Tag Archives: Super Hornet

Guess what’s worse than a flameout on take off? A flameout on catapult launch from an aircraft carrier

A quite embarrassing episode marked the end of MAKS 2011 air show on Aug. 21, at Ramenskoye air base, near Moscow. The Sukhoi PAK-FA/T-50, Russia’s 5th generation fighter plane, was forced to abort take off after suffering a flameout in the right-hand Saturn engine.

As below footage shows, the T-50-2, the second prototype of the stealth fighter (52 Blue), aborts its take off roll  after bursts of flames erupted from the engine.

Deploying the airbrakes and the two drag chutes after reaching a speed of around 60 MPH, Sukhoi’s test pilot was able to halt the aircraft well before the end of the runway.

If the PAK-FA flameout in front of some 200.000 spectators had only a negative impact on Sukhoi’s reputation, similar engine failures can be quite thrilling if they occur to fully loaded planes in dangerous phases of a flight: departure, initial climb, landing.

I took the top picture in the Indian Ocean aboard USS Nimitz (CVN-68) on Oct. 19, 2009. An F-18C (BuNo 165205 Modex 405) belonging to the VFA-86 “Sidewinders” experiences a compressor stall during the catapult launch from CAT number 4. The aircraft is fully loaded with fuel and weapons, and it is taking off to perform an on-call CAS in support of Operation Enduring Freedom in Afghanistan.

Fortunately, the aircraft took off in spite of the loud bang and flames coming out from the port engine exhaust that in the second image seems to be operating without the afterburner.

Here’s the entire sequence of the launch showing the single engine departure.

The compressor surge is a particular kind of compressor stall that occurs when the hot vapour generated by the aircraft carrier’s catapult is ingested by the aircraft air intake thus creating a breakdown in compression resulting in a the compressor’s inability to absorb the momentary disturbance and to continue pushing the air against the already-compressed air behind it. As a consequence, there’s a momentary reversal of air flow and a violent expulsion of previously compressed air out through the engine intake producing some loud bangs from the engine and “back fires”.

The compressor will usually recover to normal flow once the engine pressure ratio reduces to a level at which the compressor is capable of sustaining stable airflow. Some engines have automatic recover functions even if pilots experiencing the surge can be compelled to act on the throttle or, in some cases, relight the engine.

Compressor surges are frequent on U.S. aircraft carriers. Unlike the T-50, that could precautionally abort its take off, carrier air wing airplanes can’t stop their run once it’s started. Fortunately, F-18s are used to take off even if an engine is temporarily unserviceable: this shows once again how rusty Legacy Hornet are sometime tougher than some 4+ or 5th generation “colleagues”.

I don’t know if a PAK-FA would be able to take off after experiencing a compressor surge aboard an aircraft carrier but I know for sure the F-35C (that, along with the other variants has returned to fly last week, after being grounded for an IPP failure on Aug. 3) won’t: it’s an easy-to-fly, single-pilot, 5th generation fighter jet. With a single engine.

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Fighter generations comparison chart

The appearance of the new J-20 (unofficially dubbed “Black Eagle”) raised many questions about the Chinese stealth fighter. Some experts think it will be more capable than the F-22; others (and I’m among these ones) think that the real problem for the US with the J-20 is not with the aircraft’s performance, equipment and capabilities (even if the US legacy fighters were designed 20 years earlier than current Chinese or Russian fighters of the same “class”); the problem is that China will probably build thousands of them.

Anyway, comparing the US and Chinese fighters, everybody referred to “fifth generation planes” bringing once again the concept of “fighter generation” under the spotlight.

Generations are a common way to classify jet fighters. Often, generations have been “assigned” to fighters in accordance with the timeframes encompassing the peak period of service entry for such aircraft.

The best definition I’ve found so far of fighter generations is the one contained in an article published in 2009 by Air Force Magazine, that proposes a generations breakdown based on capabilities:

Generation 1: Jet propulsion

Generation 2: Swept wings; range-only radar; infrared missiles

Generation 3: Supersonic speed; pulse radar; able to shoot at targets beyond visual range.

Generation 4: Pulse-doppler radar; high maneuverability; look-down, shoot-down missiles.

Generation 4+: High agility; sensor fusion; reduced signatures.

Generation 4++: Active electronically scanned arrays; continued reduced signatures or some “active” (waveform canceling) stealth; some supercruise.

Generation 5: All-aspect stealth with internal weapons, extreme agility, full-sensor fusion, integrated avionics, some or full supercruise.

Potential Generation 6: extreme stealth; efficient in all flight regimes (subsonic to multi-Mach); possible “morphing” capability; smart skins; highly networked; extremely sensitive sensors; optionally manned; directed energy weapons.

In order to give the readers a rough idea of the type of aircraft belonging to each generation based on the above breakdown I’ve prepared the following table with the help of Tom Cooper / ACIG.org and Ugo Crisponi / Aviatiographic.com, who provided the profiles. It’s not meant to show all the aircraft theoretically belonging to a generation and includes only the profiles available at the time of writing…

As I’ve already said on Twitter, what such a table should let you understand at a glance is that capabilities and appearance are inversely proportional: former generations aircraft look much better than more modern fighters…..

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Compressor stalls

When, last year, I visited the USS Nimitz and had the opportunity to take the following picture (Part 1 and Part 2)

I didn’t think that compressor stalls during “cat shots” (catapult lauches) were frequent events. However, a quick look at US Navy website let me realize that compressor stalls or compressor surges are common (most probably?) because the hot vapour generated by the catapult is ingested by the aircraft intake thus creating a breakdown in compression resulting in a the compressor’s inability to absorb the momentary disturbance and to continue pushing the air against the already-compressed air behind it. As a consequence, there’s a momentary reversal of air flow and a violent expulsion of previously compressed air out through the engine intake producing some loud bangs from the engine and “back fires”.

The following pictures are all US Navy images taken from the official website: http://www.navy.mil

Farewell Aussie F-111: RAAF Williamtown airshow

A week after the two days event held in Rivolto to celebrate the 50th Anniversary of the Frecce Tricolori, an extremely interesting airshow took place Down Under, in Australia, where the RAAF Williamtown airshow saw the last public appearance of the RAAF (Royal Australian Air Force) F-111s and the first public show for their replacements, the F/A-18F Super Hornets (or “Rhinos” as they are widely known). The Australian airshow was at the antipodes of Rivolto, not only under a geographical point of view: while Rivolto saw the display of many aerobatic display team and a few solos (those of the ItAF Test Wing), the RAAF Williamtown one was more focused on operative aircraft and solos and just one display team attended the event: the RAAF Roulettes. Ed Armstrong, an Australian aviation expert (and reader of this blog), attended the show and sent me the following interesting report and pictures.

The Annual Defence Force Airshow took place at RAAF Williamtown on Sept. 18 and 19. Williamtown is Australia’s largest fast jet base and home to the RAAF’s fighter force. The show marked a number of significant events. Both Nos.1 and 6 Squadrons based at Amberley are transitioning to the F/A-18F Super Hornet – “Rhinos” in place of the long serving F-111C. The first of the new jets arrived in country in March and 1 Sqn currently has 11 of its planned complement of 12. IOC is set for years end. Williamtown was the type’s public debut. 1 Sqn brought 4 jets; A44-208 for the static, A44-204 & A4-207 for the flying display and A44-209 as spare.
After 37 years of Australian service the F-111C will be retired at the beginning of December and 6 Sqn, the last user of the type, currently has 7 to 8 serviceable jets. Williamtown was the last ever public show for the “Pig” and 6 Sqn crew Flt Lt Leon Izaat and Flt Lt Matt Michel did not disappoint with a spectacular, fast and noisy, flying display finishing with a steep climb out from a touch and go whilst performing the trade mark “dump and burn”. The display jet, on both the Saturday & Sunday, was one of the unique RF-111C jets: A8-126.
All types that the RAAF is currently flying were represented at the show either static or flying. 2 Sqn had their new Wedgetail AEW&C aircraft in the static, the RAN (Royal Australian Navy) displayed their Agusta 109, Sea King, Seahawk and Squirrel helicopters. The latter two types attended the flying display also. Temora Aviation Museum contributed their Meteor F.8, the world’s only flying example, Spitfire VIII, Hudson and CAC F-86 Sabre, the only Avon powered example flying. Also present were 4 of Australia’s 7 P-51 Mustangs and HARS brought along their Catalina and Neptune for the flying and Super Connie and C-47 for the static.
Whilst the F-111 was the star of the show, Williamtown’s based units put on some superb flying, a crisp display by a Hawk 127 from 76 Sqn, the specially formed “Purple Cobras” of 3 Sqn flying four F/A-18A Hornets, lead by the unit CO Wing Commander Terry Van Harren. And 77 Sqn provided the Hornet solo. “Ackers” putting on a stunning display. The Sunday was his last show before stepping down as Hornet display pilot.
For the display rehearsals in the week ahead of the show, 6 Squadron favoured F-111A/C A8-109 (that can be seen in the first pictures below while practicing over its home base of Amberley on Monday Sept. 13).





Special tail markings to mark the retirement of the F-111 featuring a stylised “dump and burn” seen here on F-111A/C A8-113 in the static at Williamtown. Two other jets are known to carry these special marks are A8-126 and A8-135.

The Roulettes display team

Super Hornet road map

The F-18F Super Hornet was one of the highlights of the recent Farnborough 2010 not only because the multi-role aircraft displayed during the Air Show, but also because Shelley Lavender, Vice President and General Manager Boeing’s Global Strike Systems unveiled the new Super Hornet International Road Map, a disclosure that may indicate that slippage in the F-35 program has encouraged the company to market the Super Hornet more aggressively in order to persuade some countries that are evaluating the F-35 to opt on the F/A-18E/F.
The upgrade equip the Super Hornet, whose effectiveness in combat has been proven in years of operations in Irak and Afghanistan (that I was able to witness in October 2009 during my visit to the USS Nimitz involved in combat operations in support of Enduring Freedom) with conformal fuel tanks, enhanced performance engines, enclosed weapons pod and other systems. The modifications, include:

  • Conformal Fuel Tanks
  • Enhanced Performance Engines
  • Spherical Missile/Laser Warning
  • Enclosed Weapons Pod
  • Next Generation Cockpit
  • Internal IRST

that could be retrofitted to any Block II aircraft. The most interesting change is a stealth-configured weapon pod designed to accommodate a range of weapons, including four AMRAAMs, or a mix of two Mk82-class bombs and two AIM-120 missiles. The external pod would help to reduce the Super Hornet’s RCS (Radar Cross-Section) by removing missiles and bombs from external underwing pylons. Furthermore, the internal IRST (Infra-Red Search & Track) is another interesting upgrade. IRST offers a passive way to locate and target enemy aircraft – one that won’t trigger radar warning receivers. When coupled with medium-range IR missiles an IRST system offers a fighter both an extra set of medium-range eyes, and a stealthy air-to-air combat weapon. For instance, the Italian F-2000s are equipped with the IRST.
So far the systems that provide long range thermal imaging against air and ground targets was integraded in the Super Hornet in quite an unusual way: modifying a 480 gallon centerline fuel tank to carry 330 gallons of fuel + the IRST system. This approach would allow refits to 150 existing Super Hornets even if the drawback was that a centerline tank with IRST needed to stay on the airplane in combat, compromising its aerodynamic performance and radar signature (fuel tanks are often jettisoned in combat to improve manoeuvrability).