What is aircraft thrust?

What is aircraft thrust? 

What is thrust

An average aircraft weighs approximately 450 tons (Here I’m referring to the takeoff weight) which is approximately the weight of 900 whale testicles.
Now how is a body that heavy going to be able to propel itself to achieve lift?
A little background check on the little devil that decide how fast this man-made birdie can move...

What is Thrust?


Thrust: The holy matrimony of the Pressure formula and Force equilibrium gave birth to this simplified formula for thrust.
Image result for turbojet thrust equation nasa
Here the mass flow exiting the engine is the sum of the mass flow rate of air and the mass flow rate of fuel(added at the burner). But since this mass flow rate of fuel is relatively small, we will ignore the term in our simplified equation.

T = Ma(Ve-Vi)
From this, the science humans found that thrust is directly proportional to :
 1.mass flow rate of air (mass of air flowing per unit time...we like bringing time into the picture when we work with a flow in motion aka fluid dynamics, in another article we’ll tell you why)
 2. the velocity difference between the entrance to the engine and the exit of the engine. (The thrust equation is derived considering the engine as the isolated system)

It doesn’t take a rocket scientist to know that if we increase one of the two or both of them were going to get what we want. WHAT DO WE WANT? THRUST! WHEN DO WE WANT IT? NOW!
How do we achieve in increasing one or more of these two quantities?
Suck. Squeeze. Bang. Blow.

Image result for heinkel he 178
Heinkel 178, Pleasure to meet you.

Imagine a Heinkel 178 cruising in the air on a late August morning over the greenest fields of 1939 Germany. The test pilot Erich warsitz sits in his cockpit not knowing that he would go down in history as the first man to fly an aircraft powered by a turbojet engine. The gas turbine engine was a man-made marvel and took on the world war by a storm, putting its piston predecessor to shame.
Sounds radical doesn’t it, but what really happens on the inside?
There’s nothing left to do but to march through the engine, one component at a time.
Image result for turbojet engine
Just your average jet engine.

Suck: The diffuser is a welcome mat to the engine. It’s job? To reduce the velocity of the incoming air. Why? Because slower air is easily tamed by the components following it. How does it do this? It’s a diverging section by geometry. The continuity equation would tell you that area and velocity are inversely proportional. So when the area increases in the section, velocity will decrease creating a slower flow.
This doesn’t really sound like a sucking mechanism does it? Well, the sucking happens because of a pressure difference. You see a flow is established when there is a difference in pressure. High pressure to low pressure: that’s all the navigation that fluid particles comprehend. (Why? In the microscale all atoms look to settle in a place of a lower energy, lower pressure means it has lower internal energy associated with it)So in order to suck in the air, the diffuser must be at a lower pressure level than the atmospheric pressure of free stream outside. How do you make this happen? By geometry. The more the wall of the diffuser diverges, the more the air that sticks to its boundary begins to feel like it’s not wanted anymore (nobody likes a clingy neighbour...get the hint bob)
So the wall is put at an angle such that, at a distance from the diffuser inlet, the flow separates from the boundary swirling inwards and making a low-pressure region there. This low pressure pulls the higher pressure free stream towards it and they make sweet sweet love. Thus generating a flow.

Squeeze: the second is the compressor. It’s job? To increase the pressure of the air (compress) how does it achieve this? It’s composed of a series of rotating and static blades called rotor and stator. The energy equation (Bernoulli equation) tells us that the sum of pressure head, kinetic head, and a gravitational head is a constant.
Or energy is conserved. The rotor creates velocity increase (by virtue of its rotation) and this translates to a pressure increase at the stator, satisfying the conservation of energy. Moral: to properly satisfy, one must properly squeeze.

Bang: Thirdly comes the combustor. The slow squeezed air comes into the combustor hoping to get hot. Combustor’s job? To create kinetic energy increase. When fuel and air are mixed and set on fire by a spark plug, this results in a massive increase in kinetic energy. (And temperature duh) how does this kinetic energy increase? Fuel and air mixing and being set on fire is a chemical reaction. So this chemical energy is going to be converted into kinetic energy. This hot faster-moving gas goes on to the next component: Turbine. The Siamese twin of the compressor with regards to mechanical parts does the exact opposite of what the compressor does, decreasing the pressure.
Hot fact: The turbine and the compressor are Siamese twins in another aspect. They’re joined at the hip. A shaft connects the turbine to the compressor driving it.
Wait, what?
This would mean that once a sustained flow is established in the engine, the turbine and the compressor work in synergy: driving each other. That’s exactly what happens. The kinetic energy produced in the combustor is what really produces the propulsive thrust. Without the combustor, it would just be a sustained operation of a compressor turbine system. And without the compressor turbine system, the engine would only be an uncontrolled explosion courtesy of the combustor. Hot damn.

Blow: the exhaust is a nozzle which implies that it is a converging geometry. It increases the velocity by the same principle employed at the diffuser. The faster air is expelled through the nozzle thus increasing the difference in velocity portion of the thrust formula. How do we increase the mass flow rate? In a turbofan configuration, there is a portion of air which is allowed to pass along the side of the engine, not through the various components: bypassing it. Kinda like a get out of jail free card, you don’t need to be sucked squeezed banged and blew, to be a reliable contributor to the system. Or so my mother tells me.
Now addressing the question that was posted. How does this help with a lift?

Image result for lift equation
Lift formula

The formula for lift shows that lift and the forward velocity are like two peas in a pod, one increased, the other does too.  When thrust increases, the forward velocity increases...which leads to the increase in lift. (It should be noted that you must increase the other parameters of area and angle of attack to attain enough lift to take off ). That's exactly why you see aircrafts taking a running start before they lift off from the runway.

And now you know how to get 900 whale testicles to take flight.

Thanks for reading!

How are Military aircrafts named?

Ambiguous Alphabets Explained

How are Military Aircraft named?

How are Military Aircrafts named?

The Northrop Grumman B-2 Spirit.
The Lockheed Martin F-22 Raptor
The North American P-51 Mustang.

What do these have in common? Besides being some SICK aircrafts in military aviation, they all have mysterious alphabets in their name which really don’t make sense. OR DO THEY?

Let’s try and decode what their names indicate.

So the letters stand for the primary function of the aircraft.

A10 Thunderbolt

A10 Thunderbolt

 The A in A10 thunderbolt stands for attack. These tactical metal birds can mess up a place with more precision than a bomber. How they do that is by being able to fly close to the enemy grounds, launch airstrikes and flee the scene like it’s nobody’s business. They ARE equipped to engage in air to air combat but it’s not what they were MADE for.

B2 spirit

B2 Spirit
B2 Spirit
The B in B2 spirit stands for bomber, designed to drop bombs on the ground bases. They’re on the heavier side (not weight shaming or anything) and thus not as manoeuvrable as an attack aircraft.

EF111 Raven

EF111 Raven
EF111 Raven
The E in EF111 Raven stands for electronic installation. These modern marvels have the exceptional ability to engage in electronic attack (using electromagnetic energy to jam enemy systems) and electronic protection(harnessing EM power to protect themselves from being pulled into an electronic attack) among other awesome things to do with EM energy.

F-22 Raptor

f22 Raptor
f22 Raptor

The F in F-22 Raptor stands for Fighter. Made for dogfights, let’s admit these belligerent devils look the coolest in the skies.

KC-135 Stratotanker

KC-135 Stratotanker

The K in KC-135 Stratotanker stands for Kerosene tanker. These are like war nurses in the skies. When a fighter who has just gotten out of a dogfight is running out of fuel in the air, Fuelrence tankingale comes bearing fuel. They can perform air to air refuelling. Where a rod pops out mid air and attaches itself to the aircraft in need of fuel.

P-52 mustang
P52 mustang
P52 mustang

The P in P-52 mustang stands for Patrol or Pursuit. They are fighters  They later came to be referred to as the F series.

SR-71 Blackbird

SR-71 Blackbird
SR-71 Blackbird

The R in SR-71 stands for Strategic Reconnaissance. Spies in the skies more like it. They collect information over enemy regions and return to ground base. In a recon mission they are often accompanied by fighters, as they are not equipped to defend themselves against enemy fighters.

T-67 firefly

T-67 firefly
T-67 firefly

The T in T-67 firefly stands for Trainer. The teachers. These aircrafts give pilots in training the experience they need to get up and flying.

U-2

U-2
U-2
The U in U-2 stands for utility. They are used for transporting people or freight

YF-23

YF-23
YF-23

The Y in YF-23 stands for prototype. These prototype aircrafts may or may not make it to the country’s fleet.

X-15

X-15
X-15

The X in X-15 stands for Research. These aircrafts are still in the rudimentary research phase where they will be made to undergo rigorous testing before they get the chance to make it to the coveted hangars.


Check our previous articles on
How are Boeing planes named?
How are Airbus planes named?


Thanks for reading!

WE Expedition: Circumnavigation of the earth

Around the world in 100 days!

WE Expedition: Circumnavigation of the earth

Do you know about the Jules Verne's 1872 adventure novel 'Around the world in 80 days'? If yes, then you probably know how cool circumnavigation is. Oxford dictionary defines circumnavigation as The action or process of sailing or otherwise traveling all the way around something, especially the world. Travelling all around the earth isn't that exciting? (Unless you are the moon, then that's usual thing, Lame joke!) In the Jules Verne's novel, Englishman Phileas Fogg with his servant Passepartout uses various transportations to accomplish the circumnavigation. In 2004, Movie of the same name as the novel was made, directed by Frank Coraci.
This was complete fictional though! 
But there are few successful circumnavigations in the real world.

World's first Circumnavigation of the Earth

Magellan–Elcano circumnavigation

The Magellan–Elcano circumnavigation was the first circumnavigation. It was a Spanish expedition under the command of Ferdinand Magellan that sailed from Seville in 1519. They left Spain on 20th September 1519 with 5 Ships and 270 men. They traveled from Spain to East Asia through the Americas and across the Pacific Ocean. This trip was concluded by  Juan Sebastián Elcano after the death of Ferdinand Magellan at Philippine. At the end of the circumnavigation, Juan Sebastián Elcano returned Spain with only 1 ship and 18 men on 6th September 1522. 

As Aircraft Nerds, we are more interested in aerial circumnavigation, aren't we?

World's first Aerial circumnavigation of the Earth

First aerial circumnavigation
Douglas World Cruiser Aircraft Chicago
In 1924, The team of aviators of the United States Army Air Service (United States Air Force) conducted the first aerial circumnavigation of the world. In this trip, they covered 27,553 miles (44,342 km) in 175 days. 4 Douglas World Cruiser aircraft named Seattle, Chicago, Boston, and New Orleans left Santa Monica, California for circumnavigation on 4 April 1924. Douglas World Cruiser was modified version of DT Torpedo Bomber. 

Lucky Lady II
Lucky Lady II - Non-Stop circumnavigation
Not amazed yet? So, here is the exciting info. Lucky Lady II USAF Boeing B-50 Superfortress is the first aircraft to circumnavigate around the earth Non-Stop. In 1949, it was supported by in-flight refueling. The flight lasted for 94 hours and 1 minute. 

Enough talking about the past. Now, let's talk about Indian mother-daughter duo who is going to create history in the circumnavigation of the earth. They have named their this journey around the world as WE Expedition.

WE Expedition!

WE Expedition

What is 'WE'? 'WE' stands for Women Empower. WE is a movement which will inspire women & girls all over the world and help them to grow. WE expedition is the world’s first circumnavigation by an Indian women pilot in a motorglider. 

India’s daughters Keithair Misquitta (Age 23) and Aarohi Pandit (Age 22), are all set to go around the globe with microlight motor glider Mahi (which means Great Planet Earth in Sanskrit)! Actually, Mahi is Sinus 912, two-seat, ultra-light, high-wing, cantilever monoplane developed by Pipistrel with the wingspan of 14.97 m (49 ft 1 in) and max. take-off weight of 544 kg (1,200 lb). It is powered by Rotax 912UL, 4-cylinder liquid cooled engine. 

Sinus 912
Sinus 912
WE Expedition is a 100 days long journey. Young women duo will cover 40,000kms touching 3 continents.

According to the official website of 'WEfly', World records set by this WE Expedition are as follow:
  • A World Record for the first motorglider circumnavigation by a woman
  • World First for an all-woman, non-commercial, civilian expedition
  • The First motorglider circumnavigation by an Indian pilot, man or woman
The special thing about this journey is it will not only create multiple World Records but also it will motivate woman across the globe. Fund collected by this journey (WE Udaan Scholarship) will help deserving girls across various cities and towns in India to enroll in aviation training.

Track their expedition here: http://wefly.org.in/where-is-we/

More Details!

To get detailed information about WE Expedition you can visit their official website

This article is a small attempt to support WE Expedition. We wish WE Expedition to be a great success. You can support WE Expedition by contributing to WE Udaan Scholarship. Click on the link below to contribute to WE Udaan Scholarship

Thanks for reading!