AviTech Reader

                                                                           

Today we are going back to 1935, a day when millionaire film producer and amateur air racer Howard Hughes shattered the world land plane speed record using his home built Hughes Racer(AYY) plane. His company, the Hughes Aircraft Company was formed in 1932 and has pioneered many Aerospace developments. Its origin was an attempt to convert a military plane to a racer.In 1933, he lobbied the Commerce Department to lower his pilot's license number from 4223 to 80 to get some fake status for his own benefit. Charles Lindbergh's number was 69. Surely, this guy never had areal job except for 1933 when he applied for a co-pilot position at American Airways  under the name Charles W. Howard. He got the job yes, just shortly after,the trick he used was discovered and he had to resign. One of his other achievements was that he entered and won the All-American Air Meet in 1934 in Miami, after which he built and test piloted the most advanced aircraft, the H-1 which he used in 1935 to set anew speed record of 352mph. He did much more of this speed records later on till in 1938 when he piloted a Lockheed 14 around the world from July 10th to July 14th in the company of four crew members.He halved Lindbergh’s New York to Paris speed record-he did it in 3 days, 19hours and 17 minutes. Lastly guess what…with all those achievements, Houston Airport being named after him was a great show of honor bestowed on Hughes.

What are composite materials?

A composite materials is a combination of more than one material put together because each one has a desirable property that we would wish to exploit but we need other properties that are vested in other materials so we join them together and have all the properties we need. Using composite materials also allows the bad property in one material to be ameliorated by the other material that just does better.

If my material science and engineering materials course work serves me right, composites are mainly made up of two components: fibres (fibres to provide tensile strength and flexibility), and a “matrix” to hold the fibres together (providing compressive strength and control of the overall shape).For instance, the “carbon fibre + epoxy resin” combination is widely used in aerospace.

Is it new?

The use of composite materials to build aircraft is not something we can call “A new trend”. It has been around for decades(even before the mid 1980’s) but what we have seen now is a huge increase in the number of parts that are being made with composite materials. In fact in 1988, Airbus introduced the A320 while in 1995, the Boeing Company introduced the Boeing 777-both airplanes in production had all-composite tail sections.Even the DC-9 has parts made of composite materials in it, only that they are few compared to the modern airliners that are being rolled out of factories like the Airbus A350 and the Dreamliner. These aircraft that started offering commercial services after 2011 like the A350 and the Boeing 787 do fly, yes that’s true but being the first generation of aircraft to be mostly composed of parts made of composite  materials other than those made of the long safety-trusted metals.this quick transition is something many are deeply questioning despite trusting the work of the engineers and researchers that have worked on it.

The Dreamliner was the first mostly composite aircraft with 50% composite fraction(without the engines) and ferries 210-290 passengers. Next is the Airbus A350, having composite material fraction nearly equal to that in the Boeing 787 but with longer range and higher seating capacity from 250 to 400-plus passengers.

3 – Why did these guys decide to go put in more composite?

Seemingly, we were asleep for all that time only to wake up and find our sleep dream lined….But let us try to understand the truth of the matter because it is not true that long ago, our grand fathers did not realize that composite materials did better. Something imperative to note is that technological breakthroughs in engineering, materials sciences and manufacturing have propagated the notable increase in the use of composites over the past two decades. The use of composite materials has not only invaded aerospace, but also commercial and race car industry, marine industry and the sporting world among many other industries.

 

Advantages and disadvantages

Composite materials normally result in materials with increased strength, toughness and stiffness. Compared to metals, they have a better strength and stiffness-to-weight ratio. They also boast  better corrosion properties and  fatigue resistance.This means the planes will last longer and will not require so much maintenance as often. Because of the low weight, there will be lighter aircraft, hence lower fuel consumption and reduced pollution to our environment.

Of course there is no way on earth we will just get all these goodies for free…we must pay something. Setting up a composite production industry is very expensive just say several millions of dollars. Though, over the past decade prices have reduced making composites more accessible and suitable for large-scale aviation projects. Moreover, most manufacturing processes are labor-intensive and high engineering materials knowledge is a necessity. Even the training on composite materials is very expensive making the general manpower package not a very cheap idea to think about.Something else is that we can’t just handle composite materials anyhow….there are handling equipment and specialized storage facilities that are required and this adds more costs, For example, some composites come in “prepreg” form (fibers pre-impregnated with resin) that need frozen storage and have a very limited shelf-life (a few weeks/months).

Then there are issues to do with the safety of workers and staff handling the composites. Several composite material components are classified as hazardous because they have related health issues including complications from inhaling fibers and exposure to suspected carcinogens.

Hurdles to jump

Something else often overlooked by many is the process of commercialization. You don’t just wake up and have your way…there is definitely a process to follow.Before a company is authorized to start manufacturing commercial aircraft, there must be certification and safety assurance procedures first. The US Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA) are in charge of investigating aircraft safety and delivering the required certification.

For example, before Boeing started manufacturing the Dreamliner, it was not a question of the many orders already in place for the aircraft but first it had to prove its safety standards to the FAA and EASA.

Lets bring in Robotics now

Lets take an example of a company like Airbus that has received so many order for the Airbus A350 or A380, how do we expect it to deliver 12 aircraft per month all with manual labour? To me, it seems impossible. But if we think about it, we can bring in assistance from robots to make it faster. This will ensure the process is very efficient and will run even during the night, tirelessly. This idea of automation, I remember from a certain magazine, came up in the 1970’s but technology had not developed that much hence it was somehow rendered impracticable as it would be so expensive to implement.

However, in the recent past, low-cost robotic arms have been used for a number of manufacturing processesand Robotic Fibre Placement (RFP) heads started to register their presence more frequently in the market. These placement heads can lay composite materials (using different methods depending on the part at hand) either in a mould or directly on to a desired structure (see video).

So far, the Antonov manufacturer has as per this moment had the most number of aircraft that have crashed-3 within a period of twelve months.Today, 12th September, the Antonov AN-28 operated by Petropavlovsk-Kamchatsky Air took off on a domestic flight from Petropavlovsk-Kamchatsky to Palana in Russia with12 passengers and 2 crew members onboard. The aircraft crashed just before landing at Palana killing 10 of those on board while 4 were lucky to survive though with very serious injuries.
The plane was finalizing its landing approach to Palana airport when it suddenly disappeared from radar screens. Later on, the wreckage together with remains and survivors were found on the wooded slope of Mount Pyatibratka, in the thickets of mountain pines, 10 km from the airport, at an altitude of 900 metres. I surely had not heard of such a type of aircraft so I had to find out how it looks like and I attached its picture below. This is not the one that crashed…the one that crashed looked like this, though.

                                                                    

We are going back to this date many years ago. On this day in 1942, history was made by a breakthrough leading to the First flight of the Miles M.38 Messenger liaison aircraft.The M. 38 is a single-engine four-seat liaison and touring aircraft produced by the British manufacturer Miles Aircraft Limited and was developed form the M.28. Only 93 of them were produced and are no longer in production. It carries one crew member and three passengers onboard. As can be seen, its driven by a ingle propeller engine.

It was not only that, earlier in 1934, but still on the same date, there  was also the  First flight of the Gloster Gladiator biplane fighter. It was the last biplane fighter of the Red Army Faction fighter(RAF). To see about it. Go here.

 

 

 

 

 

 

 

Again, in 1930, still on the same date, there was the maiden flight of the Taylor E-2 ‘Cub’ utility aircraft. It's designer, C.G. Taylor pulled resources together with William T. Piper to form the Taylor Aircraft Company in 1931.  This company’s first product was the E-2 and 351 of them were manufactured from 1932-1937. Due to financial constrains, Cub production was transferred to the Piper Aircraft Corp in 1937 and the Taylor E-2 design was redeveloped and improved to become the famed Piper J-3 “Cub”. So this was the grandfather of the piper..in short!

 

 

 

 

 

 

 

Going back further to 1906, on this same day, the Ellehammer semi-biplane made history by successfully going for its maiden flight.This aircraft is a pioneer one flown in Denmark in 1906 and was designed by the Danish watchmaker and inventor Jacob Christian Hansen Ellehammer. Further details can be found here.

On this blog, we are going to put our minds together in discussing and learning about issues in Aviation Technology. First, may I introduce the subject: aviation. Each of us may have his or her own definition of what it is but with my high school knowledge, I would define it as the science that studies how man made objects fly in the air. As per my definition, the subject appears so wide but I am going to choose where I concentrate. My interest in this subject developed since I was in class 6 of Primary School-an equivalent of sixth grade…I think. So there was this jet that flew very close near where I was grazing our cattle and I can’t actually remember the exact registration number but I can make out the fact that it started with a 5Y followed by some other letter. I have used the same model of the jet as my background image of this blog theme as it symbolizes the roots of my inspiration and interest in Aviation Technology. It actually gave me the impetus to go ahead, work hard and join the best High School in Aviation Technology in the Country-Maseno School where I struggled hard to be in the group of the twenty selected students who end up pursuing the subject for their four years at High School. So as I continued learning more and more things, I remember we covered units like History of flight,Theory of flight, Aircraft Power plant, Stability, Aircraft systems,Instrumentation,Aircraft Structures, Engineering drawing and Fabrication. These units gave me the urge to delve further into the field and find my favorite field. I am mostly interested in the engineering which can be divided into  areas dealing with the engines(Power plant), The airframe and Avionics.

All I remember that this year I was starting my Primary school studies. On this day in 1996, the first flight of the McDonnell Douglas/Boeing Bird of Prey stealth aircraft was accomplished and written down in the books of History. It was developed from 1992 but still its specific details were concealed even after the end of the program in 1999. It was officially unveiled to the public in 2002 after the specific design features were thought to have become familiar aviation standards that did not need to be hidden. More details about the program can be found at this site. It is pretty good stuff to read…especially on the performance of this aircraft. One word…Amazing!

In the beginning there was the Airbus A300-600 variant which was then modified to become the Airbus A300-600 ST(Super Transport). However, with time, the name Beluga just became more popular than the Super Transport name such that the name Beluga was officially adopted. The plane was designed and manufactured to specifically carry huge loads with awkward shapes that could not fit in the normal cargo aircraft. It was meant to serve multinational companies like Airbus itself which is a consortium made up of specialized companies in Spain, Germany, Britain and France. Each of these companies makes unique parts which have to be shipped to a central assembly point for n integration into a functional aircraft. Normally, the individual details of each design are different but the general trend is normally that the wings and landing gear are made in the UK, the tail and doors in Spain, the fuselage in Germany, and the nose and center-section in France, with final assembly in either Toulouse, France; Hamburg, Germany; or Seville, Spain.

So, at the beginning when Airbus was found in 1970, the transport of the parts was by road…so slow because as the production rate increased with time, there was need for a faster and more efficient form of delivery. This called for the air transport to come in. Airbus actually used four highly specialized "Super Guppies", just modified from the  Boeing Stratocruisers of the 1940’s. Again with time, they became less efficient, for instance, the fuel consumption was quite high due to the age and as Air bus ferrying capacity distended, their load could not be carried well by the modified fuselage structures and turboprop engines. This generally distraught their production capacity as they had schedules to meet and ended by necessitating the development of better carriers.

As Airbus embarked on a course of action in 1991 Aérospatiale and DASA, two of the major Airbus partners,expediently came up with a company to facilitate the project. They commenced by designing  a wide-body twin-engine Airbus A300: the wings, engines, landing gear, and the lower part of the fuselage is an exact replica of the A300 while the upper part of the fuselage is a colossal horseshoe-shaped structure of diameter 7.7 m.To enable access to the cargo area from the front without having to disconnect or mar any electrical, hydraulic and flight control connection(without mentioning the lengthy recalibrations before each flight), the standard A300 cockpit was lowered below the cargo floor level, and the tail structure was enlarged and strengthened to maintain directional stability.

The design of the Beluga, with reference to the Airbus A300, was mainly meant to carry lighter but huge loads. Its construction began in September 1992 and it was ready for testing after two years. After 335 hours of testing, it received restricted certification in October 1995. Four other airbus A300 ST’s were made at an average 1 per year.

Compared to the C-5 Galaxy or the Antonov An-124 , it has a larger main deck cargo volume but still below that of the Antonov An-225.On the other hand, it has a low cargo weight capacity of 47 tonnes compared to 122.5 tonnes of the  C-5 Galaxy and 150 tonnes of the An-124. Still, though it has a huge fuselage, it cant carry many parts of the Airbus A380 and they have to be ferried by ship and road.It is not totally useless though, as it can transport a few of those parts.

Sometime ago, the U.S Air force advanced 23 million dollars to Boeing to finish the second phase of the B-1 laptop-controlled Targeting Pod software upgrade. The second phase enables the bomber’s targeting pod to find stationary targets and transmit GPS co-ordinates using its avionics system to the weapons- a process that was very manual and used to introduce many errors. It will also complete the integration of the Sniper pod with B-1 programs enable single-moving –target kill capability using laser technology of the Guided Bomb unit.

ESP PC-based visual simulation for better pilot training is also provided to ensure pilots are best equiped with knowledge and practical exposure of the combat missions with less expenses for faster learning.

War fighter pilots stand to highly benefit from this massive resource to hone up their skills in battle. This is after Lockheed Martin and Microsoft Corp. signed a license agreement to continue development of Microsoft’s ESP PC-based visual simulation software platform. Lockheed Martin, now with access to the ESP technology portfolio, will be able to build more economic simulation solutions for customized training of the various customers.

With that in mind, testing and learning has been accelerated in recent times and is nearly done, and may lead to the Air Force's Air Combat Command plans to approve sending pod-equipped bombers on operational missions by mid-summer. With the powerful software, the Pilot in command can easily cross check co-ordinates and visual locations of targets before dropping weapons and would be very profitable for combat for example in places like Iraq and Afghanistan where the B1 Bomber has been used in the past.

By airframe when it relates to an aircraft we are referring to the mechanical structure of the plane. This includes the fuselage, wings, fin or vertical stabilizer(form the empennage), ailerons and the landing gear. It does not include the electronic system(avionics) or the engines. In aerospace engineering and research, its important to note that the airframe design is a vital elements and combines aerodynamics, manufacturing techniques and material science to achieve its designated purpose or objective. For example, the wings has a certain aerodynamic shape to achieve lift while the landing gear is to be made using specific shock absorbing material and at the same time possess the toughness to withstand impact. The whole airframe has to be robust enough to withstand the stresses it goes through and also balance the safety, reliability and economics. Airframe structures is not something that just came out recently, it can be clearly seen even when you look at the aircraft built by Orville and Wilbur Wright. It has only been advanced and developed over the years to couple its development with technology. I remember during our Aviation Technology classes at Maseno School we learnt about the warren truss structure, the monocoque and the semi-monoloque structures and differentiated between them in details.

The fuselage is also what we know as the main body of the aircraft and provides room for controls, our payload, passengers and the crew.It also provides attachment for wings, the landing gear, the empennage and the powerplant. In the early days, the fuselage was made by welding, riveting or bolting together aluminium tubes and steel rods to form a tapering box like structure whose strength mainly dependent on the weld joints and the strength of the aluminium and steel. The longitudinal members called longerons and the vertical web members had to bear the aerodynamic stresses depending on the direction in which the stresses will be acting. Later on as technology advanced, designs were developed to enclose the truss with a covering, first was cloth which paved way to the light metal sheets like aluminium that ended up bearing most of the flight loads in the monocoque and semi-monocoque construction. The stressed skin provides enough force but if dented or deformed then it can easily give in.It just works like an aluminium can, if it has no dent or deformation, it can be very strong but once it has a hole then it would give in to a substantial amount of force applied.

The true monocoque structure consists of bulkheads, formers and the skin. The formers and bulkheads give shape to the structure. Here, in the monocoque construction , the skin just has to be strong enough to bare all the stresses hence the main challenge is to make it strong without adding its weight so much-a hard compromise. That is why we have the semi-monocoque structure that that has bracing members on which the skin is attached and these bracing members take some of the stresses and its not only left for the skin. This bracing substructure is made up of stringers, variety of sizes of bulkheads and formers to support and ease forces on the stressed skin.

Let us say…we are revisiting this idea, because it is not just out of the woods. This is something that was there many years ago. Let’s take for instance, the late 1930’s when the Junkers built JUMO-the series of 2-stroke diesel engines whose advantage of fuel economy and mechanical efficiency made them very popular. Talking of such a 2-stroke engine, no poppet valves and its junky operating and timing system, no friction losses due to valves –compare this to the 4-stroke engine and you will surely visualize what I am talking about. Again, why fuel? Can you imagine that depending on size and type of aircraft, the largest portion of it is fuel, sometimes can be as high as 50%!

With the 2-stroke diesel engine, it is possible to attain a high power density and fuel efficiency while at the same time enhancing altitude performance. Another salient feature of diesel engines is that it allows a higher boosting level in comparison to spark-ignited(SI) engines whose capabilities are limited by knocking-yet we know that high octane rating fuel like JP4, JP5 and Jet A is now being subject to very strong limitations due to the damage to mother nature. We haven’t exhausted the list of advantages yet; there is the low volatility of diesel compared to other fuels meaning less explosions and fires. It also has better reliability in flight-no mixture control issues, no carburetor icing issues and safe cabin heating due to reduced exposer to carbon monoxide. Let us also not gainsay the fact that the 2-stroke engine cycle has the exemplary ability to maintain a high power density at a very low crankshaft speed, hence can be directly engaged to a propeller shaft even without the reduction gearbox hence cheaper.

These advantages, coupled with the recent developments in the 2-stroke, compression ignition(CI) diesel engine technology make this an auspicious choice for small planes that only need 100-300 hp, at a lower weight than the existing SI engines. This is very pragmatic owing to the trials by AVL in the late 1990’s when they developed a 1-L, 2-stroke turbocharged diesel engine with uniflow scavenging, achieving a brake power of 50kW and a weight less than 80kg. Another proof of possibility is given by Wilksh Airmotive that brought to the experimental aircraft market a 90kW 3-cylinder 2-stroke engine with IDI (indirect injection)-only weighing 100kg.

Generally, we can say that so far, none of the models has reached certification stages as I am writing this article but we are sanguine that more research and trials with several engine configurations will yield expected victory. Some of the selected engine configurations are like the loop and uniflow scavenging type, as opposed to the piston uniflow type.

Research at the University of Modena & Reggio Emilia and Wilksh pointed out that the uniflow type was actually more intricate (would be heavier and more expensive to manufacture) though had flexibility of exhaust timing events via cam-operated valves. On the other hand, though the loop scavenged engine had the trappings of “simple and cheap”, it brought with it symmetrical inlet and exhaust event timing. It also has more to offer in terms of Power-to-Weight ratio, Fuel efficiency, altitude performance and cooling.

For now, at least we leave the rest for research to decide.

This article has been influenced by another article from SAE Aerospace magazine August 2012.