2 stroke thread (with occasional F1 relevance!)

[manolis]

Hello Tommy Cookers

You write:
“propellors have composite-engineered structural properties giving some inherent pitch increase with flight speed “

With propellers having pitch dynamically aligned with the speed, things improve a lot, remaining simple and lightweight:
The power required at hovering drops a lot.
And the top speed increases a lot.


You write:
“to me it seems that the lower rotors would need more pitch than the upper, especially in the hover and the pitch issue is more important than yesterday's issue (contra-rotation or not)”

You are right; the lower rotors need more pitch: they “see” a higher air speed.

Thanks
Manolis Pattakos

[manolis]

Hello Gruntguru.

Securing tightly the Portable Flyer onto your shoulders / upper-torso, you release your waist, your head, your hands and your legs.

This gives a high degree of freedom: you can move – relative to the Portable Flyer – your legs, hands and head (the head doesn’t seem important for maneuvering, however Yves Rossy says he makes most of his maneuvers – flying at high speed – by “vectoring” his head towards the direction he wants to go).

The waist is much stronger than the hands.

While it seems that with the hands you can vector the Portable Flyer more precisely and faster, actually you have nothing to abut on (to be supported on). The only you have "to abut on" is your rest body (head, legs, lower torso). I.e. at the end, every part of the body participates in this relative displacement / vectoring of the Portable Flyer.

So, what I think is that the handlebars are not really necessary.
On the other hand, you loose nothing having a set of lightweight handlebar for “just in case”.

Thanks
Manolis Pattakos

[J.A.W.]

Manolis, your machine is a 'tractor' - with the props pulling the pilot, rather than a 'pusher' like Rossy's jet..

Best these factors are evaluated - are you planning a controlled/tethered test 'flight'?

[gruntguru]

Hello Gruntguru.
Securing tightly the Portable Flyer onto your shoulders / upper-torso, you release your waist, your head, your hands and your legs. . . . .
. . . . . While it seems that with the hands you can vector the Portable Flyer more precisely and faster, actually you have nothing to abut on (to be supported on). The only you have "to abut on" is your rest body (head, legs, lower torso). I.e. at the end, every part of the body participates in this relative displacement / vectoring of the Portable Flyer.

You would still mount the flyer to the shoulders. It is impossible to make this mounting very rigid (the human body is flexible) so the mounting would form a hinge joint or a ball joint and the handlebars would allow the pilot to control the orientation of the joint.

[manolis]

Hello J.A.W.

You write:
“are you planning a controlled/tethered test 'flight'?”

I think the best way to test / evaluate how the Portable Flyer flies is over the sea, at a small height (say a few meters).

Thanks
Manolis Pattakos

[manolis]

Hello Gruntguru.

You write:
“You would still mount the flyer to the shoulders. It is impossible to make this mounting very rigid (the human body is flexible) so the mounting would form a hinge joint or a ball joint and the handlebars would allow the pilot to control the orientation of the joint.”

Yves Rossy shows the way for flying controllably at high speeds like a bird of prey:
"I am the fuselage, and the steering controls are my hands, head and legs"

I think that the flexibility of the human body and the “built in” hinge (the waist of the pilot / rider) will prove significant advantages for the control over the Portable Flyer.

I also think that, just like walking, the hovering with the Portable Flyer will require soft motions and gentle response to the signals received by the brain.

The completely neutral propulsion unit, with the zero gyroscopic rigidity, is a great help for the pilot / rider.

I am not sure the handlebars are required.
What you are doing by keeping, by your hands, a pair of handlebars secured to the Portable Flyer, is to change the relative position of the upper torso wherein the Portable Flyer is secured) relative to the rest of your body.
You can do the same without keeping handlebars (the waist is much stronger than the hands).
On the other hand, practice will show.

Thanks
Manolis Pattakos

[manolis]

Hello all.

Here are an animation:



and a drawing:



showing the direction of the Portable Flyer and of the body (and wingsuit, not shown) of the pilot / rider at horizontal flight.

They are made to show that the Portable Flyer is not “seriously nose heavy”.

Thanks
Manolis Pattakos

[tok-tokkie]

I too think handlebars onto the Portable Flyer will make it much more controllable. It is a variation on a hang glider in that the pilot is suspended below the lifting device. In a hang glider the pilot is given the trapeze frame (like handlebars) to react against so he can move his mass relative to the center of lift of the wing; thereby controlling the flight path. On the Portable Flyer I believe the pilot will be able to have much more direct control of the position of his center of mass relative to the center of lift of the Portable Flyer.

[manolis]

Hello Tok-Tokkie

You write:
“I too think handlebars onto the Portable Flyer will make it much more controllable. It is a variation on a hang glider in that the pilot is suspended below the lifting device. In a hang glider the pilot is given the trapeze frame (like handlebars) to react against so he can move his mass relative to the center of lift of the wing; thereby controlling the flight path. On the Portable Flyer I believe the pilot will be able to have much more direct control of the position of his center of mass relative to the center of lift of the Portable Flyer.”

The first designs of the Portable Flyer have HandleBars, like:



Without HandleBars things get easier / relaxing.

If you can have your hands free, it is better.

On the other hand, the pilot can keep the frame by his hands (even in case it doesn’t comprise HandleBars), like:



A cane helps an old person to walk; the same cane is an obstacle for a young person.

In any case, having a pair of HandleBars is easy and lightweight.

Thanks
Manolis Pattakos

[J.A.W.]

Hi Manolis,
..as T-T noted, a handlebar will provide a positive leverage attitude control..
..& a 'handy' location for engine ( throttle/prop-pitch,etc) controls.

Think about riding a bike without touching the handlebar, sure - it can be done, but it tends to be a bit fraught..

[manolis]

Hello all.

Here is another version of the Portable Flyer:



The two OPRE_Tilting engines (which are quite short engines for their capacity) are arranged “axially” to form a long caging / frame at the ends of which are rotatably supported two pairs of rotors.



Each OPRE Tilting engine drives, through a reduction gearing comprising two sprockets and a teeth belt, two synchronized counter-rotating rotors, one per crankshaft. The one belt is substantially longer than the other.



At the top of the frame, above the top rotors, they are secured spinners inside which there are rescue parachutes for emergency landings.

The throttle cable, the fuel pipe etc pass through the pipes of the frame.

So, there are two totally independent “propulsion units” the one from the other.

Thanks
Manolis Pattakos

[gruntguru]

The two OPRE_Tilting engines (which are quite short engines for their capacity) are arranged “axially” to form a long caging / frame at the ends of which are rotatably supported two pairs of rotors.

Each OPRE Tilting engine drives, through a reduction gearing comprising two sprockets and a teeth belt, two synchronized counter-rotating rotors, one per crankshaft. The one belt is substantially longer than the other.

At the top of the frame, above the top rotors, they are secured spinners inside which there are rescue parachutes for emergency landings.

The throttle cable, the fuel pipe etc pass through the pipes of the frame.

So, there are two totally independent “propulsion units” the one from the other.

Congratulations on some very clever designs Manolis.

Thankfully they are "non-spinning" spinners!

[manolis]

Hello all.

Today the United Kingdom Intellectual Property Office (UK-IPO) granted the GB2,525,704 patent to the PatRoVa rotary valve

Click at https://www.ipo.gov.uk/p-ipsum/Case/App ... B1500885.7 for the patent documents in the UK-IPO, then click on the “Documents” at right.



Youtube video of the first run of the first PatRoVa prototype:



https://www.youtube.com/watch?v=6Q-EGdeS0ws

For more: http://www.pattakon.com/pattakonPatRoVa.htm )

It is not a two-stroke engine.
However it has the qualifications for top power-to-weight ratio and mileage.

Thanks
Manolis Pattakos

[J.A.W.]

Hi Manolis, you write "Its not a 2-stroke engine"..

Is your rotary valve design capable of effective operation as a 2T, if externally scavenge pumped?
Can it withstand CI/forced induction pressures? Or be HCCI capable?

[manolis]

Hello J.A.W.

You write:
“Hi Manolis, you write "Its not a 2-stroke engine..
Is your rotary valve design capable of effective operation as a 2T, if externally scavenge pumped?”

Here is a PatRoVa Rotary Valve for 2-stroke engines:



more at http://www.pattakon.com/pattakonPatRoVa.htm


You also write:
“Can it withstand CI/forced induction pressures? Or be HCCI capable?”

Quote from a post to another forum:

“Suppose that the rotary valve and the cavity on the cylinder head are both made of steel or of spheroidal graphite iron.

1. Take 1ton (2,200lb) force acting on each oppositely arranged front through the big diameter (say of 10cm2 section area) and short (say 25.4mm / 1’’) hub /shaft.
For simplicity forget the bending loads.
The tension load causes an extension of the hub (i.e. an increase of the distance between the two oppositely acting fronts) of about 0.001mm (one micron).

2. Take 100 degrees Celsius (180 F) temperature difference between the PatRoVa rotary valve and the part of the cylinder head between the two oppositely arranged fronts (i.e. the cavity).
Such a temperature difference causes a 0.03mm change in the distance between the two oppositely arranged fronts (i.e. 0.015mm per side).

As you see, the architecture of the PatRoVa rotary valve is anything but vulnerable "to distortions introduced by differential heat fluxes and pressure differentials".

To further reduce the distortion introduced by differential heat fluxes, a future option is to use INVAR, or other low coefficient of thermal expansion alloy, for the rotary valve and the cavity.”



However, if I had to make a 2-stroke for a motorcycle, this:





single-cylinder PatAT 2-stroke (built-in asymmetric transfer) seems superior. Imagine it as a direct injection turbocharged Diesel (or gasoline), with the turbocharger being the scavenging pump.

This Cross-Radial version of the above single-cylinder:



seems having all the good characteristics required by an airplane of helicopter.

More at http://www.pattakon.com/pattakonPatAT.htm



For RC / model engines (drones etc), this simple design (three moving parts in total):



combines asymmetric intake, asymmetric transfer, crankcage scavenging etc.



The ability of the PatRoVa Rotary Valve to operate at extremely high revs makes it way superior than the poppet valves in 2-strokes because in a 2-stroke a poppet valve has to open and close twice as fast as in a 4-stroke (from difficult to impossible, depending on the revs).



Talking for high revving poppet valves, the Ducati Panigale (Desmodromic cylinder heads) is regarded by many as the top technology today.



If the underneath mechanism (pistons, connecting rods, crankshaft, block) of the Duacti Panigale could stand 15,000rpm (the current rev limit is 12,500rpm), or 20,000, or 25,000rpm, the PatRoVa Rotary Valve would be the way:





Since we were talking about the Portable Flyer, here is a stereoscopic drawing added to the http://www.pattakon.com/pattakonPatTol.htm web page a couple of days ago :




Thanks
Manolis Pattakos