Tag Archives: VFA-86

CVW-11: flight gear in action

Following the post about the patches I took on board the USS Nimitz during my visit on Oct. 18 and 19 (http://cencio4.wordpress.com/2009/10/31/cvw-11-patches/) some readers and visitors of this site requested me to upload some pictures of the flight helmets and flight gear worn by the crews of the CVW-11.

CVW-11 patches

The following patches were among those worn (and sold) by the crews of the various squadrons of the CVW-11 aboard USS Nimitz during my recent visit. The CVW-11 composition was:
100 VFA-41 F/A-18F
200 VFA-14 F/A-18E
300 VFA-97 F/A-18C
400 VFA-86 F/A-18C
500 VAQ-135 EA-6B
600 VAW-117 E-2C
610 HS-6 SH-60F/HH-60H

Compressor stall…in the worst case scenario (part 2)

In the previous post “Compressor stall…in the worst case scenario” I explained what a compressor stall (or surge) basing on a picture I took aboard USS Nimitz. I uploaded an image within that post that I created by merging two pictures I took one after the other. Since that picture provided a view of the last few seconds of the catapult launch by a VFA-86 F-18C, I thought it could be interesting to publish the whole take off sequence that you can find here below.
Compressor stall sequence

Images from the USS Nimitz (CVN-68)

Between Oct. 19 and 20, I had the possibility to spend some 25 hours on board the USS Nimitz nuclear supercarrier. I went to Manama, Bahrain, and after a long flight in a C-2 of the VRC-30 “Providers” I trapped on the flight deck of the aircraft carrier that was sailing “somewhere” in the Indian Ocean. The purpose of my visit was to prepare a report that will be published in the next months on RID (Rivista Italiana Difesa). The following pictures are just a preview of all the images I took during my stay on the ship along with Giovanni Maduli. I will soon publish more images, reports, video and will answer some of the most frequent questions dealing with an aircraft carrier.

Compressor stall…in the worst case scenario

“A compressor stall is a situation of abnormal airflow resulting from a stall of the aerofoils within the compressor. Stall is found in dynamic compressors, particularly axial compressors, as used in jet engines and turbochargers for reciprocating engines. Compressor stalls result in a loss of compressor performance, which can vary in severity from a momentary engine power drop (occurring so quickly it is barely registered on engine instruments) to a complete loss of compression (compressor surge) necessitating a reduction in the fuel flow to the engine” (Wiki).
A particular kind of stall is the so-called compressor surge is a complete breakdown in compression that occurs when compressor’s blades stall (airfoils) just like an airplane wing stalls, because the flow is disrupted or the angle of attack gets too high, forward flow through the compressor can no longer be maintained, air piles up in the rear stages of the compressor without being compressed and a momentary reversal of flow causes a violent expulsion of previously compressed air out (sometimes) through the intakes too. The excess air can cause a loud bang a flames (because of the high temperatures).
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.
Needless to say, compressor stalls could be very dangerous especially when occurring in critical phases of the flight: departure, initial climb, landing. Look at the following image I created basing on a sequence of pictures I took “somewhere” in the Indian Ocean aboard USS Nimitz (CVN-68) on Oct. 19, 2009. It shows an F-18C (BuNo 165205 Modex 405) belonging to the VFA-86 “Sidewinders” experiencing a compressor stall during the catapult launch from CAT number 4. The aircraft is fully loaded with fuel and it is carrying weapons too, since it is taking off to support Operation Enduring Freedom in Afghanistan. Fortunately, the aircraft was able to depart 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.
Please note the image is watermarked since all rights are reserved

Panorama_compressor stall