Category Archives: Aircraft

The J-58 made simple(r)

I got a copy of the SR-71 Pilot’s Manual as soon as it became available in the early 1990s. It’s a throwback to the days of slide rules and handmade graphics and utterly fascinating. There is a lot of material on the Pratt and Whitney J-58 engine and the Lockheed inlets that powered the Blackbird beyond Mach 3 yet I have never been able to fully understand why and how that system did what it did. Thankfully, Blackbird enthusiast Tech Adams explains it all in his delightful video – The Mighty J58 – The SR-71’s Secret Powerhouse.

The Mighty J58 – The SR-71's Secret Powerhouse

Watch this video on YouTube.

All along the control tower

An air traffic controller’s day must be filled with responsibility and stress that few can imagine. The view from up above must be some small compensation. And that’s what Captain Vector offers from his perch at LAX in his View from the Tower blog. He sees them come and go and has keenly observed, wry insights on what it takes to keep the pieces moving on a sprawling chessboard that is almost always under construction. Equally interesting is his knowledge of aircraft and airline history and how they reveal themselves in the subtle details the rest of us take for granted. He and SpeedbirdHD have the LAX scene covered from on high and on the ground.

LAX planespotting from and on a different level – SpeedbirdHD

The small and very active community of aircraft photographers and videographers is putting up some superb material on the usual outlets. Close to home, many shoot from El Segundo’s Clutter Park where they can get nice views of LAX’s south runway operations although with some interference from low buildings.

Then, there is Youtube’s SpeedbirdHD. He says little about himself other than that he is an aviation enthusiast in Los Angeles. There must be more to it than that. He has unique access to LAX operations, almost assuredly through a job on the premises. His videos of the heavy metal flying in and out are in a league of their own. Speedbird and his HD camera get tarmac footage of regional jets, superjumbos, and even the occasional miltary lifter from every runway. His edits usually include relevant air-traffic control conversations in the background. Top class stuff.

Here’s his channel. His 2012 highlight reel is a good place to start.

Real-time LAX air traffic tool – a must-have for South Bay residents

Instrumentation makers Bruel and Kjaer are working with many airports to measure and display sound levels in the neighborhoods they adjoin.   B&K’s Webtrak tool for LAX is available at

See flights coming in and out of the greater Los Angeles area in real time.  See sound levels in Playa del Rey, Hawthorne, El Segundo, and Inglewood.  There’s also a replay feature.  Use Historical Mode to pick a day and time and see what happened; speed it up if you like.  If you’d like to complain about a particular flight, select the icon of the suspected flight, get its number, and click a link to file a report.

The Beach Cities are usually  quiet despite LAX but there are many nights where the engine roar is powerful despite  distance and intervening structures.  So, what can cause this?  Thermal inversion layers in the atmosphere are known to refract sound waves due to the index of refraction difference at the boundary.   Acoustical engineer  Mike O’Connor offers a nice summary of the physics, analogous to optical refraction, at

He concludes
“It is not only noise from vehicular traffic on distant segments of roadways that is boosted in strength by temperature inversions. Emissions from distant trains and commercial aircraft (during takeoffs) are also amplified. The reader who has never before taken note of this phenomenon might now try to see if it’s ‘real’. Just listen to the background noises from distant trains, distant aircraft (just during takeoff runs) and vehicles on distant roadway segments, preferably after dark or shortly before or after dawn, and note the atmospheric conditions. Disregard windy conditions, but take note of the loudness of such noises under all other atmospheric conditions. It should become apparent that the noise levels from distant sources are clearly higher on some days than on others, even though the observations were made at approximately the same time each day. With some effort it should also be apparent that the calm and clear conditions that are said here to give rise to temperature inversions are in effect when the distant sources seem loudest.”

Henry Robinson offers a more detailed treatment at with an interesting observation about amphitheatre design.

“On a day when convection near the ground causes the temperature to decrease rapidly with height, sound heard on the ground from a departing aircraft will be muffled because the sound rays, and energy, will be forcing the sound upward. Indeed, balloonists often can hear conversations of people on the ground but be unable to make themselves heard by the same people on the ground. The Greeks constructed their theaters, as in Figure 3, so everyone could see, but, in doing so, they also used the natural curvature of sound to enable everyone to hear as well in afternoon plays.

Takeoff during well mixed conditions is relatively quiet at the ground but takeoff through an inversion concentrates the sound under the aircraft.  Observe sound abatement procedures while taking off in an inversion situation.”

So, is that the mechanism at work on noisy Redondo Beach nights?  This is  worth some observation and checking against weather data.