Friday, 10 August 2018

Four Tips for Summer Flying

4 Rules-Of-Thumb For Late-Summer Flying; by Colin Cutter -
Thanks to Boldmethod for sharing...

1) Calculating Civil Twilight
Summer days are getting shorter, but there's still a lot of daylight left.
A good rule-of-thumb for calculating civil twilight is that it usually ends between 20-35 minutes after sunset. Tonight in Boulder, CO, sunset is at 8:05 PM, and civil twilight ends at 8:34 PM. That's a difference of 29 minutes. Once twilight ends, you can start logging night flight time. But remember, you need to wait an hour after sunset to log night landings.

2) Takeoff roll increases about 10% for every additional 1,000 feet of density altitude
There's no sign of the weather cooling down yet. And on hot days, you get high density altitude. For most normally-aspirated GA airplanes, you'll add about 10% of takeoff roll for every 1,000' of DA. For example, if your airport's density altitude on a hot day is 3,200' over field elevation, you'll increase your takeoff roll by about 32% over an ISA day. So if you have a 1,500' takeoff roll on an ISA day, you'll increase that roll to almost 2,000'.

3) Stay a minimum of 5 miles from storms, and up to 20 miles if you can.
Flying closer than 5 miles from visible overhanging areas in storm clouds puts you at risk of flying through hail and severe turbulence. That's not good for your plane, or your passengers. In some cases, aircraft have encountered hail, severe windshear, and severe turbulence up to 20 miles from storms. When in doubt, keep your distance.


4) Add Half The Gust Factor On Windy Day Landings.
As we approach the end of summer, windy days increase across the US, because the jet stream starts moving south. When you're dealing with a gusty day, the FAA recommends that you add half the gust factor to your final approach speed to give yourself safe padding from a stall. For example, if the winds are reported at 18 knots, gusting to 30 knots, it means you have a gust factor of 12 knots (30-18 = 12). So if you take half the gust factor, you get 6 knots (12/2 = 6).


To apply that in an SR-22T, Cirrus recommends that you fly final at 80 knots. So on a day with a 12 knot gust factor, you'd add 6 knots to the published 80 knots, for a final approach speed of 86 knots. The same math works for any GA airplane's final approach speed. Just add half the gust factor to your final approach speed.


Thanks to Boldmethod for sharing. What other rules-of-thumb are you using? Tell us...
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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 |

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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