Tuesday, April 21, 2020

This Rare Blip Of A Clip Shows India's First Hovercraft Performing Donuts

Dr. Kalam's baby, whose requirement, the Forces are increasingly expressing today.
This gem is, perhaps, the only video footage available, that captures the 1st ever Hovercraft built in India, as it is put through its paces.
The ADE GEM-1 Hovercraft, christened Nandi, India's maiden attempt at such development, has entered folklore, thanks to the project's Team Leader, Dr. APJ Abdul Kalam. In his Autobiography, Wings Of Fire [affiliate URL], he recalled how his newly-constituted team was tasked to "design and develop an indigenous hovercraft prototype as a Ground Equipment Machine [GEM]". This the, then, Defence Minister VK Krishna Menon envisaged would be "the beginning of the indigenous development of India's Defence equipment". Huge responsibilities on the shoulders of Dr. Kalam who, as a Senior Scientific Assistant, was still a greenhorn then. Without the luxury of institutional knowledge or Engineering base at his disposal, he had to go back to school, literally, to learn the ropes. Reminiscing those days, with a degree of fondness,
"When I was working in Aeronautical Development Establishment at Bangalore in the year 1958, I took up the development of Hovercraft. Hovercraft design needed the development of a ducted contra-rotating propeller for creating a smooth flow balancing the torques. I did not know how to design a contra-rotating propeller though I knew how to design a conventional propeller from MIT aeronautical course. Some of my friends told me that I can approach Prof. Satish Dhawan of Indian Institute of Science, who was well known for his aeronautical research, for help in designing the ducted contra-rotating propeller.
I took permission from my Director Dr. Mediratta and went to Prof. Satish Dhawan who was sitting in a small room in Indian Institute of Science with lot of books in the background and a blackboard on the wall. Prof. Satish Dhawan asked me what was the problem that I would like to discuss? I explained the problem to Prof. Dhawan about my project work. He told me that it is really a challenging task and he would teach me the design if I attend his classes in IISc between 2.00 p.m. to 3.00 p.m. on all Saturdays for the next Six weeks. He was a visionary teacher. He prepared the schedule for the entire course and wrote it on the black board. He also gave me the reference material and books I should read before I start attending the course. I considered, this as a great opportunity and I started attending the discussion and started meeting him regularly. Before commencing each meeting, he would ask critical questions and assess my understanding of the subject. That was for the first time I realized how a good teacher prepares himself for teaching with meticulous planning and prepares the student for acquisition of knowledge. This process continued for the next six weeks. I got the capability for designing the contra-rotating propeller. Prof. Dhawan told me that I am ready for developing the contra-rotating propeller for a given hovercraft configuration."
Dr. Kalam's team successfully demonstrated the fruits of it's efforts sometime in the early 60s, 6 months ahead of schedule, it's said. The video captures an invaluable moment of India's Technological history. Unfortunately, myopic decision-making prematurely brought down the curtains on a project of great potential. One can read more about the Hovercraft & circumstances surrounding it, in the Wings of Fire [affiliate URL]. His first of many Baptisms by fire, towards achieving objectives of National self-reliance, one he would invariably speak about at any major talk he gave. His first-born, it was.
Kalam Hovercraft ADE Bangalore India - 01
It must be stated that at least 2 variants of the Hovercraft, generically called Air Cushion Vehicle [ACV], had been built at the Aeronautical Development Establishment [ADE]. The ADE GEM-1 was the first prototype, that Dr. Kalam mentioned in his book. As seen in the footage, it contained a single point of inlet air. Yet, as seen in the above picture, another prototype ADE also built, having 2 inlet positions, one each on its fore and aft. The one seen above, is likely the follow-on that VK Menon encouraged Dr. Kalam to build, with a bigger Powerplant, that he wrote of in his Autobiography. The final prototype that was built was said to generate a lift of 1500 mm. It would imply a beam of around 9 metres!
From the glimpses offered by the clip, it looks like the Hovercraft's body was formed with a  Tarpaulin enclosing a metallic skeletal frame, held together with rope. The follow-on model, above, showed improved build quality. Controls involved a single floor-mounted Stick Shift for manoeuvring. The operator, going around in circles, doing donuts.
Hovercraft - Working Principle - 01
Utility of an Air-Cushion Vehicle is best demonstrated on transition surfaces, between water and dry land. Sludge wouldn't permit a Marine vessel into it, while also not providing traction for a wheeled transporter. A Hovercraft functions with the help of a Pad Lifting System. It primarily consists of a Centrifugal Fan blower, with ducted, self-propelled jack-up propeller, capable of accelerating large air volumes to sufficiently higher than atmospheric pressure - extreme high pressure not necessary. The Apron, usually made from Nylon Rubber, guides this air into space underneath the ACV Hull, keeping it entrapped there. The Pressure differential w.r.t. the Atmosphere, causes the Hull to be lifted up, suspending it over a constant air cushion. To ensure stability, an ACV's lift is usually designed to be restricted to less than 16% of the Hull width.

Once on the air cushion, the vehicle can be manoeuvred much freely, owing to the reduced friction encountered with air. Manoeuvrability is achieved with the help of Rudder controls affixed to the Propeller. Normally, these are powered with the help of Piston-Cylinder CI Engines. The Soviet-era Project 1239 Bora-class Guided Missile Hovercraft, however, is a different beast altogether. Bristling with an array of Cruise Missiles, Anti-Aircraft Missiles & Artillery Guns, with a full-load displacement of 1,000 MT, the behemoth is powered with the help of 2 Gas Turbines Engines & 4 Diesel Engines, cumulatively producing a staggering 60,600 H.P. of propulsive power. Killer specs, indeed. A Sidewall ACV, its operations are restricted to over water.
Post the Kalam-driven ADE effort, development of an indigenous Hovercraft never again gathered steam in any meaningful way. The Kanpur-based Aerial Delivery Research & Development Establishment [ADRDE] carried out some ACV-related studies that, unfortunately, did not proceed beyond the 'Experimental' stage. Effort prioritisation, based on resource availability played a deciding factor in project undertakings.
Hovercraft Indian Coast Guard Griffon-Class 8000TD - 01
A lost opportunity in establishing self-sufficiency in ability to build such Amphibious systems. It has proven to be an ideal transport for patrolling the vast expanses of the marshlands of Sir Creek & riverine of Sundarbans Delta. The Indian Coast Guard [ICG] presently operates 18 Griffon 8000TD-Class of Air Cushion Vehicle, designed by the UK-based Griffon Hovercraft Ltd. Of the initial order of 6, placed in 2003, 4 were assembled in India, by the Kolkata-based Garden Reach Shipbuilders Establishment [GRSE], using supplied CKD kits. Ruing lost opportunity, the 2nd time around, when ICG placed an even larger follow-on order of 12 with the British Co., it got no share of the pie. This exclusion was resulted by GRSE's own earlier decision announcing that, "Due to inadequate demand for hover crafts in the Indian market we decided to discontinue with further efforts to indigenize hover craft building.". These relatively recent inductions find a pride of place in the Coast Guard's fleet, who could be going in for more. The Border Security Force [BSF], similarly has a long-held intent of acquiring them, with the Army evincing interest in becoming an operator too, for which the Goa Shipyard Ltd. has put it's hat in the ring, with its hand held by the same Griffon Co.
That small attempt in the 60s to build a transporter travelling over air set the ball rolling towards greater Technological achievements. Not pursuing it further, big mistake.