15 July 2019

Disclaimers In Fiction

A webcomic I stumbled upon recently contained this disclaimer in its description:
This comic is only for open-minded, patient, and understanding readers. If you don't have these characteristics, you will not be able to survive this comic.
From Unintentional Game.

As a rhetorical device, the notion of an author screening an author's readers, instead of the other way around (while simultaneously complimenting those who decide to read it anyway), is an eminently clever little device to set expectations and weed out readers who will be inclined to provide negative reviews of your work. This isn't the first time I've seen this trick used, although it isn't a very common one, but it only really struck me how sophisticated a game to play this is until now.

Denver Is Usually Nearly A Desert; Grand Junction Is In A Desert

Most sources define a desert as a place with an average of 10 inches of precipitation (250 mm) per year, although I've seen 11 inches and 12 inches (in print) also used as definitions.

Denver get an average of 14.30 inches of precipitation per year (although some measurements suggest that the average is a little higher), which is 4.3 inches more than a desert. Grand Junction, where I lived from 1996 to 1999, is a bona fide desert with an average of just 9.4 inches of precipitation per year (probably an overstatement as this average does not appear to include some recent very dry years).

It is also useful, however, to think about the range of precipitation that an area experiences, as the high and the low over a long period of time (the low was 7.48 inches and the high was 20.95 inches since I've lived in Denver) is important for purposes like planning things like landscaping choices, construction specifications, and urban planning considerations like storm sewer capacities. The range is also quite relevant in valuing water rights.

This year in Denver, however, will not be a dry one. We are already at 10.59 inches of precipitation though July 14, 2019, about 2.25 inches above the year to date norm.

Denver has had three years that are below the desert threshold since I've moved here, and five more within under twelve inches of precipitation.

2018: 8.48 
2017: 11.69
2016: 11.59
2015: 18.22
2014: 18.77
2013: 16.60
2012: 10.11
2011: 17.27
2010: 12.86
2009: 18.12
2008: 10.23
2007: 14.00
2006: 8.64
2005: 12.80
2004: 14.67
2003: 13.92
2002: 7.48
2001: 16.55
2000: 14.55
1999: 20.95
1998: 15.93
1997: 19.59
1996: 10.25
1995: 18.27

To some extent, precipitation in Denver is really tri-modal with modes corresponding roughly to years marked by El Niño and La Niña events, and year with neither, respectively, although temperature tracks El Niño and La Niña events more closely than precipitation does.

Since the winter of 1995-1996, eight winters have been El Niño winters (when the central to easter tropical pacific is warmer): 2015-2016 and 1997-1998 (strong), 2009-2010 (moderate), 2002-2003, 2006-2007, 2004-2005, 2014-2015, 2018-2019 (weak).

Seven winters have been La Niña winters (when the central to eastern tropical pacific is cooler): 2007-2008 (strong), 2010-2011, 1995-1996 (moderate), 2005-2006, 2008-2009, 2011-2012, 2018-2019 (weak).

And nine winters have been neither El Niño nor La Niña winters (when temperatures in the central to eastern tropical pacific are normal): 1996-1997, 1998-1999, 1999-2000, 2001-2002, 2003-2004, 2009-2010, 2012-2013, 2013-2014, 2016-2017.

09 July 2019

Air To Air Combat Has Been Very Rare For A Generation

The stereotypical dog fight is all but dead. Just one pilot still serving in the U.S. military as a pilot has ever participated in a dog fight that resulted in a manned fixed wing aircraft in flight that was part of the fight being shot down. The U.S. hasn't had a dog fight involving guns instead of missiles since 1975.

Dog Fights Have Grown Very Rare

In the last 28 years (since the end of the Gulf War) not more than 54 manned aircraft were shot down by other aircraft in the entire world. At least 2 were from a friendly fire incident. Many are downed helicopters. See here

Just one U.S. fixed wing aircraft has been shot down by another aircraft since the end of the Vietnam War (1975) when a U.S. Navy F/A-18 piloted by Scott Speicher was shot down in air to air combat on January 17, 1991 during the early days of the Gulf War. There is been just two incidents in which a U.S. fixed wing aircraft has shot down another fixed wing aircraft in flight since the Gulf War which ended in 1991, one in Kosovo in 1999 and one in Syria in 2017.

There hasn't been a fighter ace (a pilot who has made five or more career kills of enemy aircraft in air to air combat) actively serving as a pilot the U.S. military for decades.

At least some of the aircraft crews survived in a fair number of the incidents involving fixed wing aircraft that were shot down. 

Missiles Have Replaced Slug Throwers

A key factor in the modern trend this has been the use of guided missiles. Most of these are one shot, one kill incidents, with the first shot often fired before the other pilot knows that he engaged in air to air combat at that moment.

The last time a manned fixed wing aircraft in flight was shot down by another manned fixed wing aircraft, with anything other than a missile, anywhere in the world, by any country, was on October 5, 1982 when a South African fighter pilot shot down a Cuban fighter with his canon in the South African border war (about 37 years ago). Prior to that there were a number of such dog fights in the Vietnam War (which ended in 1975) and in the Yom Kippur War in Israel (in 1973). See here.  

There are a number of incidents of helicopters being taken down with slug throwers from other aircraft, however, most often with the 30mm canons of the A-10 ground attack fighter. There are also cases of ground targets being destroyed with an armed fixed wing aircraft's canons.

The lion's share of military aircraft that are shot down in flight in the modern era are shot down by ground to air fire, most often, but not always with anti-aircraft missiles, and the aircraft shot down are disproportionately helicopters and unmanned drones.

What Does The Modern Air Force Do?

This doesn't mean that armed aircraft are irrelevant. But, armed aircraft are now almost entirely deployed in conflicts where one side or the other in a conflict controls the air space of the theater of battle. And, where there are air to air combat campaigns they have been very brief - a matter of a few weeks at most.

Guided air to ground missiles, and long range sea or ground launched guided missiles, are one of the defining aspects of modern warfare, and close air support of ground troops continues to be a significant military mission. 

As of August 29, 2017, "every deployed squadron averages at least a 97 percent hit rate" when using guided missiles and/or smart bombs, a dramatic reduction from the era of non-guided bombs and missiles. This is a recent development. In the 1995 campaign in Bosnia, 98% of bombs dropped by American aircraft were guided.  But, while "Operation Desert Storm in 1991 often invokes images of stealth aircraft and laser-guided munitions. However, only 8 percent of all bombs dropped during that war were guided. . . . In Desert Storm, the F-117 (flown by highly experienced pilots) was lauded by an unprecedented (and inflated) 80 percent hit rate." In the Vietnam War, "to hit a half-dozen targets, aircraft packages were generally built around 16 strike aircraft (escorted by other fighters performing escort and suppression of enemy air defenses)." In the Gulf War and Vietnam, Air Force pilots flew 19-20 hours a month, now they fly 10 hours a month.

It now takes far fewer missions to hit a given number of targets, and there is very little ordinance wasted in strikes that don't hit their targets.

Effective countermeasures could limit this effectiveness. 
If the enemy can’t stop your weapons, you need to send just one to have 95 percent confidence of hitting any given target. But if the enemy can stop a significant fraction of your smart bombs, say 20 percent, you need to send two to achieve that same 95 percent confidence. If your weapons have only a 50-50 chance, you need to send five. . . .  
A staggering 96 percent of the precision weapons the Pentagon has bought since 9/11 have been “direct attack” munitions. These weapons are relatively short-ranged. For example, the new Small Diameter Bomb (SDB) II has wings to glide up to 40 nautical miles from the aircraft that launches it. The older and larger Joint Direct Attack Munition (JDAM) can glide just 13 nm. 
Against a low-tech adversary like the Islamic State, a US aircraft 13 miles away might as well be on the moon. Against an adversary with modern anti-aircraft weapons, however, a US aircraft that comes within 13 or even 40 miles is begging to be shot down. . . . 
[W]e have far too few long-range weapons such as cruise missiles, which can be fired from outside enemy air defenses’ range, and the ones we do have are far too expensive to buy in bulk. The average direct-attack bomb bought since 2001 costs $55,500; the average long-range precision-guided weapon costs $1.1 million, twenty times as much.
But, the vast majority of wars, not just involving the U.S., but everywhere in the world, are asymmetric, not competitions between "near peers" where effective long range anti-aircraft and anti-missile defenses aren't present.

Also, I believe that I read recently that in a recent month in the war in Afghanistan, most of the U.S. airstrikes were carried out by drones, which makes the costs of losing aircraft much more tolerable.

Spatial Ability and IQ

Spatial ability isn't entirely divorced from IQ, but it does have a very large hereditary component, a large share of its hereditary component is distinct from IQ, and all spatial ability draw on a largely shared spatial cognitive capacity.
Performance in everyday spatial orientation tasks (e.g. map reading and navigation) has been considered functionally separate from performance on more abstract object-based spatial abilities (e.g. mental rotation and visualization). However, evidence remains scarce and unsystematic. With a novel gamified battery, we assessed six tests of spatial orientation in a virtual environment and examined their association with ten object-based spatial tests, as well as their links to general cognitive ability (g). We further estimated the role of genetic and environmental factors in underlying variation and covariation in these spatial tests. Participants (N = 2,660) were part of the Twins Early Development Study, aged 19 to 22. The 6 tests of spatial orientation clustered into a single ‘Navigation’ factor that was 64% heritable. Examining the structure of spatial ability across all 16 tests, three factors emerged: Navigation, Object Manipulation and Visualization. These, in turn, loaded strongly onto a general factor of Spatial Ability, which was highly heritable (84%). A large portion (45%) of this high heritability was independent of g. The results from this most comprehensive investigation of spatial abilities to date point towards the existence of a common genetic network that supports all spatial abilities.
Margherita Malanchini, et al, "Evidence for a unitary structure of spatial cognition beyond general intelligence" (July 4, 2019). doi: https://doi.org/10.1101/693275