Aircraft Evolutionary cul-de-sac’s

Shenyang J-13. Very peculiar looking bird that was struck down by the J-10 in China's 4th gen. fighter competition.





---------- Post added at 11:55 PM ---------- Previous post was at 11:55 PM ----------

Shenyang J-13. Very peculiar looking bird that was struck down by the J-10 in China's 4th gen. fighter competition.

Miragedriver said:

Hey delft, any thoughts on the Lavi? Even though it is smaller than the F-16, one can only imagine what a great combat aircraft this would have been. In reading some articles regarding Lavi, the design engineers mentioned that they purposely designed the aircraft to be a fully combat capable as an OCU aircraft first, thereby allowing for more fuel and avionics in the single seat version. They also mentioned that this was also done to allow more room for growth in the platform.

Click to expand...

I never looked close enough at Lavi, but it might well have had the potential to become a better aircraft than F-16. But probably the US offered F-16 on conditions that Israel couldn't refuse. The second aircraft the late Fokker company built after WWII was a twin engine crew trainer called S-13. When one, beautiful, aircraft had been build the US gave a dozen or so Beechcraft C-45 aircraft to the Dutch air force, so killing the S-13.

The J-13 looks like an interesting bird, especially with the leading edge extensions. However it seams as if it is not very maneuverable, kind of like the J-8.

Time for another subject: Variable Geometry.
In a sense extending and retracting flaps and undercarriage is already varying your geometry but that is too ordinary to count.
So what about increasing and decreasing the wing span of the straight wing? See . We won't see such aircraft again. They are just to heavy to be worthwhile.
Then there is the swing wing, beginning with the Messerschmitt P.1101, which was to vary its wing sweep only while on the ground. But it inspired the first one to vary it in the air, the Bell X-5. And they had quite a progeny including one civil supersonic transport project, Boeing 2707, that was replaced by a tailed delta before being abandoned all together. The largest actually build is the Tu-160 Blackjack. The bearings will be heavy and expensive in procurement and maintenance. So these too have reached their sell by date.
There is a simpler version, with but one bearing exemplified by the Blohm + Voss P.202 project designed by Richard Vogt. The wing was straight at low speed, but for high speed turned over 35 degrees, the starboard wing pointing aft, the port wing forward. See . This concept was realized many years later in the Ames AD-1. See .
A further simplification is a flying wing with turbofan engines hanging on pylons that can be turned so the wing can fly with a sweep of say 45 degrees at a speed of Mach 1.6? That too is unlikely to be realized. I haven't found these things on internet so have to depend on my memory.
The last of this lot: variable incidence wings have been used. The nicest seems to me to be the Blohm + Voss BV144 that was built during WWII in France and flew there after the war. Another Richard Vogt design. IIRC the angle of incidence changed 11 degrees, but I didn't find the information on the internet. See and . At the time the DC-3 was slightly larger and extremely cheap so there was no market for this aircraft.
Other such aircraft generally remained experimental but one aircraft with a variable incidence wing was produced in considerable numbers: of the F8U, later F-8, Crusader 1219 were built. The wing was tilted 7 degrees for take off.

I still hope that transport aircraft using variable incidence will appear, but I think all other variations will not

Let's bring up one very few of you will I think even have read about: water borne fighters. This is only a meager selection.
During WWI both Austria and Italy used single seat flying boat fighters to protect and intercept bombers in their actions near the Adriatic. A description of an Austrian example can be downloaded from .
Italian fighter boats were produced by Macchi, for example the M.5. and M.7. See and .
Other countries used float planes. This web site gives four single seat and two two-seat German fighter float planes: . And here are two French fighter float planes: .
Flying boat fighters disappeared after WWI due to the increase in engine power, but float plane fighters continued into WWII but during that war in most countries only as experiments, such as a float version of the Spitfire ( ) and the Wildcat ( ). Only Japan actually used fighter floatplanes, the float version of the Zero ( ) and the Kawanishi N1K Kyofu / Rex ( ), which was especially designed as a float plane.
Then with appearance of jet engines the flying boats returned: the Saro SR.A/1 ( )
and the Convair Sea Dart ( ).
The End.

Let's look at flying cars, cars that can deploy wings and fly. See for the overview .
Two were in the news recently. The Terrafugia Transition, ( ) and PAL-V ( ) were declared to be near production. DARPA, the Pentagon research organization has promised more than $60m for the development of such a vehicle. And of course Air Force Brass recently mentioned Moulton Taylor and his Aerocar ( ).
The best op the lot, historically, was to me the Aerocar, because it was near the cars of its time, 1949, and flew reasonably well. But cars have developed since then and it is much more difficult to build a car that can fly or an aircraft that can be used as a car and still fit legally on the road and in the air.
Of the recent flying cars the PAL-V is the best. It is a three-wheeled motorcycle with a closed cabin and it flies as a autogyro. But it too is not really good enough. They are and are likely to remain useless hybrids. They live in their cul-de-sac.

Excellent entries Delft! Here’s another useless, or not fully utilized, invention: The Ground aircraft. Ground effect is caused by ground interference with airflow patterns around an aircraft when the aircraft is within one wingspan of the surface. If the approach airspeed is too fast, the aircraft will tend to float down the runway, delaying touchdown of the aircraft. This can create a dangerous condition where the aircraft may actually run out of runway space, creating an unsafe landing condition. If this situation were to occur, a prudent pilot would perform a go-around and land again.
The Russians (Soviets) experimented with ground effect aircraft, preliminary over water. Some examples are:

[video=youtube;V8Nu94khHoo]http://www.youtube.com/watch?v=V8Nu94khHoo[/video]

[video=youtube;bbecl88NsEQ]http://www.youtube.com/watch?v=bbecl88NsEQ&feature=related[/video]

I was always surprised by the huge size of these Ekranoplans. The Soviets did build, experimentally, smaller ones, among them one consisting of the fuselage and engine of an AN-2 and a new wing. Other small WIG craft were built in Germany and the US. But nowadays the countries most interested in, small, WIG craft are China and Iran.
I would be afraid of a large WIG hitting a ship, otherwise such craft might find employ transporting containers between Atlantic countries and East Asian ones. Fuel consumption would be markedly less than for cargo aircraft while transport time would be much less than for container ships.

Here is the post I promised about Zeppelins.
We can divide airships in two classes: those in which the outer skin contains the lifting gas and whose who contain their lifting gas in separate gas cells. The first are the non-rigid, the semi-rigid and the metalclad airships, the second are the rigid airships.
"(zeppelin) balon with awacs / ecw / bvr missile is possible ?" refers to a non-rigid airship, not to a Zeppelin.

A rigid airship consists of a framework of great size and covered by a fabric skin within which more than ten gas cells, often called ballonets, are kept in place by nets of fine cables that transfer the lift to the framework. Graf Ferdinand von Zeppelin conceived of this system to be able to build airships much larger than the non-rigid and semi-rigid ships existing in the late 19th century. The framework was aluminum alloy ( dural was developed for building Zeppelins ), except in the competing Schutte-Lanz ship which used wood ( triplex ). ( See for a British copy , a horror story ). For the history I refer to the wiki's about Rigid Airships, Zeppelin, USN airships, &c.

Large airships need to be built in very large halls. This was always a problem. It is easier and cheaper to build a low long building and use it to build a long narrow airship, possibly lengthen the building to build an even longer airship. Early zeppelins were typically eight or more times as long as wide, later it became about six times. This is bad for structural weight and bad for air resistance.
Building an airship takes a considerable time. Hindenburg took about 4.5 years. This is bad for capital costs.
The gas cells were vulnerable and any damage to them leads to gas escaping into the space between the the ballonets and the outer skin thus causing an explosive mixture to form if that gas is hydrogen.

The last Zeppelins were demolished in 1940, LZ-126 Los Angelos in the US, Lz-127 Graf Zeppelin and LZ-130 Graf Zeppelin II in Germany.
But even in 1996 a project was started in The Netherlands to build a new rigid airship with a length of 180 meters. The project failed in 2001. ( )

All airships can use hydrogen as lifting gas, except when the engines are placed within the hull as with Akron and Macon, but this must be considered especially dangerous in Zeppelins. As Helium finds ever more uses in modern machines such as the fMRI machines in hospitals and as a US Act of Congress forces the US to dump its strategic Helium holdings before 2015 we can expect much higher Helium prices and no possibility of the return of the Zeppelin.