To perform the “wheels down” tail-slide, simply apply full up-elevator when the model begins to slide back. This will make the model fall with the wheels pointing towards the ground. If you want to perform the “wheels up” tail-slide, apply full down-elevator when the airplane begins sliding back; this allows the airplane to fall over with its wheels pointing toward the sky. In competition aerobatics, the distance that the airplane must fall backwards must only be a visible amount. Also, when the aircraft slides backwards, it will often “pendulum” past the vertical after falling through. This “pendulum” effect is completely normal and should not be considered a downgrade.

While this may seem like a fairly simple maneuver to execute, it takes a lot of practice to perform consistently. Also, different factors exist that will make this maneuver more challenging to perform. For example, if wind is present, it becomes more difficult for the model to slide backwards while holding the vertical up-line. The model may want to angle itself into the wind. If you find that after performing this maneuver a few times, you’re having difficulty getting the aircraft to slide back, you may need to move the center of gravity back (make the model more “tail heavy”). However, always remember to add tail weight in moderation, as an extremely tail-heavy model can become very unstable in conventional flight.

DOWN TO BUSINESS
The tail-slide shown here is a wheels-down version and is being performed parallel to the runway, from left to right.

1. While flying parallel to the runway and making sure that your wings are level, increase the throttle to full power. If your airplane does not have a great power-to-weight ratio, pull into the º loop gently to establish the vertical up-line.
2. The length of the vertical up-line is entirely up to the pilot. However, keep in mind that larger maneuvers often look better than smaller ones. Also, the length of up-line varies depending on your aircraft’s size. Regardless, keep in mind that you may need to apply various rudder corrections to keep the model tracking on a perfectly vertical up-line.
3. Begin pulling the throttle back until the airplane comes to a stop. If the airplane is on a perfectly vertical up-line, the aircraft will begin to fall backwards. With the “wheels-down” tailslide, you apply full up-elevator to guide the model’s tail back and away from the vertical down-line. After the aircraft rotates its nose will fall forward. When it nears the vertical down-line, release all elevator input.
4. The length of the vertical down-line should to be the same length as the vertical up-line.
5. To exit the maneuver, begin the final º inside loop by applying up-elevator and make sure that its radius is the same as the entry radius. As the model nears horizontal upright flight, increase power to keep the airspeed constant.

Even though the fundamentals of performing the tail-slide are fairly easy, depending on the wind conditions, this maneuver can be challenging. Don’t become discouraged if you cannot perform this maneuver during your first few attempts. Always practice, and if you still find difficult to perform, gradually add some tail weight and take a closer look at your aircraft’s control setup. Until next time, safe flying and always remember to have fun!

The post Master the Tail-Slide appeared first on Model Airplane News.

On the other hand, if you wait until the controls are no longer effective to start to add power, you may not recover control in time to save the maneuver. You need to smoothly pump the throttle during a harrier to maintain propwash over the tail surfaces without holding the higher throttle position long enough to cause the airplane to accelerate. The objective is to pump the throttle to maintain control and altitude. The instant you sense the controls becoming ineffective, or if the plane starts to descend, give the throttle a little extra boost. You’ll also find that you can respond more quickly when you’re continually pumping the throttle, than if the throttle is stationary. To maintain the same height during a harrier, the amplitude or range of the throttle movements is usually between quarter and half throttle, with an airplane capable of hovering at half throttle. If you lose complete control at these very low airspeeds, often the only way to regain control/recover is to go to full power.

All the maneuvers featured in this 3D flying series are flown on high rate flight mode.

Elevator technique

Pump the throttle to maintain propwash over the tail and thus control authority without accelerating. Vary the amplitude or range that you pump the throttle to control altitude throughout the harrier pass.

The simplest way to enter a harrier is to slow down to nearly stall speed, and then smoothly pull the nose up to establish a very high angle of attack while simultaneously adding power to maintain the same height.

Continually pump the elevator to maintain an approximate 45-degree fuselage angle during the harrier pass, i.e., raise and lower the nose by increasing and decreasing the size of your elevator adjustments.

While both the left and right wings are deeply stalled during the harrier, they tend not to stall exactly the same, and consequently, the wings tend to rock from side to side. Every airplane has a certain fuse-lage angle or “sweet spot” during a harrier that results in the least amount of wing rocking. That angle is usually close to 45 degrees, and it usually takes about half elevator to achieve it. You will then find that it takes constant elevator adjustments to maintain that angle due to the fact that airplanes are not designed to fly this way. Note that if you are late with any elevator adjustments, it will take a much larger input to recover, thus increasing the potential for over-controlling. Smoothly pump the elevator throughout the harrier to keep your fingers nimble and ready to instantly respond to the needs of the moment. Inputting a series of smaller adjustments, rather than waiting to respond with larger adjustments, ultimately reduces the potential for over-controlling.

Rudder-aileron technique

Hold in right rudder to correct for propwash and P-factor left turning tendencies. Correct deviations with small brief bumps of rudder and coordinate aileron and rudder to keep the wings level.

Rudder is used throughout the harrier to correct course deviations and to steer the airplane. Most of the time, you’ll have to hold in right rudder to correct for the left turning tendencies of propwash and P-factor (asymmetric propeller thrust) encountered at high angles of attack. Use coordinated aileron and rudder inputs to keep the wings level. Note that adverse yaw will be significant any time you apply aileron at high angles of attack, so you must coordinate rudder with the aileron in the same direction when leveling the wings to prevent adverse yaw from causing the maneuver to unravel.

Most important, because airplanes are typically very unstable during high alpha flight, it is crucial that you keep your rudder and aileron corrections small and especially brief (i.e., “bumps”) to avoid aggravating the wing rocking phenomena.

Conventional flying experience teaches us to relax the elevator and lower the nose when the wings start to rock during a stall. Resist the urge to relax the elevator when the wings start to rock during a harrier. Maintaining a high angle of attack can actually work to lessen wing rock by keeping both wings deeply stalled and having as little aerodynamic influence on the maneuver as possible. In other words, sometimes pulling more elevator will lead to less wing rocking.

Elevator-flap mix

An effective technique used to reduce wing rock is to activate the elevator-flap mix so that both ailerons raise up approximately 20-30% when holding in up-elevator. While you’re at it, you might as well program both ailerons to lower 20-30% with down-elevator to compliment future inverted 3D maneuvers (inverted harriers, elevators, etc.).

Harrier turns

Mixing both ailerons up 20-30% with up elevator helps reduce wing rocking at extreme high angles of attack.

Turning while in a harrier attitude consists of steering with the rudder, using the ailerons to keep the wings level, and pumping the elevator and throttle to maintain the same fuselage angle and altitude.

As unstable as an airplane is during a harrier, in order to turn without over-controlling, you must limit your rudder inputs to brief nudges every few moments. Be sure to gently nudge the plane around the turn with rudder while applying opposite aileron to keep the wings level. Attempting to turn with the rudder alone at this high angle of attack would lower the wing on the inside of the turn, and doing this at a low airspeed could cause the airplane to sharply fall off to the side. You’ll need to apply opposite aileron throughout the turn to keep the wings level. Remember, if the wing on the inside of the turn drops, the plane can fall abruptly toward the ground, so always be ready during a harrier to punch the throttle to full in order to help with recovery. Once the turn is finished, continue using the rudder to steer, but switch to coordinating aileron and rudder in the same direction to keep the wings level.

Conclusion

Control the rate of turn during a harrier with rudder, and cross-control opposite aileron throughout the turn to keep the wings level.

Note:If the plane behaves strangely, as if it is responding to alien control inputs, it is most likely that the mix percentages you’re using are far too high. This would explain why odd things are happening during other maneuvers as well.

You should, of course, practice this maneuver on a simulator before attempting it in the field. Even though you will probably find that the simulator has a different feel than real-world 3D flying, sim practice will help sharpen your reflexes and get you in the habit of manipulating all the controls simultaneously. Remember, it helps if you keep your fingers moving when flying 3D and be ready to punch the throttle to full to recover when things unravel. Good luck.
TEXT & ILLUSTRATIONS BY DAVE SCOTT

The post The Harrier Pass – 3D Acro Explained appeared first on Model Airplane News.

Model Airplane News contributor Rich Uravitch was on the scene when this impressive and highly unusual aircraft first took flight. Flown by Goetz “Doc” Vogelsang, this slick looking jet is the first true turbine powered biplane we’ve ever seen. Fully aerobatic, the all composite Quantum is like a Christen Eagle on steroids. Built from a Tomahawk kit, the prototype was developed and the molds made by Harry Behringer. Having impressive performance the Quantum has a span of 79 inches,  a length of 94 inches and weighs in at 27.5 pounds!

Photos by Rich Uravitch and David Hart.

The post Hot Turbine Biplane — Best of Both Worlds? appeared first on Model Airplane News.

Text and Photos: Paul Stenberg

(Above) The original London Bridge moved from London, England to Lake Havasu City 50 years ago in 1968.  It has become a landmark for the city.

There you will be able to fly your favorite model airplane from the largest water runway you will ever find.  It is always a treat, light winds, bright sunshine and 70 to 80 degree temperatures. The 56 pilots that registered were in for an absolute perfect day of flying as Saturday dawned bright and sunny with the temperature running to about 70 degrees and almost no wind. All six flight lines had backup lines waiting to fly all day.

(Above) Monty Welch’s Park Scale Albatros in Coast Guard colors.  The model is 96” span and is only 10.5 lbs!  Electric powered and was built by his wife Lina Welch, truly a family project.

Every registered pilot received a T-shirt, commemorative event plaque and two tickets for the pilot’s raffle.  The site is Windsor beach State Park.  The parking lot serves as the camp ground for many of the pilots that arrive in RVs.  The Desert Hawks provide trailer shuttle service to carry all pilots, planes and support equipment from the RV compound to the beach.  They also man two recovery boats all day long on the lake for those few unfortunate incidents or dead stick landings away from the shore.  At the end of the day, they return everyone to the compound, what more could you ask for?

(Above) The beach was full on Saturday.  Everyone having a great time.

At night there is night flying in the grass area of the park.  In addition, there are always great scents coming from the BBQ dinners in the RV compound.  There are always groups gathering to tell stories from the past and sharing modeling ideas.  For those interested, there is a Casino shuttle that runs until late at night to take the people feeling really lucky, from the base of the London Bridge across the lake to a Casino on the California side of the lake.

(Above) A Sopwith Schneider Baby built by Marjoe Bunney comes in for a landing.  108-inch span, 46lbs. and Quadra Q-100 for power. 

The variety of aircraft is always great.  Most common are Cubs and Beavers.  There are also many flying boats, either scale like the Grumman Albatross or one of the many different sport scale designs.  There was even a Schneider Cup racer that made one flight.

(Above) One of the Schneider cup racers. This one is a Curtis R3C-2. The full-scale was flown by Jimmy Doolittle in the 1925 Schneider cup race. This model was built by the team of Larry Tate, Jerry Lieche, John Hanks and Bob Martin in 1988.  88-inch wingspan, 39 lbs. and powered by a Sachs 4.2ci engine.

The Desert Hawks have been supporters of the historic Schneider Cup racers, and have held four Schneider Cup re-enactment races in the past.  2019 marks the 30^th anniversary of the first of these events and a 30^th reunion is planned.  The hope is to have enough aircraft to allow several race heats throughout the weekend.

(Above) Aeroworks Cessna 195 flown by Larry Ayotte of Mesa Arizona.  90 inch wingspan, 21lbs. and powered by a DLE 35.

(Above) One of the many J-3 Cubs at the event.  This one is 1/4-scale.

As November 2019 approaches and you are feeling the early effects of winter, gather up your favorite aircraft, add a set of floats and travel to Lake Havasu City for the 34^th edition of the London Bridge Seaplane Classic.  You will not be disappointed while being treated to great hospitality and the world of float flying.  What better way to spend a weekend combining the beach, flying and friends.

For more information on the club and event: CLICK HERE

(Above) Tim Hanstine of Northwest RC put on a great show with his DA 70 powered 120-inch Turbo Bushmaster. 

(Above) More Cubs!

(Above) Carlos Rangel of Tucson brought his Top Model Beaver.  Electric power using an E-Flite 150 and 10 cell Li Po battery back.  1/5 Scale model has a 90” wingspan.

If you like flying off of the wet stuff, this is a great event to attend. For more details on the Schneider cup history go to Schneidercup.com.

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