Trump Lies: He Lost the Iran War

A word of advice for all readers:  do not listen to what your politicians say,  observe only what they do!  There is an old saw:  “a politician is lying if his lips are moving”.  While that is generally an overstatement,  with Trump (and his minions) it is almost literally true!  Essentially every claim by Trump that was fact-checked,  has proven to be false,  many quite egregiously so!  That is NOT opinion,  it a fact-on-the-ground,  staring you in the face!

The fact on the ground about Trump’s Iran war,  is that he started a war that he could not possibly win,  and so he inevitably lost it! 

It was unclear why he started it for multiple weeks.  The final “reason” offered,  was “no nuclear weapon for Iran”.  We did NOT achieve that goal:  Iran still has its enriched uranium supplies,  buried deep underground beyond the reach of our weapons!  Fact,  not opinion!

Because of the war,  they are quite probably also building the equipment to make bombs of their enriched uranium,  also buried deep underground,  beyond reach of our weapons!  That’s much closer to fact than it is any opinion!

We cannot invade and dig up the materials to take them:  our available forces are too small to mount an invasion that large,  get that far into the country,  and hold off attack from all sides,  while digging-up deeply-buried materials!  Fact,  not opinion!

Trump bragged that Iran’s air force,  air defenses,  and navy were destroyed during the first days of fighting.  While that is actually true,  it is irrelevant!  Iran was NOT planning on fighting its war with us by using those assets!  They had 47 years to plan a very asymmetric war with us:  using proxy terrorist armies,  and deeply-buried supplies of missiles and drones,  plus deeply-buried production facilities for them.  Fact,  not opinion!

The proof is that even today,  after Trump supposedly destroyed their capabilities,  Iran is flinging many missiles and many drones at our bases in the region,  and at our friends and allies,  and at ships in the Strait of Hormuz!  Plus soon,  the outlet of the Red Sea may also get closed,  by Iran’s terrorist proxy army in Yemen,  the Houthis. 

And the closure of the Strait of Hormuz precisely because of Trump’s war with Iran has already cost you dearly at the fuel pump!  Those effects will spread throughout the economy for some time to come,  since fuel powers everything in the economy!  And that will cost you even more!

One possible reason for starting this war was ending Iran’s use of its many terrorist proxy armies.  So far,  none but Hamas has been sharply reduced,  but by the Israelis,  not us,  and even then only by methods that amount to genocide in Gaza.  Hezbollah in Lebanon has suffered some damage from the Israelis (not us),  but is still intact enough to fight.  The rest (there are many,  notably the Houthis) are all unaddressed!  Fact,  not opinion!

Here is a related opinion:  one can oppose the current government of Israel,  without being anti-Israel or anti-semitic!  It was wrong of political figures to falsely frame that issue as “either/or”,  playing right into the hands of extremists and terrorists!  It was wrong of the news media to go along with that false framing,  and most of them did!  Very few will yet publicly say what I just said in the first sentence of this paragraph!  Yet it is quite true!

Back to facts:

Here of late,  Trump’s “reason” for his war has shifted to “reopening the Strait of Hormuz”,  because closing it has cost us so dearly already,  at the fuel pump.  Be aware that it was wide open before he started his war!  Now that the Iranians know “for sure” that their missile and drone threat can shut the Strait traffic down,  it will never again be a freely-open international waterway!  And,  they seem about to use their Houthis in Yemen to close the Red Sea outlet,  too,  cutting off essentially all Middle Eastern oil and driving prices far higher still,  any time they want to do it!  Fact,  not opinion!

The actual objectives were (and are):  no Iranian nuke,  no terrorist proxies,  a freely-open Strait of Hormuz,  plus possibly toppling the Iranian regime.  The only real way to have accomplished any of these goals was to actually topple the Iranian regime.  That regime before the war was a sham democracy in which the Supreme Leader plus some clerics ruled,  propped up by their terrorist private army the Iranian Revolutionary Guard Corps (IRGC).   The IRGC had also infiltrated and controlled the Iranian military for them. 

Now,  after Trump started his war and killed several Iranian government officials,  the terrorist army (IRGC) is pretty much in full control,  ready to fanatically die to the last man,  rather than negotiate,  and quite willing for us to commit genocide by bombing their people!   Trump has made that situation much worse with his war,  not better!  Fact,  not opinion!

And,  by the way,  bombing their country with collateral damage like that infamous school,  has turned the Iranian opposition into supporters of their regime.  It’s an “us versus them” thing!  So,  there is no longer any hope of an internal revolution toppling it from the inside!  There really was such hope,  before Trump started his war!  Fact,  not opinion!

The only way left to achieve any of the goals (of which NONE have been achieved!!) is to invade and topple the Iranian regime the hard way.  Based on our WW2 experiences,  that would take an invasion force on the order of 1 to 2 million troops,  to sweep the entire country,  and root-out and kill all of the IRGC,  who will fanatically die to the last man rather than ever surrender!  The US cannot possibly do that alone,  it has only about 200,000-300,000 people in all its armed forces,  total!  And Trump has alienated all our allies!  Fact,  not opinion!

The truth about this war being a failure,  attributable directly to Trump,  is finally starting to come out!  He punishes news media who reveal it with lawsuits,  by being barred from events,  and with threats to their operating licenses!  We have greatly depleted our stocks of critical air defense interceptors,  and a lot of our longer-range strike weapons!  It will take years and billions of dollars to replace them!  Therefore,  Trump has made us much more vulnerable,  by that depletion of our weapon stocks,  in any other wars our enemies might well start against us!  Like over Taiwan.  Or the Baltic NATO states.  Or Poland.  All fact,  not opinion!

Trump spent our resources and left us vulnerable,  fighting a war that he started,  but which he could not possibly win!  Previous presidents were told about these dangers and chose not to start a war they could only lose.  So also was Trump informed,  but he chose to start the war anyway,  and now has lost it!  So,  he is now searching desperately for any off-ramp by which to “declare victory” and get out.   

The Iranians lead him on in the “peace talks”,  when they bother to talk at all.  They have no reason to give him that off-ramp,  because they know they won!  That is precisely why this thing has dragged on for so long!  Fact,  not opinion!

Opinion:  incompetence on that colossal of a scale,  which involves waging a war,  and which borders on treason,  cannot go unaddressed! 

It is way past time to get rid of Trump,  before he finishes destroying the US economy and its military!  He has already destroyed our reputation around the world,  and weakened or destroyed our alliances that protected us from our enemies.  He has already cost you dearly at the fuel pump,  and those costs will only rise further and spread throughout the economy!  Hence the appropriateness of the illustration: 

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Trump Treason Evidence

Update 9-27-2026:  added bits of text in red a couple of places below,  to indicate how the treasons of damaging the alliances costs you right in your bank accounts!   As well as endangering your freedoms and your lives.

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The Constitution defines two,  and only two,  things that can be called “treason”.   One is a citizen directly making war upon the US.  The other is “providing aid and comfort to the enemy”,  and that is the thing discussed here.

Trump has been waging trade wars and imposing tariffs upon our friends and allies,  angering them,  alienating them,  and making them go elsewhere for trade,  and to seek new alliances (without us).  Canada is just the latest example among many.  Prices for food,  fuel,  and construction materials have risen drastically,  precisely because of those trade wars!  That hits you in your bank accounts!

These were the alliances that protected us from our enemies,  such as Putin’s Russia,  Xi’s China,  Kim’s North Korea,  and the sham democracy that is now terrorist-ruled Iran.  Our enemies have long wanted to weaken or destroy our alliances,  but they could not. 

Now Trump has done it for them!  That is not opinion,  those are the facts upon the ground,  staring everybody right in the face!  Every ally alienated,  and every alliance weakened,  is another count of “aid and comfort” treason!

We have a friend and ally in Ukraine,  who has been holding back Putin’s desire to reconquer much of eastern Europe.  We were supporting Ukraine with weapons and aid,  until Trump took office for his second term.  He essentially stopped US support for Ukraine,  and has repeatedly pushed them to accept Putin’s demands,  in order to end the war.  That would amount to Ukraine’s surrender!  Those,  too,  are the facts,  not opinion at all!  

Ukraine holding back Putin invasions of eastern Europe meant that we and NATO did not have to!  We spent less sending Ukraine aid than we would have spent militarily opposing Putin.  Ending that will hit you in the bank account again!

Trump has therefore effectively tried to destroy our ally Ukraine for Putin,  and that is indisputably aid and comfort he has provided to our enemy Putin!

These many Trump treasons just described demand that he be brought to justice! 

The Department of Justice will not do it,  for Trump has packed its leadership with his utterly-loyal supporters,  and they have driven out all who might act against him. 

Congress cannot punish him,  but it could remove him by impeachment,  so that he cannot commit more!  However,  it has an egregious track record of letting Trump do whatever he wants under Republican control,   because Trump completely controls that party!  Part of that is using your tax dollars trying to build monuments to himself.  And if the reflecting pool is any indication,  he does a bad job of these things,  and so wastes even more of your money!

Part of them are just utterly-loyal to Trump,  and the rest have completely sold out to him,  in order to stay in office and not to be “primaried”.  It has degenerated into a Trump cult of personality,  the exact same way the Nazi party became a Hitler cult of personality!  And he has almost completely imposed a dictatorship from the inside,  just like Hitler did,  but that is another story! (See the article just below,  dated 9-19-2026.)

We need a Congress that will actually do its job for we-the-people!  This one is not it!

Here is the only opinion in this entire article:  control of Congress needs to change with the upcoming midterm elections,  or Trump will continue committing treasons until he finally destroys our democracy completely!  Hence,  the illustration:

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Trump Dictatorship Evidence

The first image below is my spreadsheet that tracks 10 hallmarks of a dictatorship.  As of this date,  I see 8 fully in place,  and 2 mostly in place.  The secret police force is definitely in place,  with them killing both demonized immigrants and US citizens who protest too strongly,  plus “detention centers” (concentration camps) where inmates die of neglect.  Immigrants are “disappeared” by deportations without due process,  instead of gas chambers.  Opponents are next!

The second image is my view of the political spectrum as a circle,  not the straight line that everybody thinks it is!  I see free societies on one side of the circle,  and authoritarian dictatorships on the other side.  There are two paths to the other side,  but once there,  there is no difference in behavior!  It does not matter what they say,  only what they do!

A military leader recently said in public that no troops would be sent to polling places during the November midterms.  Given that Trump has cashiered most of the higher officers who will not back him,  and that the fact-checking track record says about 100% of Trump’s claims are lies,  I do expect to see troops at polling places in November!  If Trump thinks he is losing control of Congress,  I predict that he will declare martial law and have the troops confiscate the ballots and voting machines from the polling places!

And THAT will be the final end of a free and democratic America!  On its 250^th birthday!

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Starship/Superheavy Hot Staging

This is not insider knowledge.  It is based only upon what SpaceX has publicly released. 

There is some kind of geometrically-shaped shield plate that protects the front end of the Superheavy booster where the forward dome of the forward propellant tank is otherwise exposed.  This shield was shed after hot staging with Version 2,  but is now integral to the booster stage in Version 3.  It deflects the plumes of the Starship upper stage engines,  from striking and damaging or destroying that forward tank end,  during hot staging.

This shield structure is coupled with an interstage ring between the stages,  part of the Superheavy,  that is “porous”,  in the sense that there are openings through which the deflected engine plumes can exit laterally,  in a more-or-less radial direction,  during the transient hot-staging event.  The force to turn a plume gets exerted upon that shield.

The Superheavy booster had four grid fins spaced 90 degrees apart,  in Version 2.  Plume blast damage had been noted to the grid fin rotated into the way of plumes,  during the booster flip maneuver,  in Version 2.  In Version 3,  there are only 3 grid fins,  still spaced 90 degrees  apart,  but somewhat larger than the Version 2 grid fins.  That leaves a space where there is no grid fin,  which is clocked to align with the dorsal side of the upper stage Starship,  as shown in Figure 1. 

Figure 1 – Version 3 Starship/Superheavy Arrangement and Intended Booster Flip Direction

The design direction of the booster flip is a plane aligned with the dorsal-ventral plane of Starship,  and the front of the booster is supposed to flip in the direction where it moves “down” as shown in the figure.  Thus,  no grid fin is exposed to plume blast damage anymore,  in Version 3.  The side of the booster is less vulnerable to plume blast damage,  being cooled by the cryogenic propellant vapors inside.  

In Version 2,  the torque to flip the booster came from a strong gimbal angle of the 3 booster engines firing during the staging event to keep the booster propellants settled into the aft ends of their tanks,  where the suction-feeds to the engines are located.   This is still the case in Version 3,  with some control of the deflected plume force directions added,  by one or both of two means:   (1) the geometric shaping of the shield and of the “porosity” of the interstage ring,  can favor a plume deflection force component in the intended flip direction,  and (2)  the startup sequencing of the Starship engines can also produce a temporary plume deflection force component favoring the intended flip direction. 

There are two separate effects going on during the hot-staging event,  which must both be successful,  but which are also linked to each other in ways that make the successful “solution space” rather small!  These are indicated in Figure 2 below,  which depicts the conditions as the hot staging begins,  but before the flip starts.  (Drag was ignored.)

First,  the acceleration of the upper stage Starship has to be larger than the acceleration of the Superheavy booster (before the flip starts),  in order not to risk a collision. 

Second,  the axial acceleration of the Superheavy booster must be a positive number large enough to keep the propellants settled,  all during the staging event,  and all during the flip maneuver. 

That last is also complicated by the flip motion possibly flinging the propellants forward,  in only the forward tank,  if the flip is too fast!

The variables available for controlling this event are the thrust levels used in the booster and upper stage engines,  the shaping of the shield and interstage ring porosity geometries,  and the sequence of ignition of the upper stage engines. 

To simplify this first look,  the author chose only a full thrust setting in the 3 booster engines,  and lighting all 6 upper stage engines at once,   but a some reduced thrust.  Guesses were made for plume deflection force component angles and booster engine gimbal angles.   All of this is indicated in the figure.

The author has no actual data for the engine thrust levels at the staging altitude,  or for the actual masses of either stage at the time of staging.  He made reasonable guesses for these,  as well,  as indicated in the figure.  So the results are inherently approximate!

Figure 2 – Finding A Thrust Setting For Starship That Keeps Superheavy Accelerating

It would not be possible to get full thrust in an engine at the moment of ignition!  It is more practical to ignite at a partial-thrust setting propellant flow rate,  stabilize after a split second,  and then throttle up quickly a split second after that,  as desired. 

The author chose to look at full and half thrust initially,  and then added a 40% thrust setting,  after getting negative booster acceleration at full upper stage thrust,  and zero booster acceleration at half thrust.  The 0.1 gee booster axial at 40% Starship thrust is in the rough ballpark of other ullage thrust applications.  The 40% thrust setting is within the capability of the Raptor-3 engine design,  so this point really is a feasible thing to do!

As the figure indicates,  the Starship upper stage has the acceleration to leave the booster behind,  at 40% thrust on 6 engines.  It cannot throttle up until the flip has proceeded enough to direct the front end of Superheavy out of the way of the Starship engine plumes.

Also indicated in the figure,  the Superheavy axial acceleration is zero at half Starship thrust,  and only 0.10 gees at 40% Starship thrust.  Starship cannot throttle down much more than that,  and still leave the vicinity at about 0.4 gees!  Which is exactly why this author says the solution space here is quite narrow!  Screw this up,  and the propellants will unsettle,  the booster engines will suck vapor,  and their turbopumps will explode!

The next step was to look at starting the booster flip.  This is illustrated in Figure 3,  which presumes the 40% thrust solution just obtained above.  Two cases were examined:  a booster engine gimbal angle of 10 degrees,  and a comparable lateral deflection force generated by shield geometry and/or interstage porosity distribution.  The booster mass moment of inertia was approximated by the solid bar formula for rotation about its center of gravity (cg).  That cg was simply presumed to be halfway along the booster.  

Figure 3 – Starting the Booster Flip Maneuver During Hot Staging

The results for time-to-clear shown lower right of figure are amazingly close to what is in the publicly-released videos of these flight tests (about a second or two to clear)!  Considering how crude all the assumed data is,  that outcome is quite remarkable!  Letting deflected upper stage plumes help the gimballed booster engines to start the flip maneuver is definitely beneficial,  but it is not an overwhelming effect.  That would seem to be the lesson to be learned here.

That brings up the “spin gravity” effect of the flipping booster upon the settling of propellants in its forward tanks by engine-induced acceleration.  As depicted in Figure 4,  this depends upon which side of the booster cg falls the free surface in the forward tank.  One must take into account relative tank sizes,  and how full those tanks are.  A very crude estimate is shown in the figure,  indicating that spin will help settle the propellants.

Figure 4 – Evaluating Whether Spin of Flip Affects Propellant Settling

Note that had the LOX tank been forward in the design instead of aft,  this outcome would not be true!

The magnitude of the “spin gravity” effect depends upon the rotation rate ω at the time the booster clears the plumes,  which is crudely angular acceleration times the clearance time,  for the two cases shown in Figure 3 above. Those would be 0.139 rad/s for the gimbal only case,  and 0.186 rad/s for both effects together. 

The acceleration in gees at the free surface would be L ω²,  where L is the distance between the cg and the free surface.  As measured from the left as shown in Figure 4,  as long as the free surface is left of the cg,  the spin gravity gees adds to the axial thrust gees.  If the free surface falls to right of the cg as shown in the figure,  then the spin gees would subtract from the axial gees!  There is a coupling between stage layout and “spin gravity” risks.

For the dimensions indicated in Figure 4,  the LCH4 free surface is 10 m left of the cg. So,  if only gimballing,  one would add about 0.020 gees to the axial 0.1 gees.  If faster for both effects together,  one would add about 0.035 gees.  The additions would be a bit over 3 times larger for the LOX tank,  as the L to its free surface is larger at something like 33.7 m.

Much more accurate dimensions masses,  and propellant-remaining percentages would be needed to get reliable results!  But these results obtained here do seem to crudely indicate what is going on during Starship/Superheavy hot staging.

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A Question

My wife found this,  and it is just too good not to post!  But it does raise some other serious questions,  beyond just the one in the image. 

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A few other questions might be:

#1.  “Why is everything that is not good always said by Trump to be either Biden’s or Obama’s fault?”  Not all those things claimed by Trump to be their fault,  can actually be their fault!  A lot of them have been found to actually be Trump’s fault,  which just means he is lying to deflect blame from himself.  Many others are no one’s fault,  just bad things that happened.  Like Covid-19 and the resulting economic depression caused by containing it.

#2. Virtually everything that Trump has ever claimed,  which have actually been fact-checked,  have turned out to be lies.  That’s not opinion,  that’s real data,  right in front of you,  me,  God,  and everybody!  Many of these were really bad,  “pants-on-fire” lies!  Given that track record,  the second question is “Why would anybody believe anything Trump says,  at all?”

#3. Trump is a draft dodger (his dad bought him the “bone spur” draft deferment),  a convicted financial felon (New York state case),  and a civilly-adjudged sex offender (the E. Jean Carrol case).  Those are also not opinion,  but fact,  real data in front of us all.  The question:  “Why would any American ever want a US Navy ship to be named after such a person?”  Re-naming the under-construction USS Doris Miller for Trump is truly a travesty!  Dorrie Miller was a true combat hero aboard the battleship West Virginia during Pearl Harbor,  and he died serving aboard the USS Liscombe Bay during that war!

You can probably think up more for yourself!

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Inlets Capable of Supersonic Flight Use

This posting is a primer about supersonic-capable air inlets for people who know very little about them.  I had intended to put t up in September,  but ended up posting it late in August.   I have another one coming soon that goes into more details about how these things behave and how the data are "book-kept".  Together,  they make a pretty good "get started" lesson in supersonic inlets.  This topic is crucial to the success of anything that flies fast with any kind of airbreathing propulsion.  

The posting follows:

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There are two kinds of inlets that could possibly be used in supersonic flight,  especially in their simplest forms for ramjet-propelled vehicles.  One is the so-called “pitot/normal shock” inlet,  useful from subsonic speeds all the way up to about Mach 1.5,  maybe even 2.0.  The other is the “supersonic inlet” that features external compression surfaces ahead of its cowl lip capture station.  These are only useful in their simplest forms from roughly Mach 1.5-to-2,  up to high supersonic,  even low hypersonic speeds.  That would be Mach 6+.

That brings up the definition of “capture area”.  It is defined as the area that is swept-out by the inlet structure as it moves at flight speed.  That varies with inlet type,  because of the varying requirements for external compression structures and cowl lip shapes.  However,  Figure 0 may help the reader to better understand how these things are defined.

Figure 0 – Definitions of Capture Area for the Various Inlets

Shock waves are inherent once supersonic flight speed is attained.  Shock waves come in two basic forms:  the “normal shock” and the “oblique shock”.  They have different characteristics and effects.  This is illustrated in Figure 1.  The normal shock occurs when a supersonic streamtube must go straight into a region of sufficiently-higher pressure.  The oblique shock forms when an angled surface forces the streamtube to divert to a new direction.  The math behind this is complex,  and given in the indicated source (Ref. 1).  The normal shock is the “stronger”,  in that flow behind it is subsonic,  and at a lower total (stagnation) pressure.  Flow behind an oblique shock is still supersonic,  with less loss of total pressure.  Total is larger than the static pressure,  reflecting high speed flow energy. 

Figure 1 – Basic Characteristics of the Two Kinds of Shock Waves

The pitot/normal shock inlet is just a pitot inlet flying supersonic.  A bow wave shock begins to form out in front (“subcritical” operation) if the outlet is obstructed.  If the pressure at the outlet of the duct reduces to just the right pressure,  the shock moves to the min area right at the cowl lip.  This is the “critical” operation point.  If the pressure at the outlet (“the backpressure”) is reduced further,  the shock will move downstream further into the divergent passage of the inlet duct (“supercritical” operation).  The pitot/normal shock inlet has no “shock-on-lip” design point,  it simply “is”.  This is illustrated to the left side in Figure 2 at critical operation.

The supersonic inlet has a compression surface exposed in front of the cowl lip capture station.  This surface is a spike if circular in cross section,  or is a flat ramp if rectangular in cross section.  It works by diverting the air stream’s direction,  thus creating oblique shocks.  At the design “shock-on-lip” speed,  these shock waves converge upon the cowl lip,  as illustrated for the two slightly-different designs on the right side of Figure 2.   

There is always a minimum channel area in a supersonic inlet,  as noted in the figure,  termed the “inlet throat”.  If the inlet throat is downstream of the cowl lip capture station,  there is also internal compression in the contracting channel.  That is the “mixed compression” design,  bottom of the two illustrations.  The cowl lip can be close to parallel with the oncoming flow for lowest drag,  and sheds an internal oblique shock,  which at design should be focused upon the inlet throat station.   At critical operation,  the terminal normal shock is also located at that inlet throat,  which is still somewhat supersonic.

Figure 2 – How the Various Inlets Incorporate Shock Waves in Their Compression Process

If the cowl lip is angled more parallel to the external compression surface,  the inlet throat can be located right at the cowl capture station.  The cowl lip does cause higher cowl lip drag,  oriented that way.  There is no internal compression by any contracting channel,  and thus no internal oblique shock shed by the cowl.  This is the “all-external compression” inlet design.  At critical operation,  the final terminal normal shock is right there at the inlet throat,  which is the min flow area at the cowl capture point.

In either supersonic design,  the sequence of oblique shocks slows the flow speed in steps,  at each oblique shock shed by a surface feature.  The diversion angles generate the oblique shock waves that the flow encounters.  Done “right” (that math is also very complex),  there is about the same total pressure ratio (a number less than 1) across each shock,  which can also be made about equal to the total pressure ratio of the terminal normal shock.  That last is because the terminal shock occurs at a quite low supersonic flow speed,  instead of full flight speed. 

The product of these total pressure ratios is essentially (but not entirely,  because of friction in its various forms) the “critical pressure recovery ratio” of the inlet (a number less than 1).  That product of ratios is higher than the total pressure recovery ratio across the single normal shock of the pitot/normal shock inlet.  That higher total pressure recovery ratio is why these supersonic inlet types are much preferred beyond Mach 1.5 to 2 flight speeds.

There is a classic problem in fluid mechanics texts,  dealing with using a converging-diverging passage as a supersonic inlet diffuser to slow a flow down,  instead of as a nozzle to speed it up.  At the “design” speed,  flow slows in the contraction to a speed just above Mach 1,  and then tries to expand again supersonically just as the channel starts to diverge,  but then shocks down subsonic with a normal shock,  for (ideally) final subsonic diffusion. 

When one attempts this experimentally,  the shock forms out front as a bow shock,  and the subsonic flow behind it tries to pass through the min area at flow speeds up to Mach 1.  But the subsonic massflow passable at Mach 1 is less than the supersonic massflow that is being swept out!  One has to speed-up the oncoming flow to considerably higher speed than the “design” speed,  in order to “swallow” the bow shock,   in order for it to become that terminal normal shock. 

This is the Kantrowitz-Donaldson problem (Ref. 2),  and mixed-compression inlets inherently suffer from it,  because such a converging-diverging passage is a part of the inlet’s design.  The only way to get the shock system swallowed is either (1) by very significant overspeed,  or (2) by adding very significant throat bleed slots that lead overboard,  in order to pass the requisite supersonic massflow rate.  The subsonic flow can make the turn to go out through the bleed slots easily!  Once supersonic,  the flow cannot easily make the turn,  so the slot bleed flow is very much lower,  once supersonic internally. 

The all-external compression inlet does not have this “starting” (shock-swallowing) problem!  That is because there is only a diverging channel,  once the flow is inside the cowl.  These inlets start easily without need of overspeed,  or any need of significant throat bleed slots.  They simply have no contracting channel with which to suffer the Kantrowitz-Donaldson problem.  That leads to the list of pros and cons for the two types of supersonic inlets in Table 1.  The pitot inlet is included for completeness.

All these inlets share the behaviors that we call subcritical,  critical,  and supercritical flow.  This is driven by the “backpressure” the inlet “sees” at its subsonic outlet.  In effect,  this backpressure is a resistance to swallowing the shock system and keeping it swallowed.  In both critical and supercritical flow,  the shock system is swallowed.  At critical,  the terminal normal shock is right at the inlet throat.  Supercritical,  it is located further down in the divergent diffuser and is thus stronger,  taking place at a higher flow speed,  and thus creating a lower total pressure in the subsonic flow downstream of it. 

In subcritical flow the entire shock system is unswallowed,  located out on the external compression surfaces.  Its position along that surface determines how much air is spilled around the cowl lip and not ingested at all,  even after passing through the oblique shocks and terminal normal shock and getting the max possible final total pressure.  This behavior is shown in Figure 3 just below for all three inlets,  at their design speeds (excepting pitot,  which is simply shown in supersonic flow).  Subsonically,  the pitot always effectively operates “subcritically” by spilling air,  it’s just that there is no shock wave at all.

Only the supersonic inlets have a design speed,  the pitot does not.  There is the possibility of operating below design speed,  at design speed,  and above design speed,  quite independently of the possibilities of operating sub- or supercritical.  At or above design speed,  the ingested streamtube is its full swept-out size.  Below it,  the ingested streamtube is smaller for geometric reasons,  because the local flow behind each oblique shock must be parallel to the surfaces of the external compression features.  This behavior is shown only at critical,  for simplicity,  in Figure 4.  The shock and spillage patterns are more complex supercritical,  and simply different subcritical. 

Figure 3 – Subcritical,  Critical,  and Supercritical Operation at Design Speed

Figure 4 – Below vs At or Above Design Speed with Supersonic Inlets at Critical

The net effect of all this is (1) subcritical spillage reduces air ingestion while maintaining full pressure recovery,  while supercritical operation ingests full air flow while reducing pressure recovery.  The point where both ingestion and recovery are their max possible values is the critical point.  This has the effect that at any one flight speed Mach number,  the operation of the inlet is per Figure 5 below.  In that figure,  the notation PRCR is the critical total pressure recovery,  which is that maximum recovery.  The notation ARCR is the critical area ratio of the captured streamtube,  to that which could be swept out by the inlet’s capture area.  It is maximum at critical.

That “any one flight Mach number” could be below,  at,  or above the design shock-on-lip Mach number for the supersonic-type inlets.  There is no such design shock-on-lip Mach number for a pitot/normal shock inlet.  Below design,  the possible ARCR ratio of the supersonic-type inlets is reduced by the geometries involved,   while above it,  ARCR is not reduced.   The pitot has no such effect.  

Figure 5 – How All Supersonic Inlets Operate at Any One Flight Mach Number

Pressure recovery is aways reduced at higher speeds,  but it reduces faster above design than below it,  with the supersonic-type inlets.  Pitot has no slope break at design because it has no design speed,  but it always has lower pressure recovery than the supersonic types,  just because of the stronger single normal shock.  That gives rise to the recovery curve shapes shown generically in Figure 6.  

Figure 6 – Generic Representation of Typical Inlet Curve Shapes with Mach number

There are drags associated with the air that is either spilled subcritically,  or not ingested for being below design speed,  among many other reasons.  These vary with the details of the inlet designs,  and where they are positioned on the vehicle.  That is a very complicated item,  beyond scope here.

The use of these inlets on turbojet and turbofan aircraft is another very large separate topic.  These inlets,  especially the supersonic types,  require a myriad of “band-aids” like spring-loaded blow-in doors admitting extra air,  with the duct sucked down below local atmospheric by the turbine engine,  in order to function well when below design speed.  The pitot inlet may need some of these “band-aids” for low subsonic and ground-run operation.  Even so,  the very same components get used quite differently for turbojet or turbofan,  as compared to ramjet!  That is also beyond scope here,  except to say that ramjet needs supercritical operation,  and turbojet/turbofan needs subcritical operation.

References

#1.  NACA Technical Report 1135 “Equations,  Tables,  and Charts for Compressible Flow”,  Ames Research Staff,  1953.

#2.  Kantrowitz, A., and Donaldson, C.,  “Preliminary Investigation of Supersonic Diffusers”,  NACA TR L5D20,  1945.

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