April 6

9:03 AM Am deschis știrile din România și am văzut aceleași figuri de oameni handicapați pe care noi îi numim politicieni și mi-am amintit de o fază de ieri.

Era televizorul pornit dar eu îmi făceam treaba pe PC și am zărit cu coada ochiului o fază. Un jurnalist american, parcă de la CBS, a avut un interviu cu un analist politic din Bulgaria pe tema alegerilor din Ungaria iar eu m-am mirat puțin dar mi-am văzut de treabă în continuare. Nu aveam ce să văd fiindcă știu totul despre Ungaria și teatrul de acolo și cel din lumea mare realizat tot de ei.

Dar pe măsură ce minutele treceau, am început să fiu atras de vorbirea fluentă în engleză cu un accent aproape inexistent, stilul literar, dar și multitudinea de probleme abordate în puține cuvinte, toate rostite la locul lor în cea mai bună engleză pe care am auzit-o vreodată de pe continentul european.

Măi să fie. Mă gândeam la persoana cu față familiară ca de pe la noi și stil de gentleman european și mă întrebam, oare de ce nu am avea și noi românii asemenea persoane vizibile în media? Cel mai aproape la care mă pot gândi, profesorul Vladimir Tismăneanu, deși trăiește în  Statele Unite are un accent mult mai gros și un stil tenebros, aservit lui Băsescu și mereu supărat și blocat într-un trecut care nu prea ne mai ajută cu nimic.

Puteți urmări interviul aici.

2:23 PM Apropo ce bine seamănă Peter Magyar cu Maclemore! (voi încerca să fac o asemănare mai târziu, acum sunt cam obosit).

April 5

9:09 AM Yeah. I don't know how to put this but please let me try. I realized most people don't know what is a "burn" in space travel terms and this seems unacceptable to me so i make it a high priority right now to explain it.

Doing some searches was trying to figure the time of the burn of the initial launch. Actually, there are several. During the initial lift off we have two solid fuel boosters that burn i don't know, a minute of two.

Those deserve a few considerations as well. Solid rocket boosters are nothing but metal cylinders filled with (slower burning) explosive attached to the tanks with liquid fuel. Lit at one end, they will burn towards the other until they are spent. One must understand there is no control over those after lighting them up. All we have to do is hold our breath and wait until they are done and jettisoned.

It is very important that they finish both in the same time. Otherwise, the ship will take a turn in one direction or the other. Or simply expel them with explosive charges seconds before they are done.

During all this time the main liquid fuel engine(s) at the bottom of the ship move(s) around two axis many times a second (thrust vectoring), doing corrections, trying to keep up with irregularities and turbulences coming from solid fuel boosters.

The solid fuel boosters are a cheap way to bring more lift to the launch, lowering the size of tanks for liquid fuel which is most of the mass of the ship at launch anyway. I don't know what the ratio is but i i think is in the order of 1-5% of mass of fuel needed for useful payload lifted in orbit (which again most mass is fuel for subsequent burns) when the ship becomes briefly a satellite.

So yes, we have solid fuel booster burn, continued main engine(s) burn, and then silence. Once the ship is in the desired Earth orbit the fuel is mostly spent, there are no more burns except for corrections and compensating for very thin but existing atmosphere that slows down (and thus lowers orbit for any satellite, reducing its life time.

I could not find that as all the keywords used lead me only to the emotional news about the firs trip to the Moon in 50 years that flood searches no matter how much i try but i would think is in the order of minutes.

The main idea was that during the whole flight to the Moon and back that takes what, days, the only powered phases of the flight are in the order of minutes and those powered phases are called burns.

Here is a diagram showing Artemis main component including the 2 solid fuel boosters and the 4 liquid fuel engines at the bottom. All engines are designed and work for minutes during the whole mission (also because the burn fuel at a very high rate). 

In the case of Artemis II most of the power phases of flight occurred within the first minutes and first day of flight, rest of it been done by inertia alone, conserving the initial kinetic energy acquired from chemical energy of fuel during burns.

The equations needed to describe the flight path are extremely complicated, and the precision of the burns and feedback such as position and speed, before, during and after those burns have to be extreme so it can ensure the precise and safe return to Earth using inertia and gravity of Moon and Earth in a very smart way.

The final burn or the so called "lunar injection" is particularly critical (but not more critical than lift off, using solid fuel rockets, other burns), cause that burn uses the last of the fuel and there is no possibility of return except through gravity of Moon during flyby and there is a narrow window of angle, position and speed in which that can be done.

Besides equations, an input is being necessary as current position and speed. There are a number of ways to calculate those, starting from comparing observed stars positions to charts, inertial data (accumulation of accelerations/decelerations/direction changes since last calibration or reset), (ground based) radar, lasers and other EM means. Lately they begin to think about extending the GPS coverage to at least areas near Earth.

Any measurements done on Earth cannot be used in real time for that input to calculate the engine's parameters since there is a lag in EM transmission of tenths of a second due to speed of light and distances.

I know from videos i have seen that rocket engines are being steered during lift off, because i saw their movements, probably using inertial feedback, to keep pushing the rocket upward and especially to avoid tipping it over, especially during very first phase where no aerodynamic forces are there to help stabilize direction of the vehicle.

There are also no aerodynamic forces at work in space like after leaving the atmosphere or during the final burn and i assume the engine is being steered using inertial input as well, but don't know if they use other data to refine the direction during the 6 minute final burn.

April 4

7:30 PM Have you read the news? Too much BS in Orion's toilet? 

April 3

8:52 Într-o lume relativă...

9:10 I was waiting for this to happen and somehow missed it because i was too busy with the stand and the monitor. Why waiting. By now they (must) have enough telemetry and know the trajectory is ok.

Why is this so important. Well of course  the name says it all. Last burn, which accelerates the ship to break Earth orbit and puts it on an irreversible course towards Moon (in other words, is a one way, irreversible trip away from Earth, until it meets Moon).

After that burn there is not or too little fuel left for the ship to return to Earth on its own power if anything goes wrong. It goes by inertia alone and the return depends only on how well the trajectory was calculated and implemented during that last burn.

Do you realize the enormity of this? An error of only a tiny fraction of degree during the last burn done by the end of the first day of flight could mean one of the following.

They miss the rendez-vous with the Moon by a too greater margin which means they cannot benefit of its gravitational pull of the Moon for a complete return and fly forever in deep space.

Second. They get on a spiraling trajectory and fall on the Moon.

Third. They get captured by Moon as a satellite and stay there forever.

Fourth. The initial calculation and implementation of the orbit has to go as far as to include the precise return and placing on an Earth orbit at the desired height necessary for the re-entry burn. Even coming at a less than optimal angle will not allow them to safely re-enter.

But what the heck. They did it 50+ years ago when computers where primitive.

Are these risks acceptable and necessary for 4 humans for the benefit of "testing equipment and humans for the flight"? (they could have done this on  Earth orbit...).

8:09 The most expensive fighter jets in 2025

10:45 Nimeni nu va ști cât de mult îl urăsc pe David Gilmour pentru melodia sa "The Wall". Dacă am radioul deschis când postez ceva ci potențial educațional, ăștia îmi pun melodia. Da s-a ajuns până aici și nu de acum sau de un an doi, de decenii. Bănuiesc că muzica e aleasă de AI.

Dar sunt momente ca acum când îi dau dreptate. Un "profesor universitar" de economie vine și îndrugă baliverne, spre confuzia tinerilor și a tuturor.

I să vedem cum facem ordine în acest talmeș-balmeș.

În primul rând, România are mai multe bugete. Două din ele sunt stabilite prin lege, și alea sunt Bugetul de Stat și Bugetul Asigurărilor sociale (pensiile). Cheltuielile de la Bugetul Asigurărilor Sociale de 158 miliarde (pensiile) sunt acoperite în totalitate de Contribuțiile pentru Asigurări Sociale din salarii (CAS pe fluturaș), cu un surplus de 66 miliarde.

Cheltuielile din Bugetul de Stat pentru salarii, spun ei, sunt de 170 de miliarde din 391 (venituri).

Pensiile (Bugetul Asigurărilor Sociale) sunt de 158 miliarde iar restul (ajutoarele sociale) sunt diferența până la 250? Asta în condițiile în care alocațiile pentru copii sunt 16 miliarde? Adică se plătesc ajutoare sociale mai mult decât jumătate din salarii bugetari? Care apropo ar putea fi suportate de surplusul de 66 miliarde creat de CAS?

April 2

2:35 PM