Yet the capabilities of Manolis' flier concept are closer to the V-22 than Martin, Rossy or Malloy.
Asymmetric Timing in the Two-Stroke engines
Posted 04 July 2015 - 04:47
“First, the power/GTOW figure you claim for your vehicle (70hp/220lb) is unrealistic. It is probably something like 100hp/320lb just to hover in ground effect at SLS conditions, which is far less than the V-22's GWVTO capability at 6K95 conditions.”
For a Flyer, the number one enemy is the gravity, the weight.
If the gravity was reduced ten times, we could fly by moving some kind of wings with our hands / legs.
A big eagle (say 8 feet / 2.5m wingspan) can fly towards its nest weighing 10Kp / 22lb with its prey.
70hp/220lb may seem unrealistic for a Portable Flyer, however it is attainable.
For the PatATi Portable Flyer:
Pilot / rider weight: 70Kp (154lb)
800cc Opposed Piston PatATi engine directly driving a pair of counter-rotating propellers and secured by a casing on pilot’s shoulders / torso: 20Kp (44lb)
Fuel: 10Kp (22lb) / 12lt
Total weight: 100Kp (220lb).
Power output: 70hp at 5,000rpm (which means a torque of only 100mN and a MEP (mean effective pressure) less than 8bar, which in turn means an engine running away from its limit: 100hp at 5,000rpm from the same engine is within reach).
With 20Kp (44lb) secured on your shoulders / torso you can seat on the ground, you can stand-up by yourself, you can walk, you can run, you can even jump safely from, say, a meter height to the ground. The fuel tank is secured on your waist or lower.
With 30Kp (66lb) secured on your shoulders / torso things start getting hard / difficult.
With 40Kp (88lb) secured on your shoulders / torso things get uncontrollable, risky and unsafe.
Yves Rossy (Jetman) bears on his shoulders 55Kp (121lb): his wing with the four Jet engines and the fuel required for just ten minutes of flight.
Martin’s Jetpack weighs 200Kp (440lb) without the pilot.
Malloy’s hoverbike is about 100Kp (220lb) heavy, without the rider.
GoFast Peroxide Jetpack is more than 50Kp (110lb) for a 20 second flight.
The weight of a Personal Flyer is vital and has to be limited to the absolutely necessary.
The small weight of the power unit of a Personal Flyer is necessary but not sufficient.
With an unbalanced engine secured directly on your body, you cannot help shaking in the rhythm of the piston(s).
Even with a "perfectly" balanced (vibration free) engine like the Wankel rotary, the power pulses turn to torsional vibrations because the engine has to be supported somewhere (on pilot’s body) in order to provide power pulses to the propeller(s).
It is also the gyroscopic rigidity. If it takes minutes to turn the thrust to the desirable direction, forget it: the Flyer gets unsafe and uncontrollable.
The PatATi Opposed Piston engine with the two counter-rotating propellers achieves all these requirements:
Besides being extremely lightweight for its power, it also leaves its basis (i.e. the body of the pilot/rider) rid of inertia and combustion vibrations; and it has zero overall gyroscopic rigidity, as explained at http://www.pattakon....pattakonFly.htm
It is "a true neutral propulsion unit": neither vibrations, nor reaction torque, nor gyroscopic rigidity; only a force that can "instantly" and effortlessly be vectored towards the desirable direction.
As for the control,
Yves Rossy (Jetman) proves in practice how effective and amusing and intuitive is the use of pilot’s body as the fuselage, with his legs, hands and head being the only aerodynamic "controls".
With 1m diameter propellers and 100Kp (220lb) total (including the rider and the fuel) take-off weight, the propeller "disk loading" is only half of the propeller "disk loading" of the Osprey (Bell Boeing V22).
As the Osprey, the Portable Flyer is capable for "vertical take-off / landing (like a helicopter) and for long distance flights at high speed and low fuel consumption (like an airplane).
The "flexible" / "variable" fuselage of the Portable Flyer and the absence of any kind of automation / servomotors / ECUs / controllers etc makes it superior as compared to Osprey V-22:
You also write:
“Second, the V-22 operates primarily in airplane mode with lift provided by the wings. So autorotation capability is not a major requirement. The V-22 can transition from helo mode to airplane mode in just a few seconds, and it can sustain flight in airplane mode with just one engine operating. It can also perform a STOL landing if required.
I don't think your PatFlyer has any similar capabilities.”
And why the Portable flyer cannot turn, in just a few seconds, from helo mode (left) to airplane mode (right)?
As described in a previous post, please read and comment, a few seconds after the vertical take-off the PatATi Portable Flyer can turn progressively to horizontal flight (just like the Osprey V22) gathering horizontal speed (just like the Osprey V22); when it gets the required speed (say 160Km/h, 100mph) it flies horizontally as an airplane (as Rossy does with his Jetpack).
A wingsuit increases the aerodynamic lift controllably: at lower speeds, say below 200Km/h (126mph), the rider extends his legs / hands, at higher speeds (say 320Km/h, 200mph) he retracts hands/legs and uses only his body surface to get aerodynamic lift. It is a better approach than Rossy’s (fixed wing), providing substantially higher top speed and optimization on-the-fly.
In a previous post they were mentioned several ways to sustain flight (or land safely) after an engine failure.
Posted 05 July 2015 - 10:42
Though I have substantial air hours in both powered and un-powered flying machines including considerable theoretical and practical training and study in flying things I have deliberately stayed away from This discussion. I haven't wanted to discourage anybody and believe that if people stay at something long enough they can succeed. I believe that so far the paths being chased are a fair way from one that will suceed.
To help to perhaps help Manolis gain in-sights as to finding and proving a concept that can work I refer people to:
The proto-typing work, control problems, safety requirements and power needs/prop area are buried in these sites.
Regards and good luck
Posted 06 July 2015 - 06:43
Thanks for mentioning the e-volo helicopter / volocopter:
Quote from http://www.e-volo.com :
VC200 – the first Volocopter to carry two people
As the federal ministry of economics and technology granted 2 million € as a
subsidy of the project-related costs, e-volo is working together with a research
and industry syndicate to build the VC200, the first Volocopter in the world to
carry two people.
Desired aircraft performance
cruising speed of at least 54 kn (100 km/h)
flight altitude of up to 6500 ft
maximum take-off weight of 450 kg
more than one hour flight time
two persons side-by-side
How Long Can The Volocopter Fly?
Currently, the limiting factor is the energy capacity of available batteries. However, a considerable advancement in battery technology is conceivable during the next few years, so that a multiplication of the energy capacity will occur within a short period of time. At present a battery flight time of 20 minutes is possible, but in the near future this will be extended to one hour or more.
To enable a flight time of several hours right from the start, our two-seater Volocopter is being developed as a serial hybrid electrical aircraft with a range extender.
A range extender is an additional aggregate in an electrical vehicle which extends the range of the vehicle considerably. The most commonly used range extenders are combustion motors which power a generator that supplies the batteries and electrical engines with electricity. Range extenders run at a constant rotation speed with optimal efficiency.
End of quote
Is a range extender module (or REM) like:
a viable solution for a considerable increase of the range of a volovopter or Flyer?
How the above REM would work in a volocopter?
You have a gasoline fuel tank feeding the Wankel engine.
The mechanical power provided on the power shaft of the rotary engine is transformed, by the electric generator (which, reasonably, is heavier than the Wankel engine itself) into electrical power that either feeds the electric motors (which are, reasonably, heavier than the Wankel engine itself) that drive the propellers of the volo, or it is stored into the batteries (which have a considerable weight, too) of the volo for “later use”.
An electric car at urban cycle needs bursts of power from time to time (which means that a small / lightweight REM (say 10kW maximum power) can be used to charge the batteries that feed a, say, 100kW electric motor).
In order to fly, a volocopter needs constantly a significant amount of power (say 200bhp, i.e. as much as the lightweight Martin Jetpack).
That is, instead of driving the propellers directly (without a transmission) with the mechanical power provided by the internal combustion engine (as happens in the PatATi portable Flyer),
volocopter adds electric generators, batteries and electric motors, weighing a few times more than the engine itself.
Not to mention the considerable power-loss during the various energy transformations from the engine to the propellers, the added cost, the added reliability issues.
The increase of the weight of a Flying Machine is a vicious circle: more weight requires more power to keep it on the air, which requires more fuel for a specific range, which increases the overall weight, which requires a more powerful engine, which increases the overall weight and so on.
By the way, if e-volo is looking for a good REM, why a Wankel REM (like those of AVL and FEV) and not a smoother, lightweight and way more fuel-efficient direct injection Diesel OPRE-REM?
The volocopter design, just like the Martin Jetpack and the Malloy hoverbike, is oriented around hovering (helo) mode and not around horizontal flight at high speed (airplane mode).
The low cruise speed (100Km/h) gives a very small range (the 20minutes maximum flight duration on batteries means a range of only 20miles / 32Km).
Is there any advantage of the volocopter as compared with a conventional small helicopter? Like the R-22, for instance.
It is also the controllability of the volocopter and its stability at strong wind gusts (big area for its weight).
Nothing to do with the controllability of Rossy’s (Jetman) Jetpack.
As an eagle, similarly Rossy is not vulnerable to strong wind gusts.
Please do see the youtube videos of Rossy with his partner flying above Dubai in a "dog fight" formation.
The high cruise speed of Rossy’s Jetpack enables a longer range (55Km) than e-volo.
Rossy with his Jetpack already flies as a bird, with his body being the fuselage and with his hands, legs and head being the only aerodynamic controls.
The PatATi Portable Flyer
is an effort to improve the advantages of the best Flyer so far (Rossy’s Jetpack) avoiding its disadvantages and limitations.
Edited by manolis, 06 July 2015 - 07:07.
Posted 10 July 2015 - 23:00
What happens if the pilot stumbles on landing (seems awfully likely to happen in real life), and quite naturally as a result a rotor tip hits the ground or another object nearby?
Posted 11 July 2015 - 08:49
I know it is a bit late to raise this, but shouldn't all this be in a separate thread? This is not the first thread hijack featuring Manolis' concepts, and I don't wish to deny him a platform for his ideas, but why not a relevant thread?
Posted 11 July 2015 - 16:02
“What happens if the pilot stumbles on landing (seems awfully likely to happen in real life), and quite naturally as a result a rotor tip hits the ground or another object nearby?”
https://youtu.be/VYeLishJ_Js (youtube video)
is what happened when the rotor tips of an Osprey V22:
hit the ground.
The pilot of the Osprey V22 must, no matter what it takes, keep the propellers away from the ground at take-off and landing.
Similarly the pilot / rider of the PatATi Portable Flyer must land smoothly and controllably onto his feet.
Alternatively the casing:
of the PatATi Portable Flyer prototype can be modified as in following GIF animation:
resulting in a Portable Flyer that can take-of and land as a conventional airplane (keeping, at the same time the ability for hovering and for vertical take-off / land).
The weight handicap is small.
The front wheels can be retractable to reduce aerodynamic resistance at high speeds.
At vertical take-off and landing the back end of the casing abuts on the ground taking most of the weight of the flyer from the torso / waist / legs of the rider.
For airplane-like take-off, the pilot/rider wears a wingsuit. At, say, 100mph (160Km/h) the aerodynamic lift is more than the total weight and the PatATi Portable Flyer takes-off. The total thrust from the propellers can be substantially smaller than the overall weight.
Similarly for the landing at airplane-mode.
The above casing (GIF animation) fits with Rossy’s fixed-wing Jetpack (provided a good engine would replace the four gas-guzzlers / Jets).
Posted 13 July 2015 - 02:03
Of course the more obvious solution is a propeller protector - even lighter.
Posted 14 July 2015 - 21:54
Manolis back in post #108 states,"Similarly the pilot / rider of the PatATi Portable Flyer must land smoothly and controllably onto his feet."
In the real world I have over 200 paraglider flights in which the objective is to land smoothly and controllably on ones feet. I also have flown with both powered and un-powered paragliders. The other plots have been some of the nation's most accomlished pilots.
Unfortunately we fly in the real world in which winds are constatly changing, landing terrain is not always smooth and where land temperature gradients always are releasing thermal updrafts of varyting internsity.
I have yet to see even the most accomplished acheive 100% compliance with totallly smooth and controllable and onto feet.
By the same token, even the most accomplished general and commercial aviation piolot with tens of thousnads of hours of flight will tell you the factors affecting smooth landings lead to occasional upsets of one degree or the other.
It is a fact that the lighter to flying vehicle and the lesser the surplus power the more frequent the landing problem. The lesser the power and aerodynamic lift the more hazardous the take off due to the same changing conditions. Take offf accidents are nearly as frequent as landing incidents for some types of craft.
This whole thing is stretching further and further away from reality. The sooner some reral life prototyping takes place the sooner some realities will become clear at which time the flying concept will either quickly die or the roads to success will become clear. Five minutes with feet off the ground is better than hundreds of hours of pictures, animations and calculations!!!
Posted 14 July 2015 - 22:41
Five minutes with feet off the ground is better than hundreds of hours of pictures, animations and calculations!!!
True - but much riskier.
Sometimes it is better to spend another 1,000 hours doing animations and calculations and perhaps reduce the risk of the first flight.
Posted 15 July 2015 - 00:54
Um, yes, that is the entire point of doing calculations. Suck it and see gave us some great gothic cathedrals, and an awful lot of ruins. However some unmanned or heavily tethered rig tests would be instructive.
Posted 15 July 2015 - 06:16
Calculations are great if they are based on sound theory and practice.
A basic tenet of contolled flight is that the centers of propulsion force and aero dynamic forces are closely aligned to the ceter of gravity. Race car design going back to thirties kept faith with this. In the fifties Frank Costin firmly married flying and race car design to coomon understandings. The contraptions being portrayed herein ignore all of this.
Whether you are flying big or small craft one of the first things you do is to load them such that your force centers are close. Then the second thing you do is to use trim tabs and the like to make fine adjustments. Hmmm, sounds like race car design and tuning.
USAF flight theory is taught before flying as is the working towards any flight licensing. Even the Wright brothers did extensive modeling to formulate their calculations leading them to getting their feet off the ground.
As this really is a motoring based forum we probably should be discussing this stuff in a more suitable forum but I will close by saying that you better have some basic aero stability and safety built in lest fool kills themselves trying to make the impossible possible.
Posted 15 July 2015 - 22:59
Paricularly this type of machine which is not "inherently" stable in any of the hover modes - needing constant feedback from the pilot just to maintain a given attitude.
Posted 16 July 2015 - 11:34
“A basic tenet of contolled flight is that the centers of propulsion force and aero dynamic forces are closely aligned to the ceter of gravity.”
Did you see the videos of Rossy / Jetman flying and making aerobatics?
Is his flight machine a perfectly controlled one?
Is he using as fuselage his body and as aerodynamic controls his head, hands and legs and nothing else?
See him flying above Dumbai with his partner. If the control had flaws, they could not follow each other as they do.
Are the center of gravity, the propulsion force and the aerodynamic force closely aligned?
I suppose not so much.
With the 25kg of fuel in the fixed wing secured on his back at the beginning of the flight, and without these 25 Kg of fuel (it is consumed in the 4 jet engines) after 10 minutes of flight, Rossy never complained for the displacement of the center of gravity; he just adjusts his body / head / hands and legs and continuous his controllable flight.
You also write:
“This whole thing is stretching further and further away from reality. The sooner some reral life prototyping takes place the sooner some realities will become clear at which time the flying concept will either quickly die or the roads to success will become clear. Five minutes with feet off the ground is better than hundreds of hours of pictures, animations and calculations!!!”
A good prototype takes a lot of money and time to finish. Both.
In the meantime, the theoretical analysis of the project and its comparison with the closest prior art seems useful.
Start with Rossy’s Jetpack (the most successful personal flyer today).
Replace the 4 Jets of Rossy by a PatATi Opposed Piston engine driving two counter-rotating intermeshed propellers.
Quote from http://www.pattakon....pattakonFly.htm “
“With the symmetric counter-rotating propellers (and crankshafts), the total "gyroscopic rigidity" is zero, i.e. the rider can "instantly" (as instantly as with the propellers stopped) vector the thrust to the desirable direction (…).
The above make "a true neutral propulsion unit": neither vibrations, nor reaction torque, nor gyroscopic rigidity; only a force that can "instantly" and effortlessly be vectored towards the desirable direction.”
End of Quote
Is there any drawback / control issue caused by the above replacement?
If not, the control over the flight, high in the sky, will be as good as Rossy’s.
Then replace Rossy’s fixed wing with a wingsuit.
Quote from wikipedia:
“On 25 October 2005, in Lahti, Finland, Visa Parviainen jumped from a hot air balloon in a wingsuit with two small turbojet engines attached to his feet. The engines provided approximately 160 N (16 kgf, 35 lbf) of thrust each and ran on (JET A-1) fuel. Parviainen achieved approximately 30 seconds of horizontal flight with no noticeable loss of altitude. Parviainen continued jumping from hot air balloons and helicopters, including one for the Stunt Junkies program on Discovery Channel.
End of Quote
This is the PatATi Portable Flyer.
More lightweight than Rossy’s Jetpack, it requires several times fewer fuel for the same range.
And what about its vertical take-off and landing?
The PatATi Portable Flyer seems as a scaled-down version of the Osprey V22.
Is it more, or less, stable than an Osprey V22 near the ground?
In the Osprey the centers of the two counter-rotating rotors are at a long distance relative to their diameter (about 120%), while in the PatATi Portable Flyer the centers of the two intermeshed counter-rotating rotors are at a small distance relative to their diameter (only 54%). A small variation of the thrust force provided by the one rotor of the Osprey (because, say, it is in the wake / downstream coming from another Osprey, or because the shape of the ground under the one rotor is substantially different than the shape of the ground under the other rotor) creates a big instability about the fuselage axis. An over-correction, as in the video, may be catastrophic.
The long and heavy fuselage of the Osprey V22 has a significant moment of inertia, with its center of gravity being below, but not far from the axis between the rotor centers. An oscillation of the fuselage about this axis is an issue and needs pitch control.
The engines of the Osprey are disposed quite close to the ground. A small inclination of the ground or of the Osprey may give big troubles (as in the video).
The landing wheels of the Osprey cannot compare with the legs of the pilot of a PatATi Portable Flyer.
The Osprey is the state-of-the-art in its class and is regarded as safe.
Excluding an engine stall, what makes the PatATi Portable Flyer less safe than the Osprey during a vertical take-off or a vertical landing?
Posted 17 July 2015 - 03:56
"Excluding an engine stall, what makes the PatATi Portable Flyer less safe than the Osprey during a vertical take-off or a vertical landing?"
That's a fairly significant consideration. If the PatATI Portable Flyer, with its single engine, no wings, and no autorotation capability were to experience an engine failure while hovering just 40ft AGL, the likely result would be fatal for the pilot. The crew seats and landing gear of the V-22 are designed for a 20 ft/sec descent rate. The V-22 rotors also have both collective and cyclic control,
Posted 17 July 2015 - 14:22
“That's a fairly significant consideration. If the PatATI Portable Flyer, with its single engine, no wings, and no autorotation capability were to experience an engine failure while hovering just 40ft AGL, the likely result would be fatal for the pilot.”
In the posts 94, 102 and 108 they are given several solutions.
you can take-off vertically with the PatATi Portable Flyer (preferably wearing a wingsuit) till, say, a height of 5ft / 1.5m above the ground and then you turn progressively to horizontal flight gathering speed (see the youtube video:
how nice the peroxide jetpacks accelerate horizontally in the 20 seconds of their flight duration).
When the horizontal speed gets adequately high (say 100mph / 160Km/h) hands and legs are extended increasing the aerodynamic lift.
If you fall, it is no more dangerous than falling with a motorcycle.
As you gain height having high horizontal speed, an engine stall is no more dangerous than an engine stall of the engine of a small airplane. By exploiting your speed (as the wingsuiters do) you approach horizontally the ground and land.
Similarly for the vertical landing: you can approach horizontally at high speed the ground and then loose progressively horizontal speed at a, say, 10ft / 3m height. At the end you land vertically from just 10ft / 3m height.
The previous are safer if you fly above the sea.
Imagine, for instance, flying from Aegean island to Aegean island just 10ft / 3m above the sea; like a hydroplane flying at very low height.
Even better, imagine a few PatATi Portable Flyers flying as a group 10ft / 3m above the sea, enjoying the flight and keeping an eye on the rest of the group. If something happens to someone, the others are there to help.
Compare the freedom and usefulness of the PatATi Portable Flyer flying just above the sea with the, now in fashion, “Water Jetpack”.
The one is a useful tool / vehicle (and a toy at the same time), the other is just a toy.
Edited by manolis, 17 July 2015 - 15:02.