the three things that make this new, as far as i can see, are:
- 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.
The box-wing is actually a really old design - contemporaries of the Wright brothers were experimenting with it. The main advantage is reduced drag. Airflow doesn't like points, and wingtips contribute a lot to the overall drag. Closed wing means no tip, and therefore less drag.
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.
Well the question is if they scaled everything in the 1/4 scale model, including power. They say it is flying since 2007 so we have to assume they did their homework before trying to make the current full scale prototype.
It doesn't work like that because all of the factors don't scale at the same rate. I'm not an engineer, so unfortunately I can't elaborate with much detail for you, but the general concept is that factors like aerodynamic efficiency and power efficiency can't be scaled up and down independently in a rudimentary way.
The simplest one probably is that lift and drag scale with wing area, while aircraft weight scales with its volume. That means that, if you do things at quarter scale, you have 1/64 or about 1.5% of the weight, but 1/16 or about 6% of lift. Consequently, almost everything flies at that scale. The model plane will also be extremely robust, as its landing gear can take 1/16 of the original one, but has to carry only 1/64th.
All of these are, of course, only valid to a rough approximation; look up "scaling laws" if you want to learn more)
That's not true at all. Their claims about wind tunnels are also ludicrous. Take a peak at the Reynold's number wikipedia page sometime. That's EXACTLY how aerospace engineers do preliminary calculations: by scaling aerodynamic factors (which is completely viable with a nearly incompressible fluid like low speed air).
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 haven't looked at their claims, but strictly speaking it isn't impossible that adding cargo increases efficiency. How? Well, if the cargo is added in a location that moves the aircraft's center of gravity closer to the aircraft's neutral point (the center of lift for the entire aircraft), then less trim force from the elevator will be necessary for level flight, resulting in reduced trim drag.
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.
Yeah I'm not sure this project passes the smell test. I don't know much about airplanes but a few things seems off when I think of this design in terms of basic physics.
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.
IAAAE (I am an aerospace engineer). Actually, long (or wide, to use your term) wings tend to be more efficient. The term you're looking for is "high aspect ratio," which efficient airplanes (see the Global Flyer, for example) have in abundance. It is the ratio of wing span squared to wing area (viewed from above, not the front). The explanation for why this is true is complicated, but this gives a good overview:
Yeah, this isn't insane. Basically it's a T-tail horizontal stabilizer where the vertical stabilizer has been split in four sections and placed outboard to clear the rear-mounted propeller. There's nothing wrong about this. The stabilizer might be a little farther forward than some designs (it's not clear where the c.g. would be looking at that drawing, one assumes in the middle of the four passenger seats), but not radically so.
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.
If I understand correctly, this seems like yet another reason why this Synergy design would be sub optimal. The two sets of short low aspect ratio wings are theoretically less efficient than one set of long high aspect ratio wing. Correct?
I don't know what their numbers are, but for an aircraft of its class, the lower wings don't look like they have an abnormally low aspect ratio. The upper wings look to be of a higher aspect ratio than conventional elevators. Since elevators are a source of drag (they usually have to provide some downforce to trim the aircraft in level flight, and you can't make lift without making drag), that could be a win. But then they're close to the CG, so they'll need to provide more trim force (short lever arm as you mentioned), and the advantage might be lost.
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.
Actually, if you read their Kickstarter, they claim to be getting better fuel efficiency with higher cargo weight. They claim this is because it somehow lowers their drag. They also claim that L/D is unimportant for their aircraft, which is why a scaled test is useless to them, even in a wind tunnel. This doesn't pass the smell test for this AE.
Long wings doesn't give more controll. The increased radius gives a higher inertia when rolling. It would make it more stable, but also slower. Acrobatic aircraft usually have short wings for this reason.
Vortices generated by induced drag really aren't "horrendous" except in high angle of attack situations. In cruise, even with slow planes like this, most drag is parasite drag. Commercial jetliners have been deploying winglets to mitigate the same effect for decades now, and the effect is something like a 2% fuel savings. It's worth doing, but it's not a game changer.
IMO they get at least 5x of their 10x by using a diesel engine, vs. a jet (inefficient at a range of powers) or avgas (expensive fuel, old designs, inefficient). Just putting a diesel SMA, Thielert, Deltahawk, etc. engine into a Cessna 172 would give you substantial fuel economy and cost savings vs. 100LL. 100LL is also taxed, while Jet-A (which a diesel can burn) has no excise taxes by international treaty (there are some other taxes, especially in the US). It's maybe 2x fuel economy improvement and 2.5x on per-BTU cost savings.
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.
You probably have a pretty valid point. One of my aspiration toys, the Diamond Star DA42 (http://en.wikipedia.org/wiki/Diamond_DA42) burns diesel or Jet-A in a internal combustion engines. I forget the economy figures, but I think this plane does quite well when throttled back.
I'm not a big fan of twins for infrequent pilots (just based on observing and talking to pilots, not actual flying myself except in a simulator) -- they seem to bring with them a lot of problems. You obviously have more cost and more potential maintenance downtime from two engines, and when one goes out, the asymmetric thrust and other issues often end up killing pilots who would otherwise have probably been able to deal with no power. There are exceptions like over water use, but I would have preferred a super reliable single engine (Cessna Caravan) to the less-reliable twins (King Airs and Shorts 330s) I was stuck on -- they had to use a twin for regulatory reasons, but even the pilots thought a single would be better. And those are professional (military) pilots; for someone who flies infrequently, the risks of an engine failure are lower, while the proficiency in dealing with engine out is probably lower as well. Single + ballistic parachute might be the best compromise, unless you're routinely operating over water.)
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.
Airplanes seem to be the original vaporware at times. All sorts of interesting projects that seems to be getting somewhere and then stop and have no updates for years. Like the ElectraFlyer-X. Kudos to whoever makes the first affordable to fly airplane.
The issue isn't the airframe, it's the systems. Take the Cirrus SR22. A fast, modern, relatively efficient aircraft with a full avionics suite capable of instrument flying. It's even got a ballistic parachute so that if anything goes wrong you can simply float to the ground. It's really, really dangerous.[1] Cirrus SR22's crash something like 4 times more often than Diamond DA40s (a similar aircraft).
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.
Yes, claiming. I'll be shocked if they can hit a price point below $150,000 even as a kit airplane (which then takes 2-3 years to fully assemble). Maybe they're comparing themselves to something like a Cessna Citation, so yes 10% cost but not what I would call affordable.
The cessna citation is a business jet. I don't know what price point they are trying for, but they are aiming for more mass market. The design has no moving parts in the wings and they say the design is amenable for mass production.
They are raising money to build a prototype, and it looks like they will succeed with the raise. Congrats to them! The donor levels are mostly just about recognition.
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.
"If airplanes are to re-connect with their potential customers- or their potential to society- they desperately need an update."
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 [1], and it's increasingly more affordable for the upper middle class to fly charted jets [2].
I was thinking about this recently - piloting used to be a high skill job, but now pilots are largely relegated to takeoff and landing--a technician's job. I expect more of air travel to be automated in the future (like, why do pilots and ATC speak through a radio instead of using something automatic). More automation -> lower skill required -> less pay in the future.
..except for the law of leaky abstractions, which is what get you accidents like AF447. Until the automation has situational awareness, you still need skilled pilots.
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.
AF447 was caused by a lack of systems understanding by the pilots. If they had simply done nothing, the natural stability of the aircraft would have kept it flying until the pitot tube de-icers had effect and the aircraft could return to autopilot.
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.
That's true, however I think it's a good example of why we need skilled pilots that maintain situational awareness.
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.
I didn't say it was caused by the electronics, but it was probably caused by pilot inexperience in manual flying at high altitude (among other things).
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.
> 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?
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.
> The plane would have kept flying. Perhaps it would have flown out of the storm, perhaps it would have descended.
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.
I'm a tech entrepreneur and MIT grad who is an avid pilot and type rated on single pilot jets. I've personally visited John in Montana. This project is doing groundbreaking aerodynamic work in a garage. It's what America is all about. The science is sound and based on real designs and concepts that have been studied at places like NASA but never implemented due to the risk averse hyper conservative nature of incremental airframe design and certification barriers to entry inherent to the aviation industry. This project is worth backing. John has the goods.
Too much technical aeronautical jargon going on here. As a young lad, I built a box kite. I thought it would never fly, but guess what? It flew very well, thank you very much. I see a flying box kite in the synergy, so let it fly, let it fly, and just get out of my way. Case closed. prove me wrong.
Looks interesting, but I don't have time to dig deeper into it at the moment. Anyone in the know care to tldr; this? I'd be especially interested to hear what are the innovations that make this different from existing small aircraft.
Good morning, everyone! Thank you for your interest. Synergy's premise is that direct air transport from smaller airstrips at lower-than-commercial speeds is presently inefficient, thus not profitable and therefore underserved. Targeted aerodynamic solutions are necessary and beneficial.
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.
I don't think the critical challenge here is how to design a small sexy "innovative" plane. I think the elephant in the room (I love metaphors) is solving the problem of (1) who we allow to pilot them, and/or (2) whether they can be designed to fly in a fail-safe manner. For those folks who've experienced on a daily basis what the average herp-derp car driver is like, you should, I hope, shudder to think what it would be like if there were millions of those kinds of folks flying small planes around you.
In other words, in a world where everybody has a plane we probably want "planes on rails". Whether physically-enforced or software-enforced.
I think point 1 (and by extension point 2) is a little overstated. Many, many people wouldn't set foot in a small aircraft, be it a Cessna or this. This idea is for those individuals that would easily obtain (or use) a PPL if it wasn't such a daunting financial commitment to fly.
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.
I have one of the cheapest practical family airplanes, and it's so far from affordable on the average salary that the gulf is insurmountable, IMO. And mine is 1/5 or less the likely acquisition cost of this one. That difference in capital cost will take 2000 hours of operation (more than 20 years for most private pilots) to make up in nominal dollars.
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).
I'm guessing that building a self-driving car is a much harder problem than a self-driving airplane, and we seem to be making substantial progress on the car front.
The self-driving airplane pretty much exists. Assuming perfect conditions, an airplane can climb to a desired altitude, follow a GPS course, switch to a nonprecision VOR/DME approach, and follow a precision ILS approach (and descent) to within a few hundred feet of the runway. And that's a Cessna 172 with a mildly recent avionics package -- a modern airliner can take you to the runway surface in zero visibility. (Taxiing and takeoff are still manual operations that require more than zero visibility, however.)
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 :)
http://verticalpower.com/vp-400/ In an emergency it'll automatically calculate the best airport to land at (factoring in rwy length, winds, terrain & distance), fly the approach and land the plane - all at the press of a button.
The software was written by the same team that make the X-Plane flight sim (http://x-plane.com/)
The avionics they plan to use are very impressive. As long as the pilots don't touch the controls and don't try to fly the plane themselves, we're safe.
I don't think those are elephants in the room, those will happen. The elephant in the room is cost. Can he make a plane with a order of magnitude difference in price.
- 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.