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Anonymous asked in Cars & TransportationAircraft · 1 decade ago

What makes the concept of a fast VTOL aircraft so difficult?

VTOL being Vertical Take Off and Landing, but if you don't know that you probably can't answer me anyway.

And if there have been successful creations of "practical" VTOL aircraft, please list examples.

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  • Anonymous
    1 decade ago
    Favorite Answer

    collision of two opposite design approaches, something like a family supersport car.

    FAST aircraft generally have to ly fast during the approach and landing, too. (remember the MiG21? its approach speed was somewhere about 350 kmh-1)

    this is due to the different lift producing systems - fast ones use thin airfoils to reduce the drag to reach high speed. because of that, the sheer speed or lots of wing mechanisation is required for lift production.

    on the other hand, the STOL/ VTOL aircraft use relatively thin airfoils with high critical AoA, that produce lift from very low speeds, yet produce enormous drag when attempting to reach higher speeds.

    as far as VTOL non-rotary, Harrier, Jak 38, Jak 141, German Kestrel are the most likely to encounter when searching for some information about them. the first two, Harrier and Yak 38 made it to the serial production.

    oh yeah, and the JSF in its vtol version.

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  • 1 decade ago

    There have indeed been successful attempts to make practical VTOL aircraft. The V-22 Osprey, F-35 Lightning II and, to a lesser extent, the Harrier (due to it's inability to take off vertically when fully loaded) come immediately to mind. Mostly, I'd say it's the design of the VTOL aircraft that limits it's top speed. The Osprey, for example is driven by turboprops, which have very limited top speed compared to turbojet engines. However, the F-35 has a very respectable maximum speed of ~Mach 1.7, so it appears that many of the design concerns of the past have been overcome.

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  • 1 decade ago

    There are many difficulties in making a fast VTOL aircraft and I can give a few examples below.

    1. To make a VTOL you need lift engines or lift fans. The Harrier has 4 lift engine nozzles that push the air down to create lift. The draw back to is that the thrust used to create high speeds are used to produce thrust thru 4 bi-pass ducts rather than straight out the back as in regular fighters.

    2. If lift fans are used then these are usually placed behind the pilot reducing the amount of space for electronics and weapons space. This also reduces the amount of fuel carried as the space is needed for the lift fans instead.

    3. Fuel. Using VTOL on planes uses an more fuel to get airborne as more thrust is used to get the aircraft airborne. By doing this you reduce the amount of fuel left to reach Mach 1 or faster as these speeds require lots of fuel. Most VTOL aircraft are Ground Attack aircraft so flying faster than Mach 1 is not practical as what are you going to shoot at going faster than Mach 0.7? Not much and most people don't realize that Air to Air engagements occur at speeds around Mach1.0 or less as at higher speeds it is harder to turn or even do evasive maneuvers.

    http://en.wikipedia.org/wiki/VTOL

    http://en.wikipedia.org/wiki/Harrier

    http://en.wikipedia.org/wiki/Yakovlev_Yak-38

    Hope this helps

    Source(s): Aviation Knowledge
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  • Anonymous
    1 decade ago

    Since the Harrier is a 20+ year old fast subsonic jet design, by "fast", I assume you mean supersonic.

    In order to do VTOL, the thrust must be greater than the weight of the airplane at zero airspeed. To do that requires a single HUGE fan (check out the Pegasus engine on the Harrier) to move a large amount of air through a small velocity change, or several turbojets, which drives up the weight to be lifted.

    Supersonic flight is best accomplished by pushing less air through a higher velocity change..

    The two regimes of flight are contradictory in terms of their thrust requirements.

    As did the AV8, the F35 gives up a great deal of "single mission capability" to do VTOL.

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  • 4 years ago

    the fast answer is fee, costly to construct and expensive to run. although, that became the case for mounted wing AND helicopters in the start of their progression. there is likewise the ingredient of mechanical reliability however the early planes crashed at an spectacular fee as nicely. So what's it if not fee and reliability is the respond ? How approximately this for an answer is that lots of the infrastructure is designed around the airplane we've not VTOL. i think of that there may well be a case made for a VSTOL commuter airplane those we've greater healthful the bill particularly nicely. the protection tension has a perceived use for VTOL airplane which they stepped forward for the period of WW 2 and Korea with the bombing of airfields. via having VSTOL airplane they experience that they might function from forward positions. This has yet to be proved, fortuitously. purely considering the fact which you're able to do it for the period of a peace time workout does not advise that that's carried out while the balloon is going up. in case you go searching in the present day you will see that helicopters are constrained as to the place they might land and take off from.

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  • Anonymous
    1 decade ago

    "Fast" is in the eye of the beholder. Lets assume a modern attack aircraft should go super sonic. Not much chance of the Harrier doing that.

    the problem is all the extra weight and equipment needed for the "V" portion.

    the YF-22 (I think) uses only one engine but has a lift fan amidships and a vectored nozzle in the rear to provide V-lift. As a result, there's not much "Usable-Load" left for munitions. Check and see if its payload isnt lighter than its Air-superiority cousin.

    wer

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  • WRG
    Lv 7
    1 decade ago

    A Harrier is fast so is an Osprey.

    If you mean why are helicopters limited the answer is the difference in the relative speed of the advancing and retreating side of the rotor disk.

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  • 1 decade ago

    Lift and Drag

    Practical as far as what? The Harrier, CV-22/MV-22, and the F-35 will all do the job they were designed to do.

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