2 stroke thread (with occasional F1 relevance!)

[manolis]

Hello all.

Weight and Flying Devices


The JB11 JetPack of Mayman weighs, dry, 50Kg (110lb) :



i.e. 2.5 times more than the Portable Flyer.

For the average person, lifting 20Kg from the ground above their head is not difficult.
For the average person, lifting 50Kg from the ground to their torso height is impossible.

Worse even, for a "decent" range (say 20 miles) Mayman has to carry (to bear on his back) another 70Kg (150lb) of fuel.

For the same range the Portable Flyer needs less than 5Kg of fuel.

I.e. the overall weight of the propulsion unit (including the fuel for 20 miles) of the Portable Flyer is five times lower than that of Mayman's JB11 (20+5=25Kg versus 50+70=120Kg).

Including a 75Kg pilot, the overall take-off weight of the Portable Flyer is half than Mayman's JB11 JetPack.



Where the abovementioned 70Kg of fuel for 20 miles comes from?

According the Internet,
in order to cross the English Channel (~ 22 miles) with his FlyBoard_Air JetPack,
Zapata not only consumed 70 Kg of fuel,
but he had to land on a refueling platform, at the middle of the channel, to refuel.


And why the JetPacks have such low mileage?

The mileage has to do with the BTE (Brake Thermal Efficiency) of the engines used and with the way the thrust is generated.
The low BTE of the turbines of the JetPacks combines with a highly inefficient "propulsion method" wherein the supersonic exhaust gas takes most of the energy provided by the engine, leaving only a small percentage to the flying device.

The 1,000hp (or so) of power from their turbines, for which the JetPack makers are proud of, is indicative.
In simple words: they consume 1,000hp for something that can be done with 50hp.


To the rest requirements of a personal Flying Device (my last post) they have to be added the high BTE of the engines used and the high efficiency of the propulsion system.
For a given range, with half BTE you need to carry two times more fuel.
And with x times less efficient propulsion system (say, jets vs propellers) you have to carry x times more fuel.

While the weight of the fuel in the case of cars and motorcycles is not significant, for Flying Devices it is a crucial factor.

See the body posture of Yves Rossy and his partners:



They barely carry their Flying Devices having fuel for ten minutes of flight.


Quote from https://www.pattakon.com/GoFly/index.html (Abstract) :

• A personal flying device must be lightweight.
  
  The more lightweight (including the fuel or the energy source) the better.
  
  Every oz of additional (beyond pilot's) weight requires additional power and additional fuel; the added weight makes the control of the flight more difficult, the landing more risky and dangerous, the noise louder, the range shorter, the mileage smaller, the emissions worse.
  
  A personal flying device must be as lightweight as possible; and because weight cannot be removed from pilot's body, weight can only be removed from the power unit and from the energy source (fuel or batteries).

Thanks
Manolis Pattakos

[nzjrs]

Given that the PF could work with any engine, these speculations are mostly off topic. Any more news on your engine?

[Tommy Cookers]

... the power to weight ratio is well below 0.5hp/Kg for the Red Bull racing airplanes that can hover.....

they can't hover
yes they can give a good impression of hovering (as I did in an Extra 300)
in the past such impressions were available - but only from masters of the tailslide exit manoeuvre

hover presumably meaning no wing lift .... but .....
eg typically a body attitude of 80 deg to the horizontal would give zero groundspeed (but non-zero airspeed)
half the wing is prop-blasted with 250 mph air - and wing lift component acts maybe 15 deg upwards (of horizontal)

is there an RB stunt plane that truly hovers ? - I haven't found anything on it or any other that does

[manolis]

Hello Tommy Cookers

You write:
"they can't hover
. . .
hover presumably meaning no wing lift .... but .....
eg typically a body attitude of 80 deg to the horizontal would give zero groundspeed (but non-zero airspeed)"


I don't get it.

If they can keep zero groundspeed, i.e. if they can remain in one place, don't they hover?

• Hover: to remain / to stay in one place in the air.

Around a hovering balloon the airspeed can be zero, but around a hovering helicopter the (local) airspeed is non-zero.

Thanks
Manolis Pattakos

[uniflow]

Not even twostroke relevant any more?

[nzjrs]

Not even twostroke relevant any more?

Nope, manolis has ruined this thread. He just gives sermons on the PF now (it doesn't even need his engine).

[Dr. Acula]

Hello Tommy Cookers

You write:
"they can't hover
. . .
hover presumably meaning no wing lift .... but .....
eg typically a body attitude of 80 deg to the horizontal would give zero groundspeed (but non-zero airspeed)"


I don't get it.

If they can keep zero groundspeed, i.e. if they can remain in one place, don't they hover?

• Hover: to remain / to stay in one place in the air.

Around a hovering balloon the airspeed can be zero, but around a hovering helicopter the (local) airspeed is non-zero.

Thanks
Manolis Pattakos

What TC means is that technically these aircraft need to generate lift with their wings and do not simply hang under their propellers. The Propeller alone does not create enough thrust to keep the aircraft in the air. So the aircraft is still fyling pretty much like any other fixed wing aircraft just with zero ground speed.

[manolis]

Hello DrAcula

And why it is important who provides the lift?

I am not sure if the Red Bull racing airplanes really can,
but if they can fly remaining in one place (I mean with true zero groundspeed (horizontal and vertical)), they hover.

And if they hover, they can be used as helicopters for rescue etc.

For a rescue in the sea an airplane can go much faster than a helicopter, but it cannot hover to collect people. If it can hover . . .



Hello Uniflow.

Several highly unconventional two-stroke engines are shown in the last few pages of this discussion.

Here is one that utilizes reed valves:







In the first video, from 0:30 to 0:40 they are shown the reed valves (yello pentals, red block)

In the second video, from 1:00 to 1:05 they are shown the reed valves (black).

In the third video the engine stands free on a desk and runs on Diesel fuel.


Is there another single-cylinder single-crankshaft engine having similar vibration-free quality?


The vibration-free is just one of several advantages this design provides.


Specifications / characteristicas of the above prototype engine:

• Bore: 79.5mm
  Stroke: 64+64=128mm
  Displacement: 635cc
  Compression ratio: 17
  Scavenging pump bore: 130mm (1.34 scavenging ratio)
  Total engine height: 500mm
  Total engine weight (without the flywheel): less than 20Kp

It is an:

• opposed-piston,
  two-stroke,
  single-cylinder,
  single-crankshaft,
  full-balanced (vibration free),
  cross-head,
  direct-injection Diesel engine,
  with built-in "volumetric" (for a wider rev range and flat torque curve) scavenging pump,
  with four-stroke-like lubrication,
  and with some 35% as compared to the conventional, or some 20% as compared to the Junkers-Doxford and to the OPOC of EcoMotors, additional time for the injection and combustion of the fuel.

More at https://www.pattakon.com/pattakonPatOP.htm

Thanks
Manolis Pattakos

[uniflow]

Id like to show progress on my single cylinder 175cc OP uniflow engine, with unconventional scavenging and some other ''special'' features but Id only get shot down because its not a Manolis design.
Manolis, you are not always right, but you don't listen, you got it so wrong about E85 for example, you treat this forum as some sort of debate game where you must always win, you go right ahead, you will have no debate from me.

My projects are not just theoretical or rough short run prototypes, if my engines can't do the job intended i.e. fly for hours or run four hour off road motorcycle enduro's back to back, then I consider them a failure, so far so good, KTM and TM are running my successful TPI fueling as an example.
I post elsewhere, the real world.

[nzjrs]

Id like to show progress on my single cylinder 175cc OP uniflow engine, with unconventional scavenging and some other ''special'' features

Please post your engine! I'd love to hear more.

Ignore manolis and his sermons.

[Rodak]

I'm with nz, manolis is on robotic autopilot (which still won't control his 'flyer'). Please post stuff and get us out of this rocket fallacy world......

And manolis, it's difficult enough to control a chopper in a rescue at sea with waves and wind, lowering rescue persons and recovering. And the helicopter actually has directional control; how on earth would your hovering plane control its position and lower a cable/person to effect rescue while having no control in x or y axes, all while being vertical? Oh, oh, I know, the pilot could stick out his arms and legs.....

[manolis]

Hello Uniflow.

You write:
"Manolis, you are not always right, but you don't listen, you got it so wrong about E85 for example"


Quote from page 195, April 13, 2020

• Hello Uniflow.
  
  You write:
  “I'll stick to my ''personal flyer'' gyro thanks. But next one will more than likely run ethanol, forget batteries, forget fossil fuels.”
  
  
  For Flying Devices ethanol and methanol fuels have a serious problem: they are “heavy”. Instead of taking the required for the combustion Oxygen from the air, they carry a part of the Oxygen inside their molecules.
  
  Their specific energy (energy content to weight ratio) is low relative to other fuels.
  Their specific energy (energy content to weight ratio) is low relative to other fuels.
  
  Gasoline specific energy: 47.3MJ/Kg
  Ethanol specific energy: 29.7MJ/Kg (i.e. for the same energy content, ethanol weighs 60% more than gasoline).
  Methanol specific energy: 22.7MJ/Kg (for the same energy content, methanol weighs more than two times than gasoline).
  
  For instance, if for a specific flight your autogyro needs 40Kg of gasoline, for the same flight you need 64Kg ethanol (i.e. your take off weight increases by 24Kg, i.e. more than two OPRE Tilting engines).
  
  For the same flight you need 83Kg methanol, i.e. you add 43Kg to the take off weight of your gyrocopter.
  
  Ethanol is good for cars / trucks / motorcycles, but too heavy for flying devices.
  
  Thanks
  Manolis Pattakos

End of quote.


The ethanol and methanol fuels are too heavy for flying devices not because I say so, but because they are. You should thank me for the above post.


One more useful piece of info:

If your new OP design is not yet revealed, and if it has innovations, do file a patent application before presenting it. Otherwise they will copy it as they did with your TPI.

Thanks
Manolis Pattakos

[uniflow]

You better tell this guy he can't be flying Manolis.

[Tommy Cookers]

as MP says ethanol (and methanol) are very poor regarding fuel weight (for aviation)

but higher alcohols eg butanol (used as the mandatory bio ingredient in recent F1) aren't
plus eg butanol also has outstanding energy per unit air

compared to gasoline ...
ethanol/methanol are c.5%/10% better IN ENERGY PER UNIT AIR - but 0% better IN ENERGY PER UNIT VAPOUR MIXTURE

because gasoline VAPOUR displaces c. 7% of engine air but ethanol/methanol VAPOUR displace 11%/15% of engine air
this if and to the extent that vaporisation occurs before combustion

importantly F1 DI prevents such premature fuel vaporisation (and current F1 isn't air-limited as NA F1 was)
those silly old carbs or low pressure injection used in the old days weren't at all silly
eg for this reason touring car race-legal high pressure Kugelfischer injection gave less power than SU carbs

again .....
butanol is quite competitive with gasoline (that's why F1 uses/used bio-butanol as its compulsory biofuel ingredient)

butanol energy per unit air is freakishly good - a 100% butanol-fuelled engine can be significantly smaller
RETRO-EDIT - ENERGY PER UNIT AIR ISN'T FREAKISHLY GOOD EXCEPT IN WIKI on BUTANOL FUEL

[uniflow]

So, Methanol 4 to 1 by weight
Ethanol 7 / 8 ish to 1 by weight
Ethanol can run at a higher efficiency than petrol (compression ratio, intetnal cooling) so Ethanol turns out to be an effective fuel. Granted not as good as petrol but not too shabby either.
My fuel injected Kawasaki air cooled twostroke will do a 45 Kilometer trail circuit on E85, about 57 on petrol, carburetor.