How do radial engines work ?

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February 14, 2016
An aircraft's propeller is powered by a radial engine

Nothing much to give introduction on Radial engines except that they were widely used during World War II.
More efficiency & power were the greatest needs of that time. Having many advantages over the rotary engines used in World War I, radial engines proved to be great for aircrafts.

Radial engines :-

Radial engines are Internal Combustion Engines same alike the piston-cylinder arrangement except one change – the piston in the cylinders radiate(oscillate/reciprocate) outward from the central crankcase(like the rims of a tire). Radial engines are also called “Star engines” as they resemble the shape of a star when viewed from the front side. The radial configuration was very commonly used for aircraft engines before the gas turbine engines came into existence.

History :-
C. M. Manly constructed a water cooled 5 cylinder radial engine in 1901 – a conversion of rotary engine for an Aerodrome aircraft. The machine was unsuccessful, but the Manly-Balzer engine(later in 1903) pointed the way to high power, low weight aircraft engines.

Parts :-

Piston – The piston is used to transfer the expanding force of gases to mechanical rotation of crankshaft via a connecting rod. The piston is able to do this because it is secured tightly within cylinder using piston rings to minimize the clearance between cylinder and piston !
Crankshaft – A crankshaft is a part which is able to convert the reciprocating motion to rotational motion.
Connecting rod – A connecting rod transfers motion from a piston to crankshaft which acts as a lever arm.
Inlet & Outlet valves – It allows to enter fresh air with fuel & to exit the spent air-fuel mixture from the cylinder.
Articulating rod assembly – The assembly joins all the connecting rods of pistons with a single part as the cylinders are coplanar (discussed later).
Spark Plug – A spark plug delivers electric current to the combustion chamber which ignites the air-fuel mixture leading to abrupt expansion of gas.




Working :-

Animation of radial engines
Animation of a radial engine consisting of 5 cylinders ! source:- wikipedia

Radial engines work like any other 4 stroke engines. They both have similar parts but their construction & design are different. Each cylinder has an intake, compression, power & exhaust stroke.
If you consider the above engine consisting 5 cylinders, numbering the top as 1 & going clockwise, then the firing order is 1-3-5-2-4 & again 1 !
Nothing complicated to understand, the firing order & opening/closing of valves are such adjusted that the ongoing power stroke directly helps compress the next cylinder to fire, making the motion more uniform.

Why odd number of cylinders ?
For smoother operation of the engine, consistent power should be produced. For producing consisting power, odd number of cylinders are used so that every other piston firing order can be achieved.
If an even number of cylinders were used, an equally timed firing cycle would not be feasible.[Source]

How do inlet & outlet valves open & close at that particular times of strokes ?
Unlike the engines used in cars & bikes, the axes of the cylinders are coplanar, hence the typical camshaft cannot be used for controlling the inlet & outlet valves nor the same crankshaft could be use to deliver the power.
Instead the pistons are connected to the crankshaft with a master-and-articulating-rod assembly.  I know it is quite difficult to imagine especially which we’ve never heard of, so I’ve included an animation 🙂 !

The articulating rod assembly which controls the inlet & outlet valves by moving 2 rods.
The articulating rod assembly which controls the inlet & outlet valves by moving 2 rods.

Radial engines generally use poppet valves which are overhead the cylinders. These valves are driven by the push rods- which are controlled by the cam plate which rotates in opposite direction than of the crankshaft.
The cam is made to spin slow with the help of a geared mechanism.

Advantages :-

  • Smoother operations :- Radial engines are great at producing consistent power(contribution of each piston) as discussed earlier. This consistency helps the engine to run smoother.
  • Tougher & easier maintainence :- All thanks to simple design which makes it less vulnerable to damage as well as it makes much more easier for maintenance workers during routine check-up.
  • Cost :- Radial engines’ parts, repair costs, & maintainence costs are inexpensive. A cheaper option is welcomed blindfoldedly in a expensive field of work.

Disadvantages :-

    • Drag :- As the cylinders are clearly exposed to the airflow during flight, drag increases considerably.
    • Visiblity :- The pilot may experience visibility problems, due to huge single engines located near the nose of aircrafts.
    • Installation :- It is more difficult to ensure adequate cooling air in a buried engine installation.




Gas turbines OR popularly known as jet engines stole the market as they were much more powerful, efficient & light weight than radial engines.
To know more about gas turbines/jet engines, read one of my previous articles in which I have explained in detail about working of  jet engines !
I have also written a post on types of jet engines (it’s pretty cool…you should give it a try 😉 )

Connection, Interfacing & Programming of Ultrasonic Sensor HC-SR04

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February 13, 2016

Today I will give you a tutorial on the Ultrasonic sensor HC-SR04 ! Also called as PING sensor or RANGE sensor; it is one of the most basic & easiest sensors of the beginners kit ! more “Connection, Interfacing & Programming of Ultrasonic Sensor HC-SR04”

Types of Jet Propulsion Engines (animations)!

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January 22, 2016
types of jet engines compared

The first jet engine successfully flew in August, 1939.
Hans von Ohain of Germany was the designer of the first operational jet engine, though credit for the invention of the jet engine went to Great Britain’s Frank Whittle. Whittle, who registered a patent for the turbojet engine in 1930, received that recognition but did not perform a flight test until 1941.
Its been more than 75 years, there has been continuous development in jet engines & has a significant increase in their efficiency. There are many types of jet engines depending on their construction & power they can deliver. Todays jet engines are able to produce so much of thrust that airplanes could fly at speeds multiple times the speed of sound ! more “Types of Jet Propulsion Engines (animations)!”

Antikythera mechanism – The most ancient & mysterious Greek machine !

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January 17, 2016
what is antikythera mechanism ?

The Antikythera mechanism is more valuable than Mona Lisa !

says professor Michael Edmunds from Cardiff University, who led a 2006 study of the mechanism !

Honestly, this is one of the most mysterious, extraordinary, fascinating & interesting  machine I’ve ever seen in my life ! The Antikythera mechanism is one of the most remarkable inventions of the ancient world came to light in 1900 when a Greek Sponge diver discovered the wreck of an ancient Greek or Roman cargo ship that had sunk off the Greek island of Antikythera around 80 B.C.E ! more “Antikythera mechanism – The most ancient & mysterious Greek machine !”

NASA’s Starshade to help find another Earth !

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January 10, 2016

I mean seriously what do these engineers & scientists at NASA are made of ? How do they come up with such awesome cool stuff every time !
This time, it’s something you would not have even thought of. Yea… we are talking about NASA’s Starshade ! (watch the video below)

The project, also referred as New Worlds Mission comprises of sending a large occulter in space to block the sunlight of nearby stars(bright stars like sun) in order to observe other exoplanets(planets that orbit star other than Sun) & their orbits. The deployable structure called the Starshade is being developed by NASA’s JPL (JET PROPULSION LABORATORY) in Pasadena, California.
The hunt is on for planets that resemble Earth in size, composition and temperature. Rocky planets with just the right temperature for liquid water — not too hot, not too cold — could be possible home for life outside our solar system.




Picking out the dim light of a planet from a star billions of times brighter is similar to finding a needle in a desert.
In order to achieve this feat, researchers are developing techniques to block out the starlight while preserving the light emitted by the planet. This is called starlight suppression.With the starlight supressed, astronomers would be able to take actual pictures of the planets. Unlike the other space instruments, it’s one part is the starshade which will block the light while the other one – the space telescope will capture photos.

Jeremy Kasdin, a reseacher in Princeton is the principal investigator of the Starshade project.
“Our current task is figuring out how to unfurl the starshade in space so that all the petals end up in the right place, with millimeter accuracy,” said Kasdin.

The step by step stages of the Starshade while opening itself.
The step by step stages of the Starshade while opening itself.

The flower-shaped petals are part of what makes the starshade so effective. “The shape of the petals, when seen from far away, creates a softer edge that causes less bending of light waves,” said Dr. Stuart Shaklan, JPL’s lead engineer on the starshade project. “Less light bending means that the starshade shadow is very dark, so the telescope can take images of the planets without being overwhelmed by starlight .”

“One of the starshade’s strengths is simplicity. Light from the star never reaches the telescope because it’s blocked by the starshade, which allows the telescope system to be simpler.” said Kasdin. The starshade has thrusters that will allow it to move around in order to block the light from different stars.

Fact:-

The starshade idea isn’t new: Lyman Spitzer, the Princeton University astronomer who lobbied for the creation of what became the Hubble Space Telescope back in the 1960s and 1970s, also suggested using such a screen in a 1962 paper. But it wasn’t until recent years that technological advances made it feasible to build one and operate it in space according to the extremely precise specifications necessary.

A video showing complete animation of the Starshade splitting of with the telescope & then moving to a position to block the sunlight !


NASA’s starshade team of engineers strongly believe that this mission is gonna be a huge success & it will lead to major exoplanet discoveries in the future.
Kasdin ends up by saying,

We’ll be able to show people a picture of a dot and explain that that’s another Earth.





source:- planetquest.jpl.nasa.gov

Formula racecar designed & built by students of Bangalore !

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January 8, 2016

Designing a car & making it is not as easy as sitting & watching a movie on a couch. Making a car doesn’t just mean to join the parts we bought; it needs to have deep knowledge of thermodynamics, fluid mechanics, dynamics & must also be able to do calculations which fits the rules & which doesn’t damage the car.  One cannot do this being a book worm; it requires lot of creativity, ‘engineering expertise and motor racing skills. Team Ashwa has proved that they have all these qualities.

While the students in BCom colleges in Bangalore were having fun, some engineering students – the Ashwa team of RV college of Engineering; were working hard to make their super car.
Ashwa Racing is India’s premier Formula SAE (FSAE) team. The FSAE (Formula Society of Engineers) event is one in which SAE student members conceive, design, fabricate and compete with other similar formula-style student racing cars in a race organized by SAE in a different country every year.

R S Kulkarni who advises the team says:

The team is the number one formula racing university team in the country. It competes with teams from US and Europe who have vast financial and other resources at their disposal.
We have to work with what we can afford. They are also competing against teams which have more than two decades experience in automotive racing. Yet the team has bagged the best Asian team award and is in the top rankings

FSAE
FSAE India. The event is also called as SUPRA SAEINDIA ! source:- http://edu.autosportsindia.com/

The body of the car is made from glass fibre. Also the engine is taken from an crashed bike to reduce the expenses.
They say that the engine capacity is 600 cc & can hit a top speed of 100 km/hr or a few more.
It cost them around 15 lakh Rs to make it. Total 7 prototypes were made; the last one made in 2011.

Kulkarni says that this amount may seem high at first, but when compared to foreign teams who spend around whooping Rs 2 crore to design and build their own cars. “One thing we have been appreciated for is the cost-effectiveness of our car and yet its very good performance.”

The car model name was earlier RVIANZ, to commemorate student life at RVCE. Later, it was shortened to RZ.

Ashwa team has been participating in the competitions of FSAE  since 2005. This is because they completed their first prototype(out of 7, as I mentioned earlier) in 2005. They participated in the competition in 2005 & 2006 in Australia followed by 2007 & 2008 in Germany & 2009-10 in Italy.

The team’s last prototype, RZ X, successfully completed the Formula ATA Italy event in 2010 winning The Best Asian Team award.

If anyone is wondering – why the word Ashwa ? what does it mean ? Well, I should tell you that Sanskrit is most ancient & philosophical language of India. According to Sanskrit, Ashwa means Stallion. Hence, the name was chosen for the team.

 

source:- timesofindia.indiatimes.com

How does a Wankel engine work ?

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January 6, 2016

No more boring introductions, lets get started & understand how does a Wankel engine work & what exactly it is !

History :-
The first Wankel engine was developed by German engineer – Felix Wankel. Wankel received his first patent for the engine in 1929. more “How does a Wankel engine work ?”