LOVE the exercise ball landing gear! That\'s awesome - find the simplest solution and run with it!
That thing is great - SO want!
1st November, 2011 @ 12:33 p.m. (California Time)
Looks like one of those murderous contraptions from \"Saw.\"
1st November, 2011 @ 5:06 p.m. (California Time)
That seems like a fun way to enjoy a lazy sunday afternoon...as long as one does not go to heavy on the roast!
1st November, 2011 @ 6:10 p.m. (California Time)
I think this is brilliant - but I can\'t help thinking that taking a few feet of metal pole up the arse - as a way to die in a hard landing - would make that my first choice in aerial transport.
1st November, 2011 @ 8:14 p.m. (California Time)
Congrats with the great new toy...
Murderous maybe (Im sure that they will put the rotor axis up \'out-of-the-way\' for a retail version), but, who ever said that RC flying has no relevance to the real world...
This is part of the future...
Blurring of the lines between Radio control and piloted..
Also a blurring of Autopilot and Manual control..... With stability controlled at all times by the computer. (much better than the dumb ass at the stick...
Imaging using similar as a skydiving launch vehicle, fly it up, jump out, and have it return to base... great fun.... (just have to avoid the sharp blades in this model)
(Note all mechanicals and electricals here appear to be exactly the same as used in Electric RC planes....outrunner brushless motors, composite props, SS gyros etc.)
1st November, 2011 @ 8:36 p.m. (California Time)
Funny, only a few days ago I was wondering what would happen is someone created a manned quadracopters and now I see the manned multicopter!
It currently looks like those wacky experimental flying machine from photos at the first years of the 20th century - but hey - it flew!
Congrats Mr. Senkel and team e-volo!
1st November, 2011 @ 9:16 p.m. (California Time)
Best not fall out of the seat in this one...
1st November, 2011 @ 9:42 p.m. (California Time)
Why not carry the rider under the propellers and carriage? The arms could be shorter, and the rider would not be near the blades. It should improve wind drag figures when the craft is moving forward.
2nd November, 2011 @ 12:35 a.m. (California Time)
That thing looks like it\'s a ground effect machine - I suspect it hasn\'t solved the issue of what happens when the ground stops offering it resistance via \'reflected\' air - that probably means that it wouldn\'t work with the passenger suspended.
And with those figures, I guess we\'re all still waiting for 1000x lectric storage improvements (Watts per kg, cubic inch and $) - could take some time.
A lot of fun though.
2nd November, 2011 @ 6 a.m. (California Time)
Looks like an early 1958 Curtiss Wright VZ-7 flying platform, from which it shares the same design flaws, that is being unable to autorotate in case of TOTAL power failure (all propellers are fix pitch).
Motor redundancy does not cover all failure scenarios (eg: lightning strike), and is not necessarily a practical solution. As it stands, this concept cannot be certified as per FAR part 27. Helicopter is not dead yet
2nd November, 2011 @ 7:19 a.m. (California Time)
The Sikorsky \"Firefly\" was first manned helicopter and based on a tried and true human pilotable airframe. This is a gimmic.
2nd November, 2011 @ 9:12 a.m. (California Time)
I couldn\'t help thinking about that old short film,
\"The Red Balloon\".
It has to do with the film\'s ending,
where he flies off with all those balloons...
2nd November, 2011 @ 11:12 a.m. (California Time)
Sikorky has not flown their Firefly yet, Joshua.
World's first electric manned helicopter flight was completed 2 months ago, by a French team lead by Pascal Chretien with a coaxial helicopter; then came the Multicopter from the German team, lead by Stephan Wolf. Sikorsky might come next. God knows.
Amazingly enough, both French and German have achieved great results at a fraction of the cost of what is being spent by a major player like Sikosky. Congratulations to those winning teams !
The good thing about the Multicopter is that they distribute the batteries in small packs. It is not ideal for maneuverability, as it increases the polar moment of inertia, but it is safer than the French machine that has all the batteries located under the pilot's seat. Although if one pack burns, on the Multicopter, it stands good chances to compromise the airframe's integrity and/or burn the control cables connecting the next lot of motors, down the line.
The posting on autorotation is true: the Multicopter will not autorotate in case of complete power loss, and having a multitude of motors onboard for sake of redundancy is not going to help you in the case of an electric fire. This architecture is perfect for UAV, but is an inherently dangerous concept for manned operations, as opposed to helicopter. One could also argue on the fact that many small propellers will never achieve the efficiency of one larger rotor, and airframe\'s weight quickly becomes a major obstacle once the craft is scaled up if you want to avoid aeroelasticity, but does are minor concerns compared to the safety flaw.
From what we understood, the French team removed the swashplates only to gain weight for the record, but those can be installed on their craft, and then they can reverse to a conventional machine, that will autorotate just like any helicopter does.
Rotary wings are moving forward, after almost 20 years of next to zero innovation.
Looking up; Way up !
2nd November, 2011 @ 2:13 p.m. (California Time)
Most of the parts in the photo are either available at my hardware store or via Hobbyking. Guess what I am doing this weekend.....
2nd November, 2011 @ 2:30 p.m. (California Time)
I\'m not sure but I think enclosing the propellers in vertical cylinders (ducts) would make this concept more efficient. If you look at the Martin Jetpack, that\'s how they got sufficient lift.
2nd November, 2011 @ 3:05 p.m. (California Time)
Chanoch, you\'re in for a surprise. Looking at those liPo packs stuck to each wing I can\'t see more that about $2000 in batteries there. All up there\'s less than $10k that I can see. And thats without a second hand parts grab.
2nd November, 2011 @ 3:14 p.m. (California Time)
I know lots of cash, effort and time went into this project...so I say welldone! Hope to see an improved model soon. Congrats!
2nd November, 2011 @ 3:29 p.m. (California Time)
To increase efficiency you wouldn\'t need speed controllers on all 12 motors. One motor on each boom could all be controlled with a simple on/off switch. This simple change would increase over all efficiency by about 2-3% and would also reduce the cost of the quadcopter.
2nd November, 2011 @ 3:51 p.m. (California Time)
Mike, the \'speed controllers\' are actually current-controllers on most electric motor applications... but e-bikes have issue of needing current-limiting when first accelerating... and maybe with air providing low near-constant resistance, one could try just on/off switching. But it would certainly make it harder to do the computer control for gentle landings, and gental banking etc. Componentry for current-control should not weigh much more than relays for on-off.
Interesting question as to whether cowlings around blades might improve efficiency.. given low speed over ground is all that is required.
There is much inherent stability offered by multiple spaced half-opposite-spin propellers, compared to just one.
Improvements could be done to \'fully separate\' wiring of major systems, so that batteries were separate, current-controllers were separate, minimal gyro/mercury-switch were separate, and two wireless receivers. That way four motors on four quadrants could allow a slow descent if everything failed. And \'big red button\' right in front of pilot (on-frame) could put just those four rotors onto FULL (bypass all control logic) to allow controlled descent, and they stop only when big red button is pulled back out.
They\'ve used wireless R/C to control, as so many unmanned flights. But they should consider some basic switches in front of pilot to do 1-2 different rates of controlled descent, or \'hover in place\' (while wireless issue resolved) as it is one thing losing wireless with an UAV, and quite another with a human on-board.
Vertical rod under pilot could be changed to 300mm (foot-plus) diameter lightweight spring, to avoid rod-up-ass scenario one poster mentioned. Or just use solid aluminium rods splayed out from above ball, and then join at 600mm diameter circle and other rods come back from there in to meet under pilot, so in crash it all acts like an automotive steering column one-time deformation system... or use hinges and a few MTB shocks to allow multiple hard landings without any gear failure.
I know computer control can achieve stability with existing pilot-above rotors design, but I\'d have thought that inherently more stable design would be to have the \'flexible landing legs a bit longer, and to have cross-beams above pilots head, so any broken blade is above pilot, and deadweight hangs below lifting rotors. Then just having 4-6 rotors on full power will result in more assured stability on emergency descent (coming down like a parachutist, not an out-of-control plane). Having pilot beneath rotors also allows \'parachute-evacuation\' from higher test flights.
And I love the exercise ball application. Not only light and neat, but using a silver one looks like the thing is carrying a nuclear payload!
Another useful tweak would be to clip some small fairings to leading and trailing edges of the square aluminium support beams only where they cross the rotor flow just beneath the rotor blades.
This is the future - small IS beautiful. We should be able to buy kit multi-copters, where the redundancy is built-in, and the componentry is cheap/available. Currently helicopter costs $100+ per hour.. so even emergency services only call one in when absolutely needed. With this technology, every remote rescue base could have one, every forestry station monitoring for fires etc. And all of the Australian outback farmers (not just the richest ones) could do their large acreage mustering using a helicopter! [Yes, I know we need further battery break-throughs.]
Good practical design work.
2nd November, 2011 @ 6:43 p.m. (California Time)
Small is definitively NOT beautiful.
1- Due to their small size, all props are continuously working out of ground effect, which requires 7 to 10 % more power than a conventional helicopter.
2- Basic calculations show that for a given thrust, many small props, are never as efficient as one single large rotor. If you account for Reynolds number, boundary layer centrifugation, and cumulated tip losses, then system propulsive efficiency appears like it is: ugly. Why did they fly only 1.5 minute instead of 15 or 20 minutes? Just because they can\'t. The claim/goal violates basic laws of physics.
Overall, Multicopter type solution is an INEFFICIENT and inherently UNSAFE concept, that we abandoned in the 60\'s. It is only coming back today due to the \"miraculous\" ease of integration of electric motors, that allows to violate basic laws of aerodynamics, but the safety issue will remain unsolved.
2nd November, 2011 @ 11:24 p.m. (California Time)
How does one violate the laws of aerodynamics? Considering they are part of the laws of physics, you know.
3rd November, 2011 @ 6:17 a.m. (California Time)
3rd November, 2011 @ 11:41 a.m. (California Time)
Though I realise the technology is different, can someone please take a quick look at the moller sky car and the other tech from the company, where they had something that to most of us, though not all, looks pretty much the same but 40 years ago, which is a toy compared to their current models which outperform practical modern aircraft.
I realise this is still a good step and advancement in a parrallel tech, but still, 40 years?
3rd November, 2011 @ 4:34 p.m. (California Time)
UNBELIEVABLE! HOW?...HOW is it possible that this concept has not been proven decades ago?? Obviously there is a plethora of experts with endless solutions, complete with imaginary equations and imaginary exact dimensions of parts that can make this work.
Clearly, it\'s only the dummies that actually put these things together and begin these innovations. If only the 1000\'s of joy-stick-jockies, with all the solutions locked jealously in their genius minds, would just come the their aid! I am shocked at all the brilliant minds that AREN\'T working at NASA. No doubt we would be the one\'s making first contact on other worlds.
What about all the other super-geniuses who post comment under all the other emerging and unproven technologies? They seem to know exactly how to criticize other peoples hard work and innovations as well. I am confident that if as many as say...two of you got together...this concept will be hauling passengers to the stratosphere by early next week. at the latest. :^D
3rd November, 2011 @ 8:29 p.m. (California Time)
45 years ago, NACA (they were not called NASA yet), the Brits, the French and other countries thoroughly investigated multi rotor flying platform as it was perceived as being a practical solution for the army. A wealth of excellent technical reports is available on NASA AMES server.
After years of prototype testing, all reports converged to the very same points:
Multiple rotors are never as efficient as one single rotor, hence power requirement is higher.
The props continuously work out of ground effect. Consequently, a \"multicopter\" requires 7 to 10 % more power in hover than a conventional helicopter.
Unable to autorotate: Even if variable pitch props and freewheeling systems are used, there is still a major issue: not enough rotor inertia, and not enough physical space to integrate tip weights. As such it precludes FAR 27 certification. Not sure if the Germans have considered this issue, when they claim that \"helicopter is obsolete\".
They use ducted fans, which offers up to 20% improvement in propulsive efficiency. Yet they have spend almost 30 years on this concept, wrecked Millions of Dollars, and are still toying with prototypes. Meanwhile, Robinson has produced thousands of machines. Carrying two PAX on a Robinson only takes a fraction of the fuel used by a Sky Car.
There is room for improvement on the German machine, both on a structural and aerodynamic point of view. As a consequence, they may get slightly longer flying time, but with today\'s best batteries offering only 170 Wh/Kg, they definitively don\'t have the best mean of exploiting such limited power.
It is a great human achievement, though.
4th November, 2011 @ 12:11 a.m. (California Time)
OK, so this is all fine and dandy-- If it can mow my yard at the same time, I would be very interested.
Keep up the good work.
4th November, 2011 @ 6:11 p.m. (California Time)
As Rollerking mentioned, multiple rotors will never autorotate, and never be as efficient as a conventional helicopter. But multicopters are a great way for lifting weight a short distance, and fairly fail-safe.
Not that it ever will be registered as an aircraft, nor allowed to fly higher than it did in the video, with a human on board.
A possible way is to make the electric motors, with help of their propellers, power a helicopter rotor, thus creating a nearly torque-free helicopter.
The rotor speed seemed fairly high, so quite quickly the rotors will reach speeds close to Mach 1, when the aircraft moves forward at speed, so the rotors have to be rotatable, to reach a more (or less) horisontal position, for the thing to work well, and then we\'re talking complications aplenty!
If you put all these motors and propellers on the wing of a glider/sailplane you\'ll have a nice powered plane, that probably easily could be registered and used in normal airspace!
21st November, 2011 @ 4:26 p.m. (California Time)
A good solution can be: Santos Dumont who applied, add a balloon of silk fabric above the driver\'s seat, so would have less weight and more to help move propellers.
Congratulations from Peru
27th November, 2011 @ 6:15 a.m. (California Time)
This is a very interesting project. I did some checking and the builders didn\'t use off the shelf outrunner motors. The motors were rewound to give optimum performance. I did some figuring and came up with some number I think could work to build your own. http://www.makermasters.com/?p=701. Would some one check my numbers please? Love this blog.
2nd December, 2011 @ 7:21 a.m. (California Time)
This is a fun idea with an actual flying prototype.
One gentleman noted \"Unable to autorotate: Even if variable pitch props and freewheeling systems are used, there is still a major issue: not enough rotor inertia, and not enough physical space to integrate tip weights. As such it precludes FAR 27 certification. Not sure if the Germans have considered this issue, when they claim that \"helicopter is obsolete\".
If NACA reached the conclusion that a device like this one is \"Unable to autorotate\", you don\'t need to be a aerodynamics designer to understand that concern is mistaken and that there is a \"simple\" solution.
Autorotation does not require rotor inertia or tip weights.
It only needs to be able to put the blades at a negative angle of attack.
For control of rotor speed and to allow a positive pitch for landing, obviously that negative angle of attack must be adjustable.
PS Here\'s the FAR part 27 (Helicopters)
5th January, 2012 @ 8:04 p.m. (California Time)
In his post, Mr David Dilworth wrote: “ Autorotation does not require rotor inertia or tip weights. It only needs to be able to put the blades at a negative angle of attack”.
This comment is absolutely untrue: there is no point entering into autorotation if landing is precluded by the lack of kinetic energy: where do you draw the energy required to cushion the landing, if not from the kinetic energy stored in the rotor?
At a given Rotor RPM, Kinetic energy is directly related to rotor’s moment of inertia, that is a function of: number of blades and their geometry, as well as weight. When designing rotorcrafts, we use what is called “Equivalent Hover Time”, or t/k, that is the time that the stored kinetic energy could supply the power required to hover, before stalling.
Early R22 that had hardly no tip weight and were quite scary in autorotation, with Rotor RPM fluctuating rather quickly. Today’s R22 have heavier blades, and a t/k of 0.8 second, which still requires swift reactions from the pilot.
When designing a rotor blade, it is desirable to use tip weights rather than uniformly distributed weight in view of lowering rotor mass and centrifugal related stresses, yet keeping the t/k as high as possible...
Mutlicopter-type machines use multiple small rotors, and need highly tapered blades to be efficient, and not cumulate tip losses. As a result, those rotors exhibit low polar moment of inertia, hence poor autorotation characteristics.
There are numerous textbooks treating this subject, and detailing related analysis.
David may want to read the excellent references written by Ray Prouty and Wayne Johnson from NASA.
15th May, 2012 @ 6:58 a.m. (California Time)