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We welcome and encourage responses, (comments and questions), concerning the information presented here.
Contact Gevers Aircraft by e-mail at <mgevers@iquest.net>
Or write to:
Some of the most commonly asked questions are:
Q: What is the reliability of the belts in the propeller drive?
A: Belts of this type have been used for many years in machinery having much harsher environments, (i.e. higher loads, dirtier surroundings, little or no maintenance, etc.), and have been proven to be very effective and reliable. In addition, this is a redundant system consisting of 3 sets of belts in each segment, any 2 of which can carry the maximum power required.
Q: Can the aircraft be landed safely with the wings retracted?
A: Yes. Not only can the aircraft be safely landed in the fully retracted wing configuration, but it is intended to be taken off and landed in the wings retracted configuration in flight training to simulate high performance aircraft. Think of the extended wing as nothing more than span-wise flaps as opposed to conventional chord-wise flaps. Normal landings are intended to be conducted with wings extended, however, as with other aircraft, safe landings can be performed with flaps retracted. With the wings retracted stall speed is just over 100 MPH, the retracted configuration landing will be typical of a conventional high performance twin. In addition, the aircraft can maneuver and land safely with the wings in any position including transition between extended and retracted.
Q: Is there enough aileron power to handle a failed prop in "short-wing" configuration?
A: The short wing has a large aileron-to-wing area ratio, and therefore, sufficient aileron control. Although there is sufficient aileron control in the short wing configuration it would be appropriate to detail the further aerodynamic benefits resulting from our design elements in the event of a prop failure.
* Simply lowering the landing gear brings the prop centerlines close to the center of the aircraft.
* Counter-rotating props reduces asymmetric thrust.
* With the gear/prop arm retracted the props are nearly centered on the wing trailing edge. The angle of attack of the prop remains nearly constant, therefore the thrust line does not shift toward the down going blade (P-factor) because the wing forces the airflow through the prop at a constant angle.
Q: Does the aft engine & forward passenger design pose a C.G. problem?
A: No. The passenger loading is typical of conventional aft-engine designs. The center of gravity envelope will accommodate occupancy by either a single pilot or the full compliment of passengers and baggage.
Q: How do you accommodate the very high propeller shaft bending moments due to changes in angle of attack and sideslip, created by the large gyroscopic forces in maneuvers?
A: The prop arm is designed as a rigid box structure. It is relatively short (spanwise) and deep (chordwise) and is quite strong in torsion due to the triangular cross-section (taken in a plane parallel to the wing ribs). The arms are stronger than typical engine mounts on aerobatic aircraft, which have to resist not only gyroscopic forces but also landing impact loads of the engines.
Q: The pictures don't show a step in the hull bottom for water operations.
A: The aircraft does have a conventional step for water operation even though the pictures do not show its details. With the gear retracted, the outriggers are stowed in the recess in the aft bottom of the fuselage behind the step filling it in to provide an aerodynamically clean hull in cruise. When the outriggers are extended, that recess becomes the ventilated area behind the step. The step is the heel of the main center gear skis when they are retracted and as such provide a shock absorbing nature to the step. Note that in the water configuration the outriggers are fully extended while the main center gear and skis remain retracted.
Q: Doesn't the thick vertical fin produce extra drag?
A: The significant strength and stiffness improvement of this tail boom design allows for a weight reduction over conventional tail booms which more than compensates for the few pounds of added drag which have been calculated.
Q: Does the propeller drive system require specialized pilot training?
A: No. In fact, pilot training will be easier in the Genesis. All seaplanes have the propellers mounted high to keep them clear of the water spray. When increasing from idle to full power the conventional high engine mounting produces a change in pitching moment that is greater and more sudden than that for the Genesis when moving the propellers from low to high positions. So no more pilot training is needed than for any other amphibian. We should have less pitch change than a typical amphibious aircraft since the prop wash downloads the "T" tail. The pitch down tendency due to a high thrust line is offset by the added down wash across the horizontal tail. One of the most difficult and dangerous situations for a twin engine pilot is when one engine fails on takeoff. In this situation the Genesis' interconnected engines vastly reduces the workload on the pilot in the emergency situation. Props are only de-coupled for taxi operation.
Q: Is a computer controlled system required to provide gain/trim changes for stability and control in each configuration?
A: No.
The Landing gear drag is approximately balanced above and below the wing - thus little pitch change.
The wing pitching moments are approximately balanced (inboard vs. outboard wing) - thus little pitch change.
The prop wash downloads the tail - thus approximately balancing nose down thrust with tail down inverse lift.