Blowing hot smoke!

April 7, 2010 at 3:05 am | Posted in 1 | Leave a comment

Some people may wonder why smoke and gas comes from the tail of an airplane when the engines are usually located under the wing? Check out the picture below which is the typical tail configuration for all commercial aircraft (including the 787).

What most people don’t know is that another “engine” actually exists inside the tail of the aircraft. However, unlike the engines that already hang out on the wing, this engine (called the auxiliary power unit or APU) actually supplies all the electrical and hydraulic power for the aircraft. Just like an engine on the wing, this APU burns jet fuel and make a very noticeable sound when running.

So next time you are at the airport and notice smoke coming from the tail of your airplane, don’t start fretting that something is wrong with the plane. Instead, know that the APU is working to provide you with interior lighting and that trusty ding from the flight attendant switch.

Pressure at the end

April 3, 2010 at 7:45 pm | Posted in 1 | Leave a comment

Last week I briefly touched upon static pressure ports in some of my other social media streams (http://www.facebook.com/people/Matthew-Fife/3215001). This week I would like to share a little bit more on this topic.

So what exactly are static pressure ports and why do we have them trailing the aircraft? One of the best sources of information I have found on this interesting piece of test equipment is actually Wikipedia (http://en.wikipedia.org/wiki/Trailing_Cone).

While all airplanes are able to measure the pressure surrounding the aircraft, test flight aircraft need to ensure the pressure they measure is the true ambient pressure. Unfortunately, pressure changes as the air flows over the aircraft. These changes are taken into consideration during the design of the aircraft pressure monitoring system. However, in order to validate these designs, test aircraft must be able to accurately measure the ambient pressure far away from the aircraft itself. By taking these measurements, engineers can be sure that the aircraft’s fuselage is not affecting the pressure measurement. Check out the picture below taken from Wikipedia. The pressure is measured using the trailing cone attached to the top of the vertical tail. In flight the trailing cone  is allowed to drift further from the aircraft as more static pressure tubing is released.

Together at last…well sort of

April 2, 2010 at 1:13 am | Posted in 1 | Leave a comment

Boeing has finally got its wish this year with both the 747 and 787 now fully involved in their test flight programs. As a flight line engineer, it is truly remarkable to see these two beautiful aircraft together at the same airfield. What is especially interesting is Boeing’s management of space. With six 787’s slated for the test flight program and three 747-8 aircraft expected to be running flight tests this year, it is quite easy to see how spots can fill up quickly. Simply put, Boeing has too many great products and not enough space to keep them.

So what do you do when you have this problem? Well a recent decision by Boeing upper management has been to locate the 787 test flight program in Seattle, Washington and move the test flight program for the 747-8 to Palmdale, California. This decision was made to ensure neither program stepped on each other’s tires (if you will) and everyone could complete their testing on time.

However, for now, the two airplanes remain in happy proximity next to each other on the Boeing Field flight line and I am really starting to enjoy the view!

Truely Amazing!!!

March 30, 2010 at 1:23 am | Posted in 1 | Leave a comment

Another milestone yet again in the testing and development of the 787. Last night Boeing successfully bent the 787 wings to 150% of their in-service aerodynamic load (http://www.seattlepi.com/business/388382_air19.html).  This is a HUGE accomplishment considering the last static wing test found delamination at the root of the wing which required an engineering repair that held up flight testing on the aircraft.

The goal of the static wing test is the prove the wings of the airplane will support all possible loading conditions the aircraft might see in flight. The picture below shows the test rig and wing bending.

One of the questions that might be running through people’s minds at this point is, why do we bend the wings at all? Why don’t we just make them rigid? The answer to these questions is actually quite simple. We can build a lighter airplane which can support more load by allowing things to bend and flex. Consider the following example:

Just image if you didn’t let your knees bend when you jumped off a truck bed. You actually “feel” more load. By allowing your knees to absorb some of the energy, you are able to jump from greater heights without feeling anything. The same basic principle applies to aircraft wings.

A quiet word about noise….

March 26, 2010 at 3:48 am | Posted in 1 | Leave a comment

We’ve all heard it. That growing roar as a plane approaches, the deafening sound when the plane is overhead and the constant ringing in your ears after it leaves. For many people this is just part of the joy of aviation. However, what if you could make that noise go away… or at least turn into a whisper. Enter the 787. Along with its increase in fuel efficiency, warmer lighting, bigger windows and nicer seats, the 787 is also reducing the noise standards for commercial aircraft. Perhaps the most interesting part about it is how it is being done. Chevrons… no not the gas station… are formed in the trailing edge of the engine nacelle to reduce the amplitude of the  sounds waves coming from the jet exhaust. The exact engineering behind this is rather complicated and something I don’t claim to know. However, check out the following article for more information on the 777 chevrons http://www.seattlepi.com/business/236095_quietjet11.html.

The following pictures shows a good view of the chevrons on the 787. The chevrons are the wavy parts of the engine fairing at the back of the structure.

Flutter Testing!

March 24, 2010 at 2:59 am | Posted in 1 | Leave a comment

The 787 is now fully involved in flutter testing. In light of this new event taking place in the 787’s flight test program, I wanted to talk briefly about aerodynamic flutter. Aerodynamic flutter is basically aircraft vibrations caused by flight loads imparted on the aircraft. Flutter is not something that is good for an aircraft, especially since it can lead to fatigue and ultimate failure!  Check out this great video on a piper PA-30 flutter test. Notice how the oscillations in the horizontal tail grow throughout the test. Now imagine looking at your window and seeing the same thing happen on a commercial aircraft wing. Clearly, these tests are very important.

Composite vs. Aluminum

March 21, 2010 at 9:37 pm | Posted in 1 | Leave a comment

As many of you already know, the biggest breakthrough with the 787 is its all composite design.  Unlike all of the other commercial aircraft to come before it, the 787 has nearly every part made from some form of carbon fiber and epoxy. So what exactly is this “composite” material and how is it any different from the traditional material for airplanes.

First off, nearly all commercial airplanes in service today are made largely from aluminum. Just think of airplanes as a giant roll of aluminum foil flying at mach 0.84, 30,000 feet in the sky. Aluminum has been traditionally used in aviation because it is a rather ductile metal which can be easily worked and formed. In addition, aluminum is also very light making it ideal for something that needs to be as light as possible in order to fly. Composites, refer to any material which is a combination of two different materials. Generally, within aviation composites refer to fiberglass epoxy (glue) materials or carbon fiber epoxy materials.

In the case of the 787, carbon fiber and epoxy is used extensively. Unlike aluminum, carbon fiber require a mold in order to form it to the correct shape. However, it is also extremely light (lighter than aluminum). Of course there are also drawback to carbon fiber such as its inability to take an electric charge (think about lighting strikes in flight). However engineers have developed ways to avoid this problem. Take a look at the video below which goes into detail about creating carbon fiber parts. This is very similar to what Boeing does for many of its parts on the 787.

The Great Debate: Airbus vs. Boeing

March 19, 2010 at 4:17 am | Posted in 1 | Leave a comment

Most of us realize that not all commercial airplanes look the same. Just like people there are small ones, big ones, fat ones and skinny ones. While it is not always apparent to the untrained passenger,  there are also Airbus planes and Boeing planes. Within the U.S. that’s it! The difference between these two aircraft manufacturers is summed up rather well in the book “Men Are From Mars Women Are From Venus” (http://en.wikipedia.org/wiki/Men_Are_from_Mars,_Women_Are_from_Venus)….They just are flat-out different and sometimes just don’t get along.

Boeing latest aircraft the 787 is being haled as one of the greatest aircraft of the 21st century. It’s carbon fiber design is truly revolutionary within the commercial aircraft market. Airbus’ big leap within the modern area of commercial aircraft has been the A380. Why doesn’t that plane sound or look familiar. Well for starters the thing is about the size of Canada and can only land at certain airports around the world. Unlike Boeing, Airbus bet its airplane’s success and its company’s success on the future of hub travel (i.e. everyone will fly into large airports first and then take small airplanes to get to where they actually want to go). In contrast Boeing has designed the 787 to be an airplane that can take you from point A to point B without have to stop at point C first. Unlike the A380, the 787 can land at nearly all commercial airports within the United States.

Check out the pictures below and decide for yourself. Which one would you rather fly on:

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Strange Sights After Midnight

March 17, 2010 at 1:22 am | Posted in 1 | Leave a comment

I have had a rather interesting week following the 787 through its flight testing down at Boeing Field in Seattle. For starters, trying to stay awake on third shift has presented in challenges. However, there are truly some amazing things to see in the wee hours of the morning out on the flight line. Last night I had the opportunity to visit two of the first six 787 flight test airplanes out at the flightline at 3 am. Wow, what I sight, even for sleepy eyes.  I think what most people don’t realize is the fight test airplanes for any new commercial aviation program look like more of a scene out of Star Trek that something you might find at your local airport terminal. For starters there are computers and “modules” spread out all across the airplane. Unfortunately, I can’t post any pics of this one, but check on the image below from a similar flight test program. Now image many of these “modules” spread out everyone on the airplane and you have a pretty good idea of what a flight test airplane looks like!

Imagine the possibilities…..

March 15, 2010 at 10:49 pm | Posted in 1 | Leave a comment

So the answer to last weeks quiz question was….drum roll please…the first flight of the Boeing 707 took place on December 20th, 1957! Wow, that is almost 45 years ago! Since that historic commercial aviation milestone, we have come a long way. Advancements over the years have included the introduction of the engine bypass fan (the big blades in front of all airline engines), composite tail designs (AKA the 777 tail) and the first airplanes to be designed completely by computer. These are certainly some remarkable achievements.

With the dawn of the 787 there is no telling what is in store for us. Just image what we might be able to see in the future….

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