Monthly Archives: January 2008

Voli spaziali low cost

Alzi la mano chi non ha almeno una volta alzato gli occhi al cielo per contemplare un il firmamento, per osservare un’eclissi o cercare una stella cadente. Alcuni (ed io sono tra quelli) avranno certamente sognato di viaggiare tra le stelle per vedere la terra dallo Spazio o per provare l’assenza di peso come gli astronauti delle missioni Apollo (per citare solo quelle più famose).
Ebbene, quello di vedere la Luna da vicino e navigare nello spazio come un astronauta potrebbe non essere un sogno irrealizzabile. Con la presentazione alla stampa della Space Ship Two, avvenuta il 23 gennaio all’American Museum of Natural History di New York, è infatti iniziata l’era dei voli di linea spaziali. Almeno all’inizio non si tratterà di viaggi alla portata di tutte le tasche, men che meno di voli low cost visto che il prezzo dei primi biglietti venduti si aggira intorno ai 140.000 Euro (l’uno). Tuttavia, stando a quanto afferma Richard Branson, proprietario della neo-costituita Virgin Galactic, nel giro di qualche anno (sembrerebbe ne bastino 5), la preziosa carta d’imbarco potrebbe costare molto meno e già la seconda tranche di passeggeri della navicella dovrebbe potersi avvelere di biglietti che costeranno la metà del prezzo attuale.
La Space Ship Two inizierà i collaudi quest’anno ed è previsto per il 2010 il primo volo passeggeri. Sebbene il prezzo non sia di favore, sono già più di 200 le persone che hanno messo mano al portafogli per aggiudicarsi i biglietti che danno accesso alla navicella progettata da Burt Rutan, lo stesso che nel 2004, per 2 volte è riuscito a portare il suo primo aereo-astronave, denominato Space Ship One, a quota orbitale e a tornare a terra tutto d’un pezzo.


Anche se a quanto pare l’unico prerequisito che è necessario soddisfare per fare un volo suborbitale è quello di avere un conto in banca “rassicurante”, la gita spaziale non si preannuncia come una vera e propria passeggiata: la navicella, in grado di trasportare 2 membri dell’equipaggio e 6 passeggeri (questi ultimi in una cabina lunga 3,7 metri e larga poco più di 2), raggiungerà la quota di 15.200 metri grazie ad un aereo-vettore, il “White Knight Two”. Sganciata dalla “nave-madre”, la navicella inizierà una salita a Mach 3,5 fino all’apogeo della traiettoria orbitale situato a 110 chilometri di altezza, punto in cui i passeggeri potranno per alcuni minuti slacciare le cinture e sperimentare l’assenza di peso osservando la terra e le stelle attraverso gli oblò larghi 43 centimetri. Dopodiché, il rientro e l’atterraggio, per un totale di circa 2 ore e mezza, il tempo di un volo di sola andata sulla rotta Roma – Londra. Tutto facile quindi? Non proprio, visto che mentre il Roma – Londra lo si vive comodamente seduti nel proprio posto, meglio se di prima classe (e visto il prezzo del biglietto galattico dovrebbe essere questo il settore in cui i futuri viaggiatori spaziali sono abituati a volare sugli aerei di linea), sorseggiando una bibita o sonnecchiando, il rientro dal volo orbitale prevede che durante la fase di rientro i passeggeri incassino qualcosa come 6 G! Certo, non si tratta di un rientro a 25.000 chilometri orari tipo Space Shuttle e oltretutto i sedili sono reclinabili per attutire gli effetti dell’accelerazione (avete presente l’F-16?) ma il ritorno a casa non è neanche il comodissimo Continuous Descent Approach dei widebodies civili.
Per quanto riguarda gli “aeroporti” di partenza, terminata la sperimentazione nel deserto del Mojave, la base di armamento della Virgin Galactic sarà Spaceport America, nel New Mexico, anche se si parla già di una base alternata situata al Polo.

A chi volesse acquistare un biglietto o avere più informazioni, segnalo il sito della Virgin Galactic: http://www.virgingalactic.com/

Photo courtesy of Virgin Galactic


AMX and F-15 grounded (with some differences)

For the second time in the last 6 years, the Italian AMX fleet has been grounded by a judge for an investigation. This time the magistrate decided to stop the AMX because there would be elements, surfacing from the investigation of a 2005 crash, suggesting that the “Ghibli” (as the aircraft has been dubbed in Italy) is not safe. In particular, the investigations dealing with the accident happened on October 20th 2005 near Decimomannu airbase (with the pilot ejected safely), discovered that the cause of the loss of the aircraft was the canopy. According to the investigators, canopy faults in the past years caused the loss of many AMX (“tens” according to reports of the media) and the death of 14 pilots, statements widely “advertised” by newspapers but not correct: the ItAF has lost 12 aircraft and 5 pilots (+ 1 prototype and 1 test pilot). Decimomannu crash aside, no one was caused by a canopy opening or failure. The grounding, started on December 18th 2007, is for the moment “indefinite” since the investigators are still evaluating the aircraft and studying the technical documentation that was sequestered in 2006. The last crash occurred on September 25th 2007, in Poland, where an AMX-T of the 32nd Stormo involved in a Squadron Exchange, flown by a 51st Stormo pilot with a Polish one in the backseat (who both ejected safely), crashed after a birdstrike.
As said, this is the second time this aircraft is grounded by a magistrate: as part of the investigation of an AMX on April 15th 2002 near Ramon di Loria, 35 aircraft belonging to the 51st Stormo (132nd and 103rd Gruppo) were grounded. Even if the magistrate asked for only the Istrana based aircraft to be grounded, the ItAF decided to ground also the aircraft assigned to the 32nd Stormo (Amendola) and to the RSV (Pratica di Mare). The stop lasted for 50 days and in that period the Italian pilots flew with the MB.339 in order to keep their proficiency and qualifications. Actually, the fleet had been limited for a short period of time also in 2001, the year in which most crash were recorded (3), to fly particular maneuvers. In particular: air-to-air refueling, tight formation, ultra-low level, formation take-off and landing, take-off and landing with strong wind were denied between December 5th and December 21st 2001.
Despite proving extremely effective and reliable during its baptism of fire in the Allied Force operation (for an in-depth description of the involvement of the Ghiblis in the Kosovo war read here: http://cencio4.wordpress.com/works/ghibli-italys-amx/


Italian readers can click here: http://cencio4.wordpress.com/works/operazione-ghibli-gli-amx-in-guerra/) the aircraft has been tormented by media (and consequently) public whose perception of the AMX was deceived by poor information and a presumed high crash rate. The AMX is still considered by the Italian pilots and experts a good aircraft (I flew with the AMX once and would fly with it again). In 2001, the aircraft’s crash rates were 0.79 aircraft losses for 10.000 flight hours (1989-2001); in 2006, the rate was 0.57 and today is 0.75, a percentage that is lower than many other NATO aircraft, like the Harriers and F-16s (Note: until today the Italian Tornado had a lower crash rate than the AMX; today an IDS of the 6th Stormo aborted the takeoff for a engine fire and overran the runway. The crew ejected safely and the unmanned aircraft remained within Ghedi airbase’s perimeter fence but the crash rate will raise as a consequence of the mishap). Furthermore, the AMX has been involved in an upgrade program in order to extend the operative life of the type to 2018, when the aircraft will be replaced by the JSF (Joint Strike Fighter). 42 single seat and 10 AMX-T will be modified to the ACOL (Aggiornamento delle Capacità Operative e Logistiche – Operational and Logistic Capabilities Update) standard that includes a new IN/GPS navigation system, NVG (Night Vision Goggles) compatibility (only for the single seats), a new MFD (Multi Function Display), enhanced HUD, a Computer Symbol Generator with Digital Map, upgraded IFF and comms capabilities, and a crash recorder.









Fleet grounding has been affecting another fighter these days. Since November 3rd 2007, the F-15 fleet has been grounded after an inflight breakup of a C model belonging to the 110 FS of the 131 FW of the Missouri ANG occurred on Nov 2nd. The aircraft, tail number 80-0034, using callsign “Mick 2”, was number 2 of a 4 ships formation departed from Lambert Field IAP to perform Basic Fighter Maneuvers (BFM); during one of the engagements, at 18.000 ft, speed 450 KTS, in an offensive break turn at 7.8 Gs, the aircraft began shacking violently side to side. The pilot saw dust entering the cockpit and just levelled the wings when the cockpit section separated from the fuselage. He was able to escape with the ejection seat but suffered serious injuries. The following investigations revealed that all the F-15 but E version have fatigue cracks that could result in a structurale failure. In fact, the upper right longeron that caused the accident of the Missouri ANG F-15C 4 miles south-southeast of Boss, MO, is a critical support structure in the Eagle. The grounding ended on January 8th 2008 for a part of the F-15 A/B/C/D: around 60% of the fleet was cleared to a limited return to flight while some 180 aircraft with fatigue cracks in the forward fuselange and/or whose longerons don’t meet the original specifications remain grounded; it is unclear if these aircraft will be ever airworthy again. In this particular case, reasons for the grounding are clear and understandable. I suggest visiting the Website of the Air Combat Command and in particular the following webpage: http://www.acc.af.mil/f-15fliesagain/index.asp for extensive news coverage, images and videos. Noteworthy are the following computer generated simulations of the inflight break up of “Mick 2”:
http://www.acc.af.mil/shared/media/document/AFD-080110-018.wmv
http://www.acc.af.mil/shared/media/document/AFD-080110-028.wmv

Was the B.777 FADEC deceived like the ADC of the F-16 that crashed in September?

Another accident, involving a USAFE F-16CG of the 31st FW may have something in common with the near accident of the British Airways 038 at London Heathrow last week. As previously reported, one of the possible root causes of the engines failure that compelled the B.777 G-YMMM to a successful crash landing could be the corruption of the pressure sensors signals received by the engine control systems. Noteworthy, something similar was one of the contributing factors that on September 18th, 2007, caused the loss of an F-16CG of the USAFE. According to European edition of Stars and Stripes, the recently issued Air Force report, in addition to weather and human factors, blames a malfunction of the Air Data Computer (ADC) of the Aviano based F-16. “According to the report, a drip ring in the device that tells the aircraft its trajectory froze as the plane flew through thunderstorms over the base. The result was that plane computers continued to receive the same information, even as it climbed in altitude and lost air speed. The incorrect information also fooled the sophisticated aircraft from correcting itself in time to prevent an uncontrolled spin”. The report underlines also that the same problem with the ring has been a contributing factor to other three F-16 crashes and for this reason it is going to be redesigned. It is still too early to say if the FADEC of BA038 was really confused by the signals coming from some sensors, however, the Aviano accident surfaces a problem: on-board systems (either Air Data Computer, Autopilot, Autothrottle, etc), despite working properly, can be deceived by corrupted signals. Since most of modern aircraft are platforms in which avionics, communications, navigation and targeting are based on calculations provided by powerful computers, this kind of problem should let you to think also to the “network” that interconnects those computers to the sensors that feed them. Even if carrying enough processing and storage capability is important, ensuring the availability and the integrity of the data that travel in the network is paramount. For sure, data must travel from source to destination without being compromised. What has to be investigated more is if a corruption of the signals can occur when a mobile phone is switched on during the approach.

BA038 crash pictures

Three high resolution pictures of the British Airways B.777 crash landing at London Heathrow airport on Jan. 17th were published in the last days around the Internet. Those images were taken from a perimeter road by David Spalton who was taking pictures outside the airport when flight BA38 from Beijing crash landed short of runway 27L.
The pictures can be found here.
What is really interesting is that those pictures (which David immediately handled to the police in order to provide as much information as possible to the investigators) show the aircraft overflying the rooftops, touching the grass just inside the airport’s perimeter fence and the passengers escaping thorugh the emergency chutes.
The first picture of the series is very interesting: the aircraft is depicted in a very unusual pitch up attitude with both engines still running. Consequently, it confirms that the aircraft didn’t suffer a birdstrike induced engine flame-out or compressor stall; both engines failed to respond to an autothrottle request for more thrust needed to keep the desired rate of descent and speed. Previous pictures of the engine were not clear enough to determine if engines were running when the aircraft struck the ground.

BA038 crash landing caused by a software glitch?

Even if the investigation from the AAIB is still in progress and the preliminary report is expected to be released in about one month, new theories are emerging about the BA038 crash landing’s root cause. Since a simultaneous engine failure is extremely unlikely, a software glitch affecting the engine control system is among the possible causes being investigated.
An interesting article dating back to October 2006 (http://www.iasa-intl.com/folders/belfast/BA777_Unthrustworthy.htm), focuses on errors introduced with a FADEC (Full Authority Digital Engine Control) software update that affected the B.777 equipped with GE90 engines. The article reports about two thrust rollback recorded on the 777-300ERs that suffered the failure during take off (and 5 occurred in flight). Subsequent troubleshooting found that the rollbacks were caused by a glitch in the software of the FADEC and that the reductions “only likely to occur at reduced powers”. The article explains that the flawed software was installed after a FADEC software update.
So, the FADEC has already caused worries to the B.777 operators using GE engines. The British Airways aircraft was equipped with RR Trent engines, even if the software used to control them is probably the same (or mostly similar). Even discarding the possibility that the current software may still cause Loss Of Thrust Control or LOTC for the same flaw (the AD was issued in 2006 and by now the software should have been patched), the above mentioned article provides also details dealing with an Airworthiness Directory applied to the GE90 engines that confirms the risks of corruption of the FADEC signals because of clogging of the sensors feeding the engine control system. The GE90 engines incorporate now a design modification aimed to prevent signal corruption but what about Trent engines?

For pictures and a more in-depth analysis, I suggest visiting this link that was provided from a visitor: http://www.iasa.com.au/folders/Safety_Issues/others/The_BA038_LikelyCause.html