2 stroke thread (with occasional F1 relevance!)

[coaster]

This is personal mobility device yes? In my childhood i watched a cartoon named 'inspector gadget' voiced by Don Adams of 'get smart'. His device was a fold away propellor and controls which had 2 control rods directly from the swashplate above his head.
Of course this is a cartoon and the device would need contra rotating propellors to work for real, based on helicopter design rather than Mr Patakos inspiration from RC bicopter.
Bicopters need freedom to gimbal independantly rather than be fixed in all axis.
Maybe you could use the cylinder sleeve as an axis of articulation, each crankshaft rotates independently on the cylinder axis, that would create a true Bicopter combined with variable pitch props. Im spoiling the fun though, others can conclude the dynamics involved via RC drone bicopter knowledge, please share video footage of test flights, it seems exciting.

[gruntguru]

I suspect, manolis, you are applying the 'rocket pendulum fallacy ' incorrectly. In the disputation of the rocket pendulum the structure is rigid and the c.g. does not change. You require the structure to be flexible and the c.g. to change in order to control your machine.

The reason the Flyboard is so easily controllable is that it emulates the directional control system of rockets; the engine (water jet) pivots on its thrust axis (ankles) to change the thrust vector. You're not doing that.

With handlebars rigidly connected to the flyer and the inevitable flexibility of the mounting at the shoulders, there will be no trouble vectoring the thrust in addition to using the legs as elevators and ailerons.

[manolis]

Hello Rodak.

You write:

• “I suspect, manolis, you are applying the 'rocket pendulum fallacy ' incorrectly. In the disputation of the rocket pendulum the structure is rigid and the c.g. does not change. You require the structure to be flexible and the c.g. to change in order to control your machine.

The opposite is the case.

In the Portable Flyer,

the “rigid structure” of the rocket and the “rigid vectoring” (relative to rest rocket structure) of the thrust (case of “PendulumRocketFallacy”)

are substituted by:

the “flexible structure” of the human body and the “flexible vectoring” (relative to the human body) of the thrust:



Compare the arrangement of the body of the pilot in the above shown two cases: hovering / take off / landing (at left) and cruising (at right)

Worth to mention here:
While a rocket cannot interact with its surrounding, the pilot / rider of the Portable Flyer besides the “weight displacement control” (wherein the thrust is continuously re-vectored to the desirable direction), can also take the advantage of the “aerodynamic control” (as being inside the high speed downstream of the propellers)

• With only an altimeter and timer, Rossy uses his skin and ears as airspeed indicators.
  "You feel very well, you feel the pressure," Rossy says, "you just have to wake up these senses. Inside an airplane we delegate that to instruments. So we are not awake with our body."
  
  
  
  As Rossy says : "I am the fuselage, and the steering controls are my hands, head and legs"

Like the pilot / rider of the Portable Flyer, Yves Rossy combines “weight displacement control” and “aerodynamic control”.

The video is so good that it worths seeing it again.



You write:

• The reason the Flyboard is so easily controllable is that it emulates the directional control system of rockets; the engine (water jet) pivots on its thrust axis (ankles) to change the thrust vector. You're not doing that.” /i]

Zapata’s FlyBoard_Air is not using water jets.

See Zapata’s videos in the previous pages.

Zapata has his jet-turbines secured to his feet:



Mayman has his jet-turbines secured around his waist / torso.

Browning has one jet-turbines secured at his back and fourjet-turbines secured on his arms (above image).

All of them (Zapata, Mayman and Browning) use their bodies to control (intuitively as they claim) the trust vectoring (and so the flight).

Thanks
Manolis Pattakos

[manolis]

Hello Coaster

You write:
"Bicopters need freedom to gimbal independantly rather than be fixed in all axis."

There is a "wide angle" gimbal joint; it is the spinal cord of the pilot / rider:

Stand on the floor and bend your spinal cord forwards, backwards, to the left side, to the right side.

If you had the Portable Flyer secured on your shoulders / torso, the thrust would vector towards the direction you bend.

The characteristic of the engines and the propelers arrangement make this "vectoring" of the thrust immediate and easy.



For more, read the Device Technical Report at https://www.pattakon.com/GoFly/index.html , or read the previous pages.

Thanks
Manolis Pattakos

[coaster]

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I saw this early prototype, I like how your ideas turn into machined assembly rapidly, you must have a good machine shop with plenty of workholding options and tooling.
This prototype seems compact and light, whereas the the current cad model seems very top heavy, do you have concerns for centre of gravity? Im guessing the early prototype wasnt making enough lift, maybe develop the horsepower to a higher level and use a wide 4 blade propeller like on C10 Hercules scaled to fit the tip diameter. Im sure that first model will work, maybe do hopping tests with 90kg sack of rocks first?

[NathanE]

I suspect, manolis, you are applying the 'rocket pendulum fallacy ' incorrectly. In the disputation of the rocket pendulum the structure is rigid and the c.g. does not change. You require the structure to be flexible and the c.g. to change in order to control your machine.

The reason the Flyboard is so easily controllable is that it emulates the directional control system of rockets; the engine (water jet) pivots on its thrust axis (ankles) to change the thrust vector. You're not doing that.

With handlebars rigidly connected to the flyer and the inevitable flexibility of the mounting at the shoulders, there will be no trouble vectoring the thrust in addition to using the legs as elevators and ailerons.

Hmm, action/reaction? In a fundamentally stable system there may be no trouble, but there might be gymnast like strength and balance control required.

[Rodak]

More than, in my opinion. I really think manolis is confused about the aerodynamic effect of flailing limbs and the strength of the lower pelvis, as well as the ability to coordinate them, if possible.

[manolis]

Hello Coaster.

You write:

• “I saw this early prototype, I like how your ideas turn into machined assembly rapidly, you must have a good machine shop with plenty of workholding options and tooling.

You’re joking, right?



You also write:

• "This prototype seems compact and light, whereas the the current cad model seems very top heavy, do you have concerns for centre of gravity? Im guessing the early prototype wasnt making enough lift, maybe develop the horsepower to a higher level and use a wide 4 blade propeller like on C10 Hercules scaled to fit the tip diameter. Im sure that first model will work, maybe do hopping tests with 90kg sack of rocks first?”

The 800cc prototype PatATi Opposed Piston engine:



is good for powering small airplanes, helicopters, paragliders, gen-sets etc.

Its Cross-Radial version:



is even better (for more: https://www.pattakon.com/pattakonPatAT.htm )


However, for the Portable Flyer the OPRE Tilting:



is better.

With the same weight (and nearly the same capacity) you have two independent propulsion units, which is more than crucial for the safety.



If one engine (or its propellers) malfunctions (fall apart), the other “healthy” propulsion unit is capable for an emergency safe landing.

With the transmission (sprockets, toothed belt) from each crankshaft to a propeller, the engines rev at their optimum rpm, while the propellers rev at their own optimum rpm (typically much lower than the engine rpm; in the photo the transmission is 2.4 to 1).

Etc, etc, etc (read the previous pages of the forum, or read the “Device Technical Report” at https://www.pattakon.com/GoFly/index.html )

Thanks
Manolis Pattakos

[Tommy Cookers]

regardless of how the DUC Swirl achieves its proclaimed 'constant speed' effect ....
CS means that as airspeed increases the Cl/AoA is maintained - ie thrust and torque are maintained without rpm increase
so equivalent in behaviour to an increase in pitch

as the thrust of a propeller (for a given power) is always least when airspeed is zero .....
wouldn't the PF (with DUC or other CS props) be poor in height-stablity in hover out of ground effect ?
ie it would tend to accelerate vertically up (or down ?) from HOGE

( btw the same factor seemingly applies when a aeroplane tries to climb vertically or hover ....
as at a steady non-zero speed the thrust will be greater than the thrust in hover
Chi-Town Hustler flew a Pitts at 360 hp ? on nitrous oxide ... and there was a (bigger-engined) 450 hp Pitts
maybe they couldn't hover but could genuinely maintain a vertical climb ? )

of course the helicopter isn't subject to this effect as there's no automatic increase in pitch
to climb in hover a manual increase in pitch must be applied (via the collective control)

but what about the hover stability of a PF with the intended PatPitch props ?

(and there must be a essentially progressive or non-regressive engine torque/rpm curve ?)

[coaster]

The contest does not require a patented engine such as the opposed 2 stroke, it would seem a good showcase for marketing your designs, such as early honda had done in tt races parallel to sales of the cub.
Are you going to market your motors?
Maybe portable equipment?
Mower? chainsaw? concrete saw? generator?
I think this is your true calling, your patents will be provisional and need full purchase at a later time, that time is needed to build a business.

[gruntguru]

I suspect, manolis, you are applying the 'rocket pendulum fallacy ' incorrectly. In the disputation of the rocket pendulum the structure is rigid and the c.g. does not change. You require the structure to be flexible and the c.g. to change in order to control your machine.

The reason the Flyboard is so easily controllable is that it emulates the directional control system of rockets; the engine (water jet) pivots on its thrust axis (ankles) to change the thrust vector. You're not doing that.

With handlebars rigidly connected to the flyer and the inevitable flexibility of the mounting at the shoulders, there will be no trouble vectoring the thrust in addition to using the legs as elevators and ailerons.

Hmm, action/reaction? In a fundamentally stable system there may be no trouble, but there might be gymnast like strength and balance control required.

I don't see a need for strength. The pilot is "hanging" from a harness and only needs to push and pull on a pair of hand grips (or even a "joystick") to articulate a "joint" at the shoulders with only two degrees of freedom - pitch and roll.

Likewise balance control will be straightforward - pull the stick back to rotate (and translate) forward -push the stick to the right to roll left and translate left. In hover mode, yaw control would require a pilot with two legs - One forward and one back in the propwash.

I agree the system is not fundamentally stable but control would be easier than the machines of Zapata, Browning and Mayman. In fact easier than a helicopter.

[Rodak]

If I recall correctly, some pages ago when there was a discussion about control manolis stated that the mounting would be rigid and extend down to the waist. Please correct me if I'm wrong. If that is the case there is no pivoting motion at the shoulders and the only means of control is by bending forward at the waist or folding legs up and back; raising legs forward is equivalent to bending at the waist. Really, I tried this stuff hanging on my chin up bar; 'taint easy and very tiring.

[NathanE]

With handlebars rigidly connected to the flyer and the inevitable flexibility of the mounting at the shoulders, there will be no trouble vectoring the thrust in addition to using the legs as elevators and ailerons.

Hmm, action/reaction? In a fundamentally stable system there may be no trouble, but there might be gymnast like strength and balance control required.

I don't see a need for strength. The pilot is "hanging" from a harness and only needs to push and pull on a pair of hand grips (or even a "joystick") to articulate a "joint" at the shoulders with only two degrees of freedom - pitch and roll.

Likewise balance control will be straightforward - pull the stick back to rotate (and translate) forward -push the stick to the right to roll left and translate left. In hover mode, yaw control would require a pilot with two legs - One forward and one back in the propwash.

I agree the system is not fundamentally stable but control would be easier than the machines of Zapata, Browning and Mayman. In fact easier than a helicopter.

Still no reference to action/reaction of these control inputs in a system with multiple degrees of freedom.

Gyroscope? Ever held/angled a spinning bike wheel?

[manolis]

Hello Nathan

At the middle of the 180 page of this discussion is a video showing a runner running.
Read the relative posts there. They reply to your question.

If the gyroscopic rigidity of the Portable Flyer was not insignificant, its control would be slow (too dangerous because any ”correction” would take seconds to complete) and difficult (requiring a juggler pilot).

One of the characteristics of the Portable Flyer is its substantially zero gyroscopic rigidity: for every rotating part (mass) there is a counter-rotating symmetrical part; the video:



shows the previous.

With zero gyroscopic rigidity, the vectoring of the thrust to the desirable direction is “instantaneous” and effortless.

This is the basis for an effective, fast and intuitive control of the flight.

The control unit is the brain of the pilot.
The sensors are pilot’s eyes, otoliths, skin, ears.
Servomechanisms are pilot’s muscles and bones.

These (brain, eyes, ears, muscles, bones) add neither weight, nor cost.

It is exactly what birds, bats and bugs do to fly.
The only difference is that the human body is not capable to provide adequate thrust, making a propulsion unit obligatory.

Thanks
Manolis Pattakos

[manolis]

Hello Tommy Cookers.

You write:

• as the thrust of a propeller (for a given power) is always least when airspeed is zero .....
  wouldn't the PF (with DUC or other CS props) be poor in height-stablity in hover out of ground effect ?
  ie it would tend to accelerate vertically up (or down ?) from HOGE

This is why there is a gas cable and a throttle-valve.

If the pilot feels he loses height at hovering, the pilot opens wider the throttle (and vice versa).

The same happens when you drive your car: if you feel it decelerating (say, due to a strong opposite wind), all you do is to press deeper the gas pedal.


By the way: being high in the open sky, a lateral displacement (shift) of several meters (even of several hundreds of meter) from the ideal path is OK. The same for the altitude.
Driving a motorcycle on the road, a lateral displacement (shift) of a couple of meters may be fatal.

Thanks
Manolis Pattakos