Memahami Koefisien Performansi

Sebuah refrigerator (Mesin Pendingin) tak mungkin bekerja secara siklis dengan tak menghasilkan efek lain di luar transfer panas dari benda dingin ke benda panas.

Ukuran performansi refrigrator adalah rasio Qc/W, yang dinamakan koefisien performansi COP
(Coefficient of performance):

COP = Qc/W

Dimana Qc = Panas Buangan dan

W = Usaha (Joule)

Lihat Juga:

• Seasonal energy efficiency ratio (SEER)
• Seasonal thermal energy storage (STES)
• Heating seasonal performance factor (HSPF)
• Thermal efficiency
• Vapor-compression refrigeration
• Air conditioner
• HVAC

Sources:

Arip Nurahman

Inovasi Strategi dan Solusi Permasalahan Energi

Kenapa setiap kenaikan harga BBM/Energi, termasuk listrik terjadi kegaduhan yang amat sangat di negeri ini?

Beberapa solusi mendasar yang ditawarkan adalah:

• Mengembangkan mekanisme harga keekonomian energi
• Memprioritaskan kebutuhan energi dalam negeri
• Meningkatkan keamanan pasokan energi dengan memperhatikan aspek lingkungan
• Menerapkan prinsip-prinsip good governance dan transparansi
• Mendorong investasi swasta bagi pengembangan energi
• Melakukan konservasi sumber daya energi
• Menjamin penyediaan energi untuk seluruh lapisan masyarakat
• Meningkatkan pemberdayaan masyarakat dalam pengelolaan energi
• Meningkatkan efisiensi penyediaan dan pemanfaatan energi
• Melakukan diversifikasi energi dengan memaksimalkan sumber daya energi yang ada yang ada di dalam negeri
• Memaksimalkan pemanfaatan energi setempat (Desa Mandiri Energi)
• Meningkatkan kapasitas SDM dan penguasaan teknologi
• Memaksimalkan dana penerimaan negara sektor ESDM bagi pengembangan sektor ESDM

Solusi-solusi tersebut baiknya dapat diterjemahkan oleh segenap lapisan masyarakat untuk menyelesaikan semua permasalahan energi kita.

Peran pemuda dan masyarakat mesti ditingkatkan di sini, bagaimana tidak penguasaan energi kita banyak sekali dikuasai oleh pihak asing.

Oleh karena itu perusahaan-perusahaan energi lokal mesti ditumbuhkan di setiap daerah.

Komunitas ilmuwan energi juga perlu mengaplikasikan hasil temuannya di masyarakat luas.  

Sources: 

1. Arip Nurahman Notes
2. Kementrian ESDM
3. Pertamina
4. http://petronomist.com/

Pertempuran Udara Masa Depan: Iron Man and F-22 Raptors

Dominating the Skies. Overwhelming the Threat.




The F-22's Avionics

The F-22's avionics include BAE Systems E&IS radar warning receiver (RWR) AN/ALR-94, AN/AAR 56 Infra-Red and Ultra-Violet MAWS (Missile Approach Warning System) and the Northrop Grumman AN/APG-77 Active Electronically Scanned Array (AESA) radar. The AN/ALR-94 is a passive receiver system to detect radar signals; composed of more than 30 antennas blended into the wings and fuselage that provide all around coverage.

It was described by Tom Burbage, former F-22 program head at Lockheed Martin, as "the most technically complex piece of equipment on the aircraft." It has a greater range (250+ nmi) than the radar, allowing the F-22 to limit its own radar emissions to maximise stealth. As a target approaches, the receiver can cue the AN/APG-77 radar to track the target with a narrow beam, which can be as focused down to 2° by 2° in azimuth and elevation.

The AN/APG-77 radar, designed for air superiority and strike operations, features a low-observable, active-aperture, electronically-scanned array that can track multiple targets in any weather. The AN/APG-77 changes frequencies more than 1,000 times per second to lower interception probability. Additionally, radar emissions can be focused in an electronic-attack capability to overload enemy sensors.

Integrated Avionics

• F-22 has demonstrated integrated avionics providing the pilot unprecedented situational awareness with a single battlefield display. It allows pilot to manage the air battle rather than invest time in interpreting/deceiphering multiple sensor inputs
• F-22’s complex avionics have revolutionized situational awareness throughout the battle space. F-22 sensors can passively collect - and eventually distribute - information on the enemy order of battle that guarantees our distinct advantage over hostile forces

 


The radar's information is processed by two Raytheon Common Integrated Processor (CIP)s. Each CIP can process 10.5 billion instructions per second and has 300 megabytes of memory. Information can be gathered from the radar and other onboard and offboard systems, filtered by the CIP, and offered in easy-to-digest ways on several cockpit displays, enabling the pilot to remain on top of complicated situations. The F-22's avionics software has some 1.7 million lines of code, the majority involving processing data from the radar.

The radar has an estimated range of 125–150 miles, though planned upgrades will allow a range of 250 miles (400 km) or more in narrow beams.In 2007, tests by Northrop Grumman, Lockheed Martin, and L-3 Communications enabled the AESA system of a Raptor to act like a WiFi access point, able to transmit data at 548 megabits per second and receive at gigabit speed; this is far faster than the Link 16 system used by U.S. and allied aircraft, which transfers data at just over 1 Mbit/s.

The F-22 has a threat detection and identification capability comparative with the RC-135 Rivet Joint.The F-22's stealth allows it to safely operate far closer to the battlefield, compensating for the reduced capability. The F-22 is capable of functioning as a "mini-AWACS", however the radar is less powerful than dedicated platforms such as the E-3 Sentry.

The F-22 allows its pilot to designate targets for cooperating F-15s and F-16s, and determine whether two friendly aircraft are targeting the same aircraft. This radar system can sometimes identify targets "many times quicker than the AWACS". The radar is capable of high-bandwidth data transmission; conventional radio "chatter" can be reduced via these alternative means.The IEEE-1394B data bus developed for the F-22 was derived from the commercial IEEE-1394 "FireWire" bus system. Sensor fusion combines data from all onboard and offboard sensors into a common view to prevent the pilot from being overwhelmed.

In a critical article former Navy Secretary John Lehman wrote "[a]t least [the F-22s] are safe from cyberattack. No one in China knows how to program the '83 vintage IBM software that runs them." Former Secretary of the USAF Michael Wynne blamed the use of the DoD's Ada as a reason for cost overruns and schedule slippages on many major military projects, including the F-22 Raptor.

The F-22 uses the INTEGRITY-178B operating system from Green Hills Software, which is also used on the F-35, several commercial airliners and the Orion Crew Exploration Vehicle. However cyberattacks on Lockheed Martin's subcontractors have raised doubts about the security of the F-22's systems and its usefulness in combat as a result.


Herbert J. Carlisle has said that the F-22 can datalink with the Tomahawk (missile).

Alih Ipteks pesawat tempur canggih dari berbagai belahan dunia dapat diserap oleh para ilmuwan tanah air denga cara mendirikan perusahaan dan badan riset yang bekerja sama dengan pihak pemerintah khususnya pihak militer.

Semoga Bermanfaat.

Sources: 

1. Wikipedia
2. http://www.lockheedmartin.com/us/products/f22.html
3. http://www.f22-raptor.com/
4. http://www.af.mil/ [US Air Force]
5. www.pw.utc.com [Pratt & Whitney]
6. http://www.boeing.com/boeing/ [Boeing Corporation]

Mesin Jet Tempur Super Canggih: The Propulsion Story

 F-35B Propulsion Story



Mesin Jet Tempur Super Canggih

The engine used on the F-35 is the Pratt & Whitney F135. An alternative engine, the General Electric/Rolls-Royce F136, was under development until December 2011 when the manufacturers canceled the project. 

Neither the F135 or F136 engines are designed to supercruise in the F-35, however the F-35 can achieve a limited supercruise of Mach 1.2 for 150 miles. The F135 is the second (radar) stealthy afterburning jet engine and, like the Pratt & Whitney F119 from which it was derived, has suffered from pressure pulsations in the afterburner at low altitude and high speed or "screech" during development. Turbine bearing health will be monitored with thermoelectric-powered sensors.

The F-35 has a maximum speed of over Mach 1.6. With a maximum takeoff weight of 60,000 lb (27,000 kg), the Lightning II is considerably heavier than the lightweight fighters it replaces. In empty and maximum gross weights, it more closely resembles the single-seat, single-engine Republic F-105 Thunderchief, which was the largest single-engine fighter of the Vietnam war era. The F-35's modern engine delivers over 60 percent more thrust in an aircraft of the same weight so that in thrust to weight and wing loading it is much closer to a comparably equipped F-16.

The STOVL F-35B is outfitted with the Rolls-Royce LiftSystem, designed by Lockheed Martin and developed by Rolls-Royce. This system more resembles the Russian Yak-141 and German VJ 101D/E than the preceding STOVL Harrier Jump Jet and the Rolls-Royce Pegasus engine. The Lift System is composed of a lift fan, drive shaft, two roll posts and a "Three Bearing Swivel Module" (3BSM).

The 3BSM is a thrust vectoring nozzle which allows the main engine exhaust to be deflected downward at the tail of the aircraft. The lift fan is near the front of the aircraft and provides a counterbalancing thrust using two counter-rotating blisks.

It is powered by the engine's low-pressure (LP) turbine via a drive shaft and gearbox. Roll control during slow flight is achieved by diverting unheated engine bypass air through wing-mounted thrust nozzles called Roll Posts.

Diagram of turbojet energy for LiftSystem

F136 funding came at the expense of other parts of the program, impacting on unit costs. The F136 team has claimed that their engine has a greater temperature margin which may prove critical for VTOL operations in hot, high altitude conditions.

Pratt & Whitney has tested higher thrust versions of the F135, partly in response to GE's claims that the F136 is capable of producing more thrust than the 43,000 lbf (190 kN) of early F135s. The F135 has demonstrated a maximum thrust of over 50,000 lbf (220 kN) during testing; making it the most powerful engine ever installed in a fighter aircraft as of 2010.

Mesin jet adalah sebuah jenis mesin pembakaran dalam menghirup udara yang sering digunakan dalam pesawat. Prinsip seluruh mesin jet pada dasarnya sama; mereka mempercepat massa (udara dan hasil pembakaran) ke satu arah dan dari hukum gerak Newton ketiga mesin akan mengalami dorongan ke arah yang berlawanan. Yang termasuk mesin jet antara lain turbojet, turbofan, rocket, ramjet, dan pump-jet.

Mesin ini menghirup udara dari depan dan mengkompresinya. Udara digabungkan dengan bahan bakar, dan dibakar. Pembakaran menambah banyak peningkatan energi dari gas yang kemudian dibuang ke belakang mesin. Proses ini mirip dengan siklus empat-gerak, dengan induksi, kompresi, penyalaan, dan pembuangan terjadi secara berkelanjutan. Mesin menghasilkan dorongan karena percepatan udara yang melaluinya; gaya yang sama dan berlawanan yang dihasilkan adalah dorongan bagi mesin.

Mesin jet mengambil massa udara yang relatif sedikit dan mempercepatnya dengan jumlah yang besar, di mana sebuah pendorong mengambil massa udara secara besar dan mempercepatnya dalam jumlah kecil. Pembuangan kecepatan tinggi dari mesin jet membuatnya efisien pada kecepatan tinggi (terutama kecepatan supersonik) dan ketinggian tinggi. 

Pada pesawat pelan dan yang membutuhkan jarak terbang pendek, pendorong yang menggunakan turbin gas, yang umumnya dikenal sebagai turboprop, lebih umum dan lebih efisien. Pesawat sangat kecil biasanya menggunakan mesin piston untuk menjalankan pendorong tetap turboprop kecil semakin lama semakin kecil dengan berkembangnya teknologi teknik.

Efisiensi pembakaran sebuah mesin jet, seperti mesin pembakaran dalam lainnya, dipengaruhi besar oleh rasio volume udara yang dikompresi dengan volume pembuangan. Dalam mesin turbin kompresi udara dan bentuk "duct" yang melewati ruang pembakaran mencegah aliran balik dari situ dan membuat pembakaran berkelanjutan dimungkinkan dan proses pendorongan.

Mesin turbojet modern modular dalam konsep dan rancangan. Inti penghasilan-tenaga utama, sama dalam seluruh mesin jet, disebut sebagai generator gas. Dan juga modul tambahan lainnya seperti gearset pengurang dorongan (turboprop/turboshaft), kipas lewat, dan "afterburner". Jenis alat tambahan dipasang berdasarkan penggunaan pesawat.

Semoga Industri Permesinan Canggih di Indonesia semakin maju dan berkembang.

Sources:

Wikipedia

Lockheed Martin

Pratt & Whitney
http://www.pw.utc.com/

Rolls-Royce
http://www.rolls-royce.com/

Nusantara Turbin & Propulsi, Bandung, Indonesia.
http://www.umcntp.co.id/