(1) Takeoff / landing experiment

In addition to the aforementioned Beachcraft 99 and Dornier, Islander and Dash Eight planes being used in regular flights to remote islands were borrowed for use in the takeoff / landing experiment. About 150 takeoffs and landings altogether and about 100 touch-and-goes were done to measure accelerations in the planes in addition to noise and vibration on the model and underwater sounds.

Nothing to worry about was found in takeoff / landing performance itself or in any other respect.

The takeoff / landing test is shown in Fig. 3.

(2) Survey on pilots' impressions

The aircraft pilots who participated in the takeoff/ landing tests were asked to answer a questionnaire on how they had felt in the tests. Pilots from other airlines and aircraft manufacturing companies, who had ridden the test planes as observers, were also asked to answer a similar questionnaire. Their impressions were that the runway on the airport model was no different from any runway on land.

(3) Survey on influences of takeoff / landing

The performances of various items of aircraft instrumentation in taking off and landing on the floating structure were checked. Since the steel-built floating structure was feared to have some magnetic influence, its impact on magnetic compasses was checked with particular care. Some errors in compass readings during flight over the model and momentary fluctuations of the compass during the passage of the plane above an edge of the model were reported, but they would pose no substantial problem according to the users' opinions.

(4) Research on internal navigation system (INS)

The INS is a device for determining the aircraft's own flying position by integrating the direction in which the plane has flown and its acceleration. In order to let it work properly, its count should be reset to zero at the airport before taking off. It had been feared that this zero resetting might be disturbed by even a slight motion of the floating airport, but an experiment on the airport model disproved the fear. A laboratory test was also conducted to determine the maximum permissible oscillation.

　

　

2.4 Development of Airport Simulation Program

Whereas the Phase 2 research comprised a series of verification tests with small aircraft taking off and landing on the 1,000-meter long floating model, it was further decided that performance of any Mega-Float airport with any aircraft, irrespective of their size, could be estimated by simulatory calculation.

First, the simulation program for floating body behavior developed in Phase 1 was modified for exclusive high-speed use in Phase 2. This made possible confirmation of the safety of takeoff / landing by calculating that the deformation of every part of the floating airport could be kept within a permissible range of smoothness. Incidentally, the program for floating body behavior had already been verified with the airport model.

Regarding PAPI, the program allows confirmation according to the angle of inclination in the installation site.

Concerning ILS / GS, since the state of the electric wave reflected by the surface also counts in addition to the transmission angle of the original electric wave, a program for electric wave reflection was newly developed, and combined with the program for floating body behavior to work out a new program to simulate the motions of the floating body and the electric wave from the landing guidance device. The results of calculations according to this program were incorporated into a simulator for training with large aircraft, and this simulator was then used for checking the state of landing guidance devices installed in a large floating airport and their perceived performances. The results demonstrated that these devices would work satisfactorily even in a typhoon with a little attention by pilot.

　

　

2.5 Research on Airport Facilities

In order to utilize various devices installed on the Mega-Float for floating airports in the future, some of them may require new developmental work because airport facilities as such have their own functional requirements. In this aspect of research, such devices were developed, and their functions were confirmed by verification tests or on drawings. More specifically, low-headed and restrictive mooring equipment, connectors between the floating section (subject to ups and downs due to tidal fluctuations) and the access section (without ups and downs) and an oscillation-free control tower structure were developed among other things.

　

2.6 Research on Environmental Assessment

Whereas the Phase 2 research was intended for verification tests regarding airport functions, it was decided to take the opportunity of installing the gigantic model to do some environmental research.

(1) Accumulation of environmental data

For reference in environmental assessment, environmental data around the airport model were collected with a view to accumulating more data in addition to the store of knowledge built up in Phase 1 research.

(2) Research on removal of fouling organisms

Research was done on ways to remove organisms adhering to the floating body, and an air layer was found effective in preventing their adherence and removing what did adhere.

(3) Assessment of effect of underwater sounds on fishes

Underwater sounds around the floating body during the aircraft takeoff / landing test were measured to assess the level of their possible impact on fishes, which was found negligible, if any.

　

3. Closing Remarks

Whereas the research project has produced the results summarized so far, it is up to the MOT's Civil Aviation Bureau, which is authorized to approve the use of such floating airports, to give a final assessment of these findings. Therefore, its assessment will be sought when the whole research project is finished. Eventually, it will be also necessary to submit the research findings for evaluation by the International Civil Aviation Organization (ICAO).

The Mega-Float research project, carried on for six years with support from the MOT and the Nippon Foundation, will soon be completed with successful results as expected. As this project has succeeded in developing construction technology needed for Mega-Float, the next challenge is to bring it into a real being. Although the Technological Research Association of Mega-Float will be disbanded with the completion of the research project, the technology it has developed will be succeeded by the Shipbuilding Research Centre of Japan, which will mainly engage in consulting service related to Mega-Float with an eye to helping realize Mega-Float construction.

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