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Testbed Aircraft Cameos As a young engineer in the 1960s at Pratt & Whitney Aircraft (now UTC’s Pratt & Whitney) in East Hartford, Connecticut, I was involved (along with many others) in the development of their 44,000 pound thrust (lbt) JT9D turbojet, which powered the first Boeing 747 jumbo jet aircraft[ Display footnote number: 2 ]. ...


42

The AvHerald comment is correct, you generally do not want to turn towards the dead engine. The aircraft will tend to turn (both yaw and bank) towards the dead engine due to asymmetric thrust, allowing it to do so at low speed will make it difficult to end the turn, possibly to the point where you lose control. If you turn away from the dead engine, you'll ...


42

Well, the 3 points you make are easily demonstrable to be true, and also a fairly unique feature of all three if looked at side-by-side. The 747 is the only one with an obvious hump towards the front of the aircraft. This upper row of windows is unlike either of the other two Photo Aldo Bidini:: source: http://www.airliners.net/photo/Alitalia/Boeing-747-...


41

It doesn't quite work that way. When an engine wears out it's rated thrust doesn't decline; its "ITT Margin" (or some similar phrase - basically its thermodynamic margin at takeoff) declines. When setting takeoff thrust on a turbofan there is a target N1, or target torque on a turboprop or turboshaft, or Engine Pressure Ratio on a pure jet, and the engine ...


37

Torque is less of a problem due to the effective roll damping of a wing, but gyro effects and prop wash are important. Gyro effects first became an issue with rotary engines in WW I. A rotary engine has its crankshaft fixed to the airplane, and both the cylinder block and the propeller rotate. This gives better cooling at low speed and produces a flywheel ...


34

Short answer It's the vastly different flow conditions from static to cruise which demand a separate placing of high-bypass-ratio jet engines. They would produce less thrust and more drag when paired. Why were there paired engines at all? The early jets had their engines mounted directly beneath or in the wing, and comparisons between separately mounted ...


31

Engines on airliners turn the same direction. The torque isn't as much an issue on jets as it is on props. A lot of multiengine prop planes have propellers that turn in opposite directions. In turbine engines this can be done in a gearbox to allow the same engine to be used on both sides. Some turbine engines, such as the PT6, have two turbines turning in ...


31

This is sort of explained in the linked question already. Specifically this answer (which I consider better than the accepted one above it) says: Today, high power propeller aircraft tend to use identical engines but left- and right-handed gearboxes so the propellers run in both directions. This is less due to gyro effects and mostly to produce benign ...


29

Airbus aircraft have 3 hydraulic systems (Green, Blue, Yellow). Green is pressurized by left engine, Yellow by right engine, and each one can be pressurized by the other using the PTU. In addition the Yellow circuit has an electric pump. The Blue circuit is a backup pressurized on demand by several means (electric pump and RAT). Each circuit powers ...


27

I'm sure someone else will come along and give you a better answer with illustrations and everything, but until then, here goes :) Multi engine aircraft usually have their engines off to either side of the fuselage. This means that if one engine fails, the other engine will produce what's called asymmetric thrust (one engine is stronger than the other). ...


26

I don't know how it is achieved, but here is the reason: If you have two sources of the same noise, with nearly the same frequency, the sum of both noises will be a noise of slowly increasing and decreasing volume. It's called beat and can become very annoying. The math says $$\sin(2\pi f_1t)+\sin(2\pi f_2t)=2\cdot\sin\left(2\pi \frac{f_1+f_2}{2}t\right)\...


21

On the Junkers Ju-52 the pilot had two little discs which rotated with the beat frequency between two engines. The upper left one would show the beat frequency between the left and the center engine, and the lower right one that between the center and right engines. The pilot would try to stop them rotating by advancing or retarding the throttles, equalizing ...


21

Most twin-engine aircraft with counter-rotating propellers have the rotation set up so that the propellers are rotating inward towards the center at the tops of the propeller arc. This configuration reduces the P-Factor effect at slow speed high angles of attack, and eliminates the "critical" engine that is present on multi-engine aircraft where both ...


21

The plane in the pictures is Boeing JB-52E -test plane. It used to test for instance the General Electric TF-39 engines for the C-5 Galaxy as it was under development


19

That depends on a lot of factors. Are you declaring an emergency? What altitude are you at what speed are you at when this happens etc? What kind of aircraft are you flying? Does it have enough power to continue to climb on one engine? Some trainers do not. For a typical airliner, loss of a single engine is not a big deal. The pilot will simply declare ...


18

In my experience, admittedly dated (retired 1999) whether it's 'better' or not didn't enter into the consideration. A reduced-power assumed-temperature was always used (unless there was something that prohibited it) because of the cost factor, and the power reduction used was always such that there was the proper amount of runway but not 'plenty' of runway. ...


17

I have 3000 hours in jetstar.... The answer is no... It will not fly on one... Two yes and you really don't need that much rudder.. In the simulator with two out I used to put the inboard operating engine at 98% and modulate the outboard engine to control speed/sink doing that it really only needed 1/4 rudder trim


16

To certify any Commercial Jet Plane worthy of flying, a 2 engine plane must be able fly with just 1 engine running a 3 engine jet like the Lockheed L1011 or DC10 with just 1 a 4 engine jet with just 2. Although not a requirement, the 747, A380 could fly on one engine but are not be able to maintain the cruise altitude indefinitely and will ...


16

It's more correct to say this is an unintended roll induced by flying at a speed below Vmc. Vmc (V=Velocity, mc = minimum controllable) is the minimum speed a multi-engine aircraft can remain in control in case of a single engine failure. When an engine quits, thrust is no longer symmetrical. Rudder and a little bit of aileron are used to keep the plane ...


16

Yes, the dead foot, dead engine does apply (but not as much as you might think), and, yes, airline pilots need to rely on their engine instruments in order to figure out which engine has failed, especially when you're flying a 4-engine aircraft. Actually, and with obvious prejudice, I prefer to say that the Flight Engineer will use the engine instruments to ...


16

According to Wikipedidea In aviation, propeller synchronization is a mechanism that automatically synchronizes all propellers of a multi-engine, propeller-driven aircraft so that they rotate at the same speed. As for why its used the article states Propeller synchronization serves mainly to increase the comfort of crew and passengers, since its ...


14

A big part of this is probably related to maintenance, as you observed. Currently, engines are generally taken straight off of the pylon. If they were paired on a pylon, They would either have to be removed together (making them essentially half as reliable) or attached in a different way. With modern jet engines, only the largest aircraft make sense to ...


13

This will vary from plane to plane depending on design, and the best method to use for a particular airplane would be listed in the engine out procedures in the POH/AFM. When the manufacturers are flight testing the airplanes they try various combinations and tell you the absolute best one so that you can get the best performance out of the airplane in a ...


13

(Cessna 185 Skywagon and Cessna 340) See here for the major points: What are the pros and cons of single-engine vs. twin-engine? Regarding your specific question: Wouldn’t a single engine plane weigh less and thus can fly longer on a specific amount of fuel comparative to a twin engine plane? Both airplanes above are powered by the same 300 hp engine, so ...


13

If you are talking about the one prevalent in this trailer its an Piper Aerostar 600. The tail number is legitimate and the full registration details for 164HH can be found here. Some of the movie may also have utilized a Beech Queen Air Model 88


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Judging from this video, it does not have an automatic prop sync. When throttles are advanced you can hear the harmonic beat of the twin propeller blades, and during the climb the instructor seems to manually set the levers to reduce the harmonic set the correct manifold pressure. He may or may not have an indicator to help him, but judging from the sound ...


12

This doesn't fully answer the question, but the B727-100 also had an oval engine intake. AIRLINERS magazine Sept/Oct 99 edition: "The oval shape inlet on the 727-100 series was changed to a circular design on the stretched 727-200. This was a direct result of the new aircraft's longer fuselage. In flight, the increased lengths from the nose to the center ...


11

Let's give a short and snappy answer regarding jets: it's all about efficiency. If a part of an engine is damaged then the engine will most likely be replaced and repaired while the aircraft is flying with another engine. An engine turning clockwise and an engine turning counterclockwise are two different engines. Let's do some simple economics now: is it ...


11

What a positively delightful looking aircraft! I see no reason you couldn't log time in this as multi-engine time - it clearly has two engines, with two separate sets of controls (at least throttles, from what I can see). Similarly I see no reason you couldn't fly it IFR as an experimental aircraft, provided it's "properly equipped" (consult the FARs for ...


11

I tested this out in the Seminole today. My (extremely nonscientific) results are as follows: Wings level, hold aileron to maintain roll and correct using rudder: 200 FPM Ball centred, ailerons flush and correct using rudder: 0 FPM 5 degrees bank angle, hold aileron to maintain roll and correct using rudder: 100 FPM 2.5 degrees bank angle, hold aileron to ...


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