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However, auto buyers aren't willing to deal with the limited cargo room and tight quarters in a plane. Go look at how narrow some of those cockpits are, they leave some elbow room to be desired.
We built a solar car in university, and based the design off of a glider minus the wings.
My point was that even a typical plane gets better mileage relative to most cars. A slight take off from the article title.
I'm guessing that if he said "We built a solar car in university," that he's not from the US as that's not really American-English...
But yes, 30mpg is considered good mileage here.
Color me unimpressed.
This shouldn't weigh too much and would eliminate the faring weight over the wheels
Also, the VariEZ has a retractable nosewheel. It's often parked with the nosewheel retracted, but it doesn't takeoff or land that way. The VariEZ seems to have the worst of both world's from the pilot's perspective (you to put the gear down or else), but it may be a sweet-spot from the airplane's perspective -- you can probably have a simpler retract system.
Anyway, I just thought I'd point out that retract systems are heavy, complicated, and often not worthwhile on small aircraft. As a weekend pilot, I certainly prefer that my GUMP-check reads "(U)ndercarriage, down and welded" -- small airplanes cost more than my house and I fly for fun.
Using two in-production aircraft as another point of comparison: Look at the published cruise speed of the Columbia cum Cessna 400 vs. that of the Mooney Acclaim. To within the airframe-to-airframe variation in cruise speed, these two airplanes fly just as fast, using the same TSIO-550 engine, but the Cessna has fixed gear.
Compared to car engines in the millions. Many car derived power plants would make a good basis for a good GA engine; if the market was so big someone would do it.
It's the combination of a comparitively small market and the long expensive certification process that means we are still trolling round the skies in engines with magnetos on them. Know anybody else still using them?
There have been very few successful automotive to aircraft engine conversions, partly because the engineering requirements are so different. Airplane engines need to produce near-full power for hours on end, while auto engines only need to do so for a few seconds before producing a small fraction of rated power for long periods. Auto engines are just designed to do something different from airplane engines. Going the other way would probably be just as disastrous, but nobody tries to do it because the economic incentives aren't there. The successful conversions have mostly been small engines that were designed to run at rated power most of the time (because that was the only way they could propel the vehicle at highway speeds).
None of this is to say that auto engine technologies (especially ignition, induction, management, and fuel delivery) couldn't be successfully employed in an airplane engine (as the article aptly demonstrates).
http://en.wikipedia.org/wiki/Rutan_Quickie
In any case, 100 octane "low-lead" fuel is the standard fuel for piston-driven aircraft. The fact that most small airplanes are still running on leaded fuel just shows that, except for panel-mounted GPSs and the occasional $40k glass-cockpit, citizen-aviation is still stuck in the 1960s.
Also, aerodynamically speaking, a windmilling propeller generates just about as much drag as a sheet of plywood with the same radius. You really don't want a windmilling propeller when gliding, unless you're hoping that you can use that effect start the engine again (like, for instance, you change to a fuel-tank that actually contains fuel).
If you're a glider pilot, you can already fly electric:
http://www.lange-aviation.com/htm/english/produ...
A hybrid airplane seems like a really bad idea at first, but it might have some merit. Airplane engines run at WOT an awful lot of the time, and not much energy is wasted in descents (very few small aircraft have dive-brakes, except for gliders). But, if you're willing to cruise a little slower, you could just use a plugin electric motor for the initial climbout and then run the piston engine at WOT for the whole flight. I'm still not convinced that this is a good idea -- but I'd love to see someone try it. But since we don't even have EFI in most airplanes, I'll be surprised if a hybrid system would get anywhere. I expect to see fully electric GA airplanes first.
What do you thing regenerative brakes do? Not creating something from nothing, just using what is there. Hybrids will give you the torque needed for quicker shorter takeoffs, backup when engines fail, and I have already seen a device which deploys on electric failure that uses the wind to create enough electricity to power the plane long enough to get back your mind you probably lost when the lights went out!
The first thing you need to know is that when you fly an airplane, you consider the throttle to be your "altitude" control, and you consider the pitch (elevator) to be your speed control. The main reason flying is taught this way because normal airplanes (meaning anything that isn't an F-15) do not have to power to get themselves out of a stall -- but it's also because your rate of climb is Power - Drag. So, if you maintain level flight, and you shove the throttle forward, you'll climb. If you pull the throttle back, you'll descend.
So, how do you approach an airport? Let's skip the formalities, and go to the physics. Suppose you're cruising along at 8000 feet and you're a few miles out (how many miles will depend on how draggy your airplane is), you pull back the power and gradually descend down to the pattern altitude (usually 1000'). Then you put down your gear and flaps and fly around until you're lined up on the runway, and pull back the rest of the power. (The procedure is a little different if you're flying an instrument approach.)
At no time during this procedure do you have energy that you really want get rid of -- except for the gear and the flaps, the airplane does not have and does not use brakes. Up until the time you put the gear down, there is absolutely no advantage to descending at a steeper angle.
People do fly slam-dunk approaches from time to time -- but the reasons usually involve weather or trying to make a schedule. Those don't seem to justify adding weight and complexity to the aircraft -- if you want to fly efficiently, just wait until the last reasonable moment to put the gear and flaps out.
The best place to get performance in a light aircraft is through drag reduction aerodynamic design. That's why the Mooney M20C that I used to fly went 200mph on 180hp, and the Cessna 172 I flew went 120mph on 175hp. Drag increases at the cube of velocity, so you'd need something like 1400hp to get it to 240mph. The Cessna was a forgiving and charming aircraft -- and the Mooney was like a sports car. :-)
The other think you can do to save fuel in an airplane is to cruise at it's best-glide speed. If you fly slower, you get more drag because the wing is at a high angle of attack, and if you fly faster you're going faster than you have to. This is around 70mph in a Cessna 172. Most people I know fly faster than this if they're going somewhere, but if you've got the time it'll save money. Just remember to turn the carburetor heat on, 'cause carb ice sucks.
It's possible that you could put a smaller engine on an airplane that is sized to run at WOT in cruise and use a plugin electric + the engine to climb out, but I'd like to see someone try it before I claim it works. Using standard techniques for descent and approach are about as efficient as you can get.
P.S. I drive a Prius. But since I don't race to stoplights (physically analogous to flying a slam-dunk approach), I get less benefit out of the hybrid system than someone who insists on driving aggressively -- but I get better efficiency than the aggressive driver. The difference between the car and the airplane is that there are stoplights and the brakes work at all times on a car -- and airplanes fall out of the sky when they stop, so the airplanes just don't have the same erratic power requirements as the Prius on a public road.
Also the air used on the flaps to slow the plane down would not be "gotten rid" of but recaptured to charge the batteries.
You're right that improving the aerodynamics the airplane works wonders -- that's how the Quickie can fly fast on 20hp. Even though the details can choke some of the biggest supercomputers on the planet, aerodynamics in this range is well enough understood that it's a matter of making tradeoffs and small improvements -- rather than a eureka moment. I sure wish it were different -- I'm a geek and I love the eureka moments (even 2nd or 3rd hand).
But, as it stands, a conventional single engine airplane with fuel injection (a newish technology in general aviation) costs as much as a Ferrari. Aviation is not friendly to new technology, because of the legal and economic framework. :-(
I expect we'll see practical fully electric airplanes from EAA members (like the guy in this article with the Vari-EZ) long before any hybrid airplane engine flies.
I've made surprisingly useful improvements to the efficiency of my house with about $50 worth of insulation. Insulation is about the least exciting thing possible at first glance, but if you get thinking about the right places to put it, a few experiments can turn into a geeky hobby fast. :-)