Tuesday, 12 June 2018

World's Most Beautiful Grasshopper


Image Credit: Photograph by Philippe Martin.

The most beautiful grasshopper in the world, Phymateus saxosus madagascariensis, is limited to medium-altitude regions of Madagascar.

The family of grasshoppers to which it belongs is commonly known as the gaudy grasshoppers.
See more great images via Surreal Portraits of Wildlife in Nature | DiscoverMagazine.com

Tuesday, 29 May 2018

6 Design Improvements That Reduce Aircraft Drag

Thanks to Boldmethod for sharing..

Want to fly fast and efficiently? Reducing drag should be one of your top goals. These are some design improvements that counter drag's negative effects on performance.

1) Flush-Mounted Rivets.
Even microscopic changes to the smooth surface of a wing or aircraft fuselage can dramatically increase drag. Rivets are one of the most common drad-inducers. In the picture below, notice the protruding rivets on the wing vs the flush, or recessed, rivets used by engineers to reduce drag as much as possible...

2) Gap Seals.
The gaps between flight control surfaces and a wing are perfect spots for drag creation. Airflow moves from areas of high pressure to low pressure through these small gaps, making airflow turbulent, and increasing drag.

Some manufacturers install gap seals on their aircraft to counter this problem. They're also available as installation kits for some aircraft.

3) Fairings.
Wherever two surfaces meet, interference drag forms behind the trailing edge of them. This happens on struts, gear, and the wing/fuselage connection point.

Interference drag can be minimized by using fairings to ease the airflow transition between aircraft components.

4) Wheel Pants

In the POH for C172S Skyhawk, the addition of wheel pants increases airspeed by around 2 knots. Their smooth, rounded surfaces allow airflow to move around the struts with less drag created than bare wheels sticking out in the wind.

5) Winglets.
Winglets are actually little wings that generate lift. And, just like any other wing, they generate lift perpendicular to the relative wind. It might not seem like much, but just a little bit of forward lift helps. It opposes the drag produced by wingtip vortices.

With composites and new manufacturing technology, you can now blend winglets into the wing, significantly reducing interference drag and making the winglets even more efficient.

Learn everything you need to know about how winglets work.
Jose Luis Celada

6) Feathering Propellers.
Some constant speed propeller systems allow props to moved into a "feathered" position. Naturally, if free movement was allowed, a propeller would tend to flatten itself into the wind. Think about driving with your hand outside of a car window. The wind naturally wants to flatten your hand into the wind. And when that happens, suddenly it's harder to hold your hand in place.

When feathered, the propeller aligns itself with the wind to ensure the least amount of surface area is exposed. This significantly reduces drag, allowing air to flow past the propeller with minimal interference. This is one reason why you feather the propeller during an engine failure in a multi-engine airplane. It improves glide performance by reducing drag.

What else reduces drag? Tell us in the comments below!

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Tuesday, 30 January 2018

How To Time Your Flare For A Perfect Landing

Thanks to Boldmethod for sharing...

How To Time Your Flare For A Perfect Landing | Boldmethod
How To Time Your Flare For A Perfect Landing.  By Colin Cutler

Have you ever felt like you can't figure out when you should flare? You're either flaring too early and leaving yourself high above the runway, or flaring too late and landing hard?

Flaring is by far the hardest part of your landing to master, and it takes the most finesse. But, if you set yourself up properly, with your airspeed on target and your glide path steady, it's really pretty simple.

To have a really great flare and landing, you need to have a couple things under control as you approach the runway: airspeed, and flare height.
First Things First: Airspeed

Let's start with airspeed. Your final approach airspeed depends on two things: your landing weight, and your flap configuration. For most aircraft, you'll find the published final approach speed in your Pilot's Operating Handbook or Airplane Flight Manual. It's often in Section Five, next to your landing distance information, or in Section Four, in your landing procedures.

For our SR-22T, Cirrus recommends that we fly final at 80-85 knots with full flaps. And as we cross the runway threshold, we should be at 79 knots. That's the speed required to achieve the published short field landing performance.

Cessna recommends 60-70 knots with full flaps on final, and 61 knots across the threshold for a short field landing distance for the 172. Again, that's the speed required to achieve the POH published landing performance.

Remember that these speeds are published for maximum gross weight. If you're lighter than max gross, you should fly a few knots slower. If you don't, you'll be too fast for your weight, and you'll float your landing.

If you're lighter than max gross and you're still floating down the runway when you flare, continue taking a couple knots off each time you cross the threshold, until you find the speed that works for you. Small changes in airspeed can make a big difference.

If your aircraft's manufacturer doesn't recommend a final approach speed, the FAA recommends that you use 1.3 x VS0.
Altitude: When Exactly Are We Supposed To Start Flaring?

Now that you're on speed for the flare, you need to judge the right altitude to start pulling the aircraft's nose up for the flare and landing.

For almost all general aviation aircraft, you should start the flare at about 10 feet above the runway. Unfortunately, 10 feet isn't very useful to any of us. That's because your altimeter isn't sensitive enough for you to pick out 10 feet above the runway.

Fortunately, there's a better way judge your flare, which leads us into the video below...
When The Runway Zooms In Size...

Watching for the runway to expand in your windscreen is the perfect way to judge your flare. As you fly down final, the runway grows steadily in your windscreen. But then, as you get about 10 feet above the ground, the runway grows at a rate of nearly 10 times faster than before. When you see the runway "zoom" in your windscreen, it's time to flare.

So what does the zoom look like, exactly? Watch the video below - we've mapped the runway width from short final to touchdown.

The Right Combination For A Perfect Landing

Airspeed and altitude control are the recipe for great landings. If you fly the published speed on final approach, and start your flare when the runway starts zooming in your windscreen, you're setting yourself up for a smooth, soft landing.

When you put it all together, you'll impress your passengers, and yourself.

Want to learn more about making great landings in all kinds of weather conditions? Check out our Mastering Takeoffs and Landings course. It's full of tips and techniques you can use to improve your takeoffs and landings on your next flight.

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Tuesday, 23 January 2018

How To Fix The Splitting Pain Of In-Flight Ear Block

Thanks to Boldmethod for sharing...

You've probably experienced ear block when climbing or descending when you've had a cold. It's an extremely painful experience and can lead to some nasty physical consequences. Here's what you need to know...

We spoke to Steve Martin, a professor of aerospace medicine and manager of the altitude chamber at the University of North Dakota to find out more.
Why Your Ears Won't Pop

If you've had a sinus infection, cold, or even allergies, you're at risk for a painful ear block. It's especially true when flying unpressurised airplanes.

Your sinuses are a series of connected hollow cavities in the skull surrounded by soft tissue. The largest is about an inch across. Experts don't really know why we have them, but a few theories suggest that sinuses help humidify and filter air. When you're sick and your sinuses become inflamed, it's difficult for air to pass in and out of the sinuses, leading to a buildup of pressure.

In addition to your sinuses, your Eustachian tubes help equalize the pressure around your eardrums. They're about the size of a pencil, and run from your nose to your ear. When you have a sinus infection or cold, the membranes in your nose block off the Eustachian tube, and your ear subsequently loses much of it's ability to manage pressure changes. This is why sounds become muffled and you begin to feel pressure around your ears.

As you climb in altitude, air pressure decreases, and the air within your sinuses and Eustachian tube also decreases. You typically won't notice pain during climbs, because it's easier for the Eustachian tube to push air out than to suck it in. Because of this, you and your passengers might go most of the flight without any pain.

But once you begin descending, the air around you increases in pressure. This increased pressure pushes on your ears and sinuses. Since they're inflamed, it's difficult for any air to pass back in. This high pressure air pushes in on your sinuses and ears, leading to a painful experience.

Left unchecked, a rapid descent can cause so much pressure buildup that an eardrum might become perforated. In rare cases, the tiny bones around an ear could go to the inner ear and cause a blowout of the "round window," leading to a loss of inner ear fluid and complete disorientation. This is the same fluid that surrounds the tiny hairs in your ears, and gives you a sense of motion.

How Long Should You Wait After Having A Cold?
After a bad cold, you may have to wait up to a week to fly comfortably again. Just because you feel better doesn't mean your sinuses have fully cleared. They could still be inflamed and unable to handle the pressure changes of flying.

You Fly Anyway, Now What?
If you get an ear block, there are a few steps you need to follow:
First, level off. When you or a passenger begin to experience pain, stop the pressure change. If necessary, initiate a climb back to higher altitude, which lowers the pressure on your sinuses and ears. Make sure to request your level off and climb with ATC, and keep them informed about your progress and timing requirements.
Second, attempt to equalize pressure in your sinuses and ears. Yawning, chewing gum, and swallowing are a few good ways to equalize pressure. (Keep reading below to learn how the valsalva maneuver and vasoconstriction can help).
Third, begin descending at a slower rate. Once you're ready to try a descent again, don't exceed a 500 feet per minute on descent. Your ears will likely clear themselves slowly. As long as the pain doesn't become too severe, you won't hurt yourself.

If you need extra time and distance, extend your route, slow your speed, or both. This will give your ears and sinuses more time to adjust to changing pressure.
Don't Do The Valsalva Maneuver Wrong
Avoid simply squeezing your nose and attempting to blow out the pressure. If your right ear is blocked:
Tuck your chin into your left shoulder while tilting your head forward.
Pinch your nose.
Close your mouth.
Give one good burst of air pressure from your lungs.

The key to success is a quick, gentle pop of pressure that will help open up the Eustachian tubes and sinuses. Reverse these directions when your left ear is blocked. When the valsalva doesn't work after a few tries, don't blow harder. If you do it wrong, you could risk over-pressurizing yourself and making the situation even worse...

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