New answers tagged

2

While I don't know of any airplanes that move load in flight for CG purposes, there are definitely airplanes that have various fuel tanks that can be used to trim the airplane during flight. Some of these systems will move the CG aft after takeoff for better performance in cruise, and then move the CG forward before landing for a more stable approach and ...


0

Let's start from the fact that nearly all airplanes have 'AoA protection' in the form of stall warning. For automatic stall prevention, strictly speaking, one doesn't need FBW: this can be achieved with traditional automatic control means (the infamous MCAS is, in essence, an example of such a system). On the other hand, FBW does not have to have stall ...


0

Two engines are better than one for safety, but one engile is cheaper to develop and maintain. And these days modern engines do give you more bang for your buck so you don't need as many. Plus you get more missiles/bombs/etc. per kilo with a single modern powerful engine. US pilots initially hated the idea of the F16 because it was small and had one engine. ...


1

Yes they do use a lot of extra fuel, but the amount is depending on the operating conditions (Mach flight speed and altitude)! Comparing MIL (military) power setting (maximum power without reheat) to MAX power setting (engine will be in MIL power, but the reheat will be scheduled and the exhaust nozzle opened) you can see that it is not uncommon to have 3 ...


10

To explain if the afterburner makes the engine louder, you must understand what the afterburner does. In the afterburner, the exhaust gases are re-heated by injecting fuel in the afterburner duct. The left oxygen is used to burn the fuel, which results in an increased exhaust gas flow. Note that the engine itself will not spool up faster: this is done by ...


1

From an energy standpoint, the engine produces heat, thrust, and less significantly, sound. Ignore the afterburner for a second and just consider throttling up, whether a jet or your car. The engine gets louder. That's not a law of physics, that's just what happens. There's no theoretical reason why the extra waste energy can't go 101% into heat, and -1% ...


5

The result of being shot up changed a lot for fighter planes over the years. Modern fighter planes rarely get hit by bullets, but rather by missiles. A missile hit usually takes out the whole aircraft, so there are far less instances where having a second engine would help the aircraft to get back home. With this negating a lot of the reliability benefit of ...


10

The other answers address the question "Why 1 engine?" but this begs the question: "Why do some fighters have 2 engines?" as actually, 1 engine is the norm for fighter aircraft. Note the list of 2 engine aircraft in the OP: F-22 Raptor, the Dassault Rafale, the Eurofighter Typhoon, the Su-27 family, the F/A-18 Hornet With the exception of the F/A-18 ...


1

If you look at it in terms of thrust vs fuel flow, then yes, they're very inefficient. However, if you just look at the amount of fuel burnt to get an interceptor from the runway to 30,000ft, then they can be more efficient. Without afterburners the same climb would take significantly longer and could use more fuel. Without afterburners, you'd need much ...


28

This PDF indicates an increase by ~10 dB for an F-8K in afterburner versus the same aircraft in 100% dry thrust. This PDF indicates smaller increases: +5 dB for an F-15 +4 dB for F-22 and F-35


-4

If you are asking if the engine is louder, no it is not. The afterburner and the diversion of the exhaust is what makes it louder. Just like in a car motor running straight pipe to gain horsepower. You can take the same motor and put an exhaust system on it and it will give that motor a different tone.


5

Yes the specific fuel consumption of the afterburner, lbs of fuel used per lb of thrust, is much higher than the core engine. This is because the fuel is being added to a part of the engine where the air is less compressed, so the energy conversion is a lot less efficient. The bright orange flame coming out the tail pipe when in reheat is pretty much all ...


14

I would say definitely yes, because of all the extra energy added to the exhaust flow and it's obvious to anyone who attended enough military airshows. Watch an F-16 depart with reheat on, then reduce thrust to military power (max thrust with reheat off) on the climb out, and it almost sounds like the engine flamed out. The flow out the nozzle may be ...


24

It has been around 20 years since I've been on a carrier deck, but I recall that it wasn't as dramatic of an increase as you might think. It may have gotten a little bit louder, but what I remember more is that the tone changed. The sound was more "full" when the afterburner was engaged. I realize this is a rather subjective answer.


35

Fighters don't carry passengers. The figure of merit for combat aircraft isn't passenger-miles flown between accidents, it's objectives completed (like enemy targets destroyed) per billion dollars spent. Adding redundant engines only improves this figure if single engine failures are very common. Today, military engines have gotten much closer to civilian ...


48

Because single engine fighters are substantially cheaper to purchase and operate. Exact figures are hard to obtain, but as an example, an F-15 squadron will spend about 25,000 USD per flight hour whereas an F-16 Squadron spends about 15,000 USD per flight hour. Effectively, you can purchase and operate twice the fighter force with single engine fighters ...


9

There is no major problem to be solved by moving the cockpit inside. The canopy adds minimal drag, considering how much drag the whole of a fighter's airframe produces. It also offers the highest quality of vision. To expand on the latter, let's define a few items that go into visual quality: Field of view Acuity, including in motion Noise Dynamic range ...


6

In addition to all the other reasons: Every camera-to-screen system has lag. Lag in a dogfight can be fatal. There will be some distortion between the camera and the screen, no matter how well designed. Distortion can be fatal too. Cameras and screen cannot reproduce depth perception (yes there are ways to do it but they are a LOT more complicated than ...


4

The human eye is 576 Megapixels. When a helmet mounted "virtual reality" type of helmet display comes out some day, in conjunction with cameras and hardware that can record and process at that resolution, then you might see a canopy-less fighter. By that time, the pilot will be software, or at minimum, located remotely anyway.


6

Unless you can have a continuous display over the entire field of vision WITH fail-safes I dont think it'll ever happen. Anything less will either require transitioning from one display(screen) to another or from display to display. If you've ever used a car GPS you will know the lag in shifting from the in-car display to outside view. Mark 1 eyeball is ...


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