2 stroke thread (with occasional F1 relevance!)

[autogyro]

https://books.google.co.uk/books?id=_9A ... gs&f=false

Ever since Farnborough dropped the concept in the 1960s, the tilt wing idea for rotor craft has been a flawed concept.
The Osprey has killed many people since its original conception but you will hear very little about this.
I would love to see one land in a glide after engine or gearbox failure in hover, I think it would simply result in a pile of bits.

I take great interest in the design from Manolis but I wish he would stay away from rotor powered flight.

https://en.wikipedia.org/wiki/Fairey_Rotodyne

In 1959 in the UK we had a far superior vtol aircraft to the Osprey in service and fully developed.
Like all superior UK aviation products the Americans made sure it became forgotten.

https://www.youtube.com/watch?v=VFk5Y_F-dwg

Projected modern version of rotodyne

https://en.wikipedia.org/wiki/Ken_Wallis

My late associate Ken Wallis developed a fully capable light autogyro that served with the military for many years in covert opps. The military W116 completed anti tank trials, rapid deployment trials and sea landings as well as operations still on the secrets list.

Both the Wallis and the rotodyne flew in permanent autorotation and were safer than any other aircraft in engine failure.
The Wallis used a unique rotor head with teeter stability and held many world records.
By comparison the American rotor craft designs are still decades behind.

[Andres125sx]

https://books.google.co.uk/books?id=_9A ... gs&f=false

"(Vortex ring state) The pilot had just to tilt the [page 337 is not available for preview]"

Ouch!!


If someone have access to this page, please post it!. It was a very interesting read to me, apart from the related Osprey problems, because I´m a RPA pilot (multirotor, octocopter), and vortex ring state is very very noticeable for us too, specially when the RPA is used for aerial filming, as any unstability is very visible in the media, we need rock solid stability for aerial filming, and I´ve spent many hours trying to minimize this problem

Right now it´s not a big problem to me, as I can descend up to 6m/s with no forward speed at all without any big unstability (the camera is mounted on a stabilizer wich removes most movements), but the read was being very interesting to me

Projected modern version of rotodyne

https://en.wikipedia.org/wiki/Ken_Wallis

My late associate Ken Wallis developed a fully capable light autogyro that served with the military for many years in covert opps. The military W116 completed anti tank trials, rapid deployment trials and sea landings as well as operations still on the secrets list.

Both the Wallis and the rotodyne flew in permanent autorotation and were safer than any other aircraft in engine failure.
The Wallis used a unique rotor head with teeter stability and held many world records.
By comparison the American rotor craft designs are still decades behind.

Hey I´ve seen this flying in person here in Spain. I think it was on a MX World Championship when it was in Talavera de la Reina (Cerro Negro track), because I had the camera and took some pictures. It was a very fast and agile aircraft.

[Andres125sx]

Correction, the autogyro I saw some years back was in Portugal MX gp (Agueda) and it´s not the same model, it was very similar, same size, but a two seater version with a horizontal stabilizer

[LucF]

Hello LucF

Tell Harry Ryger that 30,000 rpm with 54mm piston stroke is not at all easy, at least according the Laws of Physics.

With 200gr total mass of the reciprocating assembly (including the piston, the piston pin and the upper 1/3 of the connecting rod(s)), it is required an average force of 5.5 tons (12,000lb) acting on the piston from 40 crank degrees before the TDC till 40 crank degrees after the TDC.

http://www.pattakon.com/tempman/Ryger_Force.gif

With only 23cm2 piston surface, in order to decelerate the piston assembly by the pressure into the cylinder, you need an average (not peak, average throughout 80 degrees around the TDC) pressure of 240bar.


By the way, the piston of the 2-stroke Yamaha DT200 (195cc) weighs alone (i.e. without its piston pin and without the upper part of the connecting rod) 200gr.

Thanks
Manolis Pattakos

Thanks Manolis for the nice calculations, but we do made them self too. And mr Ryger knows all about this.
But the goal is not that 30.000rpm, because the max power is between 17-18k.

Beside the princple can go far more than 30k that is a typical Ryger property, which is completely different with the current 2t principle we already used for more than 100 years.
So today 2stroke laws you can forget for a very big part, if it is about tuning, with the Ryger engine it starts all over again.
The mechanical construction determine what is the maximum possible. So see that 30k more as a test that the engine can handle it.

[Tommy Cookers]

good reference on the Osprey, auto !

but the Rotodyne was of course always intended to have a powered rotor and to make use of that on every flight
because the engines were perenially below spec no doubt many test flights were made with the rotor unpowered throughout
and the intended rotor tip powering was in desperation replaced with the notoriously noisy ramjets powering the rotor

an important point is that autorotative landings depend on the stored energy of the rotation
lighter helicopters have relative to their mass disproportionately little stored energy
and so the judgement and timing of the operation tends to become impossibly difficult
and afaik practice autorotative landings were/are anyway never done in any helicopter, for this reason

yes, those of us who only sit and write give praise to those who work to progress the 2 stroke

we once had an old Tilling-Stevens school bus, but I don't think it/they had the 2 stroke diesel
a onetime co-worker was at the shoot-down of a (2s) diesel powered Junkers at Manston ('bomb alley') in 1940
88-like, but I said an 86P, this having heavy supercharging for altitude minimised the power through the crank-coupling gears

[LucF]

Any two-stroke that drags oil across cylinder ports with the piston rings can never be a "clean" motor. The claims for the Ryger engine are unfounded, I would say. Also, all the suggestions for "improved" two-stroke designs suffer from the same fateful flaws.
I will make no stupid claims for my own two-stroke engine (which is being developed right now) until I have some genuine proofs of its efficacy.

Frederic, where does the Ryger claims a 100% clean engine?
When the word "clean" is used it was meant in comparison with the current 2 stroke design.
And what do you mean by "the same fateful flaws" ?

Ryger Engine built by Mcd Twist Ryger Engine
125 cc, over 80% less emissions, 70 bhp, max. rpm 30.000.
https://www.facebook.com/mcd.twist.9?fref=ts

[J.A.W.]

Ok then..
..for those who can't handle the actual 2T machinations, but still want a sniff of the sensual ambiance..

http://www.flyingtigermoto.com/products ... oke-candle

[manolis]

Hello LucF

Tell Harry Ryger that after applying for a patent, the inventor can reveal to the public his “patent pending” (which means “protected if a patent will eventually be granted”) invention without risk.

I understand the “secrecy” as a way to spark the fantasy of the potential customers and investors. But after a point, it turns negative and spoils the picture.


If the power drops after 18,000rpm (70bhp at 18,000rpm means a torque of 27.5Nm, i.e. 220Nm/lt) what is the advantage of “can go far more than 30k”?
54mm stroke at 18,000rpm means a mean piston speed of 32.4m/sec.


You write:
“When the word "clean" is used it was meant in comparison with the current 2 stroke design.”

In the “current 2 stroke design” there are engines like the direct injected Rotax 800 E-TEC (2-stroke, 2-cylinder, 800cc, 147HP / 8,100rpm, 35,8 Kg).
Rotax also claims way lower emissions than the “current 2-stroke design”.
On the other hand, in the EPA “fully warm and steady state” tests for snowmobile engines, the Rotax 800 E-TEC emissions (HC and CO, gr per kWh) are several times higher than the 4-stroke competitors (of the same company).


The patented crosshead uniflow 2-stroke direct-injection PatMar Diesel:



(more at http://www.pattakon.com/pattakonPatMar.htm )

has many reasons to be cleaner than the state-of-the-art 4-stroke Diesels.

It has lower specific lube consumption than the 4-strokes of similar power, it has lower specific fuel consumption than the 4-strokes of similar power, it has more compact combustion chamber etc.

If there is interest, I can further explain.

This long-stroke / push-rod design is for low – medium revs (from giant marine engines (less than 100rpm) to truck engines (say 2,500 rpm))



Similarly for the uniflow 2-stroke direct-injection PatPortLess Diesel:



(more at http://www.pattakon.com/pattakonPatPortLess.htm )

With its pull-rod design it allows some 30% increase of the efficient rev range and of the power.

Why Diesel?
Because the compression ignition engine is based on the lean burn that fits with 2-strokes.

Thanks
Manolis Pattakos

[autogyro]

good reference on the Osprey, auto !

but the Rotodyne was of course always intended to have a powered rotor and to make use of that on every flight
because the engines were perenially below spec no doubt many test flights were made with the rotor unpowered throughout
and the intended rotor tip powering was in desperation replaced with the notoriously noisy ramjets powering the rotor

an important point is that autorotative landings depend on the stored energy of the rotation
lighter helicopters have relative to their mass disproportionately little stored energy
and so the judgement and timing of the operation tends to become impossibly difficult
and afaik practice autorotative landings were/are anyway never done in any helicopter, for this reason

yes, those of us who only sit and write give praise to those who work to progress the 2 stroke

we once had an old Tilling-Stevens school bus, but I don't think it/they had the 2 stroke diesel
a onetime co-worker was at the shoot-down of a (2s) diesel powered Junkers at Manston ('bomb alley') in 1940
88-like, but I said an 86P, this having heavy supercharging for altitude minimised the power through the crank-coupling gears

Not true
The rotodyne was fully operational as an autogyro. My late friend Ken Wallis flew in the aircraft and confirmed this to me.
A speed of over 200 mph was also achieved in this flight mode.
The rotodyne was also far more efficient on fuel without a powered rotor.
It is true that both the American and British governments restricted investment on the later engine developments after the Elan turboprop with compressor and that with the later engines the rotodyne would have far exceeded any current American rotorcraft performance even of today.
One of the biggest aviation scandals of all time was to scrap rotodyne and the TRUTH is still not public.
It is because of the American domination of aviation since that period that we are now stuck with dog aircraft like the Lockheed F35, which IS the biggest aviation scandal of all time.
Just think of how much better modern aircraft both civil and military could have been.

[autogyro]

Because the Wallis W116 is so stable in ALL flight modes, in the training schedule the novice pilot has to undertake a landing with the engine switched OFF.
That is correct Tommy OFF in the official training schedule.
So much for not being able to land in autorotate in a small rotor craft.

From the posts you have made Tommy, it seems to me that you have no idea how the rotodyne worked.
The tip jets were solely for VTOL not cruise flight.
They were NOT added as an after thought.
Using two prop driving engines for thrust requires far less power in autogyro mode than when the rotor is powered.
A powered rotor requires a more acute angle of attack on the blades the result even with powered rotor lift results in a higher drag over all than with the fine angle of attack using autorotating blades.
The airflow in autorotate is far smoother.
The rotor wash from powered blades goes down over the aircraft and is highly turbulant.
There is little rotor wash from unpowered blades and the airflow is smooth and goes up away from the aircraft.

[Tommy Cookers]

you seem to have energetically attempted to refute a number of things that I did not say
eg I did not say the Rotodyne couldn't fly with the rotor unpowered - I said exactly the opposite (though maybe not clearly)

an autogyro will always have more stored energy in the rotor (than an equivalent helicopter) because it will have a bigger rotor
my words were clearly specific to the autorotative landing issue of (light) helicopters
yes, I have flown both

the vortex ring issue is quite minor according to the books, but maybe not with side-by-side rotors

[Carlos]

Several posts mention concerns about the problem of building a 2T that meets emission stands while lubricating con-rod and big end bearings adequately ... reading a Cycle World column by Kevin Cameron commenter 'Tony' contributed "Skidoos di’s use ball main bearings same as sleds have used forever, but sealed like your bikes wheel bearings, and packed with super long life Isoflex synthetic grease.
Rotax actually began using the sealed bearings in 1999 on their carbureted reed valve engines [10 years before the direct injected e-tec ] simply as a way to reduce bearing failures. Big end and wrist pin bearings are normal caged roller."
No mention of how the piston rings were lubricated. Several columns on 2T engines in Cycle World, just search 'Kevin Cameron.
http://www.cycleworld.com/2014/03/07/as ... ke-engine/

[LucF]

Hello LucF

Tell Harry Ryger that after applying for a patent, the inventor can reveal to the public his “patent pending” (which means “protected if a patent will eventually be granted”) invention without risk.

Why do you think you are the only one to know this?

If the power drops after 18,000rpm (70bhp at 18,000rpm means a torque of 27.5Nm, i.e. 220Nm/lt) what is the advantage of “can go far more than 30k”?
54mm stroke at 18,000rpm means a mean piston speed of 32.4m/sec.

Read again what I wrote before?

In the “current 2 stroke design” there are engines like the direct injected Rotax 800 E-TEC (2-stroke, 2-cylinder, 800cc, 147HP / 8,100rpm, 35,8 Kg).

Yes that is right, Honda also tried a direct injected engine with more power than ever before already in the past century, but nobody wants to drive it beacause nobody can handle it on a circuit.
Besides the Rotax should be far more to reach the RSA level of the year 2007. You may correct it for a 2 cylinder for about 10% lower. See the graphic. Sorry can't attache it so: https://www.facebook.com/photo.php?fbid ... tif_t=like

Rotax also claims way lower emissions than the “current 2-stroke design”.

Also 80% ?


Thanks Manolis for your reply,

For new engine designs keep always in mind the following.
All nice designs you show us, but all to complicated and therefore to expensive to introduce in this automotive world.

The biggest advantages of the Ryger engine are:
1. 80% less emmissons,
2. Very simple to change almost all existing engines into a Ryger engine,
3. Much more power over a very wide rpm range, so much lighter engine with the same power.

Most people, even not involved in automotive, can imaging what this means.

Regards, Luc

[manolis]

Hello LucF.

Given that Ryger knows that a technical solution officially filed in a patent office is protected, what is all this “secrecy” for?

The 80% less emissions is not an answer; it is an advertising trick.
Unless Ryger engine has 80% less emissions than the “current 2-stroke” Rotax 800 E-TEC.
He could simply give the gr/kWh of HC, CO, NOx and CO2 at some conditions.

The same for the “can go far more than 30k” while its breathing capacity (power) drops after 18,000rpm. Suppose it “can go far more than 50k or 100,000rpm”; then what?


You write:
“For new engine designs keep always in mind the following.
All nice designs you show us, but all to complicated and therefore to expensive to introduce in this automotive world.”

Thanks for the advise and for the opportunity to explain how things are.

Take the PatMar 2-stroke:



(the details and the granted patents (wherein more technical details are available) are at http://www.pattakon.com/pattakonPatMar.htm )

With 86mm bore and 210mm stroke (uniflow, stroke to bore ratio 2.5:1, short connecting rod, cross head architecture), the capacity per cylinder is 1164cc.
An even-firing 4-in-line (4.6lt) is as vibration free as the best V-8 4-strokes.

There are many technical reasons for being cleaner not only than the “current 2-stroke designs” as Ryger claims for his engine, but also than the state-of-the-art 4-strokes.
And there are many technical reasons for having lower specific fuel and lube consumptions than the current 4-strokes.

For instance, during the combustion, the total wall surface around the hot gas and the burning fuel is similar in size with that of a conventional 2lt 4-stroke 4-cylinder Diesel engine.

Or, for instance, think the friction loss saving as compared to a similar power 4-stroke.

Is the PatMar too complicated / expensive to introduce in the real world?

Think it as a truck engine making its peak power at 2,000rpm (14m/sec mean piston speed).
It is way simpler and cheaper than the current 4-stroke truck engines (with the same mean effective pressure, a 4-stroke needs double capacity in order to make the same power at the same revs).

Quote from http://www.pattakon.com/pattakonPatMar.htm

With the "pants", the state-of-the-art low speed two-stoke marine and power station engines (like the Wartsila - Sulzer, the MAN B&W etc)



which are the by far most efficient stand alone working machines today, become:

- even more reliable (increased scuffing resistance, longer time between overhauls),
- cheaper and simpler (no special equipment and control for the cylinder liner lubrication),
- more economical (lower lubricant specific consumption),
- greener (less lubricant into the combustion chamber, better combustion, reduced emissions).

With the "pants" the low-speed two-stroke engines combine their own advantages with those of the medium-speed four-stroke engines.

End of quote.



By the way,
in a previous post (August 16, 2015) regarding a “new 2-stroke design” of Honda:



the most obvious issue is the low revving capacity (even for small engines) due to the poppet exhaust valve and its actuation mechanism (a two-stroke poppet valve opens and closes at double frequency than a 4-stroke poppet valve engine operating at the same revs)..

Here is a PatRoVa rotary valve for two-strokes that can eliminate this limitation of Honda’s design:



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

Thanks
Manolis Pattakos

[gruntguru]

Hello LucF
Tell Harry Ryger that after applying for a patent, the inventor can reveal to the public his “patent pending” (which means “protected if a patent will eventually be granted”) invention without risk.

Why do you think you are the only one to know this?

Perhaps Manolis (like most of us here) is struggling to understand why it is not possible to post details of the engine here when it is supposedly protected by the patent system.

The claims sound wonderful but this is a technical forum and we are more interested in technical detail. We can find all the claims we want elsewhere.