Sunday, February 25, 2024

Tricky Landing

The “Odysseus” robot lander created by Intuitive Machines seems to have landed successfully on the moon,  although reports say it is on its side rather than upright.  Details as of yet are quite sparse,  but depending upon whose reports you read,  it would appear the lander had a non-trivial and unintended horizontal speed at touchdown.  Odds are,  it was also tilted a bit in the direction of that horizontal motion.  It seems to have “tripped” on one of its legs being somehow obstructed,  overturning the lander as it touched down.

This is always going to be a serious problem for a robot moon lander,  as opposed to a manned craft.  It is still difficult-to-impossible to program a robot to do what a human pilot can do,  and robot vision is still nowhere near as good as human vision. 

Consider what Neil Armstrong had to do,  landing the Apollo 11 lunar module.  The computer-controlled trajectory was taking the vehicle into a tightly-packed field of multiple boulders as big as houses:  a guaranteed fatal crash!  Armstrong had to take manual control,  stop the descent into an unplanned hover,  and then direct that hover toward a clear landing site nearby.  The depletion of his rocket fuel was but a single handful of seconds away at engine shutdown.  

The rule-of-thumb stability criterion used for all successful landing leg-equipped craft on the moon and Mars,  is that the span between foot pads at least equals the height of the craft center of gravity,  and preferably exceeds it. The Odysseus lander only just barely met this,  and the also-recent Japanese lander did not meet it,  and was photographed upside-down after its landing!

It is not yet known what “tripped” the Odysseus lander,  but the odds favor either a leg striking a fixed rock or similar obstruction,  or else a landing pad digging into the surface dirt.  The “fix” for this is two-fold:  (1) increase the pad span to center-of-gravity height ratio significantly,  and (2) hinge the pads on the ends of the legs,  and spring-load them to tilt upward toward the radial-outward direction at each leg.  The first decreases the net overturning torque of a “tripping” incident,  and the second acts to prevent a pad from digging-in. 

Seems “intuitive” to me.  Maybe we old farts still have things to contribute,  after all. 

Update 2-26-2024:  The quote below,  from a PBS NewsHour story published this date,  confirms what I hypothesized about the Odysseus lander.  It apparently will cease operations tomorrow for lack of sunlight on its solar panels,  according to the story.  Highlighting is mine.

“The lander, named Odysseus, is the first U.S. spacecraft to land on the moon in more than 50 years, carrying experiments for NASA, the main sponsor. But it came in too fast last Thursday and the foot of one of its six legs caught on the surface, causing it to tumble over, according to company officials.”

What I found about the Japanese “SLIM” lander is enlightening,  although it is still unclear just exactly how it ended up on its nose.  It was supposed to hover and then tip over onto its side,  with its landing legs extending out that side.  In the long dimension,  pad span exceeds cg height,  meeting the criterion.  From side-to-side,  it does not meet the criterion,  a very real risk. 

But it did not fall over to one side,  somehow it instead went tumbling end-over-end,  which is the only way it could have ended up on its nose!  Some stories mention a problem with a main thruster (there were two in its bottom).  Those should be “off” during the actual tip-over-and-landing because they are too powerful,  so any main thruster-related hypothesis would have to have occurred before that process.

One possible main thruster-related hypothesis is that it may have experienced suddenly-asymmetric thrust just as it approached hover for final tip-over-and-landing.  If so,  that could have sent it tumbling end-over-end while still aloft,  instead of hovering into a controlled tip-over. There should be marks in the regolith if that hypothesis is true,  marks where it hit while already tumbling end-over-end.  In the low gravity,  it would have continued to bounce end-over-end after hitting the surface.  It just happened to quit bouncing,  while on its nose.  Improbable,  but possible.  Still,  only a hypothesis. 

Monday, February 12, 2024

GW’s Ramjet Book Is Now Available!

This has been a long time coming,  because I originally finished writing the book back in 2017.  I offered it to a technical publisher,  who took over 2 years to decline publishing it as a hardcopy,  hardcover book.  It then languished as a back-burner item,  while I figured out how to really do this myself,  in between more pressing obligations.  But I knew that I really did need to get this book “out there”,  because I am an old retired person,  and so I will not be around for that many years yet to come.  I’d rather this knowledge and experience to not die with me.

This is not your usual academic tome.  It is more of a very extensive “how-to” compendium of the things that actually worked for me and my colleagues,  while actually doing real ramjet work.  The scope is subsonic combustion ramjet,  not combined cycles,  and not supersonic combustion ramjet (scramjet).  It covers mainly liquid-fueled and solid gas generator-fed ramjets.  It bears about the same relationship to ramjet engineering,  that Sighard F. Hoerner’s self-published books,  “Fluid Dynamic Drag” and “Fluid Dynamic Lift”,  bore to aerodynamical engineering.  No real publisher wanted to publish those books,  either,  but scads of people found them very useful anyway!  I hope you find my book useful. 

I now have an initial solution:  I can literally email the book as pdf files to those who want to buy it. 

It exists as some 27 pdf files:  one for the “up-front” stuff,  one each for all 22 chapters,  and one each for all 4 appendices.  Each chapter has its own page numbering,  its own figure numbering,  and its own reference list.  The “up-front” stuff includes a foreword,  biographical data,  a table of contents,  and (quite uniquely !!) another table of contents with a paragraph indicating content for each chapter!

If you want to buy the book,  just contact me,  email is best!  My email is  (I will need your email to send the files,  in any event.)  I will give you my physical address,  to which you can send the purchase amount by check or money order. 

When I receive it,  I will email the files to you in multiple emails,  since there are so many and they are large.  Plus,  I will follow up to make sure you get them all! 

Base price is $100 per copy.  Out here rural,  the Texas sales tax is only 6.25% (and I have a Texas sales tax certificate),  so the sales tax amount is $6.25.  That puts the total purchase amount at $106.25,  turn-key. 

That’s how I need to do this for now.  Soon I hope to be able to take credit cards by voice over the phone,  which would speed the process up for you.  But that is not ready yet.  Watch this space for updates,  I will add that capability soon. 

Eventually,  if I can find qualified help,  I hope to set up another site that automates the payment and send-out processes.  But that is for the future.


As examples of my real-world experience,  I have included some pictures here.  I hope these help inspire in you enough confidence that I really know what I am talking about,  so that you will be more inclined to buy the book.

Figure 1 below shows the hybridized ground test hardware that I used to great advantage,  doing ramjet tests on the ground in a direct-connect facility,  long ago.  It coupled a heavyweight lab motor as a short-burn solid gas generator,  to a flight-weight combustor and inlets.  This hardware was extremely effective for testing experimental fuel propellants,  experimental combustor insulations,  and one experimental fuel flow rate control approach.

Figure 2 below illustrates what the exhaust plume looked like for one of these tests,  conducted “open-air nozzle”,  with both an experimental fuel and an experimental combustor insulation,  back in 1991.  Most of the sparkler streaks were from the insulation,  not the fuel! 

Believe it or not,  this particular test was the first time anybody ever burned high-percentage boron efficiently in a ramjet!  See the smoke-free clarity of the plume downstream of the fire as proof.  Even the metal oxide smoke is barely visible downstream.  However,  the incandescent glare from it (and some soot) is part of what makes the tailpipe flame opaquely brilliant.   

Figure 3 below shows a modern cutaway display model of the Russian surface-to-air missile known to NATO as the SA-6 “Gainful”.  It was a solid gas generator fed ramjet,  with an “integral booster”,  meaning the booster rocket was housed inside the combustor itself,  not a staged-off item.  As a young engineer,  I was the lone engineer among 3 propellant chemists who did the actual exploitation work on this foreign technology.  We duplicated the solid fuel-rich propellant and its processing,  tested it static and with air,  and I put together a computer trajectory model of the system,  which matched performance seen on the battlefield.  This knowledge used to be classified,  but no longer (not with public display models).

Figure 4 below is a two-view picture of an ASALM-PTV being launched from an A-7 Corsair-2.  It was a liquid-fueled ramjet with an integral booster.  I worked on ASALM,  which was a prototype for a high-altitude supersonic ramjet-powered cruise missile that (unfortunately in my opinion) never proceeded to operational status,  because of treaty limitations. 

It was flight tested 7 times,  and met or exceeded all objectives on 6 of those.  On the first of those tests,  it accidentally went hypersonic due to an assembly error in its fuel throttle controls.  Way back in 1980,  this thing accelerated in ramjet,  at low altitude,  to about Mach 6!   A different picture of it (not here) on the same airplane,  I consider to be a sort of “family portrait”.  I worked on ASALM,  and my father was lead engineering designer for the A-7. 

Figure1 – Hybridized Ground Test Hardware

Figure 2 – Typical Experimental Open-Air Nozzle Ramjet Test

Figure 3 – Modern Cutaway Display Article of the SA-6

Figure 4 – Two-View of ASALM-PTV Launched From A-7 Corsair-2

Thursday, February 1, 2024

Swatting at Proxies is Pointless

There has been a lot of violence and danger in the Middle East in recent decades.  Most,  but not quite all of it,  is summarized in Figure 1.  This article is about things since about 1980.  For earlier history,  see “Israel vs Hamas:  It Is Worse Than You Think”,  posted 29 December,  2023,  on this same site. 

I drew that figure on 22 January.  Since I drew the figure,  there has been an attack by Iranian proxies on a US base in Jordan,  killing 3 of our troops.  However,  that still fits the same pattern shown!

Note that Western nations in general,  and Israel in particular,  have been combatting the proxies listed since about 1980.  There is however a common thread to all of that listed evil,  and that common thread is shown in the figure to be Iran.

Figure 1 – A Summary of Where Most (But Not All) Middle Eastern Violence Really Comes From

It is my contention that Iran is ruled by a terroristic dictatorshipmasquerading as a democracy.  The ruling figures pose as religious mullahs to justify what they do,  but their actions clearly make that claim false.  They can over-rule anything the “elected” officials come up with,  making it a sham democracy.  This group is propped up in power by the Iranian Revolutionary Guard,  which is essentially their private army that ruthlessly suppresses domestic dissent.  My contention cannot be far from the truth!

In point of fact,  there is very little operational difference between this situation,  and 1933 Germany,  with Hitler propped up by his private army,  the brutal and ruthless SA. And we all know where that led!  I did generalize this to a warning about leader cults,  published 13 February 2020 as “Beware of Leader Cults” on this site.  Such can be political,  religious,  or both.  To find any of these quickly,  use the navigation on the left.  Click the year,  then the month,  then the title if need be.

This terrorist government in Iran fundssupplies,  and commands a bunch of proxy terrorist armies in multiple places.  Those proxies are killing and wounding lots of people,  and even killing and wounding US troops,  as noted.  Iran already has cruise missiles and drones,  as well as an army,  a navy,  and an air force.  It is going for a nuclear weapon,  and has been for some time now.  Iran is even launching shipping attacks from within its own territory now,  so their vile behavior is escalating

Striking at proxies has proven ineffective, because the outfit giving the orders does not suffer any consequences!  This is indicated in Figure 2,  where Russia has been unsuccessful for 2 years now swatting at the West’s proxy,  the Ukrainians.  We in the West are not generally terrorist dictatorships,  not yet,  anyway.  We should care a lot more about our proxy than any dictatorship ever would,  and therefore we all should see to it that they win.  Or overtly help them to win,  if needed.

Economic sanctions against dictatorships have also proven ineffective,  because those do not hurt the dictator,  only those oppressed under him,  and he cares not that they suffer!  Our experiences with Iran,  Russia,  North Korea,  and now China,  all prove that thesis.  This is also indicated in the figure.

Figure 2 – What Does and Does Not Work,  Dealing With Proxies,  Plus a Suggestion

My firm opinion:  there will not be peace of any kind in the Middle East until Iran is dealt with effectively.  Basically,  that government must fall!  And none of us want to invade and occupy Iran,  we’ve already had enough of that nonsense with Afghanistan and Iraq.

As the suggestion indicates,  one uses a surprise strike to kill as many of the ruling mullahs as possible,  in one fell swoop.  After that,  one then conducts strikes from long range to destroy as many of the Revolutionary Guard’s facilities and assets as can be found.  But you do not invadeAnd leave the general infrastructure alone.  Just hit the Revolutionary Guard stuff,  and some of the military assets.

With the Revolutionary Guard thus weakened,  and the ruling mullahs in disarray or dead,  there can be a successful popular uprising,  like the one about a decade or so ago,  that Mr. Obama failed to support.  The Iranian people are actually good folk who would just as soon not be our enemies!  This would give them a chance to be free and become our friends (once again). 

Dealing with our multiple adversaries:

We the West face 4 really bad adversaries:  Iran,  North Korea,  Russia,  and China.  Iran is now escalating from using all proxies into overt attacks,  and they are close to having nuclear weapons.  They really do need to be dealt with immediatelyI just told you how.

North Korea is the one most likely to fling a nuke right now,  with Iran not far behind.  The North Koreans don’t have very many nuclear weapons yet,  so we can afford some damage to take on Putin’s Russia next instead,  by forcing their utter defeat in,  and complete expulsion from,  Ukraine,  any which way we can!  Putin will be overthrown from within if that happens,  although there is no guarantee his successor won’t be just as evil as he is.  However,  it will take time for the new one to consolidate power,  during which time we can act.

Putin’s defeat and overthrow will tend to deter Xi’s China,  perhaps preventing World War 3 from starting over Taiwan in the Pacific.  His country’s mounting economic stress (from going to a war production footing during peacetime without much excuse other than starting a major war that the Chinese people do not want) can possibly induce his overthrow from within,  especially if that economy continues to falter into serious recession. 

With Russia and China out of the way,  North Korea can be easily taken down.  South Korea and Japan will be happy to help.  That one IS an invasion!  It results in a reunified Korea,  too.

Final related remarks:

Do not be fooled by my inclusion of Israel among the nations of the West.  In the current war with Hamas,  they have used tactics and weapons that bespeak of a total disregard of Palestinian lives,  well in excess above the appalling casualties one would have to expect,  from striking at your enemy through their human shield.   It may actually qualify as some sort of war crime.

That disregard of Palestinian lives is driven by the far-right political coalition that currently governs Israel:  they do not want a 2-state solution,  they apparently want instead for there to be no Palestinians left to have a state at all.  Very typical of authoritarian hard-liners!  The Israeli people need to change that government,  before it becomes a dictatorship.  Netanyahu trying to “reform” the Israeli judicial system was actually him trying to enable his staying in power permanently.  Israelis,  you have been warned!

As for the UN looking at war crimes charges against Israel:  why are you not also looking at Hamas?  Using human shields is a war crime,  as is attacking civilians!  And Hezbollah,  for dropping rockets on civilians for decades now.  What’s good for the goose is good for the gander!  Hypocrisy at the UN stinks!

As for everybody else:  look out for your own right-wing extremists!  They are among you!  They are invariably very authoritarian,  and they invariably want to “eliminate” (kill) their opposition.  If they have committed any crimes,  jail them for it!  Even if not,  you need to vote them out,  not in!  Or else you will have to revolt after they have established their dictatorships over you.  Doing it at the ballot box instead,  leaves a whole lot less mess to clean up!

And when I point my finger at you all,  my thumb is pointing back at me!  We face the same peril here in the US,  with multiple failed attempts (including an insurrection) to set up a right wing extremist dictatorshipprecisely because we voted an authoritarian in,  instead of out,  and he did not want to give up power when his term in office was over.  And now he wants another shot at it!  Surprise,  surprise!