Drones

Today's trivia is all about drones, and some of the interesting developments in the field of drones.

One of the key characteristics of a drone or UAV (Unmanned Aerial Vehicle) is that it unpiloted. Control for the aircraft might be remote control or it might have a varying degree of autonomous control built into it.

A drone configured for racing, as we'll see more of later.

We will only be focusing on the civilian usage of drones for this article. Military usage is ever expanding in a variety of roles. The US military is now training more UAV pilots than conventional aircraft pilots.

Technology

There have been a number of key contributing technologies which have all recently been developed to bring drones to the wider consumer market. Remote controlled aircraft have always been present in the market for hobbyists. Drones however are marketed at a much wider audience and a price which makes that feasible. It is now even easier to build your own drone.

The following are the key components which make up a quad-copter.

Battery - The battery of choice is LiPo - Lithium Polymer or more accurately a hybrid which uses a liquid electrolye instead of a completely dry cell LiPo. Functionally we are dealing a light, compact and high energy density battery technology which gives out more power than conventional rechargeable battery technologies. Because it is made of folded layers of coated material it also does not need to be packaged in a metal container thus saving weight. A trade off in these batteries is that they have less potential charges than earlier batteries.

Motors - The motors of drones are another key area of development. Small and compact with high power outputs. Either brushed or brushless motors are used, with brushless motors becoming increasingly popular. Brushless motors flip the existing motor design on it head by having the rotating part of the motor hold the permanent magnet, and the electro magnets are fixed inside the casing. This allows brushless motors increased efficiency over brushed motors.

Example of the sensor board which could be combined with Arduino to build your own drone

Flight Controller - The flight controller of a drone is made up of three main parts. Electronic Speed Control drives the motors, Inertial Measurement Unit provides position inputs and the Flight Controller which is typically an 8-bit processor. These three elements combined together allow the drone to not only hover but perform a whole range of operations.

13 people indicate they have made this mini quadcopter design

Frame - There are numerous frames to choose from, each with a different intended purpose. It is also possible to 3D print the frame for a drone. This allows even more customisation around the design and functionality of the drone. The sharing and refinement of designs might further simplify the ability of individuals to build their own drones.

Uses

The usage of drones has grown rather dramatically. The following are a subset of the uses for Unmanned Aerial Vehicles:

Delivery: Both Google, Amazon and others are actively exploring the idea of drone based delivery systems. I would hazard a guess that if they succeed in participating with the regulatory authorities in each country, drone deliveries will be actual reality.

The latest version of the proposed Amazon Prime Air drone, video

Photography: From amateur photography to journalism to wildlife research and more. The fact that a camera can be mounted on a drone and the image recorded or transmitted back makes for very compelling options. Footage often appears in the media which was recorded by a drone.

Getting unique views of something which might not be possible otherwise video

Another example of gaining a unique perspective

Racing: Perhaps the most exciting possibility of drones is the ability to race them. Typically done using FPV (First Person View) allowing the pilot to see the view from the camera on the drone. Because drones fly in a three dimensional space it also makes sense to lay out courses in locations which lend themselves well to this. Drone racing is only just beginning, but it is clear that there is interest in this novel and exciting sport.

Racing drones in an empty stadium with Drone Racing League

Another example of drones and their maneuverability Drone Racing

Safety

The aviation authorities of the US and UK and many others are rapidly issuing guidelines explaining how people should fly their drones. This is a pivotal time for drones and legislation and the next few years will see developments particularly in the commercial area of drone usage.

Flying safely should be an obvious requirement, I would imagine because people are physically disconnected from their drone they make different decisions. There doesn't seem to be much people cannot crash their drone into:

• Planes
• Trains
• Buildings
• Lakes
• Power lines
• Athletes
• The White House

etc.

Wildlife may not be impressed with your drone

Tiffin

Todays trivia is all about Tiffin, or more specifically the word Tiffin.

The word is defined in the dictionary as being synonymous with lunch, or the eating of lunch. Specifically we note that it appears to be first introduced around 1775-85 as a variant of tiffing, equivalent to tiff to sip, drink.

Tiffin (Indian English)

Food served in the popular tiffin tins

In India, we learn that tiffin refers to a midday meal, though we imagine that you could infact eat tiffin at any time of day. Tiffin does not have to be specifically a savory dish, it could be sweet as well. However it is all tiffin. Including the term for the tins it is served in, also tiffin.

In India food cooked at home with care and love is considered to deliver not only healthy (and relatively cheap) food but also divine contentment. So much so that there is a growing trend of eating home cooked food at work. Workers can pay to have food cooked at home delivered to their workplace rather than eating out at lunch time.

Dabba-Wallah

This trend is gaining popularity, particularly in the city of Mumbai (formerly Bombay). Workers often have to leave home early in the morning before there is time to prepare food, and squeeze into packed trains. Instead they can pay (200Rs = £2) to have their food collected from their home at 10am by a Dabba Walla, literally a lunch box delivery man.

The tiffin is then delivered using a combination of bicycle, train and on foot to the recipient in their place of work by lunch time, still hot and ready to eat. They then return the tiffin tins to the household in the evening.

Once arrived at the station, tiffins are sorted and loaded onto the comparatively quiet 10AM train

This impressive hot food service is provided throughout the sprawling city by the the Mumbai Tiffin Box Suppliers Association. A charity which has been operating for the last 120 years and employs 4,500 dabba-wallahs, many of whom are semi-literate.

A key characteristic of the service provided is its high reliability. Out of 200,000 tiffins delivered daily maybe once or twice a month one of the dabba-wallahs might make a mistake. This staggeringly high level of reliability is a sign of pride among the dabba-wallahs, many of whom have a limited level of education. One customer is quoted as preferring to return his daily wage home in the empty tiffin, rather than in his pocket on the train home because he trusts the dabba-wallah delivery network so much.

Code

tiffin routing code

To achieve such a sophisticated delivery network in a complex city is commendable. The workers do all of this without maps, GPS or navigation aids, relying solely on a code system written on the top of each tiffin which informs them:

• Source: A dabba-wallah will know each customer in their group area. The dabba-wallah will be part of a group number.
• Transit: Once tiffins arrive at the source station, they are sorted and loaded onto the train. At the destination station they are unloaded and handed off to the delivery team.
• Destination: The delivery team will sort and hand out tiffins to groups who know the delivery location.

With the use of color coding and alphanumerics the tiffen can reliably make round trips across the city to its intended recipient.

Tiffin (Scottish)

Tiffen as per the Scottish is a Christmas time dessert. Resembling a chocolate cake-like confectionary commonly comprising of crushed digestive or rich tea biscuits (cookies), cocoa powder, golden syrup and dried fruit with a top layer of melted chocolate.

Said to originate in the 1900s in Troon, Scotland, I was sadly unable to verify this fact. However the interesting part is that we know the same word tiff was in use in the Scotish dictionary from around the same period.

Recipe

There are lots of variations on this recipe, here is an easy one which uses Maltesers:

• 200g milk chocolate (I use Lindt milk chocolate)
• 100g unsalted butter
• 2 tbsp golden syrup
• 125g digestive biscuits
• 135g bag of Maltesers

For the topping:

• 200g milk chocolate
• 25g unsalted butter
• 1 tsp golden syrup

Method (condensed):

• Melt chocolate, butter and syrup together
• Crush Maltesers and mix into melted chocolate
• Pour into greased baking tin
• Melt topping chocolate, butter and syrup
• Spread over the mixture in the tin
• Cover and refrigerate for 1-2 hours

Eat.

References:

• Dabba-Wallah TED talk
• Journey of a tiffen
• Tiffin Company detail
• Research Paper

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Soyuz TMA Re-Entry

Today's trivia dives into the detail of how Astronauts return from space.

On March 1st 2016 Scott Kelly (NASA) and Mikhail Korniyenko (RSC) returned to Earth in the Soyuz-TMA spacecraft. How does an astronaut return from orbit in this spacecraft?

Soyuz TMA spacecraft

The Soyuz TMA-M (transport, modified, anthropometric) is the latest in a very slow evolution of Russian human-rated spacecraft.

Soyuz TMA-17 before docking

Primary Functions

• Carry up to 3 crew into a variety of orbits
• Orbital transit
• Docking
• De-orbit and re-entry
• Soft landing

Its design philosophy is based around automation. Most of the main tasks required for re-entry are automatic. It can also be fully controlled from ground control stations. Crew can override as required, for example if they encounter an emergency. A lot of its design is focused around many levels of redundancy. Automated systems have usually two backup systems and include some kind of reasonable contingency if all were to fail.

Artistic image of the 17 July 1975 Apollo Soyuz Test Program (ASTP) the first docking of a Russian and American spacecraft showing comparable scale of the Apollo and Soyuz spacecraft

The first Soyuz was developed at the same time as the American Apollo program as part of a secretive Soviet lunar mission which was eventually halted due to a number of reasons. This same craft has undergone three main design evolutions to spacecraft used today.

Its use as a crew transportation and return spacecraft for space stations was first proposed by the Russians as the Automatic Crew Return Vehicle for both the joint NASA/RSC project on the Mir space station and the International Stance Station. If the station was damaged by space debris or a medical evacuation was required, the Soyuz would be used for these tasks. With its 110+ manned launches it has an extensive track record.

Undock

Soyuz TMA-03M spacecraft (left) eases toward its docking with the Russian-built Mini-Research Module 1

Once the crew are onboard and suited up in their pressure suits, they will go through various checklists to prepare for the flight. This takes in excess of three hours, which may include time verifying there are no drops in pressure within Soyuz.

View from the on board computer system pilots view with information overlay

Once released from the station, springs inside the docking ring push the craft away from the station. The Soyuz is only able to use its reaction control thrusters once it is far enough (20m) away from the station to prevent covering the station in liquid propellant.

De-Orbit burn

The de-orbit burn is also automatic. Once the spacecraft position is accurately known, the computer calculates the angle and duration of burn to get the required landing trajectory to a pre-determined landing site.

This burn is critical as it determines the angle of descent into the atmosphere:

• Too shallow and it will bounce off the atmosphere without showing down, resulting in overheating.
• Too steep and the crew will experience too much deceleration force (in excess of 10g) which may be fatal for the crew.

Soyuz is made up of three modules, at the front is the Orbital Module, in the middle is the Descent Module and at the back is the Service Module which includes the solar panels

Once the de-orbit burn is complete, the Orbital and Service modules are jettisoned. Explosive bolts fire which push the jettisoned modules away from the descent module. They will burn up on the atmosphere on reentry. If for some reason the modules do not separate correctly, the Soyuz is designed so aerodynamic forces will break the modules apart in any case.

30 minutes later the spacecraft will cross the Kármán line at 100km and come into contact with enough atmosphere to start re-entry.

Re-Entry

Seen from the International Space Station, the Soyuz TMA-05M descent module begins to re-enter the Earth's atmosphere, leaving a plasma trail as the Expedition 33 crew streaks toward a pre-dawn landing on the steppe of Kazakhstan.

During re-entry the capsule will decelerate from orbital velocity (17,000mph) down to speeds where the parachutes can be deployed. This deceleration is the result of the capsule crashing into the atmosphere. The heat shield of Soyuz is rated to withstand the incredible temperatures of re-entry, however the shape is also crucial as well:

"If the reentry vehicle is made blunt, air cannot "get out of the way" quickly enough, and acts as an air cushion to push the shock wave and heated shock layer forward away from the vehicle. Since most of the hot gases are no longer in direct contact with the vehicle, the heat energy would stay in the shocked gas and simply move around the vehicle to later dissipate into the atmosphere." - Wikipedia

The re-entry is also completely automatic. The computer will use reaction control thrusters to create a steering effect, enough to keep it aligned with its target landing site. Should the computer fail, or an emergency arise such as depressurisation, the backup re-entry process will start a ballistic re-entry. This re-entry is faster because it is steeper but induces up to 8g of force on the crew.

Re-Entry as seen from the inside window of Soyuz Buzz Feed

Landing

Once the descent has slowed enough, the parachutes can be deployed. First two drogue chutes, followed by a main chute. This slows the capsule down to the required landing speed.

Around the same time the heat shield, and external window covers are jettisoned.

Just before landing 6 soft landing solid rockets fire to improve the landing which an astronaut still describe as "feeling like you are being hit by a truck".

During the early Soviet missions the landing site was less predictable. The cosmonaut would expect to be greeted by team parachuted in to assist. Now days helicopters and ground support vehicles arrive at the predetermined landing site and are in constant communication with the capsule as it lands.

Soyuz TMA-01M spacecraft shortly after the capsule landed

References:

• NASA Overview
• Detail on Soyuz
• PDF on Re-entry Detail
• YouTube - ESA Landing Sequence for crew training
• YouTube - Roscosmos State Corporation
• YouTube - Re-Entry Footage from Apollo 11 1969
• YouTube - Re-Entry Footage from Orion 2015

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