Thursday, July 23, 2009

Fairchild AC-119

The Fairchild AC-119G Shadow and AC-119K Stinger were twin-engine piston-powered gunships developed by the United States during the Vietnam War. They replaced the inadequate AC-47 Spooky and operated alongside the early versions of the AC-130 Spectre gunship.

By November 1968, the aircraft had deployed to Vietnam and joined the 14th Special Operations Wing at Nha Trang. The AC-119Gs were placed in the 71st Special Operations Squadron which was formed from the activated 71st Troop Carrier Squadron, of the Air Force Reserves located in Columbus, Indiana. When the 71st SOS reserves returned to the states, in 1969, the gunships were taken over by the newly formed 17th SOS.
The AC-119Ks were placed in the 18th Special Operations Squadron. With the addition of the two types, the 14th SOW for a time in 1968 was flying eight different aircraft from ten different bases in South Vietnam. The 14th SOW was deactivated in 1971. Limited numbers continued to be operated out of Hurlburt Field, Florida as late as the fall of 1972, but the AC-119 was shortly after, phased out of the US Air Force. The AC-119G and -K continued to serve in extremely small numbers with the Republic of Vietnam Air Force (VNAF) until the de facto reunification of the country in 1975. During the Vietnam War, only five AC-119 Gunship IIIs were lost to all causes. 

Friday, July 10, 2009

Lockheed AC-130

The Lockheed AC-130 gunship is a heavily-armed ground-attack aircraft. The basic airframe is manufactured by Lockheed, and Boeing is responsible for the conversion into a gunship and for aircraft support. It is a variant of the C-130 Hercules transport plane. The AC-130A Gunship II superseded the AC-47 Gunship I in Vietnam.

The gunship's sole user is the United States Air Force, which uses AC-130H Spectre and AC-130U Spooky variants. The AC-130 is powered by four turboprops and has an armament ranging from 20 mm Gatling guns to 105 mm howitzers. It has a standard crew of twelve or thirteen airmen, including five officers (two pilots, a navigator, an electronic warfare officer and a fire control officer) and enlisted personnel (flight engineer, electronics operators and aerial gunners).

The US Air Force uses the AC-130 gunships for close air support, air interdiction, and force protection. Close air support roles include supporting ground troops, escorting convoys, and flying urban operations. Air interdiction missions are conducted against planned targets and targets of opportunity. Force protection missions include defending air bases and other facilities. Stationed at Hurlburt Field in Northwest Florida, the gunship squadrons are part of the Air Force Special Operations Command (AFSOC), a component of United States Special Operations Command (SOCOM).

Wednesday, July 01, 2009

APG-63 and APG-70

The AN/APG-63 and AN/APG-70 are a family of all-weather multimode radar systems designed by Hughes Aircraft (now Raytheon) for the F-15 Eagle air superiority fighter. These X-band pulse-doppler radar systems are designed for both air-air and air-ground missions; they are able to look up at high-flying targets and down at low-flying targets without being confused by ground clutter.

The systems can detect and track aircraft and small high-speed targets at distances beyond visual range down to close range, and at altitudes down to treetop level. The radar feeds target information into the aircraft's central computer for effective weapons delivery. For close-in dogfights, the radar automatically acquires enemy aircraft and projects this information onto the cockpit head-up display.


The APG-63 was developed in the early 1970s and has been operational since 1973, and was installed on all F-15 A/Bs. In 1979, it received a major upgrade and became the first airborne radar to incorporate a software programmable signal processor (PSP), and the PSP allowed the system to be modified to accommodate new modes and weapons through software reprogramming rather than by hardware retrofit. The APG-63 with PSP is one of the most important feature that disguishes earlier F-15 A/Bs from the F-15 C/Ds it arms, and with the exception of the final 43 (which is armed with APG-70), all F-15 C/Ds are armed with APG-63 with PSP.


The APG-70 was a 1980s redesign of the APG-63 for greater reliability and easier maintenance. Additionally, gate array technology enabled the APG-70 to incorporate new modes with enhanced operational capabilities. To reduce production costs, many of the upgraded radar's modules are common with the APG-73 (F/A-18) radar, while the computers / processors are 85% in common with that of APG-71 (F-14) radar.

Friday, June 19, 2009

Largest aircraft in Antonov An-225

The New Air craft An-225 Mriya (Russian: Антонов Ан-225 Мрия, Ukrainian: Антонов Ан-225 Мрія, NATO reporting name: Cossack) is a strategic airlift transport aircraft which was built by the Antonov Design Bureau, and is the largest aeroplane ever built. The design, built to transport the Buran orbiter, was an enlargement of the successful An-124 Ruslan. Mriya (Мрiя) means "Dream" (Inspiration) in Ukrainian.

The Antonov An-225 is commercially available for flying any over-sized payload due to the unique size of its cargo deck. Currently there is only one aircraft operating but a second mothballed airframe is being reconditioned and is scheduled for completion around 2010


The An-225 was designed for the Soviet space program as a replacement for the Myasishchev VM-T. Able to airlift the Energia rocket's boosters and the Buran space shuttle, its mission and objectives are almost identical to that of the Airbus Beluga and the United States' Shuttle Carrier Aircraft.

The An-225 first flew on 21 December 1988. The aircraft was on static display at the Paris Air Show in 1989 and it flew during the public days at the Farnborough air show in 1990. Two aircraft were ordered, but only one An-225 (tail number UR-82060) is currently in service. It is commercially available for carrying ultra-heavy and oversize freight, up to 250,000 kg (550,000 lb) internally or 200,000 kg (440,000 lb) on the upper fuselage. Cargo on the upper fuselage can be 70 m long.[4] A second An-225 was partially built during the late 1980s for use by the Soviet space program. If the second An-225 is completed, it will be built with a rear cargo door and the tail will be redesigned as a single tail. It would then be more effective for cargo transportation. Following the collapse of the Soviet Union in 1990 and the cancellation of the Buran space program, the lone operational An-225 was placed in storage. The six Ivchenko Progress engines were removed for use on An-124s, and the second An-225 airframe (nearing completion and awaiting engines) was also mothballed.


The An-225 is an extension of Antonov's earlier An-124. To meet the needs of its new role, fuselage barrel extensions were added fore and aft of the wings, which received root extensions. Two more Ivchenko Progress D-18T turbofan engines were added to the new wing roots, bringing the total to six, and an increased-capacity landing gear system with 32 wheels was designed. The An-124’s rear cargo door and ramp were removed to save weight, and the empennage was changed from a single vertical stabilizer to a twin tail with an oversized horizontal stabilizer. The twin tail was essential in order to enable the plane to carry very large and heavy external loads, which would otherwise disturb the aerodynamics of a conventional tail. Unlike the An-124, the An-225 was not intended for tactical airlifting and is not designed for short-field operation.

With a maximum gross weight of 600 tonnes (1,300,000 lb), the An-225 remains as the world's heaviest and largest aircraft, being even bigger than the current double-decker Airbus A380 even though Airbus plans to pass their current maximum landingwieght with 591,7 tons.The Hughes H-4 Hercules, known to most as the "Spruce Goose", had a greater wingspan and a greater overall height, but was considerably shorter, and due to the materials used in its construction, also lighter. In addition, the Hercules only flew once and never climbed above 21.3 m (70 ft), making the An-225 the largest aircraft in the world to take off multiple times.The An-225 is not only larger than the Airbus A380 airliner, it is also considerably bigger than the Antonov An-124, Boeing 747 Large Cargo Freighter, and Lockheed C-5 Galaxy, the nearest equivalent heavy airlifters.

In September 2001, carrying a record load of 253.82 tonnes of cargo, the An-225 flew at an altitude of two kilometers (6,500 feet) over a closed circuit of 1,000 km (620 mi) at a speed of 763.2 kilometres per hour (474.2 mph).

In November 2004, FAI placed the An-225 in the Guinness Book of Records for its 240 records.

Monday, May 04, 2009

Aircraft engine

An aircraft engine is a propulsion system for an aircraft. Aircraft engines are almost always either lightweight piston engines or gas turbines. This article is an overview of the basic types of aircraft engines and the design concepts employed in engine development for aircraft.

Engine design considerations

The process of developing an engine is one of compromises. Engineers design specific attributes into engines to achieve specific goals. Aircraft are one of the most demanding applications for an engine, presenting multiple design requirements, many of which conflict with each other. An aircraft engine must be:

* reliable, as losing power in an airplane is a substantially greater problem than an automobile engine seizing. Aircraft engines operate at temperature, pressure, and speed extremes, and therefore need to operate reliably and safely under all these conditions.
* lightweight, as a heavy engine increases the empty weight of the aircraft & reduces its payload.
* powerful, to overcome the weight and drag of the aircraft.
* small and easily streamlined; large engines with substantial surface area, when installed, create too much drag, wasting fuel and reducing power output.
* repairable, to keep the cost of replacement down. Minor repairs should be relatively inexpensive.
* fuel efficient to give the aircraft the range the design requires.
* capable of operating at sufficient altitude for the aircraft

Unlike automobile engines, aircraft engines run at high power settings for extended periods of time. In general, the engine runs at maximum power for a few minutes during taking off, then power is slightly reduced for climb, and then spends the majority of its time at a cruise setting—typically 65% to 75% of full power. In contrast, a car engine might spend 20% of its time at 65% power accelerating, followed by 80% of its time at 20% power while cruising. The power of an internal combustion reciprocating or turbine aircraft engine is rated in units of power delivered to the propeller (typically horsepower) which is torque multiplied by crankshaft revolutions per minute (RPM). The propeller converts the engine power to thrust horsepower or thp in which the thrust is a function of the blade pitch of the propeller relative to the velocity of the aircraft. Jet engines are rated in terms of thrust, usually the maximum amount achieved during takeoff.

The design of aircraft engines tends to favor reliability over performance. Long engine operation times and high power settings, combined with the requirement for high-reliability means that engines must be constructed to support this type of operation with ease. Aircraft engines tend to use the simplest parts possible and include two sets of anything needed for reliability. Independence of function lessens the likelihood of a single malfunction causing an entire engine to fail. For example, reciprocating engines have two independent magneto ignition systems, and the engine's mechanical engine-driven fuel pump is always backed-up by an electric pump.

Aircraft spend the vast majority of their time travelling at high speed. This allows an aircraft engine to be air cooled, as opposed to requiring a radiator. In the absence of a radiator, aircraft engines can boast lower weight and less complexity. The amount of air flow an engine receives is usually carefully designed according to expected speed and altitude of the aircraft in order to maintain the engine at the optimal temperature.

Aircraft operate at higher altitudes where the air is less dense than at ground level. As engines need oxygen to burn fuel, a forced induction system such as turbocharger or supercharger is especially appropriate for aircraft use. This does bring along the usual drawbacks of additional cost, weight and complexity.

Thursday, April 16, 2009

Sukhoi Su-30

The Sukhoi Su-30 (NATO reporting name "Flanker-C") is a twin-engine military aircraft developed by Russia's Sukhoi Aviation Corporation and introduced into operational service in 1996. It is a two-seat, dual-role strike fighter for all-weather, air-to-air and air-to-surface deep interdiction missions; closely comparable to F-15E Strike Eagle.

The aircraft is a modernized version of the Su-27UB and has several variants. The Su-30K and Su-30MK series have had commercial success. The variants are manufactured by competing organizations: KNAAPO and the IRKUT Corporation, both of which come under the Sukhoi group's umbrella. KNAAPO manufactures the Su-30MKK and the Su-30MK2, which were designed for and sold to China and later Indonesia. Irkut makes the long-range, multirole Su-30MK series. The series includes the Su-30MKI developed for the Indian Air Force and its derivatives, the MKM, MKA and MKV for Malaysia, Algeria and Venezuela respectively.

Wednesday, April 08, 2009

F/A-18 Hornet

F/A-18 Hornet is an all-weather carrier-capable multirole fighter jet, designed to attack both ground and aerial targets. Designed in the 1970s for service with the United States Navy and Marine Corps, the Hornet is also used by the air forces of several other nations. It has been the aerial demonstration aircraft for the U.S. Navy's Blue Angels since 1986.

Its primary missions are fighter escort, fleet air defense, suppression of enemy air defenses (SEAD), interdiction, close air support and reconnaissance. Its versatility and reliability have proven it to be a valuable carrier asset, though it has been criticized for its lack of range and payload compared to its contemporaries.

Wednesday, April 01, 2009

F-16 fighter flights

F-16 fighter flights at Luke Air Force Base -- its largest training area for the jets -- after one of the planes crashed in the desert Friday. It was the fifth such accident at Luke since October.

F-16s will be inspected before they are cleared to fly again. Rider had been airborne for 20 minutes when he developed engine problems and turned back toward Luke. Witnesses said the plane was on fire. The last three F-16 crashes were also engine-related. Pilots fly more than 100, 000 sorties a year out of Luke.

Wednesday, March 25, 2009

F-23 Black Window II

In the late 1970’s, concern arose among military planners about the aging design (first flight in 1972) of the F-15 and the possible loss of future air superiority of the fighter. Soviet fighters such as the MiG 29 and Su-27 had demonstrated remarkable maneuverability and performance. In addition, fighter technology had taken enormous strides forward with the introduction of stealth, or low observable, technology. There was also growing concern over the increased effectiveness of the Soviet air defense system that posed a highly lethal environment for the F-15. Therefore, the Air Force initiated an Advanced Tactical Fighter (ATF) Program to develop a replacement for the F-15.

In 1981, the Air Force developed a requirement for an Advanced Tactical Fighter as a new air superiority fighter. It would take advantage of the new technologies in fighter design on the horizon including composite materials, lightweight alloys, advanced flight control systems, higher power propulsion systems and stealth technology. Air Force leaders believed these new technologies would make aircraft like the F-15 and F-16 obsolete by the early 21st century. A Mission Element Need Statement for an Advanced Tactical Fighter (ATF) was released in October 1981.

In September 1985 the Air Force sent out technical requests for proposals to a number of aircraft manufacturing teams. The October 1986 Milestone I review directed a DEM/VAL phase prior to entry into EMD. On 31 October 1986, the Air Force awarded each team a $691-million fixed-price contract to build two prototypes: Northrop-McDonnell Douglas' YF-23, and the Lockheed-Boeing-General Dynamics YF-22. In contrast to the F-117A and the B-2, both of which had been point designed for stealth, these two prototypes were the first airplanes ever to blend stealth with agility and high-speed, supersonic cruise capability.

Wednesday, March 18, 2009

B-52H Buff

The B-52H BUFF [Big Ugly Fat Fellow] is the primary nuclear roled bomber in the USAF inventory. It provides the only Air Launch Cruise Missile carriage in the USAF. The B-52H also provides theater CINCs with a long range strike capability. The bomber is capable of flying at high subsonic speeds at altitudes up to 50,000 feet (15,166.6 meters). It can carry nuclear or conventional ordnance with worldwide precision navigation capability.

The aircraft's flexibility was evident during the Vietnam War and, again, in Operation Desert Storm. B-52s struck wide-area troop concentrations, fixed installations and bunkers, and decimated the morale of Iraq's Republican Guard. The Gulf War involved the longest strike mission in the history of aerial warfare when B-52s took off from Barksdale Air Force Base, La., launched conventional air launched cruise missiles and returned to Barksdale -- a 35-hour, non-stop combat mission.

Wednesday, March 11, 2009

General Dynamics F-16XL

The General Dynamics F-16XL is a derivative of the F-16 Fighting Falcon, with a cranked-arrow delta wing that is over twice the size of that of the standard F-16 wing. It was entered in the U.S. Air Force's Enhanced Tactical Fighter (ETF) competition but ultimately lost to the F-15E Strike Eagle. Several years after the prototypes were shelved; they were turned over to NASA for aeronautical study.

In 1977, the F-16XL started out as the F-16 SCAMP (Supersonic Cruise and Maneuver Prototype) at General Dynamics Fort Worth. Under the leadership of Harry Hillaker (father of the original F-16), the original goal of the program was to demonstrate the applicability of Supersonic transport technologies to military aircraft.

Working closely with NASA's Langley Research Center, the company invested significant Internal Research and Development (IRAD) funds for wind tunnel testing and that led to the Model 400. As seen in the supersonic wind tunnel model at right, the Model 400 featured all moving wing tips for roll control and an all moving vertical tail. These surfaces were actually the horizontal tail surfaces from the F-16A. These surfaces were later dropped as they did not provide adequate control at low speed, high angle of attack. Also, there would have been no provision for wing-tip mounted missiles.

Wednesday, March 04, 2009

F-35 Lightning II

The Lockheed Martin F-35 Lightning II is a fifth-generation, single-seat, single-engine, stealth-capable military strike fighter, a multi role aircraft that can perform close air support, tactical bombing, and air defense missions. The F-35 has three different models; one is the conventional takeoff and landing variant, the second is short takeoff and vertical-landing variant, and the third is a carrier-based variant.

The F-35 is descended from the X-35, the product of the Joint Strike Fighter (JSF) program. Its development is being principally funded by the United States, with the United Kingdom, and other partner governments providing additional funding. It is being designed and built by an aerospace industry team led by Lockheed Martin with Northrop Grumman and BAE Systems as major partners. Demonstrator aircraft flew in 2000, with the first flight on 15 December 2006.

The F-35 is being designed to be the world's premier strike aircraft through 2040. It is intended that its close and long-range air-to-air capability will be second only to that of the F-22 Raptor. Specifically the F-35’s requirements are that it be: four times more effective than legacy fighters in air-to-air combat, eight times more effective in air-to-ground battle combat, and three times more effective in reconnaissance and suppression of air defenses. These capabilities are to be achieved while still having significantly better range and require less logistics support than legacy aircraft.

Tuesday, February 24, 2009

A380 Airbus

The A380, will be the largest airliner ever built. Lengthwise, it would nearly stretch from goal line to goal line of a football field while its wing tips would hang well beyond the sidelines. Three full decks will run along the entire length of the plane. Upper and main decks will serve as passenger areas, and will be connected by a grand staircase near the front of the plane and by another smaller staircase at the back.

The A380 would feature an advanced version of the Airbus common two crew cockpit, with pull-out keyboards for the pilots, extensive use of composite materials such as GLARE, and four 320 to 347kN (72,000 to 78,000lb) class Rolls Royce Trent 900 or Engine Alliance (General Electric/Pratt & Whitney) GP-7200 turbofans now under development. Several A380 models are planned: the basic aircraft is the 555 seat A380-800 and high gross weight A380-800, with the longer range A380-800R planned. The A380-800F freighter will be able to carry a 150 tonne payload and is due to enter service in 2008. Future models will include the shortened, 480 seat A380-700, and the stretched, 656 seat, A380-900.

Wednesday, February 18, 2009

F-22 Raptor

The Lockheed Martin/Boeing F-22 Raptor is a fifth-generation, fighter aircraft that uses stealth technology. It is primarily an air superiority fighter, but has multiple capabilities that include ground attack, electronic warfare, and signals intelligence roles.

The United States Air Force considers the F-22 a critical component of the US strike force, and claims that the F-22 cannot be matched by any known or projected fighter aircraft. Air Chief Marshal Angus Houston, Chief of the Australian Defense Force, said in 2004 that the "F-22 will be the most outstanding fighter plane ever built."

Faced with a protracted and costly development period, the aircraft was variously designated F-22 and F/A-22 during the three years before formally entering US Air Force service in December 2005, as the F-22A. Lockheed Martin Aeronautics is the prime contractor and is responsible for the majority of the airframe, weapon systems and final assembly of the F-22. Program partner Boeing Integrated Defense Systems provides the wings, aft fuselage, avionics integration, and all of the pilot and maintenance training systems.

Wednesday, February 11, 2009

F-4 Phantom II

The McDonnell Douglas F-4 Phantom II is a two-seat, twin-engined, all-weather, long-range supersonic interceptor jet fighter/fighter-bomber originally developed for the U.S. Navy by McDonnell Aircraft. Proving highly adaptable, it became a major part of the air wings of the U.S. Navy, U.S. Marine Corps, and U.S. Air Force. It was used extensively by all three of these services during the Vietnam War, serving as the principal air superiority fighter for both the Navy and Air Force, as well as being important in the ground-attack and reconnaissance roles by the close of U.S. involvement in the war.

First entering service in 1960, the Phantom continued to form a major part of U.S. military air power throughout the 1970s and 1980s, being gradually replaced by more modern aircraft such as the F-15 Eagle and F-16 Fighting Falcon in the U.S. Air Force; the F-14 Tomcat and F/A-18 Hornet in the U.S. Navy; and the F/A-18 in the U.S. Marine Corps. It remained in use by the U.S. in the reconnaissance and Wild Weasel roles in the 1991 Gulf War, finally leaving service in 1996. The Phantom was also operated by the armed forces of 11 other nations. Israeli Phantoms saw extensive combat in several Arab–Israeli conflicts, while Iran used its large fleet of Phantoms in the Iran–Iraq War. Phantoms remain in front line service with seven countries, and in use as an unmanned target in the U.S. Air Force.

Wednesday, February 04, 2009

F-15 Eagle

The McDonnell Douglas (now Boeing) F-15 Eagle is a twin-engine, all-weather tactical fighter designed to gain and maintain air superiority in aerial combat. It was developed for the United States Air Force, and first flew in July 1972. It is one of the most recognized fighters of the modern day. The F-15E Strike Eagle derivative is an all-weather strike fighter that entered service in 1989. The U.S Air Force plans to keep the F-15 in service until 2025.

During the mid-1960s U.S. Air Force intelligence was surprised to find that the Soviet Union was building a large fighter aircraft, known as the MiG-25 'Fox bat'. It was not known in the West at the time that the MiG-25 was designed as a high-speed interceptor, (not an air superiority fighter), so its primary asset was speed, not maneuverability. The MiG-25's huge tailplanes and vertical stabilizers (tail fins) hinted at a very maneuverable aircraft, which worried the Air Force that its performance might be higher than its American counterparts. In reality, the MiG's large fins and stabilators were necessary to prevent the aircraft from encountering inertia coupling in high-speed, high-altitude flight.

Wednesday, January 28, 2009


A rotorcraft is a heavier-than-air flying machine that uses lift generated by wings, called rotor blades that revolve around a mast. Several rotor blades mounted to a single mast is referred to as a rotor. Rotorcraft may also include the use of static lifting surfaces, but the primary distinguishing feature being lift provided by one or more rotors. Rotorcraft includes helicopters, auto gyros, gyro dynes and tilt rotors. In the United States, the Federal Aviation Administration places helicopters, auto gyros (which it calls gyroplanes), and gyro dynes in the category Rotorcraft, and tilt rotors in the category Powered lift.

A helicopter is a rotorcraft whose rotors are driven by the engine(s) throughout the flight, to allow the helicopter to take off vertically, hover, fly forwards, backwards and laterally, as well as to land vertically. Helicopters have several different configurations of one or more main rotors.

Wednesday, January 14, 2009

Airport design

Airport design and location can have a big impact on air safety, especially since some airports such as Chicago Midway International Airport were originally built for propeller planes and many airports are in congested areas where it is difficult to meet newer safety standards. For instance, the FAA issued rules in 1999 calling for a runway safety area, usually extending 500 feet (150 m) to each side and 1,000 feet (300 m) beyond the end of a runway.

This is intended to cover ninety percent of the cases of an aircraft leaving the runway by providing a buffer space free of obstacles. Since this is a recent rule, many airports do not meet it. One method of substituting for the 1,000 feet (300 m) at the end of a runway for airports in congested areas is to install an engineered materials arrestor system, or EMAS. These systems are usually made of a lightweight, crushable concrete that absorbs the energy of the aircraft to bring it to a rapid stop. They have stopped three aircraft (as of 2005) at JFK Airport.

Wednesday, January 07, 2009

Bird strike

Bird strike is an aviation term for a collision between a bird and an aircraft. It is a common threat to aircraft safety and has caused a number of fatal accidents. In 1988 an Ethiopian Airlines Boeing 737 sucked pigeons into both engines during take-off and then crashed in an attempt to return to the Bahir Dar airport; of the 104 people aboard, 35 died and 21 were injured. In another incident in 1995, a Dassault Falcon 20 crashed at a Paris airport during an emergency landing attempt after sucking lapwings into an engine, which caused an engine failure and a fire in the airplane fuselage; all 10 people on board were killed. A bird strike is suspected as causing the engines to fail on US Airways 1549 that crash landed onto the Hudson River.

Modern jet engines have the capability of surviving an ingestion of a bird. Small fast planes, such as military jet fighters, are at higher risk than big heavy multi-engine ones. This is due to the fact that the fan of a high-bypass turbofan engine, typical on transport aircraft, acts as a centrifugal separator to force ingested materials (birds, ice, etc.) to the outside of the fan's disc. As a result, such materials go through the relatively unobstructed bypass duct, rather than through the core of the engine, which contains the smaller and more delicate compressor blades. Military aircraft designed for high-speed flight typically have pure turbojet, or low-bypass turbofan engines, increasing the risk that ingested materials will get into the core of the engine to cause damage.