Sunday, January 12, 2014

How to Land a Plane in Fog

The Challenge

Have you been in a plane that was attempting to land in fog or rain? How nerve racking it is as the aircraft makes each attempt to land, but the pilot is unable to see the runway far enough.

Recently, a friend of mine flew with his family from Imphal (Manipur) to Delhi. Both cities are in India. They were returning from a winter vacation. As you know, winter makes Delhi very foggy and this is not good for landing aircraft. It reduces the visibility to near zero.

When their plane reached Delhi airport, the visibility was 10 metres, not enough to land. They circled the for about an hour, but the fog did not lift. Air traffic control directed them to Jaipur airport, about 45 mins away. It was having a visibility of 300 m.

Unfortunately when the plane reached Jaipur, the visibility there fell---to 10 metres. But the pilot had no option but to land, because fuel was running low. Somehow, they landed, half on the runway and half on the grassy fields. The violent jolt set off the alarm. Oxygen masks came flying down---but only two of them were released---This was a prominent national carrier.

They had a narrow escape.

This set me thinking on an idea for safe landing of airplanes-at reduced costs and especially in poor visibility conditions.

This might sound crazy, but do bear with me. If viable, it could save human lives, time, and precious fuel..

The solution: Use a balloon

We need to go back to the days of balloons and zeppelins. Zeppelins are huge airships that were used before propeller aircraft. They were essentially huge balloons with a metal framework.


Feasibility study

A modern day jet aircraft such as the Boeing 747 is 76 m long and weighs about 100 tonnes. According to the law of buoyancy, we need a balloon that can displace air equal to this weight. Density of air at sea level is 1.225 kg/m3.  So we need an air-filled balloon of volume approximately 81650 cubic metres to carry the weight of the plane, without using the engine.

Conceive a cylindrical balloon of length 76 m and diameter 36 m, attached to the top of the plane. This will be about six times taller (thicker) than the plane (The cabin diameter of a 747 is 6.3 m.). This will be larger than the current largest hot air balloon, the George White Superbike balloon.

Research can find ways to reduce this size.

Deploying the balloon

When the pilot is circling the airport, his speed will be around 380 kmph. As he is ready to land, he inflates the balloon. This should not be difficult as we can redirect the jet exhaust to fill the balloon. The required volume will be more, because density of jet exhaust is only 0.5 kg/m3.

The fully inflated balloon will further reduce the speed of the plane. When the plane is suspended on the balloon, the pilot can guide it to the runway at a very low speed (perhaps less than 60 kmph- he doesn't need to stay afloat using speed).

Eventually, when he is directly above the runway, it is just a matter of touching down vertically, by releasing the air in a controlled manner.

Experiments will have to be done with 747 sized drones to check for any complications involved with huge sized balloons.

The benefits

  • Save tonnes of air fuel in circling over airports awaiting the landing signal. 
  • Reduce the length of the runway.
  • Land aircraft safely on runways with a vicious reputation, such as on mountains etc.

The cons

This makes planes more vulnerable to sabotage. The surveillance systems for the airport and vicinity will need to be fool proof.

What has this got to do with personal development? Perhaps nothing. However, solving humanity's problems is part of the challenges we must meet to develop our potential.

I would invite your feedback on this.
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