Saturday, June 23, 2012

Two States of Matter Sport - Sailing

Flying and Sailing - Horizontal and Vertical Wings

Air and water. A sailing boat uses gas and liquid flow to propel the boat from point "A" to point "B." In fact, this may give rise to the misconception, about the Bernoulli's Principle  role in flying.

The Angle of Attack provides the force vector that overcomes the drag of the hull in the water. Newton's Law where an equal and opposite force reaction to pushing air and water molecules in such a way that thrust overcomes drag and you can sail! Bernoulli's Principle makes  it possible for the force vector to overcome drag in lighter winds. Think about it. A plane wing, with a large camber, will provide the downward force to counteract the weight of the plane at a slower speed. Remember, Nature abhors a vacuum. It makes it easier for Newtons Law to work.

A sail is a vertical wing. A Jib Sail provides a little more power to the thrust. It also helps to maintain air flow over the Main sail when the sail is close to stalling. The tell-tales on the surface of the sail indicate a stall is eminent or the sail is actually stalled.

The keel of a sailboat is designed to create thrust as well. Look to sailboat races where the larger craft have the hull covered to prevent others to see modifications.

Big time events! The actual speed of a sailboat is comparatively slow due to friction and the drag that is difficult to overcome. In long races just a small increase in speed will secure a win.

If you design the hull so it  displaces enough water without leaving a big footprint (think less drag) that is a big advantage. Archimedies Principle at work. 

Taken together;  Sails, keel and hull designs are crucial to racing success.

Angle of Attack is the deciding factor. Do not let the sail stall. It may take a long time to recover.

Even though water is a fluid, like air, it is not compressible and the density is far greater than air. Corrections take longer to manifest for the result to show.

Don't rip on the "rag-bags" but, instead, enjoy the pleasure as you discover how close to flying sailing really is!  

Friday, June 22, 2012

Steep Turns Near the Ground A Real Killer

Danger-Low Altitude Steep Turns

The danger, with steep turns, is losing control too low and slow to the ground. There is a safe recovery "out" if the pilot doesn't give into "instinct."

If you remember your student days the instructor made you do 720 degree steep turns around a pivot point you could see and identify on the ground. The admonition not to lose altitude was another goal that worked in practice, at cruising speed, and a sufficient altitude to "recover" from a stall or spin.

It is easy to enter a steep turn from cruising speed where the angle of attack is low. If you read my posts you should all know about, "Angle of attack." The reason banking into a turn is easy is the lack of "yaw." You don't need to apply much rudder. You can also return to level flight with more adverse yaw without too much difficulty.

The problem occurs when you try to unbank out of slow, high angle of attack flight. At slow speed there is much yaw and, to prevent the yaw, much need for rudder.

If you try to visualize this condition, in straight flight, in a Cessna 120 (thats right, I'm an 'Old Timer') trimmed for landing and the approach speed seventy miles per hour try to cross control the ailerons and rudder. (Left turn aileron and full right rudder.) I went into a spin so fast it frightened me. i also lost a bet. I was the "ace" 15 year old pilot that said a Cessna 120 wouldn't spin if it was going 70 MPH with the nose down.

Where this might happen is a steep turn, at approach speed, after a missed approach. IFR or VFR flight conditions. Steeply banked with stick or wheel well back with g-loads building up something happens that might  "spook" the pilot. Turbulence close to the ground may cause the aircraft to overbank.

The uninitiated may want to get level in a hurry and you start to behave instinctively. You turn the stick or wheel rapidly to the opposite direction of the steep turn to regain level flight. Because he is flying at a high angle of attack with the stick well back the adverse yaw is very powerful and draws the planes nose inward and down. To counter this the pilot tries again to unbank by applying even more high wing aileron and more back stick to get the nose of the aircraft up. He quickly works into a spin at low altitude where recovery is impossible. Its a "killer!" 

Heres how you may save your life. 
  • Let the stick or wheel come forward which reduces the Angle of Attack that unstalls the wings. This gives the ailerons less adverse yaw that allows the wings to function to lift the plane.
  • Then apply a lot of top rudder. (left rudder if in a right turn)
  • Then apply only gentle high wing aileron to roll the plane out of the bank.
You must do the first two control actions first.  Only then is it possible to use the ailerons effectively.

If this recovery produces some uncomfortable sensation, like a side slip, who gives a hot. You recovered from a fatal mistake.

Remember: Stick forward!

Thursday, June 21, 2012

Circle, Circle my Lake of Choice

Exceed Gross Weight but Within CG Balance

Over gross but within CG balance. With a brand new amphibian the first matter of business is showing it off with all its capabilities.

The SeaBee is overweight and underpowered. It is versatile but be gentle with the plane. No rough control movement. Fly this small plane like an airliner. It is a Holiday Inn plane - no hidden surprises with gentleness on the controls.

Stick to the placarded stickers - especially weight and balance.

Otsego Lake, outside of Gaylord, Michigan is a good seven miles long and a half mile wide. Hoxies Resort is a rough and tumble back woods retreat near the North end of the lake.

Dad fueled the plane at the Gaylord Municipal Airport and he and Bob Nichols, the airport manager got in and flew to Otsego Lake, a short hop.

Dad was around 180 pounds and Bob tipped the scales at  a hefty 225. A round mound, great pilot but round. Did I mention they topped off the fuel.

They landed on Otsego Lake and put the SeaBee "on the step" to reach the resort with minimal waste of time. After powering up on the sandy shore a few feet my friend and I climbed on board for our first flight. The SeaBee has a reversible prop and we applied power to back off the sandy beach.

I tipped the scales at 165 and my friend weighed in around 230, a football guard in HS.

A hint, brought forth by a very extended takeoff run, told the pair up front a problem was at hand. We became airborne but the plane's rate of climb was very, very low.

It took three circles within the perimeter of the lake (seven miles long) to burn off enough fuel to rise to an elevation of 300 feet to clear the tops of the trees surrounding the lake.

We spent another hour, or two, sightseeing the many beautiful lakes and streams that dotted the area.

When we landed at Gaylord we retired to the airport office, with the operating manual in tow, to discover what Dad and Bob already knew. We were  over gross by 350 pounds but within the Normal CG Envelope for the plane.

Couple that with a underpowered 215 HP Franklin engine and you have a delicate climbing capability problem.

Lesson here:
  • Check W&B before you take off.
  • If you are too close to Gross Weight don't top off on fuel.
  • Warm, humid day - a long takeoff run is possible.
  • Remember - experience counts. New pilot.
We were lucky we had "wiggle room" to make shallow, gentle turns as we circled within the lakes borders. It was fun, for Dick and me but I don't think either of knew what could happen with the plane overloaded.

SeaBee Stories from the Past - Gas Cap

Nostalgia - Gas Cap Problems on PreFlight

Ancient relic from the past. Great memories flying with my Dad and the surrounding tales that make them special.

The SeaBee, powered by a  215 HP Franklin engine was a rear engine push propeller amphibian. The gas cap is located on the right side of the plane. A safety chain attaches the gas cap to the frame of the plane to prevent it from hitting the variable pitch (including reverse) prop located aft of the gas cap.

Dad and Mom, owned a small cottage on Big Bradford Lake near Waters, Michigan. At the time this story took place there was a large Hotel and a unique Bottle Fence along Old Highway US-27. This was long before Interstate 75 that was eventually built to expedite traffic from Detroit to the peace and quiet of northern Michigan.

At the turn of the Century (1910 or there-abouts) my grandmother worked as a cook at a lumber mill located at  the north end of Bradford Lake.

The owner of the Mill drank quite a bit of whiskey back then and decided to take all his empty bottles and encase them in a cement fence that was located on either side of the entrance to his Estate near Heart Lake. This is the famous "Bottle Fence" that folks on there way up north could stop and see.

Back to the eventful trip in the SeaBee! There were three human animals and one large Collie inside for the trip and landing on Big Bradford Lake. My childhood friend, Joe Trickey, was in the right front seat next to my Dad (it was Joes first ride in the SeaBee). The plane is quite noisy since the engine is located right behind the rear seat passengers. Skipppy (the dog) was sitting in the right rear seat and I was sitting next to the mutt behind my Dad.

About ten minutes before landing at the lake the gas cap, which wasn't closed properly, decided to come off. Nobody knew what happened but we couldn't see Joe! The dog leaped right on top of poor Joe. The dog was large, about 110 pounds. The banging cap against the aluminum hull of the SeaBee made a perfect duet with the noise of the engine. All this confusion continued until we landed in the lake. Joe managed to get out from under the dog, who remained in the front seat, too frightened to move.

When we docked and opened the front hatch the dog disappeared about as fast as Joe disappeared a few minutes before. It took a while before the dog showed up at the cabin.

This story made the rounds back in Lansing where it all began with a mis-aligned fuel cap waiting for its chance to blow off while tethered to the hull!

Wednesday, June 20, 2012

Is Your Life Going Around in Circles

Holding Patterns - IFR

If it is, you are probably in a Holding Pattern in a IFR Flight.

The holding pattern for aircraft on an IFR Flight Plan is like a car racing track. The track is based on a Holding Fix. The fix may be a Non Directional Radio Beacon (NDB) or a VOR. A plane will fly toward the Fix.

The fix is the start of a predefined racetrack pattern. This standard holding pattern uses standard rate right turns (3 degrees/second).

The pattern takes approximately four minutes to complete. (one minute for each 180 degree turn (two minutes) and two one minute straight ahead legs.

The ATC Center will advise the IFR Flight Pilot if extensions of the straight legs need to increase their length if  delays are required due to unusual length. (two or three minute legs).

If a plane has a DME the straight legs are defined in nautical miles rather than in minutes. If you have passengers they are more comfortable with less frequent turns over a period of time. (read longer hollding patterns).Some holding pattern turns are left turns if there is airspace restrictions nearby.

The fix is any fixed point in the air created by using two crossing VHF (VOR) radials. That fix is called an intersection.

If you have GPS capability, the waypoints define the holding pattern. This eliminates the need for ground based navigational aids.

For VFR Holding Patterns the racetrack pattern is smaller and a visible terrain below, like a lake, defines the fix.

Basically, a holding pattern delays the actual time of arrival because of traffic congestion, poor  weather or runway       unavailability (snow  removal).

Busy airports may stack holding pattern planes one above the other. New arrivals enter at the top of the stack. When the runway below clears the botom plane leaves the pattern and the ATC controller brings all the planes down to a lower level, one at a time, to continue emptying the holding pattern stack.


Middle Marker - Outer Marker - What Say -

ILS Systems

Report over outer marker inbound. Familiar phrase if you are on a instrument approach using the ILS System.

The Jepp Charts indicate the distance from the end of the runway and the height of the airplane should be when the indicator for that particular beacon lights up on the instrument on your plane's panel.

There are three lights. The outer beacon marker is the first  you come in contact with, on a  ILS approach, it emits a blue colored flashing light and a tone. (to catch your attention) This provides a check on the correct function of the glide-slope. In modern systems the DME is installed in your aircraft and provides the aircrafts distance to the runway. The DME (distance measuring equipment) is co-located with the ILS.

The tower asks you to "Report Outer Marker Inbound" on a instrument approach. When the Outer Marker Beacon in your plane signals you, that is your clue to report back on  the tower frequency, "Outer Marker Inbound." The tower should reply, "Cleared for landing."

The middle marker beacon is the second light that flashes a amber color and emits a tone of "dots and dashes" (Morse Code style) at the rate of two per second. The missed approach point and the point where you should have a visual sighting of the runway is very near.

Middle Markers are no longer required in the United States. You may have equipment, in older aircraft that have a instrument that has all three beacon lights.

The inner marker beacon is located near the runway threshold to indicate, in very low visibility conditions, the runway is just a short distance away. It emits a white flashing light and a tone that is a continuous series of "dots" Morse Code style. 

Since I am an ancient relic of the "Good Old Days" the Marker Beacons are being phased out and replaced by DMEs that provide slant range measurement of distance to the runway in nautical miles. The DME provides more accurate and continuous monitoring of correct information on the ILS glide-slope to the pilot.

The safety word here is "continuous." The importance of "continuous knowledge of exactly where you and your plane are in the airspace." Updating equipment is a necessary evil for your own safety.

Tuesday, June 19, 2012

Visual Illusions during Night Landings

Night Visual Illusions - In Air and On the Ground

Automobiles are familiar places to begin to discuss how we estimate car speed when we drive a boxy sedan or a race car.

If you own a sports car you get used to viewing the objects you pass on the road as a way to judge your car speed. If you take the family on a vacation you might use a SUV. The driver sits higher above the road in a SUV.

Now, at sixty miles per hour, it seems to the sports car driver, the Van is going slower. You just experienced a visual illusion in perception.

A runway is outlined with a lighting system. During normal night landings, in no-wind conditions, the lights help you judge when the wheels will touch the runway. As you descend towards the runway the lights move faster in your peripheral vision. 

In a strong head wind the runway lights in your peripheral vision seem to move slower than usual. You perceive you are higher than you think. Dangerous illusion. You may hit the surface of the runway before you are ready to land. You thought you were higher because of the slower movement of the lights.

With a significant tail wind the illusion changes. If you make a mistake, and fail to notice the direction of the lighted windsock, a downwind landing illusion is possible.

In this illusion you may be considerably higher than you think. Now, in your peripheral vision, the lights indicate you are just about to touchdown. You slow your plane and prepare to stall perfectly in a smooth landing. Instead, at the moment of the stall, you realize you are some distance above the runway and hit the runway in a nose down attitude. This is not good for you or the airplane.

The purpose of this post is making you aware of the possibility of illusions when landing at night. Don't succumb to them. Know the flight conditions at the airport.

Of course, if you are a newbie to flying you used landing lights to help you visualize the runway. 

Monday, June 18, 2012

VASI - How Can it Help You?

Visual Approach Slope Indicator Lights

VASI is an acronym for Visual Approach Slope Indicator that is located approximately twenty-five feet in from the beginning or start of the runway. The system consists of two separate rows  of lights on a box usually located on the left side  of the runway. It provides a proper glide path for a plane to follow to the runway.

For the two row VASI system both rows, for clarity of explanation, consists of one row of white lights and one row of red lights. The normal glide slope is three degrees with variations for sloped runways and high obstructions nearby with different banks of lighting.

When the pilot approaches the runway he is faced with three choices. He is too high. (Both rows of double lights show only the white lights.) He is right on the glide path. (Top row of double lights shows only the white lights and the bottom row of double lights show only the red lights.) He is below the glide path. Top row of double lights show only red lights and the bottom row of double lights show only red lights.

To the Pilot:

Two White Bars - you are above the glide slope.
Upper Bar White - Lower Bar Red - you are on the glide path
Two Red Bars - you are below the glide slope

The lighting system I describe is very simplistic. It is just my way of illustrating a very complex system of banks of lights.

Visibility of the lighting system is between two and four miles in daylight and upwards of twenty miles at night.

VASI allows a pilot to follow a normal glide slope of three  degrees down to the runway.

The depth of explanation is too much for a brief post . You know the basics now click on VASI. It will allow you to read the details of the system and the variations that exist at different airports.

Light Gun Signals

Light Gun Signals - Tower Instructions

Flying into controlled airports, without radio communication on the piloted plane, you must have knowledge of the instructions sent to you by light signals. These instructions may help. Try making a small readable page on a computer to keep in a plane - just in case! 

Steady Green on Land:
  • Cleared for takeoff
Steady Green in the Air:
  • Cleared to land
Flashing Green on Land:
  • Cleared to taxi
Flashing Green in the Air:
  • Return to land
Steady Red on Land:
  • Give way to other aircraft
Steady Red in Air:
  • Give way to other aircraft
Flashing Red on Land:
  • Taxi clear of runway
Flashing Red in Air:
  • Airport unsafe - do not land
Flashing White on Ground:
  • Return to starting point on airport
Alternating Red and Green Flashing:
  • Exercise extreme caution on land or in the air

If you fly into busy uncontrolled airports with a manager, during daylight hours, they may have a signal gun and will use it to convey operation instructions to the planes approaching and in the landing pattern sequencing for landing.

In all cases it is very important to increase your "scan" for other planes. First order of business, controlled or not controlled, is look for air traffic - ALWAYS.

Now, many pilots with antique aircraft, carry portable radios to communicate with controlled airports. Remember, some batteries in portable radios give a strong signal then suddenly quit. That is the nature of the batteries. Some weaken slowly, others don't.

Many of you  know these unspoken light signals. Help teach new pilots learn them for their own safety.

Crosswind Landings - Part 3 - Sideslip

The Side-Slip Technique

The Sideslip Technique differs from the Crab and De-Crab techniques when the wheels touch the runway. The upwind wheels touch first in the Sideslip.

When you start the sideslip, on your approach, you use the crab technique to correct for drift caused by the crosswind. The actual heading of the planes body, after drift correction, is controlled by using the rudder and ailerons to align with the runway center line.

If you keep the position of the rudder/aileron and apply  pressure, the plane stays at a constant sideslip angle unless the crosswind changes velocity, like on a gusty wind day.

The plane tries to correct back, under these pressures and control applied by the pilot, to the aircraft's natural stability in straight and level flight.

The sideslip configuration creates a tendency for the wings to cause the plane to roll. This is referred to as the dihedral effect.You must apply aileron to check the bank angle.

When you make contact a small amount of bank angle is present that causes the upwind wheels to touch the runway first.

The danger,in this technique, is excessive control that may cause over-banking where damage occurs to the wing.

If the crosswind is strong and gusty it makes control of any of the techniques difficult. Flying on days where gusty conditions are present is dangerous.

A Instructor can help you learn when to fly or wait for a better day.

Crosswind Landings - Part Two - De-Crab

The De-Crab Technique

De-Crab is the recovery technique to align the plane with the center of the runway where the vector component of the crosswind is significant.

This technique is different from the Crab Approach which uses a coordinated turn into the crosswind early on to align the flight path of the plane to the center of the runway.

The idea of the De-Crab approach is maintaining level wings with the aircraft in a slightly crabbed position with respect to the centerline of the runway.

This presents a visual illusion that a pilot is presented with as the plane seems to take up a heading with the plane that is different from the actual flight path of the plane.

The position of the plane is controlled by the increased drag force as the plane flies in a "skewed" manner and the application of thrust provided by the engine and propeller.

This allows the plane to approach the flare point with level wings. Just before touchdown opposite rudder is applied gently to align the plane with the center line of the runway and, at the same time, opposite aileron is applied to maintain a level wing approach.

The cross controlling of rudder one way and opposite aileron the other way can increase the angle of attack that, in some cases, could precipitate a stall. Save the cross control effect  until the last moment before touchdown.

If you practice this technique so that at touchdown the plane body, velocity vector and bank angle are all aligned with the runway centerline you have accomplished a successful crosswind landing.

Please consult your Flight Instructor for further refinement of this crosswind technique.

Sunday, June 17, 2012

Crosswind Landings - Techniques: Crab, Sideslip and De-Crab

The Crab Technique

What is a crosswind landing? Think of wind blowing at right angles to the runway. Thats a true crosswind. In real life it is the component of a crosswind that is considered perpendicular to the runway. If a wind is at a 45 degree angle to the runway there is a vector component  perpendicular to the runway that determines the way a pilot plans his crosswind technique for landing.

Crab Technique:

The idea is,at the moment of touchdown, the axis of the plane is aligned with the center of the runway without drift.

If drifting across the runway takes place when your wheels touch the runway, damage to the aircraft can occur if you don't correct the drift.

The "Crab Technique" the plane makes a coordinated turn into the crosswind to stop the lateral movement of the plane and align the plane with the center of the runway while descending to land. A sideslip is not used.

On normal dry runway surfaces at touchdown the wheels track towards the windward side of the runway while the pilot de-crabs to align the plane with the center of the runway. Forward momentum aids in the effort to align the plane. Use  the upwind aileron to keep the wings level and the rudder to keep the plane aligned to the runway.

It is important to first make a coordinated turn into the crosswind. Maintain the plane level all the way to touchdown. Timing, of course, is important.

Flying from High to Low Look out Below

Why Reset your Altimeter on IFR Center Command

What does this phrase mean? In Instrument flight you are in contact with a person from air traffic control, like Atlanta Center, that starts with the current altimeter setting expressed in inches of mercury. For example, 29.92 inches of Hg is the normal atmospheric pressure on a aircraft altimeter at sea level.

When you are aloft the atmospheric pressure decreases as you gain altitude. Center will give you the latest pressure reading in inches of Hg as you fly towards your destination.

Your altimeter must  be set to the latest altimeter setting received from Center. Why? If you don't set your altimeter to the latest value provided by Center the phrase "Flying from High to Low Look out Below" takes  on meaning.

Each inch of Hg (Mercury) represents approximately 1,000 feet of altitude. If  your current altitude is 6,000 feet and your altimeter setting is 29.92 inches of Hg and you forget to reset  the altimeter to, for example, 28.92 inches of Hg Center just provided (a deepening Low Pressure area ahead) your aircraft is actually flying 1,000 feet lower than you think. (Read his article several paragraphs down for a detailed diagram that illustrates how the error occurs)

This is a serious mistake. Instrument rated pilots must repeat back to Center the altimeter setting he just read to you over your planes radio. He is reminding you to set the altimeter setting NOW

If the base of the clouds is only 300 feet above ground level the pilot will crash the plane while thinking he has plenty of altitude while on a instrument approach to the airport runway. 

The opposite occurs if your flying from a Low Pressure area to a High Pressure area if you don't reset the altimeter setting to the value transmitted to you by Center. You are flying a 1,000 feet higher than you think.

Remember the idea of the FAA Centers is to provide separation between planes at the same level and/or keep a vertical distance of 1,000 feet between flight levels of two or more planes.

You can purchase a Encoding Altimeter that transmits information to Center that allows him/her to see what you actual altitude is. It is embarrassing when Center tellls you of your altitude error.