2 stroke thread (with occasional F1 relevance!)

[Tommy Cookers]

your last sentence seems remarkable - have you cleared it through a lawyer ?
you might be wiser to concentrate on your unit's USP as the enabler of 'personal flyer' designs

your examples of other's successes are stable airframes using (position-constrained design) pilot weight-shift for control
though a problem with such small aircraft their inherently rapid and underdamped response to controlling moments
and weight shift moments are excessive at low airspeeds and insufficient at high airspeeds (opposite of aerodynamic controls)

auxiliary moveable aerodynamic surface(s) (in the prop slipstream) could provide powerful control moments and cruise lift
apparently the concept on the ConVair XFY-1 'Pogo' and its Lockheed XFV-1 competitor

[manolis]

Hello Tommy Cookers.

I don't know what you mean by "have you cleared it through a lawyer ?"

But here is something strictly technical.


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

http://www.pattakon.com/opre1_files/pattakonOPRE.pps

(in PDF format: http://www.pattakon.com/opre1_files/pattakonOPRE.pdf)


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) . . .


Thanks
Manolis Pattakos

[manolis]

Hello Gruntguru

You write:
"hover-mode will not be inherently stable and handle bars will be almost essential for adequate control."

Here is a version of the Portable Flyer wherein the pilot / rider has handle bars:



to control the direction of the thrust.

The complete USPTO patent application (filed early 2007) is available at http://www.pattakon.com/Fly_files/VTOL_ ... achine.pdf

It starts with:

"This patent relates to an easy to control Vertical Take-Off Landing (VTOL) flying machine which is simple, reliable, cheap and lightweight.

Compared to the prior art, it is like an oversimplified synchropter without any casing or frame, without special control equipment, without servomechanisms. The body of the pilot is the sensors and the servomechanisms: just like a rider controls his bike with his body motions.

The pilot, being inside the air stream generated by two counter-rotating rotors, can be hanged by the propulsion system the way a parachutist is hanged by his parachute. For the control of the flight, the pilot has as basic tools the position of his body relative to the propulsion system, the pose (i.e. the aerodynamic behaviour) of his body relative to the air stream, and the control of the propulsion system revs/load.

It is significant to liberate the pilot from any `reactions` generated by the propulsion system, i.e. it is necessary a `reaction free` or neutral propulsion system."




It seems that the control will be better with the propulsion unit(s) secured / tighten on the shoulders / torso / back of the pilot, leaving the hands / palms free to act as flaps.

In the video with the jet-powered delta wing (previous page, bottom), the legs / feet of the pilot appear relatively "idle", like "cloth hanged to dry in the wind", while the hands / palms seem quite active (3:39 to 3:41), like flaps controlling the flight.

The same in the following video of Rossy flying over Dubai:



(spot on 2:48 to 3:02 and 8:22).

The legs and head seem as offering stability and "steering", while the hands / palms seem as having the dominant control over the flight.

Thanks
Manolis Pattakos

[J.A.W.]

& one for the telemetry heads, a data feed from a tiny (but hi-po) 2T aero-engine, in NZ..

https://www.youtube.com/watch?v=ttqQS0CMO1o

[manolis]

Hello J.A.W.

Interesting:
39,000rpm!
Mosquito sound!

Supposing a 15mm piston stroke (as in the OS18TZ that has rev limit above 40,000rpm), the mean piston speed of the “mosquito” engine is near 20m/sec.


The video is from NZ.

Here are some recent bad news from NZ:

https://www.stuff.co.nz/business/101977 ... -quits-asx :

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 add 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 RPM:

The OPRE Tilting engines of the Portable Flyer are to run until 10,000 rpm (wherein the mean piston speed is only 10m/sec), half of the "Mosquito" engine.


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.


Thanks
Manolis Pattakos

[J.A.W.]

Yeah Manolis, I do hope the demise of the 'Martin Jetpack'..
( which frankly, really didn't add up as an actual 'goer' - in the airborne stakes)
..does not also spell "bad news" - for any needed investment into your 'Flyer'..

Same goes for several other expensively funded, but fundamentally 1/2 arsed - 2T 'developments'
- which really turn out to be a combination of ill-thought out mechanical contrivance duds,
& seemingly lucrative 'pyramid' financial scams,( if not downright money laundering schemes).

Perhaps you could add to your professional service profile, the role of a consultant 'due diligence' surveyor,
doing mechanical feasibility assessment - for would be investors - into such 'novel' designs?

Maybe contact Bill Gates... if his 'burnt fingers' haven't already blighted his interest in such machines, that is..

[manolis]

Hello J.A.W.

You write:
“Maybe contact Bill Gates... if his 'burnt fingers' haven't already blighted his interest in such machines, that is..”


It seems that “the” Bill Gates:



tries to forget the fiasco of EcoMotors / OPOC wherein his name was involved.




It is not the 23 million dollars invested by him to Ecomotors and lost.

For Bill Gates 23 millions is nothing.


What really hurts him is that he, “the” Bill Gates, was caught, beyond reasonable doubt, sucker.


This also explains the “switching off” of the the EcoMotors web site (www.ecomotors.com) .

After several thousands of articles published around the world about the innovative / promising / etc / etc / etc Ecomotors OPOC engine, now the OPOC project and the Ecomotors must be forgotten.

Thanks
Manolis Pattakos

[manolis]

Hello J.A.W.

For the 4-stroke gasoline engines the HCCI seems a big improvement, a breakthrough (according Mazda, their SkyActiv-X HCCI has 20% lower fuel consumption than their current high-tech SkyActiv-G gasoline engines).

For the 2-stroke engines, the HCCI appears even more important.


Due to their architecture, the 2-stroke gasoline engines suffer at partial loads.

Running on stoichiometric and, say, 30% load is a big challenge for a 2-stroke: the rest 70% of the cylinder is occupied by exhaust gas, while the crankcase is kept at a significant sub-pressure during intake (pumping loss etc).

The stratified charge is a solution but with many limitations.


A 2-stroke Diesel, on the other hand, is happy to run lean, or very lean, or extremely lean (lambda even above 10):



If the fuel droplets, as they are injected into the cylinder, find hot air, they don’t care for the average lambda in the cylinder; they just ignite and get burnt. Even a single tiny droplet injected into a big cylinder having hot air, will ignite.


With the HCCI / two-stage ignition, a 2-stroke engine runs – more or less – as a 2-stroke Diesel:



but without the particulates and the NOx emissions of the Diesels.

If the bggest problem of the 2-stroke engine has always been the partial load (partly open throttle, which means low pressure in the crankcase, and thereby a cylinder full of residual gas) the HCCI two-stage ignition is more important for the two stroke engines than for the 4-strokes:



Thanks
Manolis Pattakos

[J.A.W.]

A few vids showing recent 2T developments - one being a curiousity, & a couple of commercial snowcraft units.

https://www.youtube.com/watch?v=XP8tmtONnGY

https://www.youtube.com/watch?v=QOJISea8SEc

https://www.youtube.com/watch?v=iO_QoOIUang

[manolis]

Hello J.A.W.

Thanks or the videos.

The first seems to be for an oval piston Vee (if 2-stroke the crankcase may be divided).

The other two (Polaris and Arctic Cat) are quite similar (see the comments published under the youtube videos) to Ski Doo’s E-TEC 850.

At high revs / loads, the direct injection of the Ski Doo E-TEC turns, partially, to port injection.


All three engine makers claim impressive reduction of the specific lube consumption. In practice things proved not as expected.

Quote from http://www.snowandmud.com/ski-doo-rev-g ... ption.html for the BRP-Rotax 850 E-TEC:

“Who else finds it to be a slap in the face that last spring they advertised these sleds to use 40% less oil than an 800 e-tec and then changed their minds once everyone paid for their sleds this fall?? I mean, how can a company the size of BRP get away with blatant false advertising on a mass scale like this? I have been using around 2L of oil per ride if not a bit more. I think they may actually be thirstier for oil than the 800's.”


Here are two frames from the Arctic Cat 850cc / 2019 video:



In the upper frame the combustion continuous with the exhaust port already open.

In the lower frame it is shown the shape of the “combustion chamber”, the ports and the way the lubricant is provided.

The combustion chamber shape is, more or less, as in the following PatAT / PatBam:



With two-stage ignition (PatBam HCCI) the resulting low temperature combustion ends a few degrees after the TDC, several dozens of crank degrees before the opening of the ports.

The asymmetric transfer continues after the closing of the exhaust (quite important for the emissions).

The lubrication of the crankcase is four-stroke.

The lubrication of the compression piston rings is by abutting on the cylinder liner area wherein 180 crankshaft degrees before it was abutting the oil scrapper ring.
The engine runs un-throttled (as a Diesel) on lean air fuel mixtures: the lighter the load, the leaner the mixture.

The crankcase can still be used as the scavenging pump, say as:



(more at http://www.pattakon.com/pattakonPatATeco.htm and http://www.pattakon.com/pattakonPatAT.htm ).



The E-TEC (of Rotax / BRP / Evinrude) was, at its time, a breakthrough for the 2-stroke engines.

In comparison, the three modern 850cc 2-stroke snowmobile engines (Ski Doo, Polaris and Arctic Cat) have only minor improvements (“obvious to the skilled in the art”: a phrase quite common in the patent offices), nothing really innovative / impressive / exotic.


By the way, are there any news about the TPI of KTM?
Are they gonna use their green 2-strokes in street motorcycles or cars?

Thanks
Manolis Pattakos

[J.A.W.]

Hi Manolis,
There seems to be nothing particulary remarkable about the combustion chamber of the Arctic Cat,
& or piston shape design, since it features no projection into the C-C, unlike your design.

However, they do use a 'boost port' injection set-up, similar to what Yamaha patented over 45 years ago,
for their GL 750/4 2T roadbike, which sadly, never went on public sale, except as a (carb equipped) racer.




As for KTM, although their new TPI enduro bikes are road-legal, AFAIK, their off-road bike division is organisationally separate from KTM roadbikes, so KTM say 2T roadbikes are "Not in the immediate future."

https://transmoto.com.au/tpi-injected-2ts-faqs-answered

[manolis]

Hello J.A.W.

Quote from the link of your last post:

"CAN WE EXPECT TO SEE FUEL-INJECTED TWO-STROKE STREET BIKES FROM KTM IN THE FUTURE?
Not in the immediate future. The engines developed are specifically designed for off-road use. Street bike engines are a completely different scenario."


It does not fit:

A company (the KTM) has a unique product (the TPI 2-stroke engine) which is the only euro4 compliant 2-stroke engine in the world (while many reputable 4-stroke engines (like the Ducati Panigale 1299) were phased out due to their non compliance with the euro4 emission regulations).

And instead of putting their TPI 2-stroke in every kind of vehicle (street motorcycles, small cars etc), they use silly excuses for their reluctance to proceed / risk.


By the way, enjoy the following instructional video (and the rest videos of the same series):



Thanks
Manolis Pattakos

[J.A.W.]

Yeah Manolis, according to KTM - currently, at least - "It does not fit", into their marketing program..
& sadly - a not uncommon issue - for fans of 2T motorcycles, & by no means a "it does not fit" - tech issue, either..

[Pinger]

Manolis, the next issue of Engine Technology International will have an in depth report on the current state of the art of HCCI. I'll post a link to the online version when it is published.

Well, it's published - but nothing about HCCI in it.

http://viewer.zmags.com/publication/0e4 ... 0e40c1a8/1

[manolis]

Hello Pinger

Quote from http://www.enginetechnologyinternationa ... cleID=2305

February 14, 2018, Engine Technology International.

Mazda reaffirms its commitment to the IC engine

“We’ll create the first HCCI engine and be the last with BEVs,” said Kenichiro Saruwatari, vice president of R&D at Mazda Europe, at the 2016 Geneva motor show. While HCCI technology is just around the corner two years later, Mazda has reiterated that it has no plans for battery electric vehicles.



As quoted on the front cover of Engine Technology International in June 2016, Kenichiro Saruwatari, vice president of R&D at Mazda Europe, used the 2016 Geneva Motor Show to reiterate the company’s staunch support for the IC engine. “We’ll create the first HCCI engine and be the last with BEVs,” Saruwatari said. While HCCI technology is just around the corner two years later, Mazda has reiterated that it has no plans for battery electric vehicles

With the increase in electric car development, Mazda has led new research to suggest that 55% of UK drivers and almost 60% of European drivers see a positive future for petrol and diesel engines.

The Mazda Driver Project research – commissioned together with Ipsos MORI – polled 11,008 people across key European markets and an average of 58% believe there is “a lot of innovation and improvement still to come with petrol and diesel engines”.

The results contradict the current movement within the industry and has led Mazda to further develop the traditional internal combustion engine to facilitate its use in future cars.

The Japanese OEM further highlighted its belief in the IC engine, stating that 29% of UK drivers polled “hope that diesel cars will continue to exist” as electric cars become more common; 44% hope that petrol will continue; and 36% of drivers stated that if running costs were the same as an electric car they would “prefer a petrol/diesel car”.

Despite the gathering momentum behind autonomous vehicles, according to the OEM only 29% of UK drivers “welcome the advent of self-driving cars”; against this backdrop, Mazda continues to progress its pioneering advanced safety features and Mazda Co-Pilot Concept autonomous driving technologies.

“We recently launched ‘Sustainable Zoom-Zoom 2030’, our long-term vision for technology development,” said Jeff Guyton, CEO at Mazda Motor Europe. “In it, we set out how we plan to use driving pleasure to help solve issues facing people, the earth and society.”

“In the case of greenhouse gas emissions, we believe it’s necessary to have the right solution at the right time. For us this means taking a well-to-wheel view, and therefore today’s most rational offering is a combination of internal combustion engines and electric devices which consider each market’s energy situation and power generation methods. In this context, we are determined to perfect the internal combustion engine.”

Mazda continues to work toward its ‘Sustainable Zoom-Zoom 2030’ vision to combine the best of internal combustion engines with effective electrification technologies.

Central to this ambition is Skyactiv-X, the new engine utilizes compression ignition to combine the advantages of petrol and diesel engines to achieve greater environmental performance, power and acceleration performance.

“Our aim is a motorized society free of traffic accidents,” added Guyton. “There are three main keys to realize this. First, we continue to advance safety fundamentals across our range – driving position, pedal layout, visibility and our Active Driving Display.

“Second, we continuously develop, update and make standard many advanced safety features such as Blind Spot Monitoring. Finally, we aim to make the Mazda Co-Pilot Concept standard by 2025.”

February 14, 2018

End of Qoute


Mazda seems sure for their SkyActiv-X HCCI and takes the risk to put it in mass production in 2019.

Thanks
Manolis Pattakos