45

They only change one, because that one is a new engine that is being tested. If you are testing a new engine you change 1 at first so if it fails you have 3 others. If you change all 4 and there is a systematic defect in the design, now you have 0 good engines instead of 3. You will also see that the test engine isn't always one suitable for a 747. ...


43

Yes, supersonic conditions can indeed be replicated on the ground for purposes of airframe and engine testing. Arnold Engineering Development Complex (AEDC) The U.S. Air Force and NASA both operate supersonic wind tunnels, as do Lockheed, P&W, and others. The most advanced of these facilities are probably those at Arnold Engineering Development Complex ...


43

It's a Fedex 777F N894FD in (probably) pre-delivery aerial photography/test flight accompanied by one of Boeing's chase aircraft. After some maneuvers (shown below), the plane headed to MEM, Fedex's "SuperHub". (Source) The flight on flightradar24: https://www.flightradar24.com/2019-07-24/03:16/12x/FDX9032/2168b4b1 and flightaware: https://flightaware.com/...


39

One of the absolute requirements of an aircraft turbine engine (usually some sort of turbofan or turboprop) installation is that, in the event of a destructive failure of the engine, the engine cowling must be able to contain any and all fragments released in the process. No, there is not. The requirement is that the engine cowling must be able to contain ...


36

Since you didn’t specify a jurisdiction, I’ll answer for the FAA. Others should be similar. Pilots must be rated for the category, class and (if applicable) type of aircraft. Category is pretty broad, such as “Airplane”. Class is a bit more specific, such as “Multi-Engine Land”. Type is even more specific, such as “Boeing 737”. A type rating is required for ...


35

how could it be trusted? Like all aircraft, type certification requires that these be tested. I think the wings are tested to 1.5 x their load limit. A380: STRUCTURAL STATIC TESTS The A380’s structural static tests on began in November 2004, in preparation for the first flight clearance. The tests included: Flight Test Installation (FTI) calibration test, ...


33

It is a struggle, but it can be done. For the J58, Pratt&Whitney had a test facility at West Palm Beach which would simulate conditions at speed and altitude. From this site: The picture actually shows test cell A-1 at Pratt and Whitney’s West Palm Beach facility. […]. This test cell was actually an altitude simulation cell used for testing ...


33

It's a King Katmai STOL mod for a Cessna 182. From https://www.avweb.com/ownership/king-katmai-mod-safe-stol/ The full King Katmai modification consists of the canard, 300-HP IO-550, choice of 82- or 86-inch, three-blade prop, speed mods/drag reduction fairings, wing extension, increased gross weight, heavy-duty landing gear, which includes Cleveland brakes,...


31

They look very much like position markers to identify known points on the aircraft, for analysing video footage. You see similar markers on crash-test dummies used in vehicle impact trials, for instance, and also in motion-capture in the synthetic movie industry (and in orthopaedics).


30

The ugly truth is: Cracks do occur, and have occurred on the A380 wing root, but that is normal. Read on for more. The static load is only one aspect. Normally, what is driving the design is the fatigue load, which is the constant jerking of aerodynamic and inertial forces on all parts of an airplane. Today, aircraft are designed such that cracks will not ...


29

See this avherald report: https://avherald.com/h?article=4db1ccdb&opt=1 A Jet2.com Boeing 757-200, registration G-LSAN performing a test flight from Manchester,EN to Manchester,EN (UK), was in the initial climb out of Manchester's runway 05L when the right hand engine (RB211) emitted a loud bang and streaks of flame. The aircraft levelled off at 5000 ...


27

Short: The pilot has a well-defined range of discretion within progressively increasing bounds very tightly set as part of a structured development program aimed at eliciting maximum information regarding actual versus theoretical flight envelope in all conceivable modes and situations. Longer: A test pilot's main task is to carry out a progressive ...


27

To the best of my knowledge, all commercial aircraft being tested have their pilots take on parachutes and hi-vis clothing in addition to creating a possible means of egress on all important flights, such as the first flight and high-speed tests. Since getting the cabin doors open is practically difficult, the solution I think most producers use is to ...


25

It looks like an air-air photography trip by Boeing - the lead airplane is a LearJet, a type often used for this type of job with a turreted camera sticking out of the floor for views to the rear, ie for head-on shots of the target aircraft which in this case is a 777.


24

Transport category airplanes, which includes most aircraft in commercial passenger service, must meet the FAA regulations in 14 CFR Part 25. Some relevant excerpts are as follows: §25.305 The structure must be able to support ultimate loads without failure §25.307 Structural analysis may be used only if the structure conforms to that for which experience ...


21

A red/orange color is typically used to denote flight test instrumentation. Indeed, these windows do contain such instrumentation. Below you can see a similar window on a 747-8I flight test aircraft (note the 7th window from the nose): And the corresponding inside view:


21

Excerpt from McDonnell Douglas MD-11 by Arthur A C Steffen: The remaining eight aircraft were delivered bare-metal with a corrosion protection coating, except for the rudder which has to be painted prior to being installed and balanced, and was completed in the full livery in the carrier's modern paint facilities. The above text is in reference to KLM's ...


20

The details of the strength required are likely to be complicated and proprietary. However, we can do a very rough estimate. Using the equation for estimating root bending moment here, and the following numbers: Fuselage weight: 230,000 kg MTOW: 577,000 kg Engines: 25,000 kg Fuel: 260,000 kg Wings: 60,000 kg Wingspan: 79.75 m Wing taper ratio: 0.17 The ...


19

I worked as a test pilot for my aerospace employer. I have a small collection of ratings, and for unusual operations, and for experimental equipment operations we use Letters of Authorization (LOA). We are not involved in airframe certification, but have done a few Supplemental Type Certificates (STC). The most common things we have done are modifications ...


15

You can do flight tests from almost any airport, but it helps if: The weather is dry and stable, the field is not too far from the factory, there is a large unpopulated area nearby, and you have support facilities available. The support facilities were installed by the Air Force, and the other factors were already taken care of by Mother Nature in the case ...


15

Its a combination of those. US did have manuals for quite a few of the Migs- Cold war alliances were shifting too frequently to prevent any leak of military technology. As warisboring.com notes: Because Baghdad re-established its cooperation with London and the United States in late 1963, U.S. intelligence services not only received the opportunity to test-...


14

Why not? There have been several cases of near-sonic and even supersonic dashes by the Boeing 747, and the damage to the China Airlines Flight 006 elevator was done by landing gear doors which ripped off when the main gear was extended and its doors hit the elevator. There have been a few unintentional supersonic dives, and in those cases the actions taken ...


14

They will be in contact with ATC at all times and ATC can issue a clearance to operate within a defined area or within a specific flight level range, keeping other aircraft out of that area, e.g. APP: AIB97XA, cleared for turns and flight level changes in 20NM radius around ABCDE intersection, between FL70 and FL145 at your discretion. or a bit more ...


13

It ensures that the theoretical assumptions are correct in practice. Therefore it save our lives.


13

It's been pointed out that a single blade may be contained, but having a whole stage fail is an extremely high energy event. The high speed spool of a turbine engine is spinning at 10's of thousands of RPM. The energy in that system is too high to contain economically. But you can't just have engines exploding and do nothing about it. As with any safety ...


12

Flutter is a phenomenon that can occur when a structure is subjected to aerodynamic forces. It occurs not only in aircraft but also for example in buildings, power lines, road signs and bridges. Flutter is an oscillation caused by interaction of aerodynamic forces, structural elasticity and inertial effects. Perhaps the best known example of flutter is the ...


12

The aircrafts shown above are test aircraft and the windows are blanked for mounting test instrument. The image below shows the inside of Bombardier C-series test aircraft, which shows the mounting of test equipment. Image from airwaysnews.com Also, the screengrab below from this video about C series testing shows the interior of the C series test aircraft ...


12

As shown here, Lockheed Martin has a supersonic wind tunnel capable of generating wind speeds of up to mach 5. A quick Internet search revealed an extensive list of other supersonic wind tunnels, indicating that such tech is fairly widespread. In addition, as suggested by SMSvondertann, jet- and rocket powered cars such as the Thrust SSC have attained ...


11

That is a static pressure line. The "shuttlecock" device on the end pulls the line out behind the aircraft, where it can get a more accurate pressure reading, away from the air flowing around the aircraft that affects the regular pitot-static system. It will also be more accurate during flight conditions that normal aircraft rarely experience, but need to be ...


11

The test was flown on a DC-8-72. This model aircraft is certified to have its inboard thrust reversers deployed during flight, which means that the test was either within standard operational guidelines or not too far outside them (it's possible it's not supposed to have reversers deployed at Mach 0.8, but it's allowed to have them deployed at speeds over ...


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