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HCCI controllable combustion / PatBam

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#51 manolis

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Posted 28 January 2018 - 10:53

Hello Kelpiecross


You write:

I thought the whole idea was not to use a spark plug.
I imagine the timing would be similar to conventional spark ignition timing. Which raises the matter of varying the ignition point to suit the RPM and/or load. Normal spark ignition varies by up to 40 degrees or so you expect the PatBam would need to be similar. Vary the height of the "anvil" or just run the engine at the equivalent of full spark advance?



The HCCI combustion is characterized as a spontaneous combustion.


In the following gif-video:




the hcci combustion seems to complete some 6 times faster than the combustion in a spark ignition conventional engine.


See also the fist image in the #36 post.



In a spark plug engine, say like the high tech Ducati Panigale 1299, the required spark advance is big: at some conditions it is 60 degrees before the TDC.


Imagine it:

with 2:1 con-rod to stroke ratio, and 13:1 compression ratio, the actual compression ratio when the spark happens (60 degree before the TDC) is only 2.85:1.


The combustion starts at the spark and extends very slowly until the “fire ball” (as Mazda calls it when they present their HCCI SkyActive-X, see the 4th image of post #27) to get adequately big in size.

Then the combustion expands faster, yet still slowly as compared to the HCCI combustion wherein all the air-fuel mixture ignites almost simultaneously.   


In comparison, in the spark ignition engine the combustion expands progressively, with a “front” separating the not yet combusted air-fuel mixture from the already burnt gas.



Manolis Pattakos



#52 manolis

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Posted 28 January 2018 - 15:18

Hello Kelpiecross.


The progressive combustion in the conventional spark ignition engine versus the spontaneous HCCI combustion.




Manolis Pattakos


#53 Kelpiecross

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Posted 30 January 2018 - 02:57

Manny - it did occur to me that instead of launching straight into building your engine you could do some preliminary work. Such as: getting a simple (non-electronic, non-turbo) diesel car or engine and with leaving it still in the car in its normal running condition - temporarily disable the diesel injection - rig up some sort of setup to allow petrol vapour to be put into the intake. Try various mixture strengths and manifold pressures etc. to get an idea of how the engine responds. The critical one would be how the engine behaved at very lean (idle) AF ratios. The idea basically is to treat a cylinder of the diesel engine as if it were the auxiliary chamber and piston of a much bigger PatBam engine. You could try many things apart from whether very lean mixtures fire at all (- which is the critical one): cold starting; all manner of different fuels (ethanol, LPG etc.) Keeping the original injection in place would allow the engine to be warmed up, battery charged etc. Also to allow testing of different fuels etc. at higher RPM than starting RPM.
And, at the end of testing, if haven't totally buggered the engine (unlikely) you still have a diesel car to drive around in.

#54 gruntguru

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Posted 30 January 2018 - 22:41

There are a few concepts in PatBam that need testing. Your idea is a good one KC and I would go one step further and modify a single cylinder of the car engine to PatBam spec while leaving the remaining cylinders standard.

#55 manolis

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Posted 31 January 2018 - 04:29

Thanks Kelpiecross & Gruntguru.


I just wonder whether the ECU will allow the engine to run with only three cylinders.


An existing engine that makes simpler this modification is the SkyActiv-G of Mazda:






wherein the piston has already a bowl.


Despite the 14:1 compression ratio, there are deep valve pockets to provide the necessary overlap.


Mazda could make the modification /test in a couple of “hours”.



On the other hand, a single cylinder is simpler and more controllable as a “test bed”.


And we prefer to focus on the single cylinder Opposed Piston PatBam OPRE Tilting for a Personal Flyer (we used to call it Portable Flyer).


A couple of days ago an Italian friend informed me about the GoFly competition of BOEING:



More at https://www.herox.com/GoFly/guidelines







Manolis Pattakos

#56 gruntguru

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Posted 31 January 2018 - 05:00

- A Diesel ECU would be easy to deceive - especially an earlier CR system.

- A 4 cylinder engine with one modified cylinder has the advantage of acting as a 4 quadrant "dyno" - motoring or loading the modified cylinder as required.

- The "flat" cylinder head found on most Diesels lends itself to the PatBam design and to easy manipulation of combustion chamber design. (Height available from piston pin to cylinder head might be insufficient unfortunately)

#57 Kelpiecross

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Posted 04 February 2018 - 03:21

The small industrial diesel as used in portable generators etc. may be more practical than a diesel car for experiments. I have had some experience with the Honda V-twin diesels in generators - a good little unit which will run happily on one cylinder for testing purposes. Also the electrical output could be used for loading/dynamometer testing.

On the subject of the Boeing/Go Fly competition: the rules are very strict (and restricting) - I have serious doubt that any flying machine could be built that would conform exactly to Boeing/Go Fly's required size and performance characteristics. This is as I interpret the rules - which are not very clear (at least to me).

However I might have a try at the Phase 1 part of the contest where you don't have to actually build anything.

#58 manolis

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Posted 06 February 2018 - 06:32

Hello Kelpiecross


You write:


The small industrial diesel as used in portable generators etc. may be more practical than a diesel car for experiments. I have had some experience with the Honda V-twin diesels in generators - a good little unit which will run happily on one cylinder for testing purposes. Also the electrical output could be used for loading/dynamometer testing.




A single cylinder electric generator (Diesel or Otto, 4-stroke or 2-stroke) seems a good basis for the modification and the testing of the PatBam:





You also write:

“On the subject of the Boeing/Go Fly competition: the rules are very strict (and restricting) - I have serious doubt that any flying machine could be built that would conform exactly to Boeing/Go Fly's required size and performance characteristics. This is as I interpret the rules - which are not very clear (at least to me).



Quote from https://www.herox.com/GoFly


The goal of the GoFly Prize is to foster the development of safe, quiet, ultra-compact, near-VTOL personal flying devices capable of flying twenty miles while carrying a single person.

. . .

Today we look to the sky and say “that plane is flying.” We challenge you to create a device where we look to the sky and say, “that person is flying.”

. . .

Our goal is the same as Da Vinci’s and children of wonder throughout the ages: Make people fly – safely and effortlessly.


End of Quote.







A few thoughts on the above “scoring”:


The safety should be the dominant “scored parameter”, with more points than the sum of the points given for the “Size”, for the “Noise” and for the “Speed”.


Safety: when something falls apart or malfunctions, what are the available means / methods for the pilot to survive?


Unfortunately the safety is absent from the scoring.



The range should be also a dominant “scored parameter”, with several points.

Now the only requirement is the “personal flying device (to be) capable of flying 20 miles while carrying a single person”.

I.e. a personal flying device having a range of 200miles (320Km) is equivalent with a personal flying device having only 20miles (32Km) range!

Think of it: Daedalus and his son Icarus flew, according the myth, from Crete (Minoan Palace) to Athens (~150Knots / ~280Km).

With only 20miles / 32Km range, the personal flying machine is rather a toy than a transportation means.



The score for the speed is less than poor (it counts for only ~10% of the total score, while the quietness counts for the ~45% and the size for the 35%).

I.e. a personal flying device capable for 160mph (~250Km/h) is a loser against a personal flying device capable for only 30Knots (55km/h) if the second emits just 4dBA less noise at take off.

Think of it: If you run fast enough, you can keep step with the “winner”.



The overall weight of the personal flying device is also important.



The mileage (either it is the fuel consumed per mile, or the energy consumed per mile (batteries), or the quantity of CO2 emitted to the atmosphere per mile) is also an important characteristic that should be scored.

As it is now, it doesn't matter if you consume 50lit of gasoline to cover a distance of20 miles (32Km), or if you consume only 10lit of gasoline to cover a distance of 200 miles (320Km). 



The capability of the flying device to fly in bad weather is also a quite significant characteristic. 

Think a personal flying machine having 30Knots maximum speed, flying near the sea, with the wind blowing towards the sea at 40Knots.  



The cost should also be a significant scored parameter. Manufacturing cost and running cost.

A US200,000$ personal flyer machine cannot be affordable for the ordinary people.

A US3,000$ personal flyer machine can change the world.



Manolis Pattakos

Edited by manolis, 06 February 2018 - 07:39.

#59 Kelpiecross

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Posted 07 February 2018 - 03:12

There are any number of videos on the net explaining and answering questions about the rules - but I get the impression they are making the rules up as they go. I think you can enter if you go above any of the "thresholds" they set - but you would not be eligible for any prizes.

I was very impressed by this (so were a lot of other people to the point of thinking it was fake):

This gives some idea of the rotor size and power required. Maybe you should look to the model helicopter world rather than the full-size world as a guide as to what you should do. Such as - two coaxial 8 ft. diam. 4 or 5 bladed rotors with variable collective and cyclic pitch etc. (instead of fixed pitch propellers).

Also note the noise - a lot more than 87 dB I would guess.


#60 manolis

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Posted 08 February 2018 - 05:55

Hello Kelpiecross.


You write:

I think you can enter if you go above any of the "thresholds" they set - but you would not be eligible for any prizes.



Please, give me some technical arguments.


Where is the problem?


Why the pattakon Portable Flyers “would not be eligible for any prizes?



Here are some earlier designs:









Here is an intermediate design:





Here is the most recent design that focuses on the safety (two independent OPRE_Tilting engines, each driving two counter-rotating propellers) without compromising with the speed, or with the range, or with the mileage:





Putting the PatBam-HCCI in the OPRE_Tilting engines of the above Portable Flyer:




they will be further improved the range, the mileage, the emissions and – more important - the reliability: a gasoline engine rid of high voltage circuitry and of spark plugs has less reasons to fail.


For more: http://www.pattakon....takonPatTol.htm and http://www.pattakon....pattakonFly.htm



Manolis Pattakos

#61 Kelpiecross

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Posted 09 February 2018 - 03:55

Manny by "you" I meant "anyone". If you (meaning "you") can meet all the "thresholds" you have probably already won the $2 million prize. But remember you have to actually demonstrate that you meet all the "thresholds" not just claim to have done so.
90 degree cone of vision?
eight-and-a-half feet maximum size?
and the main one - VTOL or near VTOL?

I think the most obvious and simplest method is a "jetpack" (already demonstrated on the internet) or 3 or 4 jets mounted on a light frame (a lot of fuel would be needed to travel 20 miles plus a reserve) - but the noise - more like 187dB than 87dB.

There are plenty of cycle-type devices with drone-type technology being displayed on the internet - most appear to be flying in "ground effect" which is not allowed in the contest. I doubt if any could even meet one of the "thresholds"'

The "girl-lifting" helicopter technology could be modified to meet some of the criteria - but probably not range or noise.

Can you describe how your "Flyer" meets each individual "threshold"?

#62 manolis

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Posted 09 February 2018 - 08:44

Thank you Kelpiecros.


Let’s start with this arrangement:








The crankshaft-to-crankshaft distance of the 330cc OPRE Tilting prototype engine is less than 4 inches.


With 55 inches (~1400mm) propeller diameter, the maximum dimension of the Portable Flyer is 55’’+ 4’’ = 59’’ (< 60’’ = 5ft).


This means that it takes all the 3.5 points (35% of the total score) of the “size scoring”.



For the sake of quietness (low noise), the tip speed of the propellers must be low (say, 170m/sec: half of the sound velocity); to have such low tip speed, a 55’’ diameter propeller should spin at only 2,300rpm at take off / landing.


The 330cc prototype OPRE Tilting engine (~8.5Kg) can either directly drive the propellers by its crankshafts (as in the photo and in the drawing above), or, better, it can use a reduction gearing (from the crankshafts to the propellers), say as in the following animation:




wherein there are not additional shafts: all the gear-wheels are secured or supported on the two crankshafts (on the red gearwheel it will be secured the one propeller; it is supposed that another “red” gearwheel will be added at the other side of the engine to drive the other propeller).


Supposing a torque of 50mN from the 330cc OPRE Titling 2-stroke engine (same specific torque with the 300cc KTM EXC300), at 7,600rpm it makes 53bhp.


With the engine revving at 7,600rpm (with 30mm piston stroke (for a combined stroke of 30+30=60mm) the mean piston speed is only 7.6m/sec: reliability / low inertial loads / low friction),

and with a 3.3:1 reduction ratio (as in the animation),

a pair of 2-blade / 55’’ diameter / 35’’ pitch propellers will rotate at 2,300rpm at take-off, providing an overall thrust of ~1,200N (120Kp, 265lb), and requiring a total power of ~50bhp, while the top speed will be limited(?) to ~65Knots.


While with variable pitch propellers the cruising speed can increase a lot (and the take off can be done at partial load), any increase of the speed above 65Knots is scored with less than 0.2 points (2.5% of the total scoring). This makes the variable pitch optional.



With a total mass less than 110Kg at take-off (fuel included), the above described Portable Flyer can take off true vertically, fast (upwards acceleration 0.1g) and quietly.


The 20miles (32Km) minimum range seems a piece of cake (a more reasonable range for the competition should be ten times longer).


The 90 degree cone of vision seems too small, too. In the above Portable Flyer it is about 180 degrees (isn’t it?).


And it is a true VTOL (if required, it can also be a “near VTOL, too).



So, is there something I cannot see?



A better solution (that focuses on the safety without compromising in the rest) is the double engine / four rotor version:




Thank you

Manolis Pattakos


#63 manolis

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Posted 16 February 2018 - 04:02

Hello all.
Here is a Portable Flyer wherein the design is focused on the safety, without compromising in the rest areas.
Two OPRE Tilting engines, each having 350cc capacity (86mm bore, 30+30=60mm stroke) preferably the PatBam version for HCCI combustion (no need for high voltage circuit).
The two engine casings are secured / bolted to each other:
to form the Portable Flyer casing.
I.e. there are two independent propulsion units, each comprising an engine and two counter-rotating propellers.
Portable Flyer total mass: less than 20Kg / 44lb.
With 3-blade propellers having 39’’ (991mm) diameter, 
and with 21’’ (533mm) distance from propeller axis to propeller axis,
the maximum dimension of the Portable Flyer is 39’’+21’’ = 60’’ (3.5 points (35% of the maximum Final Score) in the “compact size” scoring of the GoFly competition, sponsored by BOEING).
Limiting the propeller tip speed at only 150m/sec (44% of the sound velocity) for “quiet” take off, the resulting propeller rpm is 2,900rpm.
With 28’’ pitch and 3 blades per propeller, the static thrust at 2,900rpm is ~35Kp / 350N (at least according http://www.godolloai...c_eng/index.htm ; if anybody has another static thrust calculator, he can check it out), while the power absorbed by each propeller is ~15bhp. 
At the “quiet” take off, the total upwards thrust is 4*35=140Kp (with a total mass <110Kg, this means ~0.3g upwards acceleration) and the required power from each engine is ~30bhp.
The small tip speed keeps the noise low, and the “noiseless” scoring high (GoFly / BOEING competition: the quietness counts for some 40% of the Final Score).
With 2.4:1 “crankshaft to propeller” reduction ratio, the 2,900rpm of the propellers at the above “quiet” take-off, translates into 7,000rpm for the engines.
In order a 350cc 2-stroke engine to provide 30bhp at 7,000rpm, it needs to make 30mN of torque at 7,000rpm (~90mN/lt specific torque, which is easily attainable even with 4-stroke engines). 
After the take off, the engine rpm (and the propeller rpm) increase to enable a high cruise speed (above 100mph (160Km/h)). 
At top speed (> 100kts / 185Km/h) the propellers rev at 4,350rpm (propeller tip speed 2/3 of the sound velocity), and the engines are running at 10,500rpm (at 10.5m/sec mean piston speed, which is still low and improves the long term reliability).
In the scoring of the GoFly / BOEING competition (see figure “speed” at https://www.herox.com/GoFly/guidelines) this means less than 0.05 points below the maximum possible (this counts for less than 0.5% of the maximum possible Final Score).
In case of malfunction of the one engine, or in case one propeller falls apart, or in case a transmission tooth belt is broken, or . . ., the “healthy” propulsion unit is capable for a safe landing.
With the one only engine running at 9,000rpm (mean piston speed: 9m/sec) and driving its two 3-blade 39’’ diameter / 28’’ pitch propellers at 3750rpm (2.4:1 reduction): 
the total thrust force is ~115Kp, 
the tip speed is 195m/sec (57% of the sound velocity), 
the power required from the running engine is ~65bhp (which means: ~50mN of torque from 350cc capacity, i.e. ~150mN/lt specific torque, which is attainable by a good 2-stroke: the Rotax 850 has more than 175mN/lt peak specific torque).
With “only” 195m/sec propeller tip speed, the Portable Flyer is quiet even during an emergency landing.
With both engines running at 9,000rpm, the upwards acceleration at a “fast take off” is more than 1g (10m/sec); it is like “falling towards the sky”. 
Alternatively: the Portable Flyer can carry two persons (the pilot and a passenger); in this case at a malfunction of the one propulsion unit, the emergency landing is not possible (unless the one person (the pilot or the passenger) falls, preferably with a parachute).
With the pilot wearing a wing suit, 
at 100mph cruising (87kts / 160Km/h / 44.5m/sec) the required thrust is about 30Kp (300N, 66lb) and the calculated power is ~18bhp.
(the data are taken from  http://www.dropzone....flight_613.html )
At cruising the propellers rev at 3,750rpm (propeller tip speed 57% of the sound velocity), and the engines rev at 9,000rpm (mean piston speed: 9m/sec) 
With, say, 75% propeller efficiency, the power required from the engines is ~24bhp.
With the engines running at 35% BTE (attainable with HCCI combustion and lean mixture), the fuel consumption (gasoline) at 100mph (160Km/h) cruising is easily calculated at ~5.5lt/h (3.5l/100Km), and the mileage at 67mpg (US gallons).
For a distance of 200miles (320Km), they are required some 11lt (~8Kg) of gasoline.
Each engine has to be capable of providing, at 9,000rpm, the 65bhp required for an emergency landing (as previously described). Compared to the 24bhp required for cruising at 100mph, the engine(s) at cruising will operate at substantially light load (quite lean air fuel mixture if HCCI).
The straight line a Portable Flyer follows going to a specific destination is a big advantage as compared to a car and to a motorcycle which cover a substantially longer distance following the road.
The ability for high speed flights is mandatory for the safety; at windy weather a big size / slow moving (“hovering”) flyer is like a “feather in the wind”. 
If the Portable Flyer can fly way faster than the wind, the strong wind is not a problem.
In the near future the Portable Flyers (or the Personal Flyers) appear as interesting alternatives for cars / motorcycles / boats etc (which means wide use).
For special uses, the Portable Flyers appear as a passé partout.
Think of:  
A “first aid” doctor arriving into a couple of minutes and landing 5m from the injured persons.
A rescue team flying to a sinking vessel.
A fireman who, at a skyscraper fire, is taking off the road and is landing in seconds on the roof of the skyscraper to help (or to take away) trapped persons (if each engine alone is capable for an emergency landing, the Portable Flyer is capable to lift, besides the pilot, a passenger (or two: the Portable Flyer mass is counted only once)). 
Regarding the ownership cost, a Portable Flyer like the above is way simpler than a car or motorcycle (it needs not wheels, it needs not suspension, it needs not a steering, . . . ): just two simple, lightweight, vibration-free engines forming the casing, and four propellers. 
Regarding the running cost, according the previous calculations a Portable Flyer appears more economical (and more green) than a car or motorcycle.
ENGINE (again)
The two OPRE Tilting engines are the heart and the backbone of the Portable Flyer. 
The “OPRE” stands for Opposed piston Pulling Rod Engine while the “Tilting” refers to a valve secured on the small end of the connecting rod; the tilting valve controls the intake and the transfer (no need for reed valves or rotary valves). More at http://www.pattakon....akonTilting.htm
Each “crankcase” (actually the space underside the piston crown, inside the piston) runs not-pressurized.
The thrust loads are taken at the cold ends of the engine, away from port openings.
The synchronizing gearwheels between the two crankshafts run unloaded and serve as balance webs, too.
Each engine, alone, is perfectly vibration free, and is driving its own pair of counter-rotating propellers (zero gyroscopic rigidity).
The short piston stroke (30mm) allows high revs at low mean piston speed (reliability).
With HCCI (i.e. spontaneous) combustion into a compact bowl, the over-square design is fine; the combined stroke is 30+30=60mm; with 86mm bore, the design is by far less over-square than the famous Ducati Panigale 1299 (60.8mm stroke, 116mm bore). 
The pulling rod architecture increases substantially (~40%) the piston dwell at the combustion dead center enabling more “constant volume combustion”.
The single-piece “pipe-like” casing improves the stiffness, the lightweight, the simplicity and the low cost.
All the previous are just theories; yet, interesting theories.
The safety is the “big issue”.
Having two independent propulsion units (each alone capable for emergency landings), 
having also a parachute (for just in case, say when it runs out of fuel), 
having (optionally) three small wheels like:
for emergency airplane-like-landing on a road or on a flat field, 
the safety appears better than the safety provided by the conventional airplanes and helicopters. 
In the previous the GoFly competition (sponsored by BOEING) was mentioned only as a reference point. 
Surprisingly (because the BOEING is involved) they focus on the quietness and on the maximum dimension (8.5ft maximum) of the device: 90% of the total scoring is for the noiseless take-off / landing and for the maximum dimension of the Personal Flyer.
In the double-propulsion-unit OPRE Tilting Portable Flyer presented above, nothing appears near or beyond the current state of the art limits.
Lightweight carbon-fiber propellers of various designs and sizes are available in the market at low prices.
Toothed belts are common place for power transmission and revs reduction.
The structure of the Portable Flyer utilizes the engine casings as its backbone.
The perfect vibration free (including both, inertia vibrations and power pulses vibrations) is a requirement when a powerful engine is to be directly supported / secured on the body of the pilot/rider; otherwise a long (say of one or two hours) flight would be a torture. 
The counter-rotating propellers eliminate the gyroscopic rigidity and allow the pilot/rider to vector the thrust immediately and effortlessly to the desired direction. 
Every ounce of mass that can be omitted from a personal flyer, must be omitted. The more the mass of the flyer, the more fuel is required for a specific range and the more challenging the take-off / landing becomes.
The peroxide JetPacks consume some 30Kp of “fuel” in half a minute.
The jet powered personal flyers (Yves Rossi like, Zapata like etc) consume their fuel in ten minute, or so (BTE less than too small). 
The electrical personal flyers are based on batteries; and the existing batteries have an energy density several dozens of times lower than the fossil fuels (gasoline, kerosene, Diesel etc). The energy density of the power source is more than important for a flying device.
The body and the eyes and the senses of the pilot/ride are available; why not to use them as the fuselage and the sensors and the control system? 
Isn’t this what the birds are doing?
Relative to the birds, the low power to weight ratio of the human body is the only thing that restricts us from flying / hovering. 
This lack of power is what the OPRE Tilting engines and the propellers are curing at a true “neutral” and efficient way.
Manolis Pattakos

#64 manolis

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Posted 21 February 2018 - 05:57

Hello all.

Here is the Power Point filed in 2008 for Presentation in the International Engine Expo, Stuttgart Germany:

Here is the last page of the above presentation:
In 2008 it was regarded too aggressive even to talk about a Portable Flyer. 
While that Portable Flyer (of the presentation of 2008) can fulfill the specifications of the GoFly / Boeing competition, over the years the Portable Flyer has been evolved.

Portable Flyer architecture progress:
Two OPRE Tilting engines are bolted to each other and form a strong “backbone”.
At the ends of the backbone they are secured two pipes:
whereon two pairs of intermeshing propellers are rotatably mounted:
with the one pair of propellers arranged above the backbone, and with the other pair of propellers arranged underside the backbone.
The (holed) pipes provide passageways through which they pass the fuel and the control.
At the top of the pipes they are secured two (stationary) spinners wherein parachutes can be stored.
Each engine has two crankshafts with a pair of gearwheels synchronizing them (at operation the gearwheels run unloaded).
Each crankshaft is driving, through a toothed belt and a pair of sprockets, its respective propeller. The reduction ratio from the crankshaft to the propellers enables the optimization of the revs of the propellers and the optimization of the revs of the engines.
In case the one engine fails, or some propellers falls apart, or . . .:
The other engine with its propellers allows a safe langing.
I.e. there are two independent propulsion units (each comprising an engine and two intermeshed counter-rotating propellers), each of which, alone, being capable for emergency landing.
This is a great step in safety, making this cheap Portable Flyer safer, in some cases, than the OSPREY wherein a heavily damaged rotor, during a vertical take-off or landing, may prove catastrophic).
Portable Flyer engine progress:
An issue of all Opposed Piston engines is the side location of the spark plugs or of the injectors (in case of Diesels).
With the PatBam system, the combustion starts at the very centre of the cylinder (inside the bowl of the one piston):
and completes instantaneously (HCCI).
According Mazda, their SkyActiv-X HCCI achieves a 20% fuel consumption reduction as compared to their last high-tech SkyActiv-G models.
The PatBam does the same (strict control over the HCCI combustion) but in a by far simpler / cheaper way (mechanical / geometrical control).
With substantially lower fuel consumption (HCCI) and significantly improved reliability (no spark plugs, no high voltage circuit) . . .
Manolis Pattakos

#65 manolis

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Posted 08 March 2018 - 03:34

Hello all
Here are some recent bad news from NZ: 
Martin Jetpack posts $5m loss, quits ASX
With 320Kg total mass at take-off and two 500mm diameter ducted fans, they were obvious, from the beginning, two design flaws of the Martin JetPack: its extreme disk loading (which translated into extreme fuel consumtion and noise) and its extreme weight.
Think what 320Kg take off mass means: in order to carry in the air an 80Kg man, you have also to carry 240Kg of metal, carbon fibers and fuel. . .
In comparison, the Portable Flyer:
has some 4 times biger disk area and some three times lower total mass at take off, which means a disk loading about equal to the disk loading of the OSPREY V22 and some 12 times lower than Martin's JetPack.
The extreme disk loading is incompatible with the rest Martin JetPack and its quite low cruising speed. 
They talk for some 80million dollars overall losses. . .
Portable Flyer Sound / Noise:
At a Quiet Take-Off each engine is running at 7,000rpm and has to provide ~30bhp, which means it has to provide ~30mN of torque, which means it runs at ~60% load (30mN torque from a 350cc 2-stroke).
With HCCI combustion (instantaneous burning, wide open throttle (actually no throttle, as in the Diesels)):
and lambda=1/0.6=1.7, the cylinder temperature (degrees Kelvin) at the opening of the exhaust ports is substantially lower, say 3/4 of the temperature at the opening of the exhaust ports of the same engine running at lambda=1 and spark ignition (progressive burning). 
The pressures have the same ratio with the temperatures, i.e. the PatBam HCCI OPRE Tilting makes substantially less noise. 
Portable Flyer yaw control at hovering:
The pilot displacing properly his legs / arms in the downstream of the propellers, is pushed by a pair of eccentric aerodynamic forces that cause the rotation (yaw) of the Portable Flyer about its vertical axis towards any direction:
Portable Flyer from hovering to cruising: 
The pilot by extending his legs / arms towards a destination, displaces the center of gravity of the Portable Flyer relative to the plain defined by the rotation axes of the propellers, which causes the propeller axes to "lean" towards the destination. 
The vertical component of the thrust takes the weight of the Portable Flyer, while the horizontal component of the thrust accelerates the Portable Flyer towards its destination. 
As the cruising speed of the Portable Flyer increases, the aerodynamic drag displaces the pilot away from the vertical position, reducing his frontal area. 
At some cruising speed, the pilot is at a 60 degrees leaning from vertical:
wherein the frontal area nearly halves, and wherein the lift is about equal to the drag. The aerodynamic lift balances a significant part of the weight of the pilot; the rest weight is balanced by the vertical component of the propellers thrust. 
A "nose up" in an airplane (due to a disturbance) may end up with a stall or accident; a "nose up" in a Portable Flyer causes a horizontal deceleration and - in the worst case - ends up with hovering. 
A "nose down" in the Portable Flyer is automatically corrected: the aerodynamic drag and the weight keep the center of gravity lower than the centers of the propellers. 
Manolis Pattakos

#66 gruntguru

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Posted 08 March 2018 - 22:53

Nice images Manolis. The last one reminds me of our discussion on the need for “handlebars”.


Imagine the flyer and the human connected by a hinge joint at the shoulders. If you take the last image and draw a free body diagram of the flyer alone you will see that the thrust from the flyer passes through the CG of the flyer and through the hinge. The weight of the flyer is a vertical vector at the CG and is offset from the hinge, generating a moment about the hinge. By definition the hinge cannot apply a moment to the flyer so the flyer will tend to rotate downwards. Making the hinge joint “stiffer” will help but any angle in this joint will need to be counteracted by contortion of the pilot’s body – it would be far easier to control if he had the means to adjust the angle of the joint (i.e. handlebars).


This also applies in the hovering case. The thrust vector must pass through the CG of the pilot. Any angle in the “hinge” must be compensated by the pilot contorting his body to move his CG to the thrust line. If the thrust line is not vertical the flyer will drift. Depending on the body position there may also be a horizontal component to the aerodynamic force on the human body in the prop-wash.

Edited by gruntguru, 08 March 2018 - 22:55.

#67 manolis

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Posted 11 March 2018 - 07:08

Hello Gruntguru.



In the following drawing (from the US11/679,874 patent application, filed early 2007, full document http://www.pattakon....ing_Machine.pdf ) :




the pilot / rider holds handlebars to vector the propulsion unit  (and the thrust).


A hinge joint connects the propulsion unit with the casing (not shown) secured on pilots back / torso / shoulders.



In the animation of post #65, the pilot is drawn with his torso / back “fixed” (spinal cord inflexible).


In the following photo (a stomach training exercise):




the upper torso changes position relative to the rest body like, more or less, having a hinge at the height of the heart.


If the Portable Flyer is secured on the upper torso / shoulders, then there is a physical (built in) hinge (the spine) that allows the re-direction of the thrust by displacing the shoulders and the upper torso relative to the rest body.


With the arrangement shown in the photo of post #60, using his shoulders / upper torso, the “pilot” can angularly displace the propeller axes more than 20 degrees; 20 degrees seems more than necessary.


Handlebar(s) are still useful: when the pilot likes so, he can hold by his hands the handlebar(s) (as the pilot of the GEN-H-4) to assist or fully control the re-vectoring of the thrust. The pilot can also use the handlebars to rest his hands.



Worth to mention: driving a bicycle or motorcycle in a rough terrain requires fast response and continuous / precise control, while flying in three dimensions with nothing but air around you / near you, the required accuracy is questionable: to fly 500m away from the “ideal” path is OK; only during a landing or a take off the accuracy and the fast response are crucial / vital.


With the propulsion unit secured / tighten on the shoulders / torso / back of the pilot, his hands and legs stay free for both:


Either for the control of the flight (as displaceable weights and/or as “flaps” (they are in the downstream of the propellers)),


or for grabbing / holding / caring something (a drawn person, someone in the roof of a building under fire, an injured person etc).


I.e. to can control the flight exclusively with the body, leaving free the hands / legs is significant.


As an eagle that grabs and lifts its prey, the pilot of the portable flyer could grab and take away from the danger a person.



I bet you will see several times the following video (and the rest four “body flight” videos of the same series):




Manolis Pattakos

#68 gruntguru

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Posted 12 March 2018 - 00:33

". . . . . so the flyer will tend to rotate downwards"


The key point is, unless you have either handlebars or a very rigid and correctly aligned connection at the shoulders, the flyer will be unstable.

#69 manolis

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Posted 12 March 2018 - 06:35

Hello Gruntguru.


Look at the following video from 14’’ to 18’’, and then from the 1’:02’’ to 1’:15’’



The stability of the above GEN-H-4 Flyer at the fast take-off is remarkable.

At hovering some 30ft / 10m above the ground, the stability is not only excellent (compare it to the high-tech OSPREY V22), but this excellent stability is achieved without any noticeable effort from the pilot:

From 1:02 to 1:15 the pilot of the GEN-H-4 looks around calmly, as if he is seating in a chair in the veranda of his 4th floor apartment. 
He seems so relaxed that if he had a newspaper with him, he would read the news, too.



For comparison, in the following video it is shown the vertical take off and the vertical landing of the high-tech, no budget, OSPREY V22 of Bell Boeing:



The variable pitch rotors and the numerous electronic control systems cannot hide the stability issues: look from 7’’ to 17’’ (take off) and then from 1’:05’’ to 1’:25’’ (landing). It reminds a fat cow trying to breakdance.


The oscillations of the OSPREY V22 are not harmless (the catastrophe shown in the https://youtu.be/zwZZmXgqa2U video is the outcome of over-controlled oscillations about the long axis of the OSPREY).



The simple mechanical control of the GEN-H-4 (i.e. the displacement of e lever) and the human brain (the control unit) appear far superior and safer.


What the GEN-H-4 is?

It is a Personal Flyer having a pair of contra-rotating fixed-pitch rotors / propellers and a more than simple control system: the pilot displaces the center of gravity relative to the rotation axis of the propellers.





Has any reason the Portable Flyer to be less stable than the GEN-H-4 during a take off, a landing, or hovering?

On the contrary, the Portable Flyer with its counter-rotating propellers appears more symmetrical than the GEN-H-4 (wherein the lower rotor is in the downstream of the top rotor).

As for the displacement of the center of gravity relative to the rotation axes of the propellers, the pilot of the Portable Flyer can displace his legs, arms and head more easily than the arms of the pilot of the GEN-H-4 can displace the control lever.



In both cases (GEN-H-4 and Portable Flyer) the axes of the propellers are forces (by the muscles of the pilot, either they are the arm muscles (GEN-H-4 and Portable Flyer with handlebars) or they are the back / shoulders / torso / belly muscles) to displace relative to the rest Flyer (a part of which is the pilot).


I.e. either with handlebars and a mechanical hinge joint, or with the Portable Flyer secured on the shoulders / torso / back of the pilot (in this case the hinge is the spine), some muscles of the pilot re-vector the thrust force towards the desirable direction, either to keep the Portable Flyer hovering, or to make it fly at the desirable direction.

Worth to mention: in order the pilot to control his Portable Flyer, besides the displacement of the center of gravity (or of the direction of the propeller axes) he has another “tool”:


being inside the strong downstream of the propellers (the small diameter propellers (as in the OSPREY) give a high disk loading (as in the OSPREY) which results in a high downwash speed) he can change with his limbs / head the direction of a part of the downstream of the rotors.

According the previous, the Personal Flyer (at least as regards the take-off, hovering and landing) will be “boring” for the pilot (after the initial training).

For the initial training, the tethered tests (the Portable Flyer can easily be hanged by ropes from a tall roof; the stationary upper ends of the frame, those above the rotating propellers, seem the perfect points for the ropes to be tighten) appear easy and safe.


The final training can be at small height (say 10ft / 3m) over the sea.


Manolis Pattakos