English Presentations by Hans Walrecht
presentations contain many pictures and videos. Pictures can tell a story
themselves and videos do the same, but better.
In my opinion it is very important to put a subject in a context (why then, why did they do it that way, what was the use of it?).
I like to reach a big audience, so I make use of
popular science and show the human side of the story, if possible. Some
presentations do have more layers, to satisfy the people who want to know a
little more. The same way modern educations works.
I am a retired teacher in primary education and
education for children with special needs. For the latter half of my career I
was involved in IT -especially the educational part. IT brought me into European
projects, in which IT was leading. In a few projects I was the coordinator.
Working in Primary Education leads to many subjects, broadening my interest, as you can see in the subjects below.
Technology and history I always liked most. That is why I’m a volunteer at the Steam Engine Museum in the Dutch town of Medemblik and the Aircraft museum “Aviodrome” in Lelystad.
Moreover I have been writing for papers and
magazines the last 50 years.
I live in Alkmaar, the Netherlands, just 25 miles North of Amsterdam.
I live in Alkmaar, the Netherlands, just 25 miles North of Amsterdam.
These are the subjects:
|01 The Invisible War||10 Aero Engines|
|02 The development of the jet engine during WW2||11 Moments of the Industrial Revolution|
|03 Wernher von Braun and the V2||12 ULTRA and Enigma|
|04 Pictures from Space||13 Red Ball Express|
|05 Dakota, the Allied Workhorse||Target for Tonight (by Theresia Kloosterboer)*|
|06 The Spitfire||14 Kids presentation "How does it work: The aeroplane"|
|07 The Great War at the Western Front||15 James Watt and the Steam Engine|
|08 The 14-18 Air War||16 The Steam Pumping Station of Medemblik|
|09 The de Havilland DH.98 Mosquito|
*) my partner
(The navigation beams and radar in WW2)
This presentation is
about the use of radio and has everything to do with WW2 era bombers and
I've made two versions:
The first for radio
amateurs, in which some subjects are extended, like the British “Chain
Home” radar and the “Magnetron”. And there is a link between the
Dutch Philips company (via Mullard) with British radar.
The second for a public
without knowledge about radio. Unfortunately I can’t tell the story
without informing the audience about the relationship between frequency
and wavelength. But that's all.
For the two types of
public the story is more or less this:
The beams of radio waves
that guided the German bombers to British targets, like their Knickebein
system, X and Y systems and what the British could do against it.
Further, the British
Chain Home radar, the German radar with Freya and Würzburg. The British
“Raid on Bruneval”, intended to capture parts of a German Würzburg
radar station, is a thrilling story
This starts the first
electronic warfare in history. Every measure evoked a countermeasure.
duration: 1½ hours
development of the jet
engine during WW2
paramount for military aircraft. British Royal Air Force pilot Frank
Whittle knew that at an early age and patented his design for a jet engine
in 1930. After much obstruction he could start his first jet engine in
1937. Support of the British authorities was poor until Rolls Royce
stepped in. After all Frank was “just an RAF captain” and no
Almost for nothing ($
800,000.-- ), the knowlegde of Frank Whittle came into the hands of the
Americans. Just to say “Thanks” to them, for all the war materiel
“lent” to Britain by the Lend Lease Act.
Nazi Germany was a little
late with the Heinkel jet engine, but was the “first” with a jet
flight in August 1939. Several German engine builders designed and built
jet engines during the war, but the quality was very poor compared
to the British engines.
Many pictures and
historical film fragments, including Frank Whittle playing himself in a
documentary about the “Wonder Engine”.
duration: 1¼ hours
The presentation starts with
a brief history of the rocket, German “Rocket-fever” (as a result of
the Versailles Treaty in 1919), the development of Wernher von Braun’s
"A" series by the German Army and the testing of the A4. And
more important: how does this thing work?
After loosing the
battle for Stalingrad the Germans choose a “wonder weapon”, their
Last Straw… The A4 becomes the missile V-2. Testing takes place at
Peenemünde in Germany. The British, suddenly aware of the existence of
this weapon, bomb the place in August 1943. Production had just started.
The Nazis move to the underground factory near Nordhausen. Prisoners of
the hard labor camp “Dora” (a satellite camp of Buchenwald) work until
their death in the very unhealthy galleries of “Mittelwerk”.
How did the Germans
launch their weapons? The Hague and surroundings have the honour of
becoming “Cape Canaveral behind the dunes”. Over a thousand V-2’s
were launched from there, even right from the middle of the town. What
damage did the V-2 do? How many lives were lost?
The end of the V-2 terror
leads to the beginning of the Space Adventure, which ultimately leads to
the “first step” of Neil Armstrong. Different rockets, same Germans...
Wernher von Braun plays a
significant role in this story. His dream was about travelling to other
worlds, like the Moon and planets. His dream ended in building a
weapon of mass destruction. But he gets a second chance and two decades
after WW2 his rockets put people in space and eventually on the Moon. The
dream has come true.
contains beautiful material which shows the preparation and launch of the
There are three flavours:
strong, medium and light. Please contact me about this.
duration: 1½ hours for the "light" version
from high above the Earth and in the vicinity of the Moon and planets have
always sparked our imagination. Astronauts and unmanned spacecraft showed
us intriguing worlds. Other than beautiful, these pictures are also useful.
We can check the health of our crops on Earth and forecast the weather
This is not a show
with the most beautiful pictures ever made, but the images illustrate the
way they are made.
In the 60’s telescopes
were not as good as today. The blurry pictures made us curious about what
was really there. Very soon in the Space Adventure spacecraft made the
first pictures of the Moon, Mars and the other near planets. But… taking
a picture of Mars at a distance of 200 million kilometers, how do we get
that on Earth?
The presentation shows us
how those pictures were made and we’re going back in time to see how
scientists got the best results with 1960’s technology.
I start with the old
chemical photography, like the astronauts used in their capsules, although
these cameras were heavily modified.
Then the vidicon
television recording tube, used as a photographic camera. The first
weather satellite “Tiros” had one, but “Voyager” used this way of
taking pictures too. The vidicon was succeeded by the CCD chip.
Scanning is a widely used
way of shooting pictures, used by Landsat, Meteosat and even the Viking
The Russian Luna 3, that
took the first picture of the far side of the moon in 1959, used a
combination of photography and an on board “fax”. So did the Lunar
Orbiters, in 1966 -67. LOR’s pictures produced a high definition
photographic atlas of the Moon.
duration: 1¼ hours
Dakota, the allied
A presentation about and "around" the Dakota.
What can we expect in
The DC-3 steps into the
military world and a new word arises: AIRLIFT. The plane becomes the C-47,
Dakota (named so by the British), C-53 Skytrooper, etc.
The Dakotas were used for
delivering paratroopers, dropping supplies, airlift operations and flying
from Lisbon to Londen with escaped pilots. The Dakota could also
“snatch” stranded gliders off the ground. The Dakotas could land
anywhere with their rugged landing gear. Sometimes they were 100%
overloaded, but did what they had to do.
After the war Dakotas
took part in the Berlin Air Bridge, Korea and even in the Vietnam War, as
a flying gunship. About 200 are still in flying condition.
duration: 1½ hours
The development of the British WW2 fighter, the Vickers Supermarine "Spitfire", according to specification F7/30 of the Air Ministry.
The performance and fame of the Spitfire in the Battle of Britain and the decisive role of the Hawker Hurricane in this battle
The reliable Rolls Royce Merlin engine, the World's most built aero engine of which the development kept up pace with the demands of Supermarine. The Merlin is very well known. Say: "Spitfire" and many people say: "Merlin!" and of course the other way around.
Some marks of the Spitfire are highlighted, because they are an important milestone in the history of the fighter. And of course the weaponry is not forgotten, just as the production of the complex Spitfire.
How good was the Spitfire compared to German contemporaries and in what roles was the Spitfire employed?
Restauration projects of the Spitfire -or how are they kept aloft?
duration: 1 hour
The Great War at the Western Front
...based on 8 places along the front
A war is terrible and fascinating at the same time. This surely applies to the Great War. It starts in the 19th century style, but becomes the first modern, total and technological warfare in history. There still are many traces to find of this war.
The Netherlands escaped the war by
pretending being neutral, but we knew there was a war going on, because of
blockades, shortages, stray bombs, thousands of mines washed ashore and a
great loss of fishing boats and freighters.
As a matter of fact the Great War is part 2 of a trilogy:
The presentation starts with the circumstances and events that led to this war. The life of the soldier is central: The Tommy (GB), Das Frontschwein (D) Le Poilu (F) en The Yank (USA).
The presentation brings us along the front
on the basis of 8 visits, from West-Flanders to the Vosges. Every spot is
a "Then and Now" story and also a hook for several subjects,
like trenches, life at the front, poison gas, the development of the first
tanks, trench-art, transportation, the air war, mining, the dug-outs,
equipment, start of plastic surgery and treating shell shock.
So, there is something to learn from this presentation for everybody.
duration: 2 hours
The 14-18 Air
The airplane matured during the Great War. The role of reconnaissance was very clear from the start. The Germans won the battle for Tannenberg because of their recce planes. Automatically the fighter developed as an answer to the hostile reconnaissance aircraft. Dropping bombs, first by hand and later from specially built bombers became a terror weapon against cities and so against civilians. Germany's first bombers were the airships, to intimidate the British. But halfway the war they found a way of shooting down the dreadful zeppelins. Real bombers soon followed and some were giants for their time and long after.
The aircraft industry started in small workshops, but was soon booming, in giant factories.
We take a good look at the development of airplanes, the training of the pilots, their work and the stories of chivalry.
The presentation ends with the precursor of the Royal Dutch Airforce. We started with just one hired plane in 1913. Acquiring warplanes was not that difficult. They just came out of the sky by engine trouble of fuel starvation: French and British planes in the South West and German planes in the East.
The audience will be surprised by all the developments achieved during the Great War and think: "What? Already in 14-18?"
duration: 1½ hours
The De Havilland DH.98 Mosquito
1 The plane is unarmed and therefore very fast
2 It has a crew of only two
It is made entirely of wood
De Havilland chooses wood
because of its great experience with this material and moreover it makes
little use of scarce metals. Furniture makers, coach builders and piano
builders could be employed. In this role those factories and workers could
take part in the war effort.
The Mosquito is the first
real “multirole combat aircraft” and was used as reconnaissance
plane, bomber, fighter-bomber, night fighter, pathfinder and the fright of the
German U boats.
Originally De Havilland
had only a bomber in mind, fast but unarmed. All the gun turrets on the big
bombers make such a plane very heavy. By omitting the gun turrets you can
save a lot of weight and morerover, turrets cause drag and this
reduces the speed. The Mosquito did not have turrets and by doing so
it could take a comparatively rather heavy bomb load, at great
For the same investment
the Mosquito could drop 4.5 times the bomb load of a Lancaster. In the
cost of human lives the two crew Mosquito did also better than the big bombers with
their crew varying from 7 - 10…
The “Wooden Folly”
became “The Wooden Wonder”, of which ultimately 7600 were built. There
are many video fragments to be enjoyed.
duration: 1¼ hours
It’s about How Things
Work. I do advise to choose the Piston Engines or the Jet. Not both in the
same presentation. If the presentation takes place in an aviation museum
or a museum in possession of aero engines, we can do a guided tour.
1 Piston Aero engines
2 Jet Engines
Both subjects take ¾ hours each
|Moments of the Industrial Revolution||
end of the 18th century was an era of great revolutions in North America
and France. The British Revolution was quite different; their social
revolution took place by the industrialisation of the country from the
The presentation starts
with the British Industrial Revolution and some examples in the USA. All
other Industrial Revolutions that followed sooner or later were more or
less copies of the British situation.
Situations, developments and inventions led to the industrialisation of Great Britain:
1. the natural resources like coal, iron, copper, tin and chalk.
2. the waterpower of rivers.
Problems with ground water led to the invention of the first working steam
engine by Thomas Newcomen. James Watt improved this engine and
developed it into a rotational engine. This ultimately led to an unruly
expansion of the industry.
In 1760 many people
worked at home; in 1820 many worked in factories. What happened?
We follow the
developments in the 18th and 19th century and after that the situation in
the Netherlands, which deviated strongly from the industrialisation in
The consequences of the
industrialisation are of course not forgotten; the dark side like the
living conditions, long working hours, exploitation and diseases.
I have also version that
is tailored to a female public.
duration: 1 hour
ULTRA and Enigma
the code name of the total British efforts in decrypting the German
ciphers of WW2. The Germans waged a very mobile war, so the messages had
to be send by radio and this could be received by anyone.
The Germans never knew
that the British and later the Americans could read nearly all traffic
between commands and armies, squadrons and ships.
This was such an
important and decisive source of information, that “Most Secret” was
not enough. It became “ULTRA secret”, hence the name ULTRA. Because of
safety reasons the source of information was always concealed.
The decrypting took place
in the huts near Bletchley Park and the villa’s dispersed over the
premises. At the peak nearly 10,000 people were employed in decrypting and
processing the coded messages. Spread over Great Britain and non occupied
Europe, 8,000 people of the “Y service” (wireless service) listened to
the German coded messages. These were precisely written down and sent to
The code machine
“Enigma” is well known, and in the twenties of the 19th century
everybody could buy one. But during the war it became more complicated. The British,
however, could keep on with decrypting messages, also helped by
errors made by the German operators.
For the top secret German
messages the complex “Geheimschreiber” was used. To decrypt
those messages the British build the first computer, Colossus.
The presentation contains
historical summary of different methods of coding, shows how Enigma was
used by the soldiers at the front (with help of the beautiful simulator of
Dirk Rijmenants), how the messages were received, how to crack the code of
the day and what happened with the information.
After the war general
Eisenhower said: "Ultra has been decisive to Allied victory".
|Red Ball Express||
The Red Ball express is a
tiny but important part of the logistic efforts just after the D-Day
landings in 1944.
The story begins in Great
Britain, that nearly sinks under the weight of soldiers, equipment, tanks,
moveable harbours, PLUTO fuel lines and an immense stockpile.
Just after D-Day the
materials pile up on the beaches of Normandy. The Command expected a slow
progress in taking down the German armies. However, from July onwards the
fronts are moving very fast, so fast that problems arise for fuel and
ammunition. The regular logistics are not able to cope and the Red Ball
Express is established. 6,000 lorries drive day and night on specially
allocated roads to bring the stuff at the front, a dangerous job.
This is a story of
soldiers who drive the ever longer routes, after a few hours of training,
with hardly time to rest well. Lack of sleep was the greatest enemy.
This is also the story of the GMC trucks, the Autocars, the Diamond T M20’s and other cars. And of black soldiers...
duration: ¾ hours
Target for Tonight
presentation will suit a wide audience and is not technical.
During WW2 thousands of
bombers passed the Dutch airspace on their way to targets in Germany, and
of the crew members was the bomb aimer.
The experiences of a now
98 years old British Royal Air Force veteran are the foundation of this
presentation. He completed 22 missions, dropped food over the occupied
Netherlands and made repatriation flights. The legendary British Lancaster
bomber played a leading role in his story.
The presentation is about
the work and the danger on board, the impact on the young crew members,
the airplane and its bomb load and situations that really took place
during and around the missions.
The presentation is easy to follow, even for those without prior knowledge about this subject.
duration: 1½ hours and a break halfway
Kids presentation How does it work: the
A short presentation
in which we learn about the first flights, air resistance, streamline, how
a wing works (at two levels), the propeller, the propulsion, stearing,
“light and strong”, the jet (at two levels) and brakes.
It’s intended for kids
of 10-12 years of age, approximately.
At the end we fold a paper airplane and make it steerable.
approx. ¾ hours
James Watt and the
This presentation was
made in 2019, because then it was 250 years ago that Watt had patented his
improved steam engine (1769) and 200 years since he passed away.
Watt improved the first
capable (atmospheric) steam engine, made by Thomas Newcomen in 1712. He
added a condenser and went even further. This 1769 engine was more
economic. Fifteen years later Watt made a giant leap by making his steam
engine double acting.
We follow James Watt in
his early days, his acquaintance with the Newcomen engine and his
financial problems while building a better steam engine. Meeting Matthew
Boulton was very important for him. This forward-thinking manufacturer,
with his Soho Manufactory (then the biggest factory in the world) made it possible
to live of building steam engines.
Soho was the first mass production factory ever.
The framework of the
story is the “Enlightenment” of the 18th century, a movement in which
people did not take things for granted. No, they did experiments, did
duration: 1¼ hours
The Steam Engine Pumping Station of
is a polder in the North West of the
Netherlands. As you probably will know, our country lies for the greater
part below sea level. It was not always like this. In fact we created our
own problem for a part because of draining the bog, which caused the soil
to go down. Other reasons are the rising of the sea level and the
subsiding of the surface over ages. But in fact we are living in a bathtub.
The presentation shows
the history of the land, from the most recent ice age into the Middle Ages and how we
mastered the seawater by building dikes en using windmills. But windmills
need wind and can only pump when the tide is not too high. In other words:
the mills could not always do their job. That is the reason for building
the auxiliary steam pumping station in 1869. After many alterations the
new part of the pumping station was built. It opened in 1907 and replaced
the last remaining windmills in the neighbourhood of the pumping station
You also learn about the
use of steam engines, a producer gas steam motor and the return to steam
again in 1924.
It provides insight in our struggle against the rain and seawater and this example stands for many other pumping stations.
Since 1985 the Pumping
duration: 1 hour
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