- the configuration. i don't understand what the aerodynamic advantages of a "boxwing" are, but apparently this has those while avoiding problems with stalling. it's also stronger / more compact and places the engine closer to the centre of gravity than a traditional "propeller at the front" design.
- the engine. initially, diesel, which is unusual for aircraft, and eventually electric.
- suction of air through parts of the wing to give laminar flow (reduce turbulence) and so increase efficiency.
a lot of the site reads like over-hyped snake oil, they don't have any published papers (never mind peer reviewed), and it sounds like they don't have good numerical results from full 3d simulations (but argue they are limited anyway). on the other hand, it doesn't seem to be complete bullshit - they have a working 1/4 scale model, for example, and seems to have been accepted into some kind of x-prize-like competition organised by nasa.
Of coarse box-wing has its problems, too. They claim to have solved some of those issues. I'll remain skeptical until the flight test proves their claims.
The 1/4 scale model means almost nothing. A colleague put an electric motor on an 8-ft chunk of foam and flew that around. The power to weight ratio of small r/c aircraft is ridiculous, and it does not scale to full sized aircraft.
All of these are, of course, only valid to a rough approximation; look up "scaling laws" if you want to learn more)
The idea that it gets MORE efficient by having more cargo violates the energy equation. Literally. That concept was disproved (utterly) when the sound barrier was broken.
I call shenanigans.
I'm not saying that their claims are correct, just that added weight can potentially result in improved performance, depending on how much weight it is and where the weight is placed.
Also, regarding scaling results to model aircraft, the subject is called "dynamic scaling," and it's actually a complex task to scale the various model parameters to get good results. Take a look here: http://adg.stanford.edu/aa208/dynamics/nondimen.html, under section 2.3.4, for the punchline. Also, an interesting history of dynamically scaled models can be found here: http://www.nasa.gov/pdf/601262main_ModelingFlight-ebook.pdf
The "boxwings" seem to be a worst of both world approach. It ads a lot of surface going across the air and thus a lot of drag, without providing the width which would usually make available the torque necessary for stability and control.
Torque is (force * distance) and, for roll control, this distance is usually provided by wide wings. An airplane having shorter wings would probably go through the air more efficiently (provided you didn't add a second set of wings on top of the first one) but would not provide much control to enable safe flight in all possible conditions. Short wings don't provide much leverage on the roll axis.
It also seems like in this design the top part of the "boxwings" plays the role of the tail of the plane. However, it looks like we get the same (force * distance) problem but on the pitch axis. In order for the tail to give a good amount of torque for pitch control, it has to be located away from the wings and the center of the aircraft.
Again, I'm just guessing based on physics here but since there is no tail other than the one located near the bottom wings, it might be difficult to stop the plane from pitching up or down out of control.
If we were to design planes for efficiency only, they would look like arrows or missile. They would have minimal wings or fins to slow them down. The reason, we have to have things sticking out far from their middle, is to add the ability to safely control them in a wide variety of conditions.
This aircraft has both lots of wing, thus a lot of drag and yet the extra wingage doesn't get the wings positioned away from the center where they would add the most stability and control. Unless the "Laminar Flow", "Wake Propulsion", "Open Thermodynamics", "Subsonic Area Ruling" or the other technobably things mentioned on the website somehow compensate for this, it seems like a lose-lose design.
That's not saying it's an amazing new design which will break records or anything (it can't be -- subsonic aerodynamics is literally an 80-year-old-mature technology). But it's attractive and looks like a clean design at first glance.
Of course there are other factors at work. For example, Jet A carries more energy per pound than 100LL and diesels are more efficient, so you carry less fuel for a given range. But the engine needs to be stronger to run a higher compression ratio, so that's some added weight. Every little design feature of an aircraft interacts with every other design feature. Aircraft design can be a tremendously unintuitive affair. That's why it's so fun.
So, the proof's in the pudding. The ultimate arbiter of an efficient aerodynamic design is its lift-to-drag ratio, or how much drag is generated for a given amount of lift produced. (See http://en.wikipedia.org/wiki/Lift-to-drag_ratio) They should be getting good data off their scale model, and if the model's L/D ratio is high and they've done their homework to reflect the full size aerodynamics, then they might have something.
So, it's actually kind of plausible -- the problem is the diesel aviation engines have been VERY slow in coming to market. The main market so far has been non certified use (military UAVs), where eliminating 100LL from the supply chain has huge savings on top of performance.
Maybe with FADEC it makes more sense; eventually it will de-skill some of the engine management and you'll just pay the higher operations and maintenance costs of the twin engines, while getting the reliability benefit if ones goes down.
I really want a CH-801 (extreme STOL, rough field, slow), or a Maule.
Why? Pilot error. A combination of Cirrus marketing their aircraft as a transport solution (which attracts relatively inexperienced pilots) and the comparatively unforgiving airframe leads to high accident rates.
What does this proposal do to solve that problem? It's a novel airframe, sure, but it's not that novel. I can't imagine that it will offer huge efficiency boosts over something like a Velocity XP (which has similar construction techniques and can probably be used with the same Diesel engines).
This is solving the wrong problem. The issues are regulatory and electronic.
The kickstarter page needed a short video talking about each of these points. Not photos or just gubbins.
Icon Aircraft (among many others) has been working on the challenge of making flight a little bit more accessible for some time now. Check out the icona5 channel on YouTube.
Wait, what? Airplane travel is thriving more than ever. Passenger rail is dying, the FAA is forecasting a >4x increase in the number of general aviation pilots in the next 20 years , and it's increasingly more affordable for the upper middle class to fly charted jets .
Piloting is still a high skill job, it's just that there's a surplus of young people who really love flying and will accept a crappy salary to live their dream.
The triggering cause of AF447 was the icing of a pitot tube. The reason the aircraft flew into the ocean more or less fully stalled was poor pilot training and poor human interface design.
I do agree with you that skilled pilots are a requirement. Systems are only as good as their sensors, and lack the flexibility that makes a manned system adaptable. However, AF447 is a fairly poor example of why we need pilots, as it was pretty much entirely pilot error which caused the crash.
The accident reports mentions that the pilots did not have training in high altitude hand flying, and the common belief seemed to be that it wasn't necessary because of automation.
If they had just done nothing it would not have crashed. Instead the pilot climbed until it stalled.
There have been other cases, for instance http://en.wikipedia.org/wiki/Qantas_Flight_72 where the autopilot put the plane in a dive because of a malfunctioning sensor and a software bug.
If the pilots on that plane had done nothing like like you suggested the AF447 pilots should have done, what do you think would have happened then?
Which is my entire point, until you have situationally aware computers, you need situationally aware human pilots.
The plane would have kept flying. Perhaps it would have flown out of the storm, perhaps it would have descended. Either way at some point it would have gotten low enough or warm/dry enough that the ice in the pitot tube would have melted (also the heater in the tube was on, but didn't have enough time to melt it), and the system would go back to normal and all would have been well.
Instead they did pretty much the only thing that could doom it: They ascended. This despite knowing they were near the "coffin corner" - i.e. the highest safe altitude for the Jet. The pilot clearly panicked and didn't want to crash into the ocean, so he went up, and it was exactly the wrong thing to do.
Your point about pilot inexperience in manual flying, is close. But from what I read it was actually that the pilot was used to the computer taking over and not letting him fly in a dangerous manner, this caused him to try ascend to the point of stalling the plane because he believed the computer would stop him.
So you end up with the worst of both worlds: A human who relies on the computer, taking over in a situation with no computer. You have to pick: Either computer all the time, or no computer. Perhaps computer assistance, but no control? Certainly computer override is no good (i.e. this lets you max out the controls and the computer will adjust them to the ideal levels).
> you need situationally aware human pilots.
This was impossible for both of them. The windscreen was completely blank, and (some of) the instruments were disabled. Neither the pilot nor the human had any idea what their situation was. What they should have done was remember where they were and assume they were more of less in the same situation.
I was talking about Qantas Flight 72, not AF447. In the instance of AF447, everything would have been OK if the pilots had done nothing. The airspeeds returned and were valid after ca. 1 minute. But in other scenarios, the plane would likely have crashed if the pilots had done nothing.
> Instead they did pretty much the only thing that could doom it: They ascended. This despite knowing they were near the "coffin corner" - i.e. the highest safe altitude for the Jet.
They could also have descended and risked exceeding the critical Mach speed, which could have broken up the plane.
> The pilot clearly panicked and didn't want to crash into the ocean, so he went up, and it was exactly the wrong thing to do.
Actually, the standard operating procedure called for a slight nose-up pitch (5 degrees) and maximum continuous thrust.
> Your point about pilot inexperience in manual flying, is close. But from what I read it was actually that the pilot was used to the computer taking over and not letting him fly in a dangerous manner, this caused him to try ascend to the point of stalling the plane because he believed the computer would stop him.
Exactly (although the pilots did know call out "alternate law" and should have known what that meant (no more stall protection).
> So you end up with the worst of both worlds: A human who relies on the computer, taking over in a situation with no computer. You have to pick: Either computer all the time, or no computer.
The current setup does work very well (given the current safety record of the aviation industry), and looking at GA statistics we'd likely have a more airliner crashes if pilots were hand flying all the time.
> This was impossible for both of them.
And it would have been just as impossible for the computer. Maybe some time in the future we'll have a computer that will do a better job than humans with dealing with emergencies, and then the autopilots will never need to disconnect for any reason.
But until we're there, the original assumption that more automation means that we can get by with less skilled pilots is just wrong.
> The windscreen was completely blank, and (some of) the instruments were disabled. Neither the pilot nor the human had any idea what their situation was. What they should have done was remember where they were and assume they were more of less in the same situation.
This was a reasonable assumption in this instance, but in other cases it would be the wrong assumption.
The big question is what led the pilot to follow the wrong procedure for inconsistent airspeeds, and why they didn't trust the instruments anymore even when they became valid again. It'll be interesting to see what the human factors group of the investigation comes up with.
Synergy is a double box tail aircraft that obtains high span efficiency by providing its stability and control through induced drag reduction. Since the tails push down, it is not a box wing, and the physics of this alone are worth your investigation.
What's more, and this is the basis for all the hubbub, it provides powered drag reduction at very high speeds. Both natural laminar flow and boundary layer control are utilized in the wake immersed propulsive integration. This combination of strategies provide significant benefits but is outside the practical experience of much of the industry.
Extensive discussion has been taking place for quite some time about this and some of that is linked here below. We look forward to completing our effort to provide flight test results that corroborate our results so far, which are promising.
I am available to anyone via email or telephone if you have further questions. Thank you once again for your comments. John McGinnis, EAA 797858, AIAA 289792, john (~at~) synergy aircraft (dot) commercial. fourohsix, twofive0, twentytwo twenty.
http://www.youtube.com/watch?v=nCqk7HUKMug (Synergy OSH 11 pt1)
http://www.youtube.com/watch?v=CaVCISch7VU (Synergy OSH 11 pt2)
http://www.youtube.com/watch?v=PlT4V2r4Oz8 (Synergy OSH 11 pt3)
http://www.youtube.com/watch?v=kOdaI4jQ8PA (Synergy OSH 11 pt4)
http://youtu.be/OC0itjCeGAA (synergy Osh 11 pt4B)
http://www.youtube.com/watch?v=gAJ9C5570rY (synergy OSH 11 pt5)
In other words, in a world where everybody has a plane we probably want "planes on rails". Whether physically-enforced or software-enforced.
It actually is quite challenging to design an aircraft that is efficient, capable (as in 4+ people) and cheap to operate.
The Pipistrel Panthera and the Icon A5 are about as close as it comes, but both have serious shortcomings. Panthera is fricken expensive to buy and unproven, and A5 is that and not very capable. The average Cessna and/or Piper cub is still the easiest way to get into the sky in something useful for more than a lap around the airport.
I'd love to see something that isn't going to cost the price of a house to buy and the average salary to fly before we look to make everyone a pilot, because that challenge alone is a long, long way off.
If people today can't afford a Skylane (or even Warrior or Skyhawk), they will be able to afford this even less.
Putting the "everyman" in the air is better done with a partnership or club owning 60s/70s/80s metal airplanes, IMO, and that's not even that achievable in days of $6 avgas and $75/hour "dry rental" (everything other than gas).
The reason a self-flying plane is easier than a self-driving car is because there is much less stuff in the air than on the ground, and everything in the air has a transponder that tells you its exact location and speed. (Not true of small VFR planes, but transponders are becoming more common and if we really wanted to, we could make them mandatory.) Compare this to a car, where there are kids running into the street, traffic lights, other drivers, loads falling off the back of trucks, and so on. The number of things that can suddenly change the driving conditions are dramatic. In the air, that's not the case; the environment is very controlled and you have an extra dimension to navigate in.
With that in mind, we're still a ways away from untrained people getting into an airplane, pressing a button, and arriving at their destination. But honestly, that's details and risk management rather than a fundamental lack of technology. (What happens if the engine fails? What happens if there's a thunderstorm? The corner cases are why you have trained pilots there to assist the computers. If you're willing to die because of a simple mechanical or software failure, then self-flying planes are a reality today. If you're more cautious, then not quite yet :)
The software was written by the same team that make the X-Plane flight sim (http://x-plane.com/)