PORTABLE FLYER


4.4.? Tradeoffs summary
A personal flying device must be lightweight.
The more lightweight (including the fuel or the energy source) the better.
Every oz of additional (beyond pilot's) weight requires additional power and additional fuel; the added weight makes the control of the flight more difficult, the landing more risky and dangerous, the noise louder, the range shorter, the mileage smaller, the emissions worse.
A personal flying device must be as lightweight as possible; and because weight cannot be removed from pilot's body, weight can only be removed from the power unit and from the energy source (fuel or batteries).
A lightweight power unit and, more importantly, a top fuel efficient lightweight power unit, is a good start.
With 80% of the total take off weight being the pilot's weight, and with the rest 20% being the PORTABLE FLYER and the fuel, things get promising.
With a true neutral propulsion unit (wherein there are neither vibrations, nor reaction torque, nor gyroscopic rigidity) providing only a force that can "instantly" and effortlessly be vectored towards the desirable direction, the personal flying device becomes safe, controllable and easy to use.
The small dimensions and weight make it not just "portable" but "wearable"; the pilot wears the PORTABLE FLYER like a medium weight back-pack and can walk, run, jump when on ground.
The goal of the PORTABLE FLYER is to provide the required thrust force, while pilot's brain and body do all the rest just like the birds do.
?

4.5.? Expected fly-off parameters
See the rules for further details on how these parameters are measured.
4.5.1.? Estimated size (maximum device dimension)
5.25ft (5ft 3in)
?4.5.2.? Estimated noise (sound pressure level at 50 ft)
70dBA
4.5.3.? Estimated speed (6 nmi divided by time to complete speed run)
100 knots
?4.6.? Top-level weights
Enter estimated weights in pounds.
?4.6.1.? Operating empty weight
45 lb
4.6.2.? Operator weight
200 lb
?4.6.3.? Fuel/energy source(s) weight
5 lb
?4.6.4.? Maximum takeoff weight (total of the above)
250 lb


5.2.? Market-driven design
Double (twin) extremely lightweight engines of top fuel efficiency, each capable ALONE to power the personal flying device. The top fuel efficiency minimizes the fuel weight for a specific range; the fuel (regular gasoline) is the commonest and cheapest fuel in the market The simplicity of the engines maximizes their reliability (safety) and minimizes their manufacturing cost. The PORTABLE FLYER has an ownership cost estimated to less than US3,000$ and a running cost less than a motorcycle.

High speed and extra long range. 
The high speed allows safe flights at adverse weather conditions. The maximum speed of a personal flying device must be substantially faster than the wind speed at all conditions. The more compact the personal flying device, the less risky the landing at adverse weather conditions. 
The long range minimizes the required landings and take-offs for refuelling. At take-off and at landing is the most risky part of the flight.

The hands and the legs remain free to lift / rescue persons in danger.
The difficulty of "riding" / flying a PERSONAL FLYER is similar to riding a scooter.

With its long range (the calculated range with 5 US-gallons gasoline is 500 miles) it gives access to distant islands, also to otherwise inaccessible areas.

The long range increases the reachable destinations squared (if with 20 miles range the accessible destinations are X, with 200 miles range the accessible destinations are X*(200/20)^2=X*100, i.e. 100 times more).
?5.3.? Safety-driven design
Lightweight and compact.

The landing gear is the legs of the pilot. But the legs can only withstand a lightweight personal flying device (say, no more than 50 lb with the fuel).

The compactness (small area exposed to the blowing wind) together with the lightweight and the adaptability of the legs / feet to any roughness of the landing ground, improve the safety and allow landings even on a rock. 

Two independent engines, each driving its own propellers. While the Osprey V22 crashes in case one of its rotors is damaged at a vertical take off or landing, the PORTABLE FLYER has an independently driven second set of counter-rotating propellers to keep it flying.

High speed / long range. The high speed is a requirement for safety (it allows the fly even during adverse weather conditions, it also reduces the duration of the flight keeping the pilot tireless and thereby strong for the landing (the most risky part of the journey). The long range minimizes the landings and take-offs for refuelling.

The saddle prevents the pilot from lifting his hands above his shoulders, thereby protecting them from the propellers.

The fast take-off (about 1g upwards acceleration) reduces the time the PORTABLE FLYER remains in the dangerous height zone (wherein the parachutes are useless).

The almost horizontal pose of the pilot at high speed cruising (like lying on a stream of air) keeps the pilot tireless.
?

6.1.? Single-point failures and mitigations
Safety considerations.

The PORTABLE FLYER appears, during a vertical take-off and during a vertical landing, safer than the famous OSRPEY V-22 of Bell Boeing: even if a rotor falls apart, or even if a transmission member breaks, the PORTABLE FLYER can still fly and land without a crash.

With zero gyroscopic rigidity the pilot can instantly and effortlessly vector the thrust to the desirable direction to control dynamically the flight.

With zero reaction torque the PORTABLE FLYER is smooth and predictable at all conditions (the only reaction at a sudden power off is the elimination of the thrust force).

Being perfectly (100%) vibration-free, the PORTABLE FLYER leaves the pilot tireless even at long flights. 

The engines are rid of spark plugs and of high voltage circuitry (a typical cause for aero-engine stalls).

The engines are also rid of noisy reed valves (“what is omitted cannot fail”).

The engines are extremely tolerable to the air-fuel mixture: a big change of the lambda causes just the change of the thrust force. The accurate adjustment of the air-fuel ratio is meaningless for an HCCI lean burn engine. The two stage (spark-less) ignition guarantees that whatever the air-fuel mixture is, and whatever the fuel quality is, the charge can't help but to ignite 

Each Opposed Piston engine is simpler than any known Opposed Piston engine of the state-of-the-art, comprising in total six moving parts: two crankshafts, two pistons and two connecting rods.

The crankcase runs not pressurized (so it needs not sealing means).

The thrust loads between the piston skirt and the cylinder liner are received away from the hot exhaust ports (wherein the scuffing of the conventional two-stroke engines typically starts), on the cool sides of the cylinder liner, which also reduces the lubricant specific consumption (longer TBO (time between overhauls), less emissions, lower running cost).

The "low temperature combustion" is suitable for air cooling that improves the reliability.

The easy intuitive / instictive control of the flight and the compact design, improve the safety at adverse weather conditions (at hovering, and, even more importantly, at landing).

The smaller the surface area exposed to the wind and the more streamlined the PORTABLE FLYER with the pilot (human body), the less vulnerable it is against the wind.

The two parachutes into the spinners are the final safety means.


7.4.? Risks
1) The judges to not value the importance of the lighter weight for a flying device.
2) The judges to not value the importance of a longer range and of a higher speed, especially at adverse weather conditions.
3) The judges to not appreciate the simplicity, the instinctive control and the benefit - cost ratio.