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LONG-EZ - THE WHOLE STORY
In late 1978 we at RAF were
addressing the enormous task of development and certification of the twin engine Defiant.
Knowing that once started, that job would preclude further work on homebuilts for some
time, we took a look back at the VariEze status to see if it was really what we wanted to
market over the next several years. After assessing what was occurring with a large number
of EZ projects, we decided to put the Defiant on the shelf for a while and develop an
improved EZ that would solve some remaining problems. The EZ, designed around the A-75
Continental, is generally tail-heavy when using an 0-200 with alternator. Also, a large
number of builders were being forced into using the 0-235 Lycoming engine because of the
high price and scarcity of the Continentals. Even with no engine accessories, their EZ is
tail heavy and overweight. They desire electrical systems and need a greater useful load.
We decided to design a new aircraft around the Lycoming 0-235 with starter and alternator. It would have unusually long range, thus the name Long-EZ. It would have good forward visibility on landing and a lower approach and landing speed than the VariEze, making it more suitable for the low-proficiency pilot and shorter airfields. The original configuration of the Long-EZ used VariEze wings placed out on a centersection spar that was 4 ft longer than a VariEze. The wings were swept more than a VariEze to support the heavier engine. It had Rhino rudder on the nose and no control surfaces on the winglets. That aircraft 79RA, was built in four months in the spring of 79 and made its first flight on June 12, 79. It did not fly well. Directional stability was weak. Dihedral effect was excessive. Adverse yaw was high. Roll rate was sluggish. Early airflow separation on the wing caused pitch instability at low speeds. The stall speed was too high.
During the next five weeks, N79RA made 51 flights, testing the effects of over 30 different modifications. Modifications included many configurations of wing leading-edge cuffs, wing fences and vortex generators. The winglet "can't" angle was changed. The ailerons were rigged to various neutral positions. Some of the changes resulted in improvements in pitch stability and lateral-directional flying qualities.
However, we were unable to improve the stall speed, landing attitude and roll rate to a satisfactory level. By August we were convinced that to get the LongEZ we really wanted, we would have to build an entire new aft wing.
The new aft wing, first flown in October 79, had the following improvements:
(1) Less sweep
(2) More area
(3) A new Eppler airfoil similar to that on the Defiant.
(4) Longer ailerons.
(5) Improved winglet juncture to eliminate airflow separation at wingtip.
(6) Overlaptype wing attachment to centersection spar, allowing incidence adjustment and eliminating the expensive fittings.
The new wing performed excellently in test. Approach and stall speeds were lowered. The lower approach and landing attitudes allowed "full stall" landings with good runway visibility. Roll rate was superb. Directional stability was still weak and rudder power at the new lower landing speeds was inadequate. We then built new, larger winglets with rudders and removed the Rhino rudder from the nose. That configuration completed flight tests in December 79 with very excellent results in every respect.
It has been shown to be resistant to departure during every conceivable stall entry including tailslides. Its stability is firm even at max aft cg (obtained with a 120 lb. pilot with starter, alternator, vacuum pump installed on the 0-235 Lycoming). Even though it has a wing area 41% greater than the VariEze and a 26% greater gross weight, it cruises at 184 mph at 75% - only 10 mph slower than the VariEze.
Designing an aircraft for long range also results in excellent high altitude performance. Even though the Long-EZ has a fixed pitch prop and no turbo charger, it can climb to 18,000 feet in less than 20 minutes and cruise 155 mph true at 23,000 feet at light weights. Maximum ceiling is over 27,000 feet. Its long range and up to 80 mpg per seat economy are more than welcome with todays fuel price and availability.
The Long-EZ is now the recommended airplane for the 0200 Continental and 0235 Lycoming engines. Complete electrical systems, including starter and night lighting will be approved. The fuel system and trim system are different from the VariEze. Its 142" span canard and elevators are identical to the VariEze. We will be recommending the VariEze only for the 75 and 85 horsepower engines and of course, still without electrical systems. We at RAF are currently preparing Long-EZ drawings for release to homebuilder by early March. Distribution of materials will be through the same suppliers as for the VariEze. Most of the prefab parts are common. The new wing attachment will not be available for retrofit on a standard VariEze.
Long-EZ flight test data will be published in future C.P. newsletters where room permits.