The VSKYLABS Micro-Hopper Project
An Ultralight Bush-Plane Experimental Prototype
For X-Plane 11
The VSKYLABS 'Micro-Hopper' in detail
As most of VSKYLABS projects, this is an evolving project, maybe a little research-type project also (or more of an education one).
This project's objective was to create a microlight/ultralight style of an aircraft with 'Bush-Plane' capabilities. 'Bush-Plane', by definition, is an aircraft used to provide passenger and freight services to remote and usually undeveloped areas, where ground transportation doesn't exist (or rarely exist). Such airplanes are also usually used for search and rescue operations in remote, hard-to-get areas.
Usually, a Bush-Plane would be a utility kind of an aircraft; very durable, tough, reliable and with an easy ways to convert its usage to different kinds of terrain, including water, snow, short take-of and landings etc...
By definition, there is some kind of a conflict between a microlight/ultralight aviation oriented aircraft and a utility type of an aircraft, especially in its inherent capability to carry multiple passengers and equipment. But, having a design of an ultralight aircraft that meets some of the utility-bush-plane aircraft specifications and requirements had me thinking....well...this would be quite a flexible, safe and durable piece of an ultralight aircraft to fly.
Wing configuration - The challenge:
During the design phase, I've considered some basic layouts and configurations for such of an aircraft; wing types, undercarriage type, propulsion, handling and controls, ground operations and so forth...Making this report not too long, I will say that a flying-wing configuration was very tempting to try, and the starting point of this aircraft was that it should be based on a flying wing layout.
In theory (and in practice...), the most challenging aspect of a pure flying wing aircraft is lateral stability. Without vertical surfaces, you will need other control methods to obtain lateral stability, such as the use of spoilers for yaw control. Flight envelope in terms of lateral stability will be narrow, and in complex configurations...an artificial stability system will have to take part in controlling the aircraft.
Fixing vertical stabilizers and rudder to the pure-flying wing plane will help to achieve the needed lateral stability, but in case of a high-aspect ratio wing configuration, the adverse-yaw might induce some control issues that might not allow to fly the aircraft aggressively. The short distance of the vertical tail from the C.G. will not allow to gain the great amount of stabilizing moments that are needed to obtain stability in rough conditions...unless this proposed vertical tail/fins will have a massive surface area, but such huge stabilizers will bring more "trouble" to the design and to the airplane's handling characteristics in rough conditions.
Another disadvantage of using a pure flying wing configuration for a bush-plane design is its tolerance and performance in cross-winds conditions. A pilot flying an aircraft to a remote place, without any paved runways or runways at all will probably face a condition of landing and taking off in cross winds, even severe ones. The pure flying wing design will reduce the tolerance of the aircraft to such conditions, making rough-gusty-crosswinds landings almost impossible, and furthermore, ground operations will not be effective because you can't keep an aircraft in a desired direction in crosswinds, using only the steering wheel, especially in a tail-wheel configuration aircraft. The vertical stabilizer has major part in maintaining a needed direction during take-off and landing ground rolls, in all speed ranges. Fixing vertical stabilizers into a pure flying wing aircraft will help a bit, but because of being relatively close to the CG, the moment of these tail/s will not be enough to withstand moderate cross-winds.
Wing configuration - The solution:
So the baseline configuration was a pure flying wing. Although not the best starting point to a bush-plane design, I wanted to play with this challenge, to see where it will take me...
I new from the beginning that the design will not remain a pure-flying wing because of the reasons described above. Any kind of a bush-plane design (ultralight or not) will have to allow sufficient lateral stability and control authority to withstand aggressive flying and weather, including cross-winds and gusts. So I've set a vertical stabilizer that is positioned behind the wing, using a tail-boom. The vertical stabilizer size and position were determined so the pilot will have enough ground and airborne control authority operating the aircraft in crosswinds of 15 - 20 knots, as well as allowing an aggressive style of flying without losing lateral stability.
I've designed the 'Micro-Hopper' as a tail-dragger aircraft, to allow easy operations on rough fields, (didn't want a nose-wheel to break while going through ground holes or bumps in the terrain). Another suppoting reasons are flexibility in ground operations, and...coolness ;)
The 'Micro-Hopper' is equipped with wing-tip flexible skids. These skids are for protecting the wing tips during cross-wind landings or aggressively made ground maneuvers. Such devices will not absorb too-much punish, and will probably endure wearing and tearing...but as a concept, it was worth trying.
The wheels geometric layout and contact points with the ground, including the wing-tip skids are designed to minimize the chances of turning over with the aircraft during an unexpected ground-loop, or aggressive ground maneuvers. In such cases, the wing-tips are solid contact point and pivots, preventing a possible turn-over.
Wing-tip flexible skids:
I have designed a simple, yet useful cockpit instrument panel to serve as a "serial-production" item for some of my ultralight aircraft designs. One of the reasons of making use of the same component over various models is that its concept and function features are getting matured over time, and the process of developing it based on being operated in several models for a given period of time is very useful. This panel (with some instances) can be found in some of my other models, and will soon to be upgraded, based on having some "operational" experience with it...
The 'Micro-Hopper' cockpit is very simple. Besides the basic instrumentation, there are two additional electronic devices:
Clicking on the Smartphone will toggle the Field-of-View, between 65 and 105 degrees. Click it to adjust your desired FOV. Suggested settings would be to have a narrower FOV for take-off/landings, and a wider FOV to get more of a panoramic perspective.