The place for technical discussions about GA and flying.
Forum rules: Technical discussions about GA only, please.
#1629417
There is no doubt that you can make a body fly and that for this the amount of power (thrust) is limited.

No idea what the L/D ratio of a body is but let's assume that with a flying suit is 1/3 that means that for a MAUW or 150kg you just need 500N thrust.

However for the take off and landing you need 1500N and a bit more to be able to steer and manoeuvre.

Those figures seem to be reasonable and resemble those from the EJ1 site you linked to.

Assume you do manage to transfer from vertical to the horizontal and the reduction of thust is the required 500N only then that would mean the EJ1 could fly for an additional 12 minutes (assuming take off/accelerating/decelerating/landing take a maximum of 2 minutes)

So the only thing you have to do is ensure that your engine propellor fuel combination produces 1500N of thrust, weighs less than 31kg and runs longer than 14 mins and you're sorted.
User avatar
By GrahamB
#1629428
Where does the parachute go, and how does it deploy with a bunch of blades, even static ones, in the way?

Even if you get that sorted, there is a 'death zone' up to a minimum of about 500' AGL where any parachute isn't going to be effective anyway.

There are just too many death-trap scenarios with this rig to make it attractive, even if it worked (which IMHO, it won't)
#1629430
GrahamB wrote:
There are just too many death-trap scenarios with this rig to make it attractive, even if it worked (which IMHO, it won't)


Go on Graham - be brave and live a little!

:wink:
By manolis
#1629441
Hello

You write:
“Where does the parachute go, and how does it deploy with a bunch of blades, even static ones, in the way?

Even if you get that sorted, there is a 'death zone' up to a minimum of about 500' AGL where any parachute isn't going to be effective anyway.”



Quote from the submission (at http://www.pattakon.com/GoFly/DTR_1.pdf ):

At the ends of the backbone they are secured two “vertical” pipes whereon the propellers are rotatably mounted.
At the upper end of each pipe, a spinner (inside which is provided space for a parachute) is secured.
The lower ends of the pipes are secured on a “saddle” tighten to the shoulders / torso / back / armpits / suit of the pilot. Through the pipes they pass the fuel, the control (gas cables, parachute trigger cables, signals from sensors, electric power if any, etc), the handling.”

End of Quote



Quote from http://www.pattakon.com/GoFly/Posts_to_GoFly_Forum.htm (wherein the posts to the GoFly / BOEING deleted Forum are saved):

You write:
“ if the operator is to use a chute - you would have to ensure the rotors dont hit the lines - which seems almost impossible to me”

For as long one at least (of the two) engine is running, there is no reason to open a parachute. Because each engine, alone, driving its two counter-rotating propellers is capable for safe landings. And because each propulsion unit (an engine with its two counter-rotating propellers) is fully independent from the other propulsion unit.

In case both engines fail or stall (say, run out of fuel), the parachutes in the immovable spinners above the propellers can be used for emergency landing.

Through the two holed pipes, the pilot “triggers” the opening of the parachute(s). Even if the propellers continue to spin, it is OK for the parachutes.

. . .

At full power take off, the upwards acceleration is above 1g (10m/sec2). This literally means that a guy wearing the PORTABLE FLYER “falls” towards the sky in a rhythm higher than a skydiver falls towards the ground.

End of quote.



According the last sentence,
with more than 1g (10m/sec2) upwards acceleration, the PORTABLE FLYER minimizes the time it remains in the dangerous zone (0-500’)

If case the engine malfunctions (or a propeller falls apart) you have the option to safely land with the other engine / propellers.

While the Osprey V22 crashes in case one of its rotors (or blades) is damaged at a vertical take off or landing, the PORTABLE FLYER has an independently driven second set of counter-rotating propellers to keep it flying.

Image

Compare the above OSPREY V22 with the following single-engine PORTABLE FLYER:

Image

the engine of which is here at its first run:



Besides, if you want to avoid this risk (the 0-500’ dangerous zone), you have always the option to fly just 2-3m over the ground or, better, over the sea water.

For instance imagine some friends wearing PORTABLE FLYERS and flying 3m (10ft) over the sea from Crete to Icaria (as Daedalus with his son Icarus did, according the myth).
It is a distance of about 300Km (185miles).
The wise Daedalus was flying at low height, safely.
The enthusiast but imbruted Icarus made the mistake to fly high and paid the price.



So:

The parachutes are stored in the spinners, above the rotating propellers.

The PORTABLE FLYER remains in the “dangerous zone” (0-500feet) the minimum time (lightweight and powerful).

Even a broken propeller is not a problem (while it causes the crash of the OSPREY V22 at a vertical take-off or landing).

And you have always the option to fly at low altitude.

Thanks
Manolis Pattakos
By Lerk
#1629589
Still no answer as to what the point of the thread is...
I’m going with sour grapes and given the fact that the gofly forum is still there, that our wishful thinking friend Manolis has been booted!
#1629680
Hello all.

The point of this thread is to warn the potential contestants in the GoFly / BOEING contest that things are neither transparent, not honest, nor according common sense and reasoning.

Also to inform BOEING heads that by being the big sponsor in the GoFly contest (actually the bait / the teaser on the hook) is destroying BOEING’s legacy and reputation as a big company.
In the deleted forum of GoFly, dozens of contestant threatened to sue BOEING for non-transparency.


Also to show to the Forum members some alternative solutions of the same problem.

For instance, while the electric / electronically controlled Personal Flying Devices seem as the future, the reality is quite different.


For instance, the intuitive control, used by birds, bats and bugs, is the best when a person is to fly.


IN PRACTICE:


Here is the JB11, the last JetPack of Mayman:



Quote from https://www.digitaltrends.com/cool-tech ... ion-jb-10/

“It’s like a Segway, Mayman explains.
If you want to go forward, you just lean forward.
If you want to stop, you just lean back.
It’s incredibly simple.
If you wanted to fly a helicopter, you’d need 150 hours of training — but with this, you can learn everything you need to know in about 3 hours.”

End of Quote

According Mayman’s experience on training “ordinary people” to fly with his JB10 JetPack,
some 3 hours of tethered tests / training is considered adequate before the initial low height free tests above water.
The pilot can fly at small height over the sea (or over a lake) for as long as it takes to get familiar and confident.
Only when the trained pilot feels ready, the pilot can take-off to the sky.

According Mayman, flying with his JB-10 is intuitive and easy: it is as easy and as intuitive as bicycling.


Here is Zapata’s FlyBoard-Air:



Zapata is not just flying, he is making acrobatics in the air.
And, as Mayman, similarly Zapata is based on the intuitive control.



Yves Rossy with his delta wing and his 4 jet-turbines goes a little further.
He uses his limbs and head for the control of his flight.
No electronics, at all.



Yves Rossy / Jetman "flies with the grace of an eagle, and the subtle body movements he uses to maintain flight - and perform his loops, rolls, and other maneuvers - mimics a bird of prey".

With only an altimeter and timer, Rossy uses his skin and ears as airspeed indicators.

"You feel very well, you feel the pressure," Rossy says, "you just have to wake up these senses. Inside an airplane we delegate that to instruments. So we are not awake with our body."

“I am the fuselage, and the steering controls are my hands, head and legs,” Rossy says.



Besides the “weight shifting CONTROL” (or “vectored thrust” control) of Zapata, of Mayman and of the GEN-H-4:



the PORTABLE FLYER has also the “aerodynamic CONTROL” of Yves Rossy.

In order to achieve “aerodynamic control” over his flight, Rossy needs to move at high speeds (say, above 100mph), otherwise his head and limbs cannot receive significant forces from the air.

In the PORTABLE FLYER the “Rossy like” aerodynamic control of the flight is applicable not only at high speeds, but at all speeds:
The heavy disk loading (thrust to disk area, similar to that of the OSPREY V22) causes a high downwash velocity, with the pilot inside it.
So, either at take off / landing, or at hovering, or at cruising, pilot’s limbs and head are in a high velocity air stream, which allows the aerodynamic control of Yves Rossi.

Thanks
Manolis Pattakos
#1630679
Do I understand that each of the 2 engines is capable of sustaining flight? So 1500N of thrust each?

One of my aircraft has a Rotax 582; fairly well known as a very high power to weight ratio power unit; it creates 164kg of thrust; and it weighs 57kg dry, built with a pull-start for weight saving reasons.

Your GIF of the engine design is interesting; and at 8kg it looks impressive; however that’s a single piston with no cylinder head or cooling systems (does it have a fuel system?). I struggle to see how you can achieve a reliable 65hp engine with a mass of the order of 15kg. If you can, I suggest that this vast improvement on anything ever achieved before should be the focus of your project; the aircraft is irrelevant!
cockney steve liked this
#1631005
Hello Big Dex

Thank you for your strictly technical questions.



You write:
“Do I understand that each of the 2 engines is capable of sustaining flight?”


Yes.



You also write:
“So 1500N of thrust each?”


No.

1,150N of thrust each.

Each engine, with the two propellers it drives, is capable for a thrust of 253lb / 115Kg / 1,150N allowing a safe emergency landing.

According the GoFly BOEING contest, the pilot weight should be 200lb (91Kg).
The dry weight of the device is 44lb (20Kg).
And for the Fly-Off test they are required, say, 5lb (2Kg) of fuel.
In total: 249lb (113Kg).
I.e. the thrust from the one engine is adequate for an emergency landing.

Closer to reality:
The average pilot weight is 165lb / 75Kg.
The PORTABLE FLYER dry weight is 44lb / 20Kg
The fuel weight (for a 300Km / 200 miles range) is 22lb / 10Kg.
Total take-off weight: 231lb / 105Kg.
I.e. the thrust from the one engine can give an upwards acceleration of ~1m/sec2



You also write:
“One of my aircraft has a Rotax 582; fairly well known as a very high power to weight ratio power unit; it creates 164kg of thrust; and it weighs 57kg dry, built with a pull-start for weight saving reasons. “

The thrust an engine creates depends on the propeller it drives and on the transmission ratio used (crankshaft to propeller).

Let’s focus on the 57Kg dry weight of your Rotax 582 (which makes 48kW / 64bhp peak power).

It is a 580cc 2-stroke 2-cylinder rotary-valve spark ignition gasoline engine.

Let’s compare it with the PatOP prototype engine (more at http://www.pattakon.com/pattakonPatOP.htm )

In the following GIF video they are shown the moving parts of the PatOP:

Image

Here the PatOP prototype engine is free on a desk and is running on Diesel Fuel:



The PatOP 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 engines, additional time for the injection and combustion of the fuel.

Bore: 79.5mm
Stroke: 64+64=128mm
Displacement: 636cc
Compression ratio: 17
Scavenging pump bore: 130mm (1.34 scavenging ratio; the capacity of the scavenge pump is 850cc).
Total engine height: 500mm
Total engine weight (without the flywheel): less than 20Kg (44lb)

The PatOP has one cylinder and two opposed pistons.

While the spark ignition Rotax 582 scavenges the cylinder with air-fuel-oil mixture, the PatOP scavenges its cylinder with air. The Diesel fuel is injected at the end of the compression with all ports closed.

With its substantially longer piston dwell at the combustion dead center (pulling rod architecture) the PatOP can burn its fuel efficiently at some 30% higher revs than the conventional Diesels.
The Peak power is expected at 6,000rpm (while the power of most Diesels peaks below 4,500 rpm.

The cooling fins of the PatOP are OK for its cooling.

So as compare to the Rotax 582, the PatOP weighs some three times less.

But it is more than just power to weight ratio:

The PatOP has some 10% bigger capacity,
it runs on compression ignition,
it runs on higher compression ratio (17:1),
it achieves fast combustion (most of the fuel is burnt while the pistons are still near their TDC),
it scavenges the cylinder by clean air (no unburned fuel in the exhaust),
it’s inertia forces and moments are perfectly balanced,
etc, etc.


It is a prototype engine.
If you want to make your own PatOP to test it, I can e-mail you the CAD drawing.



You also write:
“Your GIF of the engine design is interesting; and at 8kg it looks impressive; however that’s a single piston with no cylinder head or cooling systems (does it have a fuel system?).”


The OPRE Tilting has two opposed pistons and a cylinder.
It is air cooled (the cooling fins on the cylinder are inside the downwash stream of the propellers).

The fuel system in the prototype of the following videos is a carburettor (as in the Rotax 582).
The PatBam version is to work on lean burn HCCI (throttle-less) and port injection that further simplifies the induction system.

Here is the OPRE Tilting prototype running at low revs:



here is the OPRE Tilting running at medium revs:



and here is the disassembly of the OPRE Tilting prototype:



and here is a photo wherein a guy “wears” an OPRE Tilting single-engine PORTABLE FLYER to show the arrangement and the size of it:

Image

The above prototype engine capacity is 333cc.



You also write:
“I struggle to see how you can achieve a reliable 65hp engine with a mass of the order of 15kg.”


No.

The 65hp is from each engine (not the toal).

The short piston stroke allows high revs.
The lightweight / cheap transmission (with sprockets and timing belt as in the final transmission of several motorcycles) enables the optimization of the revs of the engines and of the revs of the propellers.

For instance, with the OPRE Tilting running at 9,000rpm, the mean piston speed is only 9m/sec; and with 2.4:1 reduction ratio from crankshaft to propellers, the 39’’ propellers spin at 3,750rpm (tip speed: 195m/sec, 57% of sound velocity).

The 9m/sec mean piston speed is a slow reliable piston speed.

In comparison, the Rotax 582 (with 64mm piston stroke) makes 48kW at 6,500 rpm, wherein the mean piston speed is 14m/sec, which is a high speed for continuous reliable operation.
If the OPRE Tilting was to operate at the same mean piston speed, it would run at 14,000rpm.



You also write:
“If you can, I suggest that this vast improvement on anything ever achieved before should be the focus of your project; the aircraft is irrelevant!”


You are right.

However, the best way to prove the engine advantages is to make it fly as in the PORTABLE FLYER.
And BOEING was supposed to give the opportunity to show it.
That’s why I gave them my 250USD and now I regret I was caught a sucker.

Thanks
Manolis Pattakos