A Ham Radio Series 4 - Antennas, Tuners, and Analyzers

The whole field of antennas and how to get them to do what you want comes up regularly.  There's dozens of books on the topic and an article or two isn't going to get you expertise.  Things that I think might be important may not be relevant to how you want to operate.  I've written lots on this from a more or less "how do they work" perspective.

• A general introduction:  Ham Radio - Antennas
• A more technical series:  part 1,  part 2,  part 3 

Lately, I've been playing with something like The Three Laws of Antennas, patterned after Asimov's Three Laws of Robotics.

First Law: anything you can put up works better than nothing at something.
Second Law: nothing is best at everything.
Third Law: whatever you can put up won't be as good as you'd like.  Unless you have a Jeff Bezos-level budget including the property to match. 

A friend once told me that “Engineering is the art of compromise” and antennas are a perfect example.  The three laws emphasize that, each in their own way. 

It's my experience that most hams don't go out and put up some sort of megabucks antenna installation as they're starting out, going instead for something that's a bit more of a compromise, so let's consider a compromise antenna.  This is a length of wire that can only be resonant at one frequency and unless that frequency happens to be in a ham band, you won't be able to use it.   It doesn't matter what antenna you pick in terms of this discussion: a G5RV multiband antenna; an Off Center Fed Dipole (OCFD) or just a random length of wire, end fed. 

As a general rule, transmitters are fussier about the exact impedance of the antenna than receivers are and you'll find that your transmitter might not put out power at all - especially if it's a solid state (transistor of some kind) final.  What you need here is an antenna tuner.  I prefer automatic tuners (autotuners) because I like pushing a button and letting it do the work.  There are many on the market; the first I owned was by LDG and I still have a couple of them. 

What's inside an antenna tuner?  An impedance matching network called an L network.  It's simply two parts in a configuration that looks like the letter L, if you lie on your side.   The two components can be a series L/shunt C, a series C/shunt L, both can be inductors or both can be capacitors.  There are eight possible configurations; four to match to higher impedance, four to match to lower.   It helps to visualize the direction of impedance change, to higher or lower impedance, if you draw it almost like a little ladder.  The shunt component is on the higher impedance side.  In this example, we're climbing up to a higher impedance load.  If the load was lower impedance, the shunt component would on the source side - still the higher impedance side.  Another thing I like about an autotuner is that I don't have to think about this.  I push a button and it finds a good solution. 

The autotuner is an L-network with a bunch of coils and capacitors with relays to switch the series and shunt components of the L-network end to end and change their values rapidly; series adding inductors or parallel adding capacitors.  The tuner tries a combination, measures VSWR, compares it to the starting value and goes through an optimization process to find the lowest VSWR it can get.  In the end though, it’s electrically two components.

If you shop for radios, you'll find that a number of models feature an internal autotuner; everyone I've seen is limited in the range it can tune to 3:1 VSWR or less.  By comparison, the external autotuners tune a much wider range of impedance, 10:1 or more.  There are also external tuners that are more than just a two component L network; they can tune even wider ranges.  I've had older model radios that tuned well beyond the 3:1 range, which is a fairly minor adjustment.  Newer radios have software that does that first measurement, sees that it's starting above the limit, and won't try to tune at all. 

Do you need an antenna analyzer?  What is an antenna analyzer, anyway?  An antenna analyzer measures the impedance of the antenna.  Some are manual, like the popular MFJ-259D, you set them on frequency and read off the Resistance and Reactance.  You need to tune the frequency and see how the reactance (X) varies to see if it's inductive or capacitive - if the reactance goes up with frequency, it's inductive and if reactance goes down, it's capacitive. 

The manually tuned analyzers like the MFJ are lacking in a lot of features, but you can trim an antenna for lowest VSWR with one.  There are many antenna analyzers that do a frequency sweep for you and save the impedance values, both resistance and reactance with sign, save plots, or even export files of your antenna data for use in antenna design (or redesign for new purposes). 

“In the old days,” we used to tune an antenna to resonance by turning down the transmitter power, keying it up, measuring SWR with an SWR meter, and keeping track of how it changes.  If you're putting together a station, you should consider an external autotuner if you have a radio that limits tuning to 3:1, and especially if your radio doesn't have a built in tuner.  An analyzer is a purchase that makes most sense if you plan to experiment with antennas or want to build more.  They make keeping track of changes in your antennas easier, too.  I have an analyzer (not made anymore or I'd show you a picture) and since I make little odds and ends around the shack, I use it to measure components as well as measuring antennas.  They're useful tools.

Tales From the Seattle Communist Enclave

Or You Just Can't Make This Shit Up.

According to PJ media, Seattle's breakaway communist enclave called CHAZ (Capital Hill Autonomous Zone) has encountered troubles with their independence.  The only assets they have are stolen, and people who steal other people's assets (that is, the people of CHAZ) will steal anything that isn't permanently attached.

As Divemedic pointed out on Confessions of a Street Pharmacist, the communists behind CHAZ are incredible hypocrites.  One of the first things they did was build a border wall.  I assume it was with stolen materials, like the road barricades they stole from America when they formed their little empire.  And then their border wall was stolen right back.  

Bryan Preston, writing over at PJ Media puts the thoughts together like this:

The CHAZ collective thanked the mayor for her gift of a six-block area of America the mayor does not personally own (and which includes about 500 homes of actual Americans) by storming city hall and demanding that she resign unless she disbands the police.
...
Call the police!

Right — CHAZ wants to disband the police. The police are over in America anyway, and American police have no obligation to help secessionist CHAZ.

CHAZ has no farms or orchards. CHAZ is paved over with streets and buildings. CHAZ cannot feed itself.
...
It’s a pity CHAZ has no indigenous lumber supply.

Or electricity. Or water supply.

There has been talk about putting an embargo around the CHAZ and starving them out.  Note that they report there are 500 homes in the area they've taken over.  That's got to be somewhere between 700  and a thousand innocent people that are hostages in the CHAZ.  Since that's Antifa, and they're a designated terrorist organization I believe there are protocols for situations in which terrorists hold hostages.  We assume the citizens are opposed to losing their property to Antifa, so free the hostages and if all the Antifa loons happen to not survive, those are the breaks.   


 

A Lot of Sanity in 15 Minutes

I'm a long time subscriber to Glenn Beck's internet streams, first signing up right around the time of the legendary “wardrobe malfunction” Super Bowl half time show.  Beck's right hand man for the life of the program has been Stu Burguiere and they talk about having worked together since the first days of the show in Tampa, Florida.  In my early days listening to them on the radio at work, I thought Stu was really the brains of the outfit and Glenn, who described himself as a rodeo clown, was essentially just that.  In the years since, I've come to regard them as a really good team that comes at problems from some very different directions.  Glenn is driven by his emotions while Stu is a much more logical thinker.  On his own shows and on the Blaze TV network he has done a segment called Stu-tistics, in which he takes a decidedly analytical approach to things.  The Glenn Beck show is another example of a situation where the sum is greater than the parts.

We've all seen some of the statistics thrown around about the riots and urban unrest going on.  We've seen Instagram remove the 2013 FBI crime stats because it violates their narrative standards.

Larger version at the above link (90 Miles From Tyranny).

Stu takes a look at some of these stats with a different take than I've heard anywhere else.  I thought the fact of the day Stu quotes is that 144 people a year die from constipation.  If the number we've seen elsewhere is correct that 10 black men were killed by the police last year, then they're over 14 times more likely to die of constipation than from being killed by a cop.  I've heard a lot of demands, but none for free Ex Lax. 


Over 60 people died from an unfortunate lawnmower incident but almost 700 people a year die falling out of bed.

Stu's point, and it's a good one, is that in a population of over 300 Million, something that affects 10 or 20 people is awfully hard do anything about.  All the data we can find that's from real academics and not race hustlers says the rate of these police killings has been declining for years.  If next year's statistics said it was 12 instead of 10, was that a horrible relapse or random variation?  What are the error bands? 

So the cities are going to de-fund police because some radical activists say so? 
  

As The Crew Dragon Test Flight and Work on Starship Continue

As the Bob & Doug Show continues, more formally the Demo 2 Test Flight of the Crew Dragon spacecraft, an interesting little modification to the existing NASA contract has gone through and is pointed out by a comment on the Teslarati news site.  You might have heard that NASA only wanted brand new Falcon 9 boosters for manned flights.  This contract modification, on the Federal Government's SAM.gov beta website says that they will allow reused Falcon 9s. 

THE PURPOSE OF THIS BILATERAL MODIFICATION IS TO EXTEND THE DEMO-2 FLIGHT TEST FROM TWO WEEKS TO UP TO 119 DAYS AND ADD THE REQUIREMENT FOR 45TH OPERATIONS GROUP DETACHMENT 3 (DET-3) JOINT TEST TRAINING FOR PCM-1 THROUGH PCM-6 IN EXCHANGE FOR ALLOWING REUSE OF THE FALCON 9 LAUNCH VEHICLE AND CREW DRAGON SPACECRAFT BEGINNING WITH PCM-2. [BOLD added - SiG]

My own view, worth nothing, is that a once-flown booster is probably the peak of reliability; everything has been thoroughly tested, then thoroughly reinspected afterward.  Obviously, the Demo 2 test mission isn't over until the capsule reenters the atmosphere, splashes down in the Atlantic, and the crew is safe and sound on board the recovery ship.  That should be the weekend of September 26th, if the Days From Date Calculator isn't mistaken.  The crew for the next Crew Dragon mission is already in training and undoubtedly has been in training for quite a while; Doug Hurley and Bob Behnken were assigned to this mission and worked with SpaceX for five years before this flight. 

Jim Bridenstine, explained during a pre-launch briefing that the next flight of the Crew Dragon could fly as soon as August 30. That flight, called Crew-1, would see the Dragon carry four astronauts to the space station for a six-month stay. On board will be three NASA astronauts — Mike Hopkins, Victor Glover, and Shannon Walker — who will be joined by Japanese astronaut Soichi Noguchi. 

Meanwhile, work on preparing to resume testing the Starship prototypes continues.  The debris from SN4's RUD was largely cleared away the next day and the work of rebuilding all the damaged hardware has been underway.  The cause of the explosion was quickly isolated to Ground Support Equipment, a Quick Disconnect panel that's supposed to ease connecting and disconnecting fuel lines.  It's an assembly like this one, although this particular QD is on the Starhopper that flew last summer. 

Shortly after a post-launch briefing celebrating and discussing SpaceX’s inaugural astronaut launch on May 30th, Reuters reporter Joey Roulette was able to ask Musk about Starship SN4’s spectacular demise the day prior. The SpaceX CEO was quoted saying that “what we thought was going to be a minor test of a quick disconnect ended up being a big problem”, confirming suspicions based on careful analysis of public views of the explosion that it was caused by issues with Starship’s ground support equipment (GSE).

Reading the LabPadre video sidebar, it seems there was hope of moving SN5 to the test stand today but those plans were scuttled and the road closure postponed until Thursday, June 11, at 6AM to 2PM CDT.

Meanwhile, in addition to the Starship testing in Texas, SpaceX has their first four-launch month scheduled.  Four in a month isn't a huge improvement; their previous busiest was four launches in 32 days, but it's indicative of a continuing emphasis on getting better at what they do and improving their launch tempo.  Those are:

(the first launch was Wednesday night, June 3rd)
June 12 – 9th Starlink launch
June 24 – 10th Starlink launch
June 30 – GPS-III-SV03 launch 

With a June 30th launch - as usual, a “No Earlier Than” date - it doesn't take much of a delay to push that into July, but July 3rd is 30 days later, just not a calendar month.  It's interesting to watch, not so much for the milestone of four launches in a calendar month but seeing the cadence they're attempting to hold.  SpaceX has 14 commercial launches scheduled in the second half of 2020, while an additional 20-24 Starlink launches were talked about at the start of the year.  So far, they're off their stated goals, with it looking more likely they'll get 18 Starlink launches.  

SpaceX's Boca Chica, Texas, production and test facility.  From Elon Musk.  There's talk of building something the size of NASA's Vehicle Assembly Building to accommodate the Starship Heavy that is in development now. 

A Ham Radio Series 3 - HF Propagation Practicalities

As I start writing this, I’m going back and forth between typing and working across the southern tier of the US by Sporadic E skip on 6 meters.  East Central Florida to eastern California and Arizona.  While not impossible this time of year, it’s also not to be dismissed as trivially common. 

Of course, I don’t know more than a few of you well enough to know your interests in radio, but let’s resume where we were last time. 

The practical question comes down to this: how do you know that the band you’ve set your radio to is going to go to the F2 layer and come back down far away?  It's common for the ionosphere to allow, for example, 21 MHz signals to propagate over a path, but not 24 MHz, and certainly not 28 or 29.  Which frequency escapes into space and which refracts back down depends how densely ionized the ionosphere is where the signal hits it.
 
The density of the ionization depends on how much high energy radiation is coming from the sun and that varies with the (roughly) 11 year long solar cycles.  Around World War II, a relationship between propagation and observable radio emissions from the sun was realized and the world standardized on monitoring solar radio emissions, called the Solar Flux, at a wavelength of 10.7 cm, or 2.800 GHz.  That’s just above the 2.4 GHz WiFi band.  Note to people who think being exposed to microwave or WiFi frequencies is new to humanity; 2.8 GHz radio has been coming along with sunlight for as long as we’ve been on the planet! 

The 10.7cm Solar Flux Index (SFI), is one of the longest running records of solar activity but only goes back to 1946, while sunspot observations go back hundreds of years.  The measured solar flux correlates well with the sunspot number as well as a number of UltraViolet (UV) and visible solar irradiance records.

The strongest solar cycle on record occurred in the 1950s.  Cycle 19, as it’s called, is still remembered fondly as the source of 24 hour openings on 10meters and openings on 6 meters.  Observations of sunspot numbers exist back to the time of Galileo, and those cycles show that the 20th century was remarkably active.  We appear to be settling back to more typical amounts of activity.  The consensus of groups trying to predict the next cycle, 25, are saying it’s going to be much like the past cycle, which was said to be the weakest in over a hundred years.  That’s going to put a premium on operating with denser crowds of signals in the bands, receivers that handle big (nearby) signals well, and better ways to extract hard to copy signals.

(Source) Two things about this plot; first, note the highest peak, that's 19 in the late 50s/early 60s; second, note it doesn't include the cycle just completing; that one is very similar to the peak around 1910. 

You might say, “that's cool but it still doesn’t answer how you can tell if your signal will be propagated to that location you want to contact.”  A simple answer is you can listen.  If you’re trying to hear a country with a large ham population, if you can hear them, chances are someone can hear you.  But what if you want to contact a country with a small population?  What if everyone is listening? 

There are propagation prediction programs widely available to the amateur.  Some, like VOACAP (Voice of America Coverage Analysis Program) are the result of big government studies and expenditures.  Others are the result of different analyses and there are many websites and programs available.  As mentioned in the preface, the ARRL produces graphics like this one, which shows predicted propagation from the East Coast of the US to the areas described and a graph with a few colored lines. This plot is for last month, May, 2020 and assumes an average Solar Flux of 66 which is Quiet Sun or no solar enhancement. 

The different colors represent the frequencies expected to be open to those locations to different probability levels.  The red curve is always highest; it's the Highest Possible Frequency that will be available on 10% of the days in the month (that's 3 days out of the month; which 3?  good question).  The green curve represents the 50% of days curve or that half the time, the best frequency will be that high.  That used to be called the Maximum Usable Frequency or MUF.  Finally, the light blue curve represents the Lowest Usable Frequency for a 1500 Watt transmitter using CW (Morse code).  For lower powers or other modes, that frequency may be higher; between the shown light blue curve and the green curve.  The horizontal lines seem to represent amateur HF bands.

The "East Coast" is a big area and it would help to know where this data is centered, but assume for the moment it applies to us in Florida.  Let me pick the East Coast to Australia chart.  0000 hours UTC is on the left, which is 8PM EDT.   Three days of the month, the 12 meter (24.9 MHz) band should be open to Australia, but 50% of the time, the 15 meter (21 MHz) band will be open.  By 0400 UTC, or midnight local that has closed down to 20 meters (14 MHz) and it's going away fast.  From then until dawn (around 1000 UTC), the most reliable band looks to be 30 meters, even going down to 40m.  After sunrise, the curves show the opening returning to 20 meters, and finally to 15 then possibly 12m again from 2000 to midnight UTC, or 5 to 8PM EDT. 

Should you go for the 50% chance, green curve or try for those 3 days a month that it goes to the red?  The advantage of going to the Highest Possible Frequency is that absorption in the ionosphere is lower closer to it, so a weak signal might do better.  The drawback is the other 90% of the month you sit around listening to nothing.

One of the issues of charts like these is that they don't address any of the real world effects; a guy with an 80 foot tall tower and high gain antennas experiences this differently than someone operating portable with backpack antenna and QRP power.  The good propagation programs attempt to use that sort of information to make predictions more accurate and reliable.

No matter what the propagation forecasts or predictions say, sometimes you've just got to listen.  There is no substitute for listening.  Even if you're not listening, but a piece of software is. 

A Ham Radio Series 2 - Radio Propagation Preface

It seems that one of the most popular things people wanted to read about was propagation.  That's a tall order for a couple of reasons: the first is that it's a very broad field; so broad that many books have been written about it.  So broad that none of it is applicable to every amateur radio band, but that some aspects can blend for different bands.  So broad that experts in one area can study nothing but that area and still not predict it perfectly. 

Propagation is concerned with getting radio signals from one user to another.  It's not all ionospheric; I'm not even sure I'd say it's all atmospheric, but most is.  At low frequencies, say below HF (defined as 3-30 MHz), much signal propagation is by conduction along the ground - the ground wave.  There's a ground wave at HF too, but it's much less prominent than the AM broadcast band and lower in frequency.  HF is where the ionospheric propagation is most influential.  In the entire electromagnetic spectrum, there is one piece of spectrum that allows worldwide communication without man-made infrastructure; that place is the HF spectrum. 

Most hams have probably seen a diagram somewhat like this one at some time:

It shows that as the signal leaves the transmit antenna, it splits into two components, the ground wave and the sky wave.  If the ionosphere is dense enough, from a variety of factors, the sky wave can be refracted by the electrically charged ions in the ionosphere, and come back down hundreds or thousands of miles away.  That signal coming back down can reflect off the earth, or especially the ocean, and go back into the ionosphere again - called multi-hop. Underneath that area where the signal is depicted going into the ionosphere and refracted back down, nothing can be heard.  This is called the skip zone; the signal skips over the vast path under that curve. 

A problem with this depiction is that it gives the impression that if we could be above that radio path and look down on it, it would be straight on some compass heading.  That's not always true.  The signal path can bend.  Narrow beam width HF antennas are extremely big and expensive (for most of the spectrum) so there's little experience with it. 

The radiation angle from the transmitter matters a great deal; if the angle is too high, above a critical angle for the ionosphere, the signal path will get refracted by the ionosphere, but not refracted far enough to come back down to the ground, so it travels off into space.  This graphic was published in Electronics World for April, 1969 and posted by RFCafe.  Signal paths above the critical angle are seen on the left. 

The radiation angle is a property of the antenna, including how it's mounted and the area around it.  People trying to work stations the farthest away always emphasize getting a low angle of radiation, pointed pretty much at the horizon.  Look at the bottom ray leaving the transmitter on the left.  Because it's so low, it reaches the ionosphere the farthest point from the transmitter and while we can see it coming back down, that's so far to the right we don't see it.

This is not to say that the ionosphere is the only way we have of getting signals from Here to There.  F layer skip pretty much disappears above 6 meters (50-54 MHz) - and isn't that high often.   Sporadic E, talked about last time, is regularly heard on 6 and occasionally as high as 2 meters.  Most of the time, signal propagation on 2 meters is in the lowest layer of the atmosphere, the troposphere.  Weather conditions cause the possibility of ducts to form in the air that keep the signals from going straight (and out of the atmosphere) by bending them down toward the Earth as they travel.  There are attempts to predict this based on weather modeling that post plots of the chances of tropospheric ducts.

Tropo ducting is the dominant way of propagating VHF and UHF, up into the microwave spectrum.  A friend of mine once experimented on the 10 GHz amateur microwave band and used to tell the story of testing his small (3 feet diameter) microwave dishes on the beach, from near Cape Canaveral talking with another guy down near Ft. Pierce, Florida (around 70 miles).  He'd say when there was no duct it was very hard to get the dishes pointed precisely and hear the other guy, but when a duct formed, it was very easy.  Sometimes it almost didn't matter where the dish was pointed.   

The troposphere has another trick called Scatter.  Think of blasting a high power VHF signal into the sky and listening to what bounces back, as if it were some sort of radar.  Troposcatter has been used by the military.  There are such things as rain scatter, and aircraft scatter, where signals bounce off airplanes traveling in heavily traveled corridors.  Meteor scatter is a routine mode of communications, especially now with fast digital modes like MSK144 to take advantage of meteor trails that aren't very long lived.  I'm sure there are others I haven't thought of. 

The ARRL has a propagation prediction site that has color graphics to download of HF (ionospheric) propagation predictions and some articles that help explain what you're looking at.

Tiananmen Square - The End of Limited Freedoms in China

Thirty one years ago today, June 5th, 1989, the symbolic resistance of the so-called Tank Man took place in Tiananmen Square in the People's Republic of China.  Ironically, this event that was taken as the symbol of the protests in the West took place after the protests were largely over and the protesters largely massacred. 

The resistance of this never-identified man was celebrated widely by the west as a successful resistance to the power of the column of tanks but was preceded by the Chinese Government massacring an estimated 10,000 of their citizens for the Tiananmen Square protests on the night of June 3-4 in Beijing.  The folks at Ammo.com, have written a worthwhile piece on the event, the history leading up to it and since then.  It deserves reading. 

The lead tank tried to maneuver past the man, but was met with nonviolent resistance. The man repeatedly shuffled in front of the tank to obstruct the tank’s path. After a while, the lead tank stopped in its tracks and the armored tanks behind it stopped as well. From there, a short pause began with the man and tanks remaining in a standstill.

The video footage then shows the man climbing on top of the tank’s turret and chatting with a crew member and the tank’s commander. After having a conversation, the man jumps back down and gets in front of the tank again. The standoff between the man and tank continued until two figures in blue came out and pulled the man to the side. To this day, witnesses at this event are unsure about who pulled the “Tank Man” to the side. Furthermore, the identity and fate of the man is still unknown, although there has been speculation that he was either executed or fled the country shortly thereafter.

I don't think “executed or fled the country” are mutually exclusive.  If he fled the country, he could well have been tracked down and executed.  If he survived that, he's probably smart enough to never tell anyone that he was that man.  I doubt we'll ever know the story.   

Milton Friedman once observed that economic freedom generally is a precondition for political freedom, but that's hardly a law of nature.  People who have had a taste of genuine economic freedom may develop hunger for political freedom, but the Chicom technocratic dictatorship is not likely to do anything for that hunger.  Tiananmen Square itself was the result of protests for more freedom and against the emerging class of insiders who made enormous profits through connections with the Chinese Communist Party, a problem to this day.

In the years since the Tiananmen  Square massacre, the Chinese Communists have created one of the most monitored and tracked societies on the planet.  Facial recognition systems feed into their Social Credit Score system made in the US by Google and Facebook; it is, after all, based on what those companies are doing to conservatives here in the US.  The Chicoms, of course, have gone beyond that to putting Muslim Uighurs in re-education camps, to widespread condemnation from international human rights observers.  There are reports of organs being harvested from living, healthy, people to sell on the transplant market.  

The Tiananmen Square protests were disastrous for the Chinese people.  A protest for increasing liberties led to the elimination of most freedoms and the introduction of the world's worst surveillance state.  (well... maybe)   It led to the massacre of whoever was in that square the night of June 3rd and 4th.  The only argument for the protests is that it might have wound up this way regardless.

The SpaceX Falcon 9 at 10 Years Old

 Last night, we got the chance to watch SpaceX launch their Starlink 8 mission on top of booster B1049; the booster and rocket performed flawlessly and the booster successfully landed on their drone ship Just Read The Instructions (JRTI).  This marked the first time a booster has been recovered after flying five times and brings them another notch farther in their life testing of the Block 5 boosters, designed to fly ten times.  SpaceX President and COO Gwynne Shotwell says that they may be able to fly more than ten missions without massive refurbishment.

B1049 moments after landing - screen capture from SpaceX webcast, June 3, 2020.

At the end of the Webcast, the Engineer doing the commentary casually mentioned that today is the tenth anniversary of the first Falcon 9 launch.  I recalled doing a story on the 10 year anniversary of the Falcon, but that was the first flight of the Falcon 1.  That 10 year anniversary was less than 2 years ago, September of 2018, so in less than two years, SpaceX went from a booster powered by one Merlin engine to the nine of the Falcon 9.  From that itty bitty booster on the left of the family tree to the second one.

As in that first article, I'm basing this on a piece by Eric Berger on Ars Technica.  Eric says, “Forget Dragon, the Falcon 9 rocket is the secret sauce of SpaceX’s success.”  His point is good; in the last week, the Crew Dragon capsule has gotten the attention of millions of people, but what has made SpaceX into the competitor they are is the outlandish engineering of the Falcon 9.

The article isn't long and is definitely worth going to read, but I usually excerpt a few things to whet your appetite in pieces like this, so this will be no exception.  Berger starts with a story that sums up some of the things behind that success.  He begins on June 3, 2010; as often happens, thunderstorms had come across the cape that day, the day after the vehicle had been moved to the launch pad and gotten clearance from the Air Force to launch on the 4th.  This was a humongously huge moment for the startup company, looked down on by old line NASA for being "cowboys". 

Four tall lightning towers protected the rocket from strikes during the rains, but post-storm checkouts revealed a weak telemetry signal coming from antennas on the Falcon 9 rocket's second stage. Water from the day’s downpour must have gotten into the electronics. This was a potential showstopper for the next day’s launch attempt; it had to be fixed. To do so, the launch director, Tim Buzza, drove out to the launch pad with the company’s founder, Elon Musk, and a senior director of avionics, Bulent Altan.

They arrived at the launch pad well after dark, and the Falcon 9 rocket had already been lowered from its vertical launch position back into a horizontal configuration.

Altan, who knew the avionics system as well as anyone, climbed a ladder to where the antennas were located on the second stage. He removed a cover to assess the damage, confirming that rain from that day's storms had gotten into the rocket's electronics. Overhead, bright lights shone down. Below, dozens of eyes stared up at Altan.

So now what?  Do they roll the booster back into the hanger and give up their launch position?  Swap out the electronics?  Nobody liked those ideas, so they tried a decidedly lower tech solution.  Someone got a hot air gun, virtually a blow dryer.  Altan went back up the ladder and blew hot air onto the electronics until it seemed dry.  Then he applied silicone sealant (RTV) onto the seams to keep moisture out.  What was that about cowboys?

At 2:45pm local time on June 4, 2010, the first Falcon 9 rocket blasted off from the Cape Canaveral Air Force Station.  When questioned about flying the rocket after drying out the electronics with a hot air gun, Musk replied, “I've done crazier things than dry out a radio antenna.”

The booster has etched a number of superlative firsts, from vertical landing and subsequent reuse, to flying into orbit with a record nine first-stage engines. And then there is its cost. At the time of its debut a decade ago, SpaceX offered a basic launch on the Falcon 9 rocket for $50 million. After a few incremental increases, since 2016, SpaceX has listed the base Falcon 9 price at $62 million. This put tremendous pressure on competitors in the satellite launch industry.

On the figurative shoulders of the Falcon 9, the US has gone from having virtually none of the world's commercial launch business to having about 70%, according to NASA administrator, Jim Bridenstine.  I've reported it here a few times; the world can't keep up with the US - largely SpaceX. Last year, Arianespace announced development of a booster copied from remarkably similar in appearance to the Falcon 9, after saying there was no sense in making a reusable booster because it would put people out of work.  China has been working on recovering boosters - so that they don't drop them on small villages anymore.  It has been noted their boosters feature grid fins like the Falcon 9 boosters do. 

Imitation is the most sincere form of flattery. 

The engineering behind landing boosters on a ship at sea is worth studying on its own.  I've run across one video on the subject from a channel called Real Engineering.  Between 2013 and 2017, SpaceX improved their landing accuracy by a factor of 1000x.  The video describes how they perform landings.

 

Shop Update

Seems I haven't done an update for a while because most of what I've been doing doesn't lend itself to this thread, but I still get some stuff done in the shop regularly.  This part took longer than it should have because of a "comedy of errors" (where the important word is errors, not comedy).  I wasted a couple of pieces of steel before I smacked myself upside the head about not paying enough attention! 

This is the rocker arm for the Webster.  You're basically viewing it in same (top) view as that drawing but because it's a real object and not just one view, you see part of the front of it.  I put a 4-40 Socket Head Cap Screw in the tapped 4-40 hole on the right just because.  Although that does make it look a little wonky. 

The notes you see that are handwritten are derived dimensions, usually to tell me where to place my cutter for different features. You'll see they're all 0.250" from a feature - a sure sign I was using a 1/2" diameter end mill and had to specify start and end points for tool movements. 

Getting Things Into Orbit is Hard

With the big guys doing it regularly, it's easy to lose sight of the fact that space flight is hard to do.  Everybody who thinks of it understands that safety margins are slim and launch vehicles are controlled barely-controlled explosions.  Most companies that develop a new rocket fail to reach orbit on their first attempts, even after exhaustive testing on the ground.

Last weekend Virgin Orbit proved that once again, losing their air-launched, two-stage, LauncherOne in its first test flight.

“LauncherOne maintained stability after release, and we ignited our first stage engine, NewtonThree,” Virgin Orbit said. “An anomaly then occurred early in first stage flight. We’ll learn more as our engineers analyze the mountain of data we collected today.”

The rocket was carried aloft from Mojave Air and Space Port in California by the Boeing 747 mothership, named “Cosmic Girl.”

The article doesn't say when the 747 took off, just that the release was at 2:50 PM PDT, and the anomaly occurred within the first three minutes of flight.  The aircraft landed at 4:26 PM, so about 1hr 35 minutes later.  That implies a takeoff around 1:25 PM. 

Chief pilot Kelly Latimer, a veteran test pilot, flew the the 747 through the rocket’s drop box, then entered a race track pattern to loop back around line up for launch on a southeasterly heading.

In the final moments before release, she maneuvered the airplane to pull up at an angle of about 27.5 degrees. The launch team aboard the plane then commanded release of the 70-foot-long (21-meter) rocket from a pylon under the aircraft’s left wing at 2:50 p.m. EDT (11:50 a.m. PDT; 1850 GMT).

Virgin Orbit did not livestream Monday’s launch attempt, but the company provided near real-time updates on Twitter. After confirming release of the LauncherOne rocket, Virgin Orbit followed up three minutes later with a tweet saying the “mission terminated shortly into the flight.”

Cosmic Girl with LauncherOne on the release pod - Virgin Orbit photo.

Imagery from National Weather Service radar in Los Angeles appeared to show a debris cloud in the vicinity of the LauncherOne drop zone at the time of the rocket’s release.  Those two words (debris cloud) are probably the last descriptors you ever want applied to a rocket launch you're working on.

Virgin Orbit is in tough competition to get into the small satellite launch business before it fills up.  Currently, Rocket Lab is the most successful of the newcomers in the smallsat business.  Firefly Aerospace aims to fly its new Alpha rocket into orbit before the end of this year.  SpaceX has come up with an arrangement they call Ride Sharing.  SpaceX says it charges as little as $1 million to share a launch as a piggyback payload of up to 440 pounds, or 200 kilograms, with a primary payload on a Falcon 9 rocket.  I've seen the cost of a Falcon 9 listed as $50 million, but I've also heard costs can vary and experienced boosters are cheaper than new ones. 

I thought it showed camaraderie in the business for the CEOs of Rocket Lab and SpaceX to tweet encouragement to the Virgin Orbit team. 

Virgin Orbit says the main test objectives were to launch the vehicle and start the engine, perhaps observing stable flight, making it a successful test flight but you've got to know they really hoped they'd make it all the way to orbit. 

So congratulations to everyone at Virgin Orbit, and here's hoping for more successful, longer missions soon.

Another Day, Another Falcon 9 Launch. Almost

It seems that way but it's not a daily occurrence.  Not yet.  Sunday, we were in the after-buzz of the successful return of manned space flight to the US, with a mission that though still underway seems nearly flawless, when we read that the long delayed Starlink 8 mission to put up the eighth batch of 60 Starlink satellites has been set for Wednesday night, June 3rd, No Earlier Than 9:25 PM EDT.  

The mission – deemed Starlink-8 – will be SpaceX’s eighth Starlink launch overall and the seventh launch of upgraded v1.0 satellites, pushing the company a mission past the halfway point towards its first internet beta test. If successful, it will raise SpaceX’s ever-growing constellation to some ~475 satellites strong, approximately 400 spacecraft shy of the ~840 COO and President Gwynne Shotwell believes are necessary to begin rolling out Starlink internet service.

The Demo 2 mission launched from Pad 39A; Starlink 8 will launch from Launch Complex 40, about 3-1/2 miles down the Cape from 39A, so they don't have to turn around 39A and get it ready for this launch.  I find no indications that the Falcon 9 and payload has or has not been standing on LC40 since we started talking about this mission in mid-May. 

This morning's forecast calls for an 80% chance of good weather for the launch. 

Despite the fact that this doesn't require a fast turnaround of 39A, it still pushes on SpaceX's capabilities.  Drone ship OCISLY (Of Course I Still Love You) is carrying the booster from the Demo 2 mission back to Port Canaveral, with an expected arrival time of Tuesday afternoon to evening.  There isn't enough time to get back out to the recovery zone even without any time spent working on the booster, so this mission will feature the Return to Service of their second drone recovery ship, JRTI (Just Read The Instructions).  On Saturday, the day of the Demo 2 astronaut launch, drone ship Just Read The Instructions (JRTI) was seen heading out into the Atlantic Ocean, deck cleared for the first time in the better part of a year.

JRTI at the Port of Los Angeles with booster B1049 aboard.  Pauline Acalin photo.

SpaceX intends to perform its limited manifest of future Californian launches while relying entirely on return-to-launch-site (RTLS) rocket booster recoveries back onshore, freeing up drone ship JRTI to head to Florida to support the company’s far busier East Coast manifest. After transiting the Panama Canal in August 2019 and undergoing several months of refits in Louisiana, JRTI arrived in Florida in December 2019 and has been gradually upgraded at Port Canaveral over the last few months. Now, outfitted with a new Octagrabber robot and thrusters and power supplies that dwarf those on SpaceX’s other drone ship, SpaceX has apparently given JRTI the go-ahead to attempt its first booster recovery in almost a year and a half.

The Octagrabber is a new addition to the fleet, but I don't know if this is a first use or not.  This is a low profile robot that maneuvers under the booster and grabs it to keep it from sliding around on deck.  

The unmentioned highlight here is that photo shows JRTI with B1049 aboard, the same booster it will attempt to recover on Wednesday night.  Plus, B1049 is going for its fifth flight and recovery.  You might remember that the last booster going for its fifth flight had an engine malfunction due to some alcohol left in the system by a test error.  That was B1048 two and a half months ago. 

If B1049 can successfully launch and land for the fifth time on June 3rd, it will become the pack leader of SpaceX’s fleet of reusable rockets. With a safe landing, B1049 can prepare to become the first booster to launch six times, hopefully proving that Falcon 9 can safely fly six, seven, eight, or more times – perhaps one day cresting 10 launches to achieve Falcon 9 Block 5’s design goal.

A Ham Radio Series 1 - Sporadic E Propagation

The reactions to my “Got a Question for You” post surprised me.  Mostly by the quantity; I don’t have a way to check but it’s in the top couple of comment generating posts I’ve ever put up.  Some of specific questions were a bit of a surprise, too.

One of the subjects that came up has a time sensitive aspect to it, so I’m going to take a look at  propagation; in particular E skip, or sporadic E.  It’s going on right now, as I write and we’re at or close to the peak time of the year for sporadic E; at least here in the northern hemisphere. 

As usual, let me start at the beginning for those who aren’t familiar with it.  Both references are to propagation in the E layer of the ionosphere.  The ionosphere is called that because the air density is so low that individual atoms are far from each other, far enough that energy from the sun, mostly UV radiation, can cause electrons to be stripped from some atoms, giving rise to both negatively charged free electrons and positively charged atoms that can stay separate for long times.  The density of the air is so thin that it takes a long time for collisions between these ions to neutralize them.

The ionosphere is characterized by layers, conventionally called the D, E and F layers – in order of height.  If solar energy is high enough, the F layer can split into two layers called (imaginatively enough) F1 and F2.

Because the ionization is driven by solar energy, the general rule is these layers appear in the daytime, and the highest levels of ionization are in the area where the sun is most intense; so midday and directly under the sun.  While the D layer getting denser during the day shuts down lower frequencies that tend to be open all night (say 160 through 30m), the higher frequency bands’ signals (20 to 10m) travel through the D layer to the F, so they open during the day and are shut down at night.  This isn’t like a switch, it’s a more gradual transition.  For example, it seems that 30 is intermediate between 20 and 40; most days it seems to open earlier than 40m in the afternoon, and close later in the morning than 40m.  Back around the Spring Equinox, I’d hear Australia on 30m – close to my sunset and their sunrise.

It’s probably generally known that solar activity - sunspots and higher Solar Flux Index – increases the density of the ionosphere, making the F layer propagation last longer into the night, sometimes completely overnight.  Bands that are only useful for local communications during sunspot minima can be open to somewhere in the world 24 hours a day at the peaks of the solar cycle.

E layer propagation is left out of that overview because it’s harder to fit in.  Sporadic E has been known for a long time, but that word “sporadic” in the name is an indication of the toughness of predicting when it will occur.  We know there’s no correlation between solar activity and Sporadic E; in fact, the last few years have made it seem that it could be inversely proportional to solar activity (my observation – I haven’t seen anyone else say this).  We know that the mechanism is fleeting clouds of sufficient density in the E layer, and that it tends to occur more at certain times of years than others (now in the northern hemisphere).  We know that it tends to form later in the day and linger into the evening; that is, you'd be more likely to find it at 3PM than 3AM (local time).  Finally, we tend to observe it on higher HF and lower VHF bands; 28 and 50 MHz are peak bands.  It happens on occasion on the 144 MHz band.  Hams have long noticed that sporadic E clouds seem to form above the tops of thunderstorms - long before mechanisms that could extend the charge into the ionosphere, such as red sprites or dark lightning were discovered.

3PM?  This is a plot of reported sporadic E contacts at 10:14 AM EDT, Saturday, on 6m.  Each arc is a reported contact between the two stations at the ends of the arc.  Most of those arcs are in places where it's 9:14 AM.  It’s impossible to read all the call signs in this screen capture; there’s simply too many.

The plot is from a website I visit regularly called DX Maps.  This link should bring up this display for 6m over the US as of the moment you go there - I think those reports stay there on the order of a half hour.

The area in the east central US is blanketed by reported contacts.  There are many arcs starting in the Caribbean, (Puerto Rico, Guadeloupe, St. Lucia, Trinidad) going into the states.  As I write this, 11 hours later, the map looked much the same.  The density of the red traces (reported as Sporadic E, although always hard to know) is down, but the distribution is similar.  A couple of days ago, the concentration of red traces was over the western states: Utah, Wyoming, Montana, Eastern Oregon and Washington and virtually nothing on the east side of the country.  In other words, the opposite of this.  Another day, the east coast was full of paths reported into Europe, still another was full of paths reported from the west coast into Alaska and then Japan.  26 hours later, that previous plot looked like this:  

You can see the propagation to Europe marked by dark red arcs is dense into the NW US, with some into Mexico.

They call it Sporadic E because it’s not dependable or particularly predictable; you kind of know something is likely to happen, but don’t know what that “something” is going to be. It varies all day every time.  We know late spring into early summer is better than mid summer or mid winter.  I’m not sure that doesn’t vary with where you are.  I’ve heard from a guy between my location and the Space Center that around the Winter Solstice in December, he has worked 6m into New Zealand.  Note that’s around the equivalent of our first day of summer in NZ, in terms of heat and constancy of sunshine.

Because of that unpredictability, it’s fair to ask what practical use Sporadic E is.  I know of no systems that rely on it.  For hams, it’s mostly a way to rack up novel contacts that we don’t or can’t get any other way.  The band I’ve been on, 6 meters, is just below the bottom of the old VHF TV Channel 2.  A few days ago, I had a contact with a guy in Spain on 6m.  That’s similar to (while different in important ways from) watching Channel 2 TV from Spain and I get a kick out of the novelty.   

I find the study of propagation one of the most interesting aspects of radio. 

Not Much More That I Can Say

This screen capture kinda sums it up for me.  Except that the actual mission for the crew had barely started.  The screen capture is from moments after the radio callout that the second stage had just shut down and the Crew Dragon capsule was in the desired orbit.  Then the video changed scenes to include the first stage booster had been successfully recovered.

On the left, you see the booster, now a used rocket that's experienced one flight, standing in the circle marked on the deck of OCISLY.  On right, you see the view we've never seen before: Commander Doug Hurley (l) and pilot Bob Behnken (r) at their control screens.  Instead of rows of big toggle switches, almost everything is on a touchscreen.  

The entire flight went like it had been done a hundred times before.  I think this was the 85th Falcon 9 launch. 

SpaceX Loses Starship SN4

“Loses” in the sense that it blew up so badly it's tough to figure out where all the pieces went.

SN4 has survived more than any other Starship prototype; it has been on the pad since the end of April, had its first static firing on May 5th, and then another couple of static firings. After that, they replaced the engine with a newer Raptor, and static fired the new engine.  Yeah, they had a bit of a fire and had to wait a day to inspect and clear the area, but the damage was minor.  Yesterday, they added 55,000 lbs of ballast to it and static fired the engine again; then this happened today after yet another static firing.  A commenter to that Ars article said this was the fifth static firing of the second engine. 

On Friday, SpaceX prepared its latest iteration of the Starship prototype vehicle, known as Serial No. 4, or SN4, for a static fire test in Texas. The Raptor engine appeared to fire nominally for a couple of seconds at 1:47pm local time and then shut down as planned.

However, about one minute after engine shutdown there was some kind of uncontrolled gaseous leak, and one minute later the vehicle exploded almost instantaneously—a truly rapid Rapid Unscheduled Disassembly.

RUD - for Rapid Unscheduled Disassembly - is a term that Elon Musk and his engineers seem to use regularly.  Personally, I hadn't heard it before, but I don't know they made it up.

I'm not going to speculate on what happened, but the vehicle is lost and the test stand appears badly damaged.  There will be a few days work and SN5, which has been ready for weeks, will be transported to the test area. 

Too bad.  They got their FAA approval to conduct suborbital test flights yesterday after the successful static firing.  It looked like SpaceX would lay low, let Crew Dragon get to the ISS and then try a hop test of SN4.  Maybe even Monday, June 1.  That doesn't seem possible today.

The remains of the test stand and much of the hulk of SN4.  A small flame is visible - orange, just left of center, a quarter of the way up from the bottom of the scene.

A Little More on RF Power Safety and Ham Radio

The previous post on this topic touched off a lot of discussion and I can see it's something that many people are concerned about.

I thought I'd look at a couple of examples and go through how its calculated. The ARRL has a sample worksheet to fill out that can be seen and downloaded here (pdf).  They also have a book they give away to help with this (also pdf format) – with details in chapter 5.  A word of warning: that book is copyright 1998 and based on the original FCC documents.  All of the distance limits are higher than the referenced “FCC Guidelines” from the previous post and now in effect.

Filling in every blank on the form seems a bit like overkill, but I’m sure there are questions in there that the majority of people just haven't dealt with so I thought I’d try to help with those. 

I’m going to go through an example based on a modest station to show how you’d calculate the things they ask for.  For this demonstration, I’m going to assume a 100 W transceiver and a kind of typical low power/portable stations, with a wire antenna in a nearby tree.  Let's assume they're using 30 feet of RG-58 coax to get to the feed point.

A quick look at Table 1 in the previous piece shows that nothing I can radiate matters until I get to 12m (24.9 MHz) because no matter how much power I put out, I lose some on the way to the antenna and every band from 15m (21 MHz) down has an exemption from analysis for powers less than or equal to 100 W.  That power limit for the 12m band is 75 Watts.

That 75 W is power into the antenna and although the radio puts out 100 W, there are losses in the cable, and switches or anything else in the path to the antenna.  Let’s start with loss in my coax.  There are lots of brands of RG-58 coax, so I'll choose Belden 8259 or RG-58C/U.  The table on Belden’s website doesn’t say what the loss is at 24 MHz, but it gives these points:
10 MHz  1.5 dB/100 ft
50 MHz   3.7 dB/100 ft.
For another type ("RG-" number) or brand of coax, you should try to look up the corresponding numbers for what you have.  

I’ll do a linear interpolation (assume attenuation vs frequency is a straight line).  That’s
(3.7-1.5) divided by (50-10)  or 0.055 dB/100ft per MHz.   
There’s 15 MHz from 10 to 25 (the top of 12m is 24.980 MHz – close enough), so we calculate the attenuation by:
1.5 + 15*.055 = 2.33dB /100ft.   A 30 foot run of this coax then has 0.3 * 2.33 or 0.698 dB of loss at 25 MHz.  I can use the same linear interpolation to show it has 2.58 dB/ 100 ft at 29.7 MHz (top of the 10m band). 

The problem with using the loss in dB is that the power is stated in Watts, so we need to convert that loss to a percentage of 100 W.  I’m guessing that’s probably a new thing to people.  Remember a dB is a power ratio, where
10*log (ratio)
is the value in dB and log denotes the base 10 logarithm.  We want to find the ratio that gives a loss: loss means negative dB.  It’s -0.698 dB not +0.698.
(-.698) = 10 log (ratio), so 
(-.698/10) = log (ratio)
10^(-.698/10) = ratio = 0.852 or 85.2%

That’s saying the power at the antenna is 85.2% of the transmitted power.   The worksheet asks for the percentage of power lost, so 100%-85.2% = 14.8% lost, but they only do that to get the first number we solved for, the percentage of power that gets to the antenna.

There’s a trick you can do to be finished right here.  Remember that Table 1 says my power at the antenna has to be below 75 watts.  I could just crank down my power until the power at the antenna is 75W.  That’s picking a power output from the radio that combined with the cable loss puts the power at the antenna at 75 W.
75W/.852 = 88 Watts
Which says if my output is 88 Watts, I’m always at or below that 75W limit, but I’m not going to go there, I’m going to the next step at Table 4a in the FCC report and the second table in that blog post.

Looking at the table for 24 MHz, I can see that assuming I put 100W into the antenna, I have four options for my antenna that lead to four different distances to choose from.  The first column after the band (24.99 MHz, (12m)) shows the antenna gain in dBi.

I chose an antenna that isn’t particularly good; it’s something like a random length wire, a multiband wire, G5RV or something low gain like that.  Is it 0 or 3 dBi?  Let’s be generous and give it 3 dBi (everything has gain compared to a theoretical isotropic antenna, just not much).  You’ll see two numbers: 1.7 or 3.8.  That’s the distance to keep people away from the antenna, in meters.  The difference is the smaller distance, 1.7m  is for people who are aware of the risk of being near or touching the antenna – like you and your family – while the other (uncontrolled) column is for the neighbors.   The number is 12-1/2 feet.  The smaller is 5 feet 7 inches.

That distance can be reduced because heating is different depending on the transmitter duty cycle.  The league says you can use 40% for CW, 20% for SSB with no speech processing, 40% for SSB with heavy speech processing,  50% for FM (full carrier, talk half the time, listen half the time), 50% for most digital modes – (also based on transmit 50%/receive 50%).  The bottom of Table 4a says to multiply those distances by .707 if the duty cycle is 50%, so since the others are less than 50%, we can use that as an upper limit.  Those become 1.2 m and 2.7 m, or 3.9 and 8.9 feet.

As the infomercial guys say, “but wait! There’s more!”   Since those numbers are based on 100W and we know we’re only putting 85 Watts into the antenna, we know the minimum safe distances are even less than that.

Although values can be hard to find, anything you put around the antenna is going to attenuate the signals somewhat.  The antenna distance recommendations in that FCC document are based on mounting antennas in the open.  As a rough example, HF signals will go through most walls pretty well as long as their isn't a wire grid in them.  Shortwave pocket radios with small antennas work acceptably in most houses and lots of people use attic-mounted antennas to avoid property restrictions.    

So what happens if you do a station evaluation and conclude one of those limits is exceeded?  In this case, what if that 8.9 feet just falls beyond your property line and there’s nothing you can do to guarantee that the neighbor’s kids can’t get into that your RF field.  At the bottom of the League’s worksheet for evaluating your station is this section:


Using this method, did your station exceed the FCC RF exposure limits? (Y/N)
Controlled exposure: ___________(Y/N)    Uncontrolled exposure: ____________ (Y/N)
If the station is not in compliance under all circumstances of its expected operation, attach a separate sheet describing any limitations of methods that the station operator will use to ensure compliance if people are present in areas that could be out of compliance.


In this case, you could state you limit power to keep your power below 75W at all times, in compliance with table 1, or you could say you'll only operate your station at times when the neighbor's kids are not potentially too close to your antenna, such as during the evenings or when nobody can be seen outside - if you can see outside from your operating position or with a camera.    


EDIT 052820 2235 EDT:  Left out a link for Table 4a.  Added just above the small portion clipped out of that table.  Roughly just above the middle of the post. 

The World Isn't Complying With Me

One of those nights where I bite off a subject and don't get as far as I wanted.  So - attempt at humor:

Everyone who cares realizes the SpaceX launch was scrubbed in the last few minutes due to the weather refusing to clear up.  They'll try again Saturday at 3:22.  Which is just as good from my standpoint; I wouldn't have seen a second of the launch.  I watched the live stream on SpaceX and turned it on when Doug and Bob were arriving at pad 39A in their Teslas - both with a license tag that read ISSBND - ISS Bound. 

There was a brief interview with Chris Cassidy, currently the ISS Commander.  He pointed out something that I somehow failed to think of.  This isn't just the first launch of astronauts from the US since 2011.  It's the first new, manned spacecraft in the US since 1981, when the first Space Shuttle Mission Launched.  Almost 40 years. 

The Only Hurdle Left to Demo2 is the Weather

After the years of effort and billions of dollars spread among the handful of contractors, NASA and SpaceX are at the mercy of the weather for tomorrow's 4:33 PM EDT Demo2 mission to the ISS.  To be honest, it's the best possible position to be in.  All the pre-launch reviews and dress rehearsals have been passed, the approvals have been granted and we're in the final 24 hours to launch.  The chances have improved over the last 24 hours so that the current forecast from the weather squadron at Patrick Air Force Base (pdf) is for a 40% chance of weather violating launch criteria.

There is no mention of a launch window for this mission, just the launch time.  If anything comes up to delay the countdown, the launch will be scrubbed.  The next calculated launch time will be Saturday, May 30, at 3:22 p.m. with Sunday at 3 p.m. as a backup to that.

"Everything is looking good. As of right now, we are 'go' for launch," NASA Administrator Jim Bridenstine told reporters Tuesday morning. "Our country has been through a lot. This is a unique moment where all of America can take a moment and look at our country do something stunning again."

Expected at KSC for the launch: President Trump, Vice President Pence, SpaceX CEO Elon Musk, at least half a dozen current and former astronauts, and countless other VIPs. They will be joined by a much smaller press corps and other visitors than had been expected before the outbreak of the coronavirus pandemic.
...
If all goes according to plan, Behnken and Hurley will make a 19-hour trek to the ISS and attempt a docking at 11:39 a.m. Thursday. A little over two hours later, onboard crew Chris Cassidy, Anatoly Ivanishin, and Ivan Vagner will help open the hatch, ending the first phase of the demo flight.

Something that might not be well known is that SpaceX engineered the suits for this mission as well as the capsule and rocket system.  They'll suit up in the Operations and Checkout (O&C) building; as has been tradition.  The departure from tradition is that instead of the Airstream RV to the launch pad, Bob and Doug will be driven in Tesla Model Xs. 

Doug Hurley (l) and Bob Behnken with the twin Model X Teslas that will ferry them the couple of miles to pad 39A.

While prepping this post, one of the voices in my head said, “hey, you've got pictures of the last shuttle mission; the last manned launch from the KSC.”

That's Doug Hurley, second from the left. 

On Memorial Day 2020

Let me join the chorus of folks saying that while you're enjoying your day, be it beach, barbecue, pool or whatever, take a moment to remember or think of and thank those who gave their all in service to us. The ones who don't get to mark the holiday with us.

It's a weird Memorial Day here weather-wise.  The temperature isn't supposed to get over 80 and the National Weather Service is calling for 100% chance of rain, showers, and thunderstorms with 2 to 3 inches of rain possible.  This has been an unusually mild May, with only a day or two hitting 90.  Ordinarily by now, the last week of May, 90 is an everyday thing and the afternoon thunderstorm system has started.

With 100% chance of rain, there will be no barbecue today, and probably not much of anything productive.  Good thing I just put fresh batteries in my UPS for this computer and the house internet/video streaming hub.

I've run this picture more than any other on my blog.  I guess it resonates with me.

In a final act of loyalty, Hawkeye, the dog of slain Navy SEAL U.S. Navy Petty Officer 1st Class Jon T. Tumilson walked up to his fallen master’s casket during the funeral in Rockford, Iowa, and then laid mournfully down beside the body for the rest of the proceedings  [Note: Petty Officer Tumilson was one of the 30 killed in Afghanistan in the shoot down of Extortion 17 which the families blame squarely on the Obama administration - SiG]

 

A Question for You

A question for you, dear readers. 

My article on interpreting the FCC's RF radiation limits drew several thanks.  It makes me wonder what else you're interested in reading about in the general topic of radio.  Since I made my living in high-performance, high-reliability radio design and I've been a ham for 44 years, that's naturally what I gravitate toward. 

I was thinking about a poll, but I don't even know enough to ask the right questions.

So, comments, please!