Re: New Generation Fighter
Alright, here is a 2 engine version of my jet fighter. Once again, only a rough draft:
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The biggest changes were altering the previous 4 small engines into 2 large engines, and adding the possibility of forward-swept canards and vertical stabilizers.
If you halve the mass of the engine you don't halve the diameter of it, which means that structurally you're either going to get a wider plane, or a bigger one overall.
At the same time, the aerodynamic gains would mainly be in stability and efficiency and potentially top speed, and may in fact penalize maneuverability. These would all be more suitable tradeoffs for a bomber than for a fighter...
Redundancy of engines only works if one engine is enough to keep the plane going. I don't know enough to know whether a 15,000 lbs of thrust is enough to keep a heavy weight fighter in the air.
I don't know about the changing mass of an engine relative to its changing diameter (jet engines are beyond my knowledge), but I do know basic geometry. The volume of an object increases exponentially when the object's surface area increases linearly, or the volume of an object decreases exponentially when the object's surface area decreases linearly.
Depending on various assumptions or scenarios, small engines could be advantageous or disadvantageous against larger engines. Notice how the Eurofighter Typhoon and F/A-18A to D chose 2 small engines over 1 large engine. I am guessing the Europeans and US Navy wanted the redundancy, but even then, they successfully created a high performance, reliable small engine. Good smaller engines have been created for trainer aircrafts (i.e., the Northrop T-38 Talon), missiles, and drones.
A jet with lots of lift from its fuselage is NOT necessarily an attack jet or bomber. The F-14 Tomcat, especially the F-14D Super Tomcat, had no problems with using wings and a pancake fuselage to generate very low wing loadings. From what F-14D pilots told me, the F-14D was a superb BVR fighter jet and a superb VR fighter jet. The F-14A had too many engine problems. The F-14A+, the F-14B, and F-14D got better engines (and other stuff as well). The biggest problem with all F-14 variants was its long history of maintenance and repair problems, because the F-14 (during its creation) incorporated many new, unknown designs. The F-14 arose from the partial failure of the F-111, which was an overly ambitious swing-wing design for both the US air force and US navy. The F-14 was not the first jet fighter to use swing wings, but the F-14's swing wings were much more active and precise throughout the F-14's performance than previous designs. The F-14 was the first American jet to have good BVR and VR combat abilities at various altitudes and velocities (air superiority). It used cutting edge technology for many of its components. To top it off, it had to land and take off from aircraft carriers. It even had a kicka** movie. Highway TOOO the danger zone . . .
Redundancy could work as long as more than 1 engine is active and the net total thrust of all active engines is at least adequate. For my 4 engine jet, if 1 engine goes down, the 3 engines has enough thrust to keep the jet flying. The jet should have adequate thrust with only 2 engines. I don't know about 1 active engine. It could be something similar but not exactly like the Voyager: low wing loading matched to a low T:W ratio.
Quickie said:
The fighter could possibly fly with one or even two engines downed, but I can see the problem of 2 working engines being too far away from the centre of aircraft.
The F-14 Tomcat had this minor problem. It's pancake fuselage separated the two engines so much, so it had accurate calibration and management of its 2 widely placed engines to ensure it was flying straight. NASA successfully ran tests on an F-14 with asymmetric thrusts and asymmetric wings (one wing fully forward and the other fully swept back). Some F-14 pilots used asymmetric thrusts to create unique maneuvers. I don't know the effectiveness of such maneuvers. Vectored thrust added into asymmetric thrust and/or widely spaced engines could become advantageous.
The Su-27 and Mig-29 have the same minor problem with widely spaced engines to a lesser extent. The same goes with large airplanes: the Boeing 747, the B-2 Spirit, and the Boeing C-17. Even propeller planes solved problems with 2 widely spaced engines.
