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Letters: Airships: a transport idea that won't go away

Airships: a transport idea that won’t go away

The article on airships is not the first to show the many advantages of lighter than air machines.

In April 1975, there was an article in NCE about “Skyship”, a 10m diameter lenticular shape prototype airship, designed by me and flown at Cardington in one of the hangers.

It had eight drive units with, in total, just under one horse power, but could lift over 60kg and travel at around 10 mph. Unlike planes, it could stop in flight, and even reverse.

The company, then Thermo-Skyships, had carried out wind tunnel tests and our aim was to build a ship capable of carrying up to 400t and be used for heavy lift and possibly car transport.

One of the features of the design of the larger “Thermo Skyships” was to make use of the heat produced from the engines to provide extra lift in the form of either hot air or steam.

This could be easily controlled as it would be possible to get rid of this lift quickly and in a controlled manner.

  • Robin Wren (F), rjcwren@aol.com

The article about airships (NCE 22-29 July) prompted me to wonder whether any reader of NCE involved in the design of lighter-than-air craft could explain something which has puzzled me ever since I had an interesting discussion with a hot air balloonist.

He explained to me why he used hot air not helium, namely the ease of controlling height. To descend at the end of a helium balloon flight he would have to release helium which would have cost more than all the propane he needed for a hot air flight.

What I have wondered ever since is why no one (to my knowledge) has come up with an airship that combines the two mediums; an almost lighter than air helium filled envelope with a hot air chamber which could be used for height control.

After initial lift at take-off heat from motors providing forward propulsion could be used to maintain the hot air. At the end of a flight only hot air, not expensive helium, would need to be released to descend to a landing.

Can anyone tell me if such a concept has been explored or if not why not?

  • Patrick Schicker (M ret), patrick.schicker @btinternet.com

Ironing out busway ‘truths’

May I be permitted to comment on the recent correspondence about “Guided Busways”.

According to David Eve “guidance allows the bus rapid transit (BRT) system to achieve rail-like precision level docking at stops” (NCE 22-29 July).

Here in York, without the benefit of BRT, my bus achieves the same level of accuracy through a raised kerb stop, a professional driver, a steering wheel and a footbrake.

It is then suggested that when this is coupled with an “off-bus” payment system it “will maintain reliability and credibility”. Transport for London has operated this policy in central London for the last 10-plus years without guided busways so why should this be a benefit for “guided busways” only?

As to reliability, if the bus in front is late then all those following risk being late as well. On an asphalt road overtaking would solve that.

It is accepted that the costs associated with re-opening the Cambridge-St Ives route as a railway were excessive. A lot of this is down to the current “risk averse” nature of the “heavy” railway industry. However, the guided busway solution is a railway minus the iron rails. The result is very little cost saving with none of the flexibility.

  • Neil Raw, 11 Oriel Grove, York

Nuclear power’s lost generation

It was refreshing to read about the “Nuclear Lessons Initiative” (NCE 22-29 July) and the initial discussion hosted by the ICE.

I wondered which engineers, academics and who in “government” had direct experience of previous nuclear power construction projects (bearing in mind that the last project, Sizewell B, was initiated some 30 years ago) to be able to have such a discussion.

Previous governments have attempted to maintain expertise within the nuclear construction industry but as the decades passed the age profile of those previously directly involved has mainly frustrated such attempts.

What happened to the wealth of data gathered during “pre-application” studies in Central Electricity Generating Board days in preparation for the fleet of pressurised water reactors to be constructed in the 1980s.

Hopefully it exists somewhere and is freely available to those now wishing to make the best start to the new nuclear power programme.

  • Trevor Jessop (F), trevorjessop@btinternet.com

Maintaining deadline focus

Travelling about the UK one sees numerous civil engineering contracts on-going, so many of which appear to take an excessive amount of time to complete.

One solution, successfully adopted in Hong Kong at least 35 years ago was to introduce, as part of the contract, a sign board. containing an artist’s impression of what was to be built, the name of the contractor, a project description, a start date and a completion date.

This last date had an almost miraculous effect on contractors as none wanted it publicly seen that they had exceeded the completion date. It was a rare event for contracts to over-run.
The cost of such sign boards was peanuts, and exceedingly effective. Why not try it here?

  • Don Mudd (M), muddlin@along.plus.com

Impact resistant

The article on the monitoring system at the Shard (NCE 22-29 July) highlighted an interesting part of the project that is not often reported.

I would, however, like to correct the statement that the Shard will “have a considerable impact on the surrounding ground and structures”.

In fact there has been very little movement in the ground outside the site, largely because the load imposed by the Shard almost exactly balances the load removed by demolition of the previous building and excavation for the new basement.

WSP specified the monitoring system referred to in the article to confirm our predictions, and to reassure surrounding property owners.

  • John Parker (M), technical director, WSP Cantor Seinuk, WSP House, 70 Chancery Lane, London, WC2A 1AF

Ground source misconception

The article Ground Control (NCE 22-29 July) states that “there is just one company developing geothermal power, located in Cornwall”.

This is incorrect since EGS Energy is far advanced in developing its plans at the Eden Project in Cornwall for a 3.8MWe and 3.45MWt power station.

We are now in the later stage of putting together the planning application for this project.

We started the company with a public seminar at the Geological Society in London in April 2009, attended by around 140 people and EGS Energy is now leading the development of deep geothermal energy resources in the UK and Europe on a commercial scale through its unique access to engineered geothermal system technology and know-how.

  • Guy Macpherson-Grant, managing director, EGS Energy, guymg@egs-energy.com

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