are literally less than 10 parts in the entire thing.  More parts are required for something like that 12V 20 to 30 amp supply, but aren't really much more complicated, conceptually. 

Broadly speaking, power supplies can be divided into two kinds: linear and switching.  Linear supplies use components called voltage regulators which are analog components; that is, the voltages and currents in them and through them are smoothly varying, continuous in time.  These regulators operate like the feedback circuits I've talked about before.  Somewhere inside the regulator is a reference voltage.  The output voltage is compared to this reference continuously, producing an error signal that causes the circuit to turn the voltage up if it's too low and turn it down if it's too high.

Switching regulators, as the name implies, use switching techniques to change the input voltage to the output voltage, so they're on-off circuits more like digital than analog.  They use components called regulators as well, but they work on different principles; a very common technique is Pulse Width Modulation.  Briefly, the switched on/off voltage they're producing gets filtered into clean DC, and if it the voltage runs too low, they keep the pulses on longer (so that they're wider) and if the voltage is too high, they turn the pulses off sooner (making them narrower) reducing the output voltage.   

The advantage of switching regulators is they tend to be more efficient, sometimes reaching efficiencies of 85 to 90% or higher.  The linear regulators are lower efficiency.  That might matter to you for running things when the grid is down and you're trying to stretch every watt you can produce.  The advantage moves over to the linear regulator when you want an electrically "quiet" regulator.  The fast switching voltages in the switching reply produce broad spectrum electromagnetic interference (EMI).  Nevertheless, I can assure you that every system I worked on in military, space and commercial aviation for the 40-ish years I worked in those fields were switching power supplies.  Their drawbacks can be designed around.  After almost 30 years using the same linear supply in my ham station, I switched to a switching supply 15 months ago and haven't heard it on the receiver at all.

The biggest advantage of the linear regulators for the hobbyist and experimenter is that they are incredibly easy to use.  How easy?  How about "just add two parts?"

This example is based on the series of parts called the "seventy eight hundred" series.  The last two digits are the voltage.  Over the years they've been produced (since the late 1970s) they've been produced in 5V (7805) 8V (7808) 12V (7812) 7815 and more.  Furthermore, they're available in different packages and can deliver different currents depending on the package they're in.  They're the 78L series (low power) 78M series (medium power) 78P (high power) series, for example.  There's also a 79XX series for negative voltages. 

The bigger the case, the more power dissipation the part can handle.  The TO-3 (TO is from Transistor Outline) is the highest power (78P05, for example) while the TO-92 would be the lowest power 78L05.

What makes these so easy to use is they're extremely rugged; they've been designed to handle anything that could happen to the regulator.  Too much current?  It'll shut down, and then turn on again periodically to see if the condition cleared.  You could short the output to ground and it will just stay shut down until the short is removed.  If you over heat the part by drawing too much current, it just shuts down.  If you see the power turning on and off, that's the first thing to suspect. 

Practically, the input voltage will be coming from a transformer that drops the wall voltage down to "a few" volts above the desired regulator output voltage, rectified with a diode bridge and filtered with a large capacitor (although not as large as if there were no 78XX regulator there). It never hurts to read the datasheet, and the sheets for these, along with other design notes and help, are extremely widespread on the 'net. The power dissipation in the regulator is the voltage drop across the regulator times the current it's delivering, so say you're putting 8V into a 7805 putting out 5V at 1 Amp; that dissipation is 3W (8V-5V)*1A. 

That's not all in the world of linear voltage regulators; there are adjustable regulators - and ways to make the 78XX series adjustable, too.  There are higher power regulators, and ways to make higher power with lower power regulators.  There are regulators optimized for lower voltage drops across the part, Low Drop Out or LDO regulators, so that instead of putting 8V into a 5V regulator you'd use 6V or 5.5V (depending on the part).  

It's literally an entire world of circuit design open to anyone interested in making something useful.

Friday, March 26, 2021

SpaceX's Ambitious Day Falls Flat

Last night, the word got out in a press release from Cameron County Texas, the home of the SpaceX facility at Boca Chica, that road closures were being put in place for the whole day today to accommodate a static firing and then launch of SN11 to the 6 mile height previous Starship prototypes have hopped to.  Although there was a static fire by 8:09AM CDT, something was clearly wrong because by 9:50AM cars were going to pad followed by lots of heavy equipment.  A scrub for the day was announced by 2:40PM.  A bit after 4PM Elon Musk tweeted that it looks more like Monday than tomorrow.

It’s unclear what caused the scrub but weather or technical issues from the static fire are the two most likely candidates.  It was foggy this morning, cleared at midday and then came back late in the day.  The Starship prototypes have all flown in weather that was clear enough for filming from the ground and I couldn't tell you if it was that good today.  SpaceX still has TFRs active on Saturday and Sunday, but combine the fact that the company hasn’t tested or flown on a weekend in months with Elon's tweet and an iffy weather forecast and it ends up looking like Monday or even Tuesday.

So let me leave you with a pretty picture of SN11 at daybreak, from Teslarati:

Thursday, March 25, 2021

It's Time for That Cliche' Again - Reasonable Gun Laws

Here we are two months into the administration of Jo and the Ho and - whaddya know? - they suddenly have justifications for those gun control moves they talked about for the entire year of the Evil Party primaries.  It's a miracle of miracles!  Suddenly, after many quiet months, we have a group murder of "sex workers" at a "massage parlor" and a group murder in a food store by either a sufferer of Sudden Jihad Syndrome or simply the common Muslim hatred of Jews.  

Since no one on the left seems to be capable of an original thought, it's time for them to trot out the old trope of "reasonable gun laws."  And since I've written about that term and my views of it at least a dozen times, I'll take my privilege of having the pilot's seat and reprint some of the things I've written since 2010. 

Are you as sick as I am of hearing the phrase "reasonable gun laws?"  It's not just in the last few days, it's always there to some degree.  I'm sick of explaining there is no such thing as a gun show loophole; there are no laws that don't apply at gun shows or to internet sales.  I'm tired of explaining that we already have background checks on all new guns, we don't do them on private sales because it's an individual selling their own property and the Federal Government doesn't seem to get involved in private sales of private property.  States do; if I sell a car, boat or whatever, I have to do a bill of sales and the buyer pays sales tax.  I know of no place where the does that.  I'm really sick of the "why does anyone need (fill in the blank)??" nonsense that we hear from an alarming number of people who are nominally on our side.  The ones called Fudds.  Why does anyone need 42 guns?  Why does anyone need 30 round magazines?  I want to ask why does anyone need 42 books? That's also a constitutionally protected right.  Why does anyone need a TV in every room, or a muscle car or you name it.  BFYTW!  It's None of Your F**king Business.

What would constitute real "reasonable gun laws?"  Let's start here: any adult with normal rights can walk into a sporting goods store in most places and walk out with a shotgun or a rifle with no waiting period.  But if they wanted to buy an AR-15 or a Mossberg 500 from the factory or from a store in another city, (like I've done) why does it have to go through a local FFL's hands?  Why can't anyone order a rifle or shotgun from a gun store in another city, their favorite Big Outdoor Store, or even an kind of "online superstore", and have the gun shipped to their house?  It was sold by an FFL that can do the NICS check, so why does another FFL have to get involved?  It used to be that way, until the Gun Control Act of '68.  What advantage is there to society from shipping it to an FFL?  It's not like the second FFL prevents someone from stealing it in transit - that's on the shipping company.  It does nothing but give money to local FFL holders. All they can do is look at the buyer's ID - which can be done digitally with encryption when the purchase is made. 

We all know there's no such thing as a "gun show" loophole, and that you can't just order something online from a gun store. I say, "why the hell not?"  It's the freaking 21st Century, for God's sake.  We have the technology.

In consumer goods, your local camera shop, say, really does have to compete with the big guys in New York. Gun shops don't have that. I can see how local gun shops might really like these laws. They get an easy 35 bucks (or whatever) for filling out the forms and "receiving" the shipment, but I don't see any value added to us or society.  There was certainly no value added to me.

If there's a mandatory 3 or 5 day waiting period for a handgun where you live (Florida waives that for Concealed Carry licensees), why can't you order handguns online?  What's the difference between waiting 3 or 5 days for UPS to deliver it and waiting 3 or 5 days to pick it up at your gun store?  Again, with today's computer security, you could verify age, do a NICS check - anything the local shop can do - online.  I think the waiting periods are all bullsh*t anyway, just another way for government to yank our chains and make it harder than it ought to be.  I've never seen any data that waiting periods have ever done anything except inconvenience legal purchasers.  But, fine, we'll play your infantile waiting game. 

The whole idea of a wait was a "cooling off" period, so that a hothead doesn't go buy a gun in a moment of anger and then go kill someone, but I personally have never seen data that those waiting periods do anything.  I know they started with the GCA of '68 ban on Saturday Night Specials, which (as far as I can tell) only had the effect of removing cheap, reasonably functional guns from people who couldn't afford better ones, and caused some smaller arms companies to either fold or change their product line.  Another government penalty on the poor.

What possible arguments are there against this?  That we can't guarantee security, we can't guarantee that criminals won't order guns online?  Nobody can guarantee security.  Criminals don't have any problems getting guns now while staying out of the system entirely.  If we use strong security, it's as good as what we have.  One time I posted something like this and a commenter said,  "what if your kids used your ID?"  I wouldn't want my kids buying anything under my ID on my computer.  If you can't control your own kids in your own house, I think that's a bigger problem than just what they're buying.  Maybe you should be making sure they don't know the combination to your safe and don't know where to find matches. 

Why are silencers - glorified mufflers - regulated as if they were machine guns?  Why are we required to have a muffler on a car, motorcycle or lawn mower, but we're required to not have one on a gun?  This was originally to keep people from shooting the King's deer (poaching game), but I think the problem today is Hollywood.  They created this illusion that a silencer reduces the 155 to 160 dB of a gun shot down to a barely audible, and it just isn't so.  Silencers should be completely deregulated - not even the $5 "any other weapon" class - just over the counter at your local store.  Did you know that there's nothing like an 80% lower in the construction of a silencer; no stage that's legal?  If I have a lathe (like I do) and they find pieces that someone thinks could someday become a silencer, I've broken the law.  The ban is total. 

This one actually is for the children.  And for anyone who moves next door to gun ranges or clubs and gets disturbed by the sounds.

Get rid of the stupid “sporting purpose” tests for firearms. The Heller decision makes it very clear that the Second Amendment isn’t about duck hunting. This particularly affects imports. No restrictions. Get rid of the stupid laws on short barreled rifles and shotguns. The idea that a shotgun barrel 18.05" long is fine, but one that's 17.95" is some sort of killer monster weapon is just silly. It's there simply to create law violators. It's also one of their most enforced laws - probably because it's really easy to measure barrel length.

The last time I did some looking at John Lott's data, his studies had been peer reviewed 30 times and never refuted.  There was one author who said Lott couldn't prove "More Guns Equals Less Crime"; but neither could he (the reviewer) disprove it.  Lump this one under the rule for reading medical studies: correlation does not equal causation.  However, and this is important, there can't be causation without correlation.  When you look at global rates of gun ownership vs homicides, there's almost a perfect lack of correlation, almost perfect inverse relationship between the number of guns in private hands and murder rate, across the globe.  More guns can NOT equal more murders. 

This is fairly old - the closest I can tell is that it dates from early 2013. 

Wednesday, March 24, 2021

JPL Prepares to Fly First Helicopter on Another Planet

When the NASA/JPL Perseverance rover landed on Mars back in February, I didn't emphasize it, but the rover is carrying a bold experiment in the form of an autonomous drone helicopter that will be the first flying vessel that humans have ever flown on another planet; a remarkable little drone helicopter called Ingenuity.  Tuesday, they had an open conference to discuss the plans for the coming missions.

They've now picked a site for what's expected to be the first powered flight on another planet. With the site settled, they're now targeting April 8 for the flight, which will be the first in a month long series of test flights to validate the technology.
Ingenuity, pictured above, looks familiar to anyone who's seen any of the profusion of small consumer drones that have developed over the last decade or so. But, as Ingenuity's chief engineer Bob Balaram put it, "It's the first aircraft designed for powered flight on another planet," and that makes for some substantial differences with Earth-bound drones. For starters, the hardware is much bigger than it might seem from the photos, as each of its two counter-rotating blades is 1.2 meters (four feet) long. Ingenuity also weighs in at 1.8 kilograms (four pounds) on Earth, although it's less than half of that weight on the red planet.
During the landing coverage from JPL in February, they did a fairly extensive story on Ingenuity including how it was tested in a large vacuum chamber at JPL that allowed them to fly in the simulated thin Martian atmosphere.  I thought I saw some thin wires that partially supported the drone's weight to get the thrust/weight balance that the system needs.   What they didn't mention that's an interesting touch is that while the craft was very carefully optimized to fly on Mars, it does carry some additional weight.  Following their first powered flight on Earth, the Wright brothers sold small squares of fabric from the Wright Flyer to get the funds they needed to build improved versions. One of those squares will be carried aloft on Ingenuity when it takes flight on Mars.
Håvard Grip, Ingenuity's chief pilot, said that the test flights required two distinct areas, both of which needed to be flat. The inner part, which he called the airfield, had to have very little material that could interfere with landings. That needed to be surrounded by a larger area, called the flight zone, that had to have enough material in it that the drone's onboard image-processing system could track individual features in order to assist with navigation.
In the end, things couldn't be much more convenient, as the rover landed on what will be the edge of the flight zone, which extends north from the landing site.
The drone is tucked away on the underside of Perseverance, folded up, and was initially protected by a cover.  That cover was dropped on the surface a couple of days ago.  Once on site, Ingenuity will have to be rotated 90 degrees and have its legs deploy before it can be deposited on the Martian surface; each step in that process will be monitored for success before moving on to the next. Farah Alibay, who is coordinating the rover team's support of the test, called the final drop the "most stressful" part of the process.

Assuming the drone ends up standing up properly on the surface, the next step is to get the rover out of the way because the drone is going to need to sit in the sun to charge up its battery.  Here's where the thin atmosphere actually helps it survive; the air is so thin the winds shouldn't be able to knock the drone over. 

The first flight is listed as No Earlier Than August 8th, two weeks from Thursday (tomorrow as I write).  The first flight will involve a takeoff, a climb to three meters, a brief hover, and then a landing. Chief Engineer Balaram said that each ensuing flight will be "progressively more aggressive," but there's a limit to how far aggression can go when the onboard batteries limit flight time to about 90 seconds. All told, five flights are planned, with a maximum altitude in the area of five meters.  A month has been set aside for the flights, with extensive checkouts of the system between each.

The drone will have a relatively low-bandwidth connection back to the rover, so we probably shouldn't expect video from every single flight. But a key aspect of the flight will be figuring out how well the system can navigate using optical data and whether it would be capable of scouting routes for the rover. So we can definitely expect a fair number of pictures from these efforts.

It's a technology pathfinder and not a science mission.  If the probe flies successfully, they move on to how far the drone can fly, how easily it can navigate, and other important capabilities like that. 

The ironic aspect is that the main science mission of Perseverance will be on hold until its test flights are over.  If Ingenuity is spectacularly successful and the five test flights are brimming with exciting data, the program then has to turn it off, turn the rover's back on it, and get on with the rest of the science objectives.

Tuesday, March 23, 2021


The day and evening got away from me between some spring cleaning, house maintenance and more.

So have a picture I liked.  Is it just me or does Hoppy look like some sort of Bug-Eyed Monster or BEM, as they used to say, but with an underbite?  

It has to be deliberate.

Monday, March 22, 2021

Starship SN11 Has Apparently Successful Static Fire

This morning at a few minutes before 9am CDT (UTC-5), SpaceX successfully fired up Starship serial number 11’s (SN11) three Raptor engines, completing the static fire test on the first try of the day and just two hours into in Monday’s eight-hour window.  Judging by the wording of the road closures, it sounds to me as though the Wednesday could be the earliest attempt at the kind of 6 mile altitude flight that the previous three prototypes made. It will also be the shortest preparation of any of them by a long shot, at 15 days.

It's worth mentioning that although the first static fire last week resulted in an abort with the vehicle computers shutting down the three Raptor engines quickly, none of them were replaced. These are the same three Raptors. We don't get to know exactly what was done, but it was either fixed in software or up under her skirt.

This NASA video shows today's test from several different angles as well as at normal and half speeds.

The big BUT here is that we don't have confirmation from SpaceX of any of this information; no confirmation the test was a complete success and no confirmation they might fly Wednesday.  The justification I'm using, (FWIW which isn't much) was the road closures were announced for the 22nd and 24th with backup dates of the 23rd and 25th.   I read that as something is planned for the 22nd and something else is planned for the 24th.  If they don't get the first one done on the 22nd, they'll close the road to try again on the 23rd.  Likewise for the 24th, if they don't get that accomplished they'll try on the 25th. 

A quick check of the weather forecast for the 25th shows low winds and low cloud cover, especially in the afternoon.  TFRs have been issued for Tuesday through Friday, so we'll see.  

On Saturday the 20th, a group of NASA Astronauts led by ISS veteran Christina Hammock Koch came to Boca Chica to see SN11 as it was being prepared for the static firing.  It was apparently an agency-approved trip. 

Astronaut Koch (2nd from right) and her partners who came to see SN11 up close and personal. Photo from her Instagram account.

Big things are coming next.  The next Starship prototype to fly will be SN15 but there will be a longer wait for SN15 after 11 than you're used to.  SN15 has many improvements over the design that has gotten the program to this point and no one really knows how they'll perform, yet.  Super Heavy Booster Number 1 is in some final stages of assembly before being rolled to the test stands.  BN1 has to vacate the high bay so that SN15 can use it to get her nose cone stacked.  Both BN1 and SN15 need to be tested while BN2, the first of the Super Heavy boosters that will fly, is completed.  Remember, they're aiming for a July orbital launch of a Starship on top of a Super Heavy, presumably BN3 topped by Starship SN20.   If they don't make July but launch in the fall, will you be all that disappointed? 

UPDATE 23 MAR 21 2030 UTC:  The road closure for Wednesday (24th) has been cancelled.  The road closure for Thursday is still scheduled.  No launch Wednesday.

Sunday, March 21, 2021

OK, A Couple of More Things I Can't Resist Posting

This is an uncommon photo of a fairly common optical illusion.  It's from the Guardian (UK) and was photographed in the UK.  I've seen many photos of the illusion, called Fata Morgana, over the years but not many this good.

It's caused by a thermal oddity that forms over water (usually).  The air layer immediately over the surface is cold, but it's trapped by a tropospheric duct under warm air and can't rise.  The refractive index changes with the air temperature, and the way light bends makes the ship appear to be in the air.  Except, as I say, images aren't usually this clear.  They often look blobby, and visually farther away, rather than as large and sharp an image as this.  If you embiggen the picture, it almost looks like you can see the keel of the ship - which appears to be a tanker.

The second story is a strange news story on the Blaze news email that caught my eye with the title, "Man goes viral for promoting 'Birds Aren't Real' movement — and insists he's dead serious that government is using fake birds to spy on citizens."  The Blaze piece is based on a Newsweek article and the source article is here

When dealing with something this bizarre, it's almost mandatory to use the disclaimer, "I swear I'm not making this up."  The guy in question, Peter McIndoe, says that "...between 1959 and 2001, the government killed off all birds and replaced them with surveillance drones," Newsweek reported. The thing I noticed about it is that guy is full of wonderful quotes
"McIndoe portrays the movement as completely serious," Newsweek reported. "Throughout his interview with Newsweek, he remained deadpan and appeared to be improvising as he went along, further blurring the divide between reality and conspiracy. When asked directly whether this is actually an elaborate comedy project, he swore that it's a real thing and that it was just operating underground until the advent of the internet. It should be noted, though, that the only indication that Birds Aren't Real has been around for decades is the history section of its own website."

Newsweek noted that it's worth pointing out that when first speaking with the outlet about setting up an interview, McIndoe texted, "In regards to our movement being a joke, or for real: That is the very question that our post-truth era comedy project thrives within."
and my favorite
During the phone interview, however, McIndoe said, "Whenever I type in, 'Real movement, no comedy involved,' it always autocorrects it to something like 'meta-conspiracy parody-movement, showcasing post-truth-era absurdity."
I don't know much about the guy, but I think I like him. 

Newsweek pointed out that at least one "Birds Aren't Real" Instagram account boasts more than 296,000 followers, and a related TikTok account has more than 353,000 followers.  Newsweek reports that there are chapters in several states, and McIndoe claims there are members of the movement living in every state.  And then Newsweek goes on to say, "It's not clear how many of those people are true believers, and how many of them are interpreting the accounts as a joke." 

It's as if without someone from the benevolent protective government to tell them the guy is yanking their collective chains, they're incapable of deciding.  It's sorta like an environment a post-truth era comedy project would thrive in.

Courtesy of Birds Aren't Real, from Newsweek

Saturday, March 20, 2021

A Couple of Things I Couldn't Resist Posting

A couple of small, but fun stories.  

The first is a Scott Manley story I came across during the week. When SpaceX launches a Falcon 9 mission, they recover the booster about 9 minutes into the mission. The upper stage that actually deploys the satellites is left in a higher orbit and is currently not considered recoverable. I believe they are put into a destructive de-orbit, using some onboard thrusters or perhaps some residual fuel, so that they reenter the atmosphere and are destroyed. During the couple of days this takes to have its affect, the second stage is still operating on battery power and transmitting telemetry, including video. 

It seems a group of hams in Europe figured out how receive the Telemetry and decode the video. 

Scott does an OK job of describing what the hams did.  The "gizmo" he mentions at around 3:28 or 3:29 is called a downconverter.  Fundamental, essential technology, and if you have a typical house, you're probably surrounded by half a dozen of them.  In my talk about superheterodyne receivers, every block diagram starts out with a downconverter.

All that aside, it's a fun story.  It comes down to SpaceX using open standards for their telemetry and a bunch of hams willing to try lots of stuff. 

NASA has a mission on the planning books called TROPICS - the kind of name which is almost legally required to be an acronym, in this case: Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS).  It's actually an interesting mission, but that's not tonight's story.

The story is they bid the launch of a handful of cubesats that will conduct the measurements.  the launch is to be in July of 2022.  Three launch suppliers bid the mission.  To tease the story a bit more, here are the three launch vehicles, courtesy of Twitter user SotirisG5.  One of these things is not like the others. 

The vehicle on the left and the vehicle on the right bid the same launch price: $8 million.  The company in the middle's bid was "significantly higher."  NASA choose the guys on the left.

By July of 2022, in time for the TROPICS mission, the Starship and Super Heavy booster might well be fully operational.  If they can launch 220,000 pounds to orbit for $8 million, that's $36.36 per pound or $80/kg.  That's cheaper than the over the counter rates at FedEx's website.  I just asked for the rate to ship 1 pound to Tokyo and fastest delivery was $115.94.  Another Twitter user said that's 1/35 the cost of a Falcon 9 launch.  The potential is there to completely revolutionize commercial space flight. 

Friday, March 19, 2021

The Other Milestone Yesterday

AFAIK, there has been virtually no general media coverage of this factoid.  After the SLS static fire yesterday, NASA Spaceflight (dot com) switched over to something happening at SpaceX Boca Chica.  SpaceX completed the stacking of the first Super Heavy booster.  The prototype has been in the works quite a while, and is referred to as Super Heavy BN1 (Booster Number 1).  This will eventually be the most powerful rocket in the world.  

Video here: I screen captured it before the top tank was fully in place; you can see a slightly darker (thicker) line right about the halfway up point where the cherry picker bucket is sitting.  A group of guys got out of the bucket and went inside the bottom section (the methane tank).  The process was interesting to watch.  Bluto the Crane lifted the top section (the LOX tank) until it cleared the bottom tank, which was over on the left in this view, then the bottom tank was rolled under the upper.  The upper tank was then lowered gradually while the guys inside the tank lined things up. 

There's still days of work to be finished: they need to weld the two tanks together, and connect their preinstalled plumbing and avionics runs.  Comprised of 36 of the steel rings also used to assemble Starships, the first Super Heavy prototype will stand roughly 70 meters (230 ft) tall from the top of its uppermost ring to the tail of its soon-to-be-installed Raptor engines.

Something that always puzzled me is that when they built the high bay and I found about its size, I realized it's too short to put a Starship prototype on the top of a Super Heavy booster.  I don't know if there are plans to make the high bay taller, but a Starship prototype like SN11 is 160 feet tall, and this SpaceX page says the stack of Starship and Super Heavy will be 394 feet. 

BN1 will not fly; it will be subject to all the static tests we've come to be used to and probably more.  It will be pressurized, and subjected to cryogenic temperature fluids like those it will carry.  At some point, the vehicle will get the four raptors it can accommodate.  The full payload-capable Super Heavy boosters will have 28 Raptors and there will be more on the Starship than the three engines the Starship prototypes have carried.  For test hops of the BN2 and perhaps BN3, they will apparently have four Raptors.  It's hard to keep up with these guys.

All of this is in preparation for a Starship Super Heavy orbital launch this summer.
First reported by NASASpaceflight and later confirmed by Musk himself, SpaceX hopes to be ready to begin orbital Starship launches as early as July 2021, just four months from now. Per NASASpaceflight, that first launch attempt will nominally use Super Heavy booster BN3 and Starship SN20. Super Heavy BN1 is expected to remain grounded, serving as a testbed for inaugural pressure and proof tests, as well as one or several possible Raptor static fires (Update: confirmed by Musk).

If that process goes according to plan, Super Heavy BN2 will pick up where BN1 leaves off and attempt at least one short hop test, among other qualification tasks. In the interim between that feat and Super Heavy BN3’s launch preparations, it’s safe to assume that either BN2 or BN3 will support some kind of iterative static fire test campaign similar to what SpaceX once did with Falcon 9, gradually building up from tests with a half-dozen or so engines to static fires with 20 or more – possibly up to and including a full complement of 28 Raptors.

From the SpaceX Starship page.

Thursday, March 18, 2021

SLS Conducts Successful Test Firing

I'm sure they must be breathing easier in the offices of the SLS program this evening.  They conducted an apparently flawless static test firing for the full duration, over 8 minutes. 

As you might gather from the lower left corner of that screen capture, I watched coverage on NASA Spaceflight . com, and we already have the update from Artemis program declaring this a successful static firing.  This was a complete simulation of the expected flight profile, with engines running at so-called "109%" at liftoff, throttling back during the time when Maximum Dynamic Pressure would occur (Max-Q), and throttling back to full power for the rest of the boost phase.  There were tests done to wiggle all four engine bells around and measure the dynamics that induces into the test vehicle.  They even tested the automatic engine shutoff in case the engines run too long and start to run rich on the fuel, which is liquid hydrogen.  The total test time was 499.6 seconds.

The white cloud in the picture is a mix of cooling water and the water produced while burning the hydrogen/oxygen the engines run on.  It rains on the surroundings.

As always, credit where it's due, so congratulations to the SLS team.  A successful test was absolutely required and they pulled it off.

Wednesday, March 17, 2021

Possible Next Engine?

Back on the last couple of days of February, I talked about trying to figure out what engine I'm building next.  (Feb 27 and Feb 28).  I've made some progress by hearing about engines I either didn't know existed or didn't know enough about to consider.  I'm closer to choosing a Hit and Miss engine and am looking at a few options.   

Perhaps I should explain a little bit about what terms I'm going to drop mean.  Hit and miss is a type of speed-regulated engine; an engine with a governor.  There are many examples around, but they were popular early in the 20th century on farms and in other light industry, where they'd often be mounted on a cart and wheeled to the next machine they were going to power. They had some sort of centrifugal force governor that was typically linked to the exhaust valve. If the engine was running too fast, the centrifugal force would spread the governor and the valve would be pushed open so that the engine no longer had compression, didn't fire, and slowed down. If the load slowed down engine RPMs, the valve would operate normally a higher percent of the time.  You can see the negative feedback: if RPMs are too high, the system slows it down and if RPMs are too low, the system speeds it up.  As a result, when they idle they make a kind of distinctive sound, speeding up and slowing down.  This video is an old John Deere hit and miss engine.

The two main ways we build engines are either from castings or stock shapes from the foundries.  The generic term for the stock shapes - plates, round bars, square bars and so on - is bar stock.  Castings can be any sort of metal, but most of the time are cast iron. 

The first engine I heard of and was able to download a PDF set of drawings for is David Kerzel's hit and miss engine.  It's a bar stock engine.  The displacement, though, is smaller than the Webster I just built; with a 0.75" bore and 0.8" stroke, that's 0.353 cubic inch.  (The Webster is 0.6 cu in..)  The flywheels are 3.5" diameter.

Another interesting version is an engine called the Zero Six; I assume because designer Dario Brisighella designed it in '06. This engine is bigger, with a bore of 1.125” and stroke of 2.00” (2.0 cu. in.) and it's also a bar stock engine.  The flywheels on this one are 6" diameter.  The plans for this engine are available, but I'll have to buy them for $25. This is an example from elsewhere on the web, built by "Jason in the UK".

I happen to like the looks of this one better than the Kerzel.  I've seen a couple of them in different color schemes. 

At the other extreme is the Bob Shores Little Angel.  This is the smallest hit and miss I've seen, with displacement of a blistering 1/10 of a cubic inch (better anchor the house!).  OK, not quite a full 0.1 cu in; it's .098.  It can be built either from castings or bar stock.  The flywheels are 2.5" diameter. 

Another popular engine is Jerry Howell's Farm Boy, which is between the Kerzel and '06 in displacement at1.08 cu. in.. 

The wild card is that any of these engines can be scaled to any size before you cut your fist piece of bar stock - but engines based on castings can't be scaled.  This guy on the net doubled the size of the Little Angel, simply doubling the size of all the parts, and says it runs great.

Early on, I said I have the drawings for the Kerzel.  I also have a CAD file of the engine that can be used to generate drawings for the dozens of parts in the engine.  All of which can be scaled by any convenient number.  The Kerzel has a 0.75" diameter piston.  Doubled, that turns to 1.5.  It can be scaled to the same diameter as the '06 using a factor of 1.5 or 3/2.

At this point, I haven't decided if I'm going to scale up the Kerzel or buy the plans for '06.  There's still room for something completely out of the blue to come along, too. 

Tuesday, March 16, 2021

Addendum to “How Bad is the $1.9 Trillion "Covid Relief" Bill?”

Last Thursday's piece on some of the crap hidden under the name of Covid-19 relief leads naturally to a follow up article today from FEE (the Foundation for Economic Education), featuring a list of the top 20 states getting bailout money from the bill. Let's cut to the chase and post the list, in descending order of amount of bailout money. 
  1. California: $42.3 billion
  2. Texas: $27.3 billion
  3. New York: $23.5 billion
  4. Tribal Governments: $20 billion
  5. Florida: $17.3 billion
  6. Illinois: $13.5 billion
  7. Pennsylvania: $13.5 billion
  8. Ohio: $11 billion
  9. Michigan: $10.1 billion
  10. New Jersey: $10 billion
  11. North Carolina: $8.7 billion
  12. Georgia: $8.17 billion
  13. Massachusetts: $7.96 billion
  14. Arizona: $7.48 billion
  15. Washington: $6.94 billion
  16. Virginia: $6.68 billion
  17. Maryland: $6.21 billion
  18. Tennessee: $6.12 billion
  19. Colorado: $5.9 billion
  20. Indiana: $5.7 billion
To begin with, it's much more widespread than I thought.  I knew about California and New York, but Texas and Florida?  Did you notice #4, Tribal Governments?  Why is this whole list even a thing?  The first thing they tell you, i.e., the first lie is that state incomes were down and they can't meet their expenses.  That's just not true; at least not as bad as they imply.  State revenues were down in the second quarter when the lockdowns were first ordered, but recovered fairly well in the third quarter and weren't down badly for the year.  JP Morgan said state revenue was “virtually flat” in 2020 nationwide while 21 states actually saw slight revenue upticks.

Graph from Chris Edwards at the CATO Institute.  The four rightmost bars are 2020, so compare the $474 billion in the fourth quarter of 2020 to the $470 billion in the fourth quarter of 2019.  Also note the vertical scale is exaggerated; the drop from the first to the second quarter - $22 billion - is a drop of 4.6%. 

That's telling me the $350 billion dollars was unnecessary spending.  If you assume that the taxpaying population of the US is 125 million people (derived from the USDebtClock) that means every taxpayer pays $2,793 for no apparent reason.  Except that it's never evenly divided; higher income taxpayers pay more, lower income taxpayers pay less.

The context we got before is that "red states are bailing out blue states," but there are red states in there, too.  The ratio favors the blue states, in that 13 of those got bailout money while six red states did.  The Democrats planning the spending package factored in not just population but also the number of unemployed citizens. This had the direct effect of skewing the bailout benefits toward states that enacted harsher lockdowns and punishing states who prioritized preserving economic activity.  It was, in many cases, Republican governors who opted for lighter restrictions and abandoned harsh lockdowns.  In states like this one (Florida), this has averted the unemployment and social destruction other states experienced—without producing noticeably worse COVID deaths. 

Perhaps the most incoherent and confusing aspect is that the state getting the biggest bailout, California, says they're running a budget surplus. To quote from FEE:
The only conclusion left to draw, however disappointing, is that Democrats crafted this bailout’s structure to favor states who pursued the COVID-19 policies they agree with—aka, states run by Democrats. Suffice it to say that political favoritism should never determine how limited taxpayer money is spent.

But, unfortunately, cronyism and favoritism are features, not a bug, of big government spending programs. As economist Ludwig von Mises once explained, big government programs concentrate enormous spending power in the hands of a few political officials; all but ensuring that favoritism follows.
Taxpayers in states that are doing well should not be paying Federal taxes that are functionally state income taxes in states they don't live in.  They shouldn't be paying Federal taxes to bail out other states.   

Monday, March 15, 2021

As SLS Green Run Re-Test Approaches, NASA Investigates the Program

This Thursday, March 18, NASA's Artemis program has scheduled the re-test of the Space Launch System (SLS) core stage, the test they call the Green Run, to qualify the vehicle for its first unmanned test flight.  The test will be at Stennis Space Center in Mississippi.  This re-test is due to the problem they had with the first test in January, when the vehicle software aborted the test at 67 seconds into a targeted 480 second test.  I wish them luck in their test.  Better yet, I wish them absolutely rock hard competency, something that seems to have been missing. 

It's interesting that word is leaking out in advance of this test that the new Biden administration has begun a study of the affordability of the program and whether or not to continue it.  The analysis is being led by Paul McConnaughey, a former deputy center director of NASA's Marshall Space Flight Center in Huntsville, as well as its chief engineer.  McConnaughey is working under Kathy Lueders, NASA's chief of human spaceflight, whose last job was directing the commercial/NASA partnership that's approaching the one year anniversary of the first commercially conducted manned launch.
The SLS rocket program has been managed by Marshall for more than a decade. Critics have derided it as a "jobs program" intended to retain employees at key centers, such as Alabama-based Marshall, as well as those at primary contractors such as Boeing, Northrop Grumman, and Aerojet Rocketdyne. Such criticism has been bolstered by frequent schedule delays—the SLS was originally due to launch in 2016, and the rocket will now launch no sooner than 2022—as well as cost overruns.

For now, costs seem to be the driving factor behind the White House's concerns. With a maximum cadence of one launch per year, the SLS rocket is expected to cost more than $2 billion per flight, and that is on top of the $20 billion NASA has already spent developing the vehicle and its ground systems. Some of the incoming officials do not believe the Artemis Moon Program is sustainable with such launch costs.
I know I've quoted a lot of these facts before but the prices of the SLS are stunning.  The SLS is using 4 of the Space Shuttle Main Engines, the RS-25.  These are excellent engines and probably have the most thorough documentation of their history of any rocket engine, an engine so good it has been called the Ferrari of rocket engines.  I'm not knocking the SSMEs.  The problem though, is these engine have been costed out at $146 Million a piece, or just shy of $600 million for the engines alone on one flight.  Engines that will be thrown in the Atlantic when the core stage is done.  When Rocketdyne was selling them to the Shuttle program they were $40 million as reusable engines.   

The published thrust in a vacuum of the SSME is 512,000 lbs. The stated thrust of the SpaceX Raptor v2 is 500,000 lbs.  OK, similar performance with the edge to the SSME.  The target cost at production of the Raptors is $250,000.  That's not even two thousandths (0.0017) of the cost of the SSME, or 0.17% if you prefer.  The current generation of Raptors, as they work toward that $250 thousand price is around $1 million.  That's still stunningly less than $146 million.

$146 million for the engines alone is similar to the price of a mission on a Falcon Heavy with reused boosters.  Powered by the smaller and less powerful Merlin 1D engines, the Falcon Heavy has two-thirds the lift capacity of the Space Launch System at one-twentieth the price.

These are the kinds of things that the NASA study will be facing.  Even before the study's initiation, Study Lead McConnaughey had been pushing for the SLS program to become more cost-effective. One goal of this analysis is to find ways for the large NASA rocket to compete effectively with privately developed rockets as part of the agency's Artemis Moon program.

The real wild card here is Starship.  SpaceX is continuing the Starship Launch System test campaign, as we talk about regularly.  SpaceX has said they intend to make its first orbital flight by July 1 of this year; that may be Elon Standard Time, but it seems likely it could be between July and the end of the year.  This is a launch vehicle that could potentially out-lift the SLS rocket, be reusable, and cost a fraction of the price. If SpaceX succeeds in getting Starship into orbit, how could NASA justify continuing government subsidization of the less capable SLS booster, which is expendable and costs much, much more.  

Of course the main contractors on SLS don't believe SpaceX can do it.  To me, there doesn't seem to be much profit in betting that SpaceX can't accomplish things they say they will.

NASA Artist's Concept of SLS.

Sunday, March 14, 2021

SpaceX One Launch Away From Falcon 9 Ten Flight Goal

We had a launch at 6:01AM this morning and I forgot!  It had nothing to do with the switch to DST, I just forgot the date!  I thought it was tomorrow morning.  

But that's not important. The news is that they launched another load of 60 Starlink satellites. This was the ninth flight of booster B1051, last flown on January 20th when she set the record of 8 flights.  She landed without incident on the drone ship Of Course I Still Love you.   

The mission also reused a fairing that was launched just 49 days ago on January 24th.  The turnaround time to reuse the fairing absolutely crushes the previous record – 87 days – by almost 60%.  As a reminder, they didn't reuse a fairing until 16 months ago so they're much less experienced at it.  They haven't been trying to recover fairings as long as they've been trying to recover and reuse boosters.  

If the inspection and checkout of B1051 go well, we could see the 10th flight in April.  As most of us are starting to suspect 10 might not be a magic number.  It was just last month that Hans Koenigsmann, SpaceX's VP of Build and Flight Reliability said that he didn't see any fundamental reason they couldn't keep flying. 

It may well be that they can be flown many more times.  I'm rather certain parts get replaced if need be now; that will just continue.  By the end of this calendar year, I think there will be several boosters at 10 or more flights.

Saturday, March 13, 2021

It's That Time Again

It's that time again, the day when the US goes into a reshaping of society that nobody seems to understand and progressively fewer and fewer people seem to want.   It's the weekend when the collective decides everybody gets up an hour earlier and goes to bed an hour earlier until the first Sunday in November.  So that we can go to work an hour earlier, and come home an hour earlier, so that we have more sunlight after work even though we still go to bed earlier.  They call it Daylight Saving Time, but that's an oxymoron, a contradiction in terms.  We can't affect the length of the day any more than we can affect how long the tides run.  All we can do is change what we call the hours. 

The thing is, we're supposed to be done with this in Florida.  In March of 2018, the Florida legislature passed a law halting the twice-yearly shifting of the clocks.  Unlike some other states that have plotted an exit strategy from Daylight Saving Time, Florida was going to stay on DST all year round.  Why not stay on standard time?  Apparently the tourist industry thought that shifting the time to put sunrises and sunsets at a later hour would sell better to people coming down here in mid-Winter.  That aspect was opposed by PTA groups who are concerned about it putting kids en route to school during dark winter mornings.  Still, the law was passed.

The problem is that the over-reaching insists that we get their approval for this, which certainly doesn't seem to be a legitimate Federal power to me (of course, IANAL).  According to one source I read on this years ago, the only power states have is to stay on standard time.  Which implies staying on DST is somehow wrong. 

As he should, Florida Senator Marco Rubio introduced the so-called Sunshine Protection Act in 2018 in an effort to work for his state and get the rest of the senate to vote to approve Florida's state law.  He got a small number of co-sponsors, fellow Florida Senator Rick Scott, and two from other states.  Nothing ever became of it.  Here we are, hostages of the US Senate's inaction three years, almost 1100 days later.  Sen. Rubio reintroduced the bill in '19, and again this year (I'm not sure about '20). 

Entrepreneur Scott Yates, who runs a website called #LockTheClock, says that in the life of his efforts, we've gone from not one state passing a bill to end the clock changes to there being 15 states this year. They're all hung up in the Senate. There's a bill in the house that might be an easy way around: US HR214 - Daylight Act allows states to decide to stay on DST, just as they now can decide to stay on Standard Time.  (I'm old enough that when I was a kid, we assumed everything was legal unless there was a law specifically forbidding it.  Those days are long gone.) 

There are two other bills; one in the house and one in the senate. US S623 - A bill to make daylight saving time permanent, and for other purposes.  and US HR69 - Sunshine Protection Act of 2021.  Both of those bills make DST the new standard time, stop the changing, but differ slightly in how they handle states that might want to keep both the old standard and new DST standard.  It's beginning to look like such a bill could pass this year or next, making the next "spring forward" into the last. 

It may seem a bit melodramatic to say the clocks are killing the people, but there are some well-documented side effects of the "jet lag" people get from the time changes: more car accidents, more accidents at work, higher rates of heart attacks and strokes, and more. 

Friday, March 12, 2021

The Difference Between Statistical Significance and If Something Matters

The CDC released a report this past Monday that showed statistical significance in wearing face masks vs. not and the rates of Covid 19 infection growth and the death rate.  I think it's a perfect example of the kind of association or correlation studies we get smacked with all the time.  A change that can be shown to be statistically significant may mean absolutely nothing in real life (IRL). 

Let's start with the high level conclusion, the one they use to sell the results. 
Mandating masks was associated with a decrease in daily COVID-19 case and death growth rates within 20 days of implementation. Allowing on-premises restaurant dining was associated with an increase in daily COVID-19 case growth rates 41–100 days after implementation and an increase in daily death growth rates 61–100 days after implementation.

What are the implications for public health practice?
Mask mandates and restricting any on-premises dining at restaurants can help limit community transmission of COVID-19 and reduce case and death growth rates. These findings can inform public policies to reduce community spread of COVID-19.
Wow!  That means masks matter!  To heck with the years of previous studies from the same CDC, as we talked about last November that said 14 Randomized Controlled Studies did not show a substantial effect from masks or hand washing on Influenza transmission (and presumably other respiratory viruses).  This is new and improved science! 

So let's jump ahead to the math because that's the important part. Bold and underline added. 
During March 1–December 31, 2020, state-issued mask mandates applied in 2,313 (73.6%) of the 3,142 U.S. counties. Mask mandates were associated with a 0.5 percentage point decrease (p = 0.02) in daily COVID-19 case growth rates 1–20 days after implementation and decreases of 1.1, 1.5, 1.7, and 1.8 percentage points 21–40, 41–60, 61–80, and 81–100 days, respectively, after implementation (p<0.01 for all) (Table 1) (Figure). Mask mandates were associated with a 0.7 percentage point decrease (p = 0.03) in daily COVID-19 death growth rates 1–20 days after implementation and decreases of 1.0, 1.4, 1.6, and 1.9 percentage points 21–40, 41–60, 61–80, and 81–100 days, respectively, after implementation (p<0.01 for all).  Daily case and death growth rates before implementation of mask mandates were not statistically different from the reference period.

During the study period, states allowed restaurants to reopen for on-premises dining in 3,076 (97.9%) U.S. counties. Changes in daily COVID-19 case and death growth rates were not statistically significant 1–20 and 21–40 days after restrictions were lifted. Allowing on-premises dining at restaurants was associated with 0.9 (p = 0.02), 1.2 (p<0.01), and 1.1 (p = 0.04) percentage point increases in the case growth rate 41–60, 61–80, and 81–100 days, respectively, after restrictions were lifted (Table 2) (Figure). Allowing on-premises dining at restaurants was associated with 2.2 and 3.0 percentage point increases in the death growth rate 61–80 and 81–100 days, respectively, after restrictions were lifted (p<0.01 for both). Daily death growth rates before restrictions were lifted were not statistically different from those during the reference period, whereas significant differences in daily case growth rates were observed 41–60 days before restrictions were lifted.
Note the underlined last statement in the first paragraph.  Daily case growth and daily death growth rates were not statistically different than the reference period, 1–20 days before implementation of the mask mandate. 

Allow me to put the numbers from the first paragraph in a format I find more understandable: Mask mandates were associated with 0.5, 1.1, 1.5, 1.7, and 1.8 percent decreases in daily COVID-19 case growth rates at 1–20 days, 21–40, 41–60, 61–80, and 81–100 days after implementation.     Ordinarily, in this sort of study, when they present numbers like the first paragraph, those are relative numbers.  We don't know the daily growth rate from this study, but for illustration, let's assume it was growing at 10% per day.  That decrease of 0.5% at 1-20 days is not 10% - 0.5% or 9.5%.  It's 10-(0.5% of 10) or 9.95% growth rate.  You would need a lot of samples to detect that small a difference and they did: they had 2,313 datasets for the first data set and 3,076 for the second.

In plain English, if your chances of getting the infection was 10% without a mask, wearing the mask improved it to 9.95%.  Take the worst daily case growth rate increase of 1.8%.  Converted from relative risk to absolute risk, that's 9.82%.   Just for fun, let's bump the odds of getting infected from 10% to 20%.  Those two numbers turn to 19.9% and 19.64%.

A very reasonable question is whether a relative risk of 0.5 or 1.8% really matters IRL.  Again, that's 1.018 chance vs a 1.000 chance. The relative risk of things we absolutely know are bad, like smoking, aren't 2% worse, they're 2 times worse or more. Relative risks like this could be from anything and not the thing they think they're measuring.  For example, I find no mention of the type of mask; whether an actual N95 mask, a surgical mask, or a cloth gaiter.  Are all masks the same?  I doubt it.  Read my article with the table of spurious correlations that make up much of the junk science we're subjected to daily. 

Their figure from the study. 

The exact number on what your chances are of getting infected are hard to find.  There are tons of factors that must be accounted for: how much virus you're exposed to, the health of the tissues in your respiratory tract, and a broad swath of other metabolic health questions.  A reasonable question might be, "do masks matter?"  Based on this I would have to say yes they do.  They just don't matter much at all.