Bass flute

The bass flute is a member of the flute family. It is in the key of C, pitched one octave below the concert flute. Despite its name, its playing range makes it the tenor member of the flute family. Because of the length of its tube (approximately ), it is usually made with a J-shaped head joint, which brings the embouchure hole within reach of the player. It is usually only used in flute choirs, as it is easily drowned out by other instruments of comparable register, such as the clarinet.
Kotato and Fukushima produce an instrument that they call bass flute in F, which some people refer to as a Contra-alto flute. 
Alternative terminology.
Prior to the mid-20th century, the term "bass flute" was sometimes used, especially in Great Britain, to refer to the alto flute instead (for example: the part for "bass flute in G" in Gustav Holst's "The Planets"). In 1910, Abelardo Albisi invented a bass flute known as the albisiphone which was used in scores by Mascagni and Zandonai among other composers during the first half of the 20th century.
Range and construction.
The instrument's sounding range is from C3, one octave below middle C, to C6, two octaves above middle C. Bass flute music sounds an octave lower than it is written, which is the typical concert flute range (C4 to C7). Notes written above A6 are not often used as they are difficult to produce and have inferior tone. Because manufacturers do not taper the flute body through the curve, intonation of all notes beginning with written D6 and higher tend to be sharp. The player can bend them in tune through blowing technique or use alternative fingerings.
Bass flutes often have a C foot rather than the B foot common to other flutes. The shorter tube reduces acoustic resistance, which quickens the response and makes the tone brighter, livelier, and more resonant. The shorter tube also makes the instrument somewhat lighter and less fatiguing for the player to hold.
Bass flutes are most often made with silver-plated bodies and head joints. Most basses come with trill keys which allow the player to stabilize some otherwise unstable middle register notes as well as trill between otherwise impossible notes. Kotato basses have addressed the weight problem of bass flutes by designing a graphite rod that screws onto the underside of the instrument and then rests on the chair seat between the player's legs. Adjustable rods have also been developed by Jeff Amos. Other manufacturers have added a left hand thumb support called a crutch, which helps some players with physical control of the instrument. Dutch flute maker Eva Kingma has created a vertical design for the bass flute which allows the weight of the instrument to be supported by the floor. 
Repertoire.
Many composers are beginning to write more pieces for the bass flute. These include Katherine Hoover's "Two for Two", Bill Douglas's "Karuna", Sophie Lacaze's "Archelogos II", Mike Mower's "Obstinato" and "Scareso", Gary Schocker's "A Small Sonata for a Large Flute", Lorenzo Ferrero's "Ellipse" and "Shadow Lines", Sonny Burnett's "Stone Suite", Catherine McMichael's "Baikal Journey" and Ennio Morricone's "Secrets of the Sahara". Other important works include Tristan Murail's "Ethers" for solo bass flute and small ensemble, Brian Ferneyhough's "Mnemosyne" for bass flute and tape, Mario Lavista's "Lamento a la muerte de Raúl Lavista" for solo bass flute, Michael Oliva's "Moss Garden" also for bass flute and tape, John Palmer's "Inwards" for bass flute and live-electronics, "She Cried" by Shiva Feshareki, and Marc Tweedie's "Zoli", written for renowned flautist Carla Rees. Studies and concert etudes are beginning to appear that address the instrument's many challenges (physical balance, finger technique, air stream, overblowing, etc.). Peter Sheridan has commissioned and arranged new compositions in this area, including a set of 'Etudes for Low Flutes' by Hilary Taggart. The sixth movement of Claude Bolling's suite for Flute and Jazz Trio, 'Versatile' has the soloist playing the opening melody on a bass flute. Morton Feldman's composition "Crippled Symmetry" has a part for the bass flute, as does John Cage's late work "Seven2". Hans Pfitzner's 1917 opera "Palestrina" features an early (true) C bass flute part. Another piece featuring the bass flute is John Mackey's "The Frozen Cathedral" (2013) in two separate sections of the piece.
For an extensive list of repertoire for bass flute and contrabass flute see "Repertoire Catalogue for Piccolo, Alto Flute and Bass Flute" (2004) by Peter van Munster (Roma: Riverberi Sonori). Selected repertoire graded into ability levels with short descriptions and information about basses can be found in "The Alto and Bass Flute Resource Guide" published by Falls House Press, and specialist low flutes publishing company Tetractys has a growing catalogue of works for bass flute.
Other use.
A handful of jazz musicians have used the bass flute, including flutist Jeremy Steig, beginning with his 1975 album Temple of Birth, saxophonists Henry Threadgill, Brian Landrus, and James Carter, and drummer Ronald Shannon Jackson who occasionally played bass flute as a second instrument. Hubert Laws features the bass flute on his recording of "Amazing Grace," in which he plays the first verse on bass flute, the second on alto, and the third on soprano. Steig later took up the Kotato & Fukushima bass flute in F. 
In electronic music, Jack Dangers has sometimes used bass flute as the leader of the Meat Beat Manifesto.
A bass flute is heard throughout George Bruns' score for "The Jungle Book" and the original Pirates of the Caribbean attraction.
Perhaps the best-known work to feature the bass flute is the album "Wave" by Antônio Carlos Jobim.