It may not be the ideal material. But has there ever been a LEGO model airplane with the ability to glide, under power maybe, or some other kind of successful lifting airship? Helicopter, blimp, kite, even rocket? Sliding down a string doesn't count. Has anyone produced any kind of limiting analysis for this problem?
Non powered/motorized flight has been achieved
Anna Vuurzoon made a Flying machine using only Lego parts which uses a ripcord to propel a three blade propeller on a stick (see http://www.mocpages.com/moc.php/288875). I was able to duplicate her results, so can validate it does work. It is really a modification of a bamboo copter. The 2015 Ninjago Lego Airjitzu series ( Lego #70739, 70740, 70741, 70742, 70743, 70744) are bamboo copters and work on the same basic concept as Anna Vuurzoon's flying machine.
Daron Williams (via Drat Glider) and Milan "grohl" Reindl from Czech Republic have both reported making working/flying Lego gliders using mainly Technic cross-axles components. Both gliders travelled between 20 to 30 feet with the Drat Glider with the bigger wingspan going a bit longer. The wing cross section is more or less flat (one stud tall airfoil) and acting more like an air sail (paraglider) than an airfoil. Williams uses Lego Plastic sheets from the Mars Exploration Rover Set to cover the wing (wing cowling). Plastic sheets is the lightest wing covering that can be used but Lego does not make very large ones. Reindl uses plastic from garbage bag and tape to cover the wing on his glider - this allows for a bigger but heavier cowling. I have made my own Lego glider using the plastic from Lego store bags as my wing canvas using similar construction techniques as Williams and Reindl . My preliminary indoor flying test validate the results by Williams and Reindl. Milan Reindl is now a Lego Group junior designer (you can see his profile on Lego Technic Designer Profile).
Lego does not make a quality aerial propeller or water/hydrodaulic screw-prop with a fuel efficient power stroke. The aerial propeller design for an all-electric aircraft have already be optimized by the Radio control aircraft community and can be fitted to a Technic axle but modern aerial prop design need to run from 4000 to 10000 rpm and use poly lithuim batery packs and motors that run at higher current and voltage than the Lego power function components.
The Vuurzoon design takes a lot of torque/power to fly and uses the power that it is given inefficiently. The only thing going for the Vuurzoon prop design is that it has the most efficient rotor angle to create lift. The Vuurzoon design uses hand power instead of electrical power and thus avoids the low power limitation of Lego electrical motors and battery pack systems. Lego motors without gearing don't go above 2000 rpm at their set voltage/current level and have a high weight to power ratio which is bad for flying. Going over an 8:1 gearing causes a Lego motor to lose so much power/torque that any propellers slow down due to wind resistance (even the most energy efficient light weight two blade electrical propellers has this problem). Lego motors can go a bit faster if pumped with higher current and higher voltage from a non standard non-lego power source (e.g. poly-Lithium +15V power pack) but many believe this will shorten the motor lifespan. Lego Power Function electrical packs are also too heavy for flight the lightest battery pack is a Li-ion rechargable pack which weights about 75 grams. The heaviest Lego battery pack is the AA battery pack with alkline batteries which weights 195 grams — which is enough to sink a two catamaran hull or a large single hulled lego boat. Standard Lego bricks are too heavy for an heavier-than-air airframe. The lightest Lego parts that can be used as an air frame are the technic axles followed by the half width technic beams— both are only semi-ridge so some bracing is need if air frame rigidity is required. In order to get a battery pack light enough and with sufficient voltage levels to fly as part of the aircraft — Lego needs to have to Lithium polymer battery pack kicking out between 18vdc to 30vdc — at those voltage levels the mini hi RPM motors used on Quadcopters and helicopter toys can start to be posssible.
Analysis of other attempts
There are several efforts to use Lego to make the frame of a quadcopter and uses a non lego high speed lightweight motors, hi powered batteries, and electric propeller. The high speed motors usually run at 3400 to 15000 rpm @ 13 to 30 vdc and are very light weight. In addition it is using a non lego Poly-Lithium power pack some output as high as 30vdc even with heavy current drains. Some are using a Arudino microprocessor like device for remote communication.
Lego NXT Blimp-Airship
A lighter than air Lego Airship which was made by The Lego Group for a European Lego show/convention — uses Lego education propellers (from the renewable energy kit) and standard Lego motors and power supply. Prototype (non-commerical, custom made) helium balloons are used to create a neutral buoyancy so that the propellers can create lift and push the airship forward. The Lego airship (called the C5) was demonstrated in an auditorium/stadium with a very high ceiling (there is no wind of any kind that the Airship would have to overcome).
LEGO seems to be way too heavy and not aerodynamic enough to build a plane so the best bet would be to build a zeppelin.
There's a video on youtube that shows such a zeppelin where the nacelle is build with LEGO (not sure if it's pure LEGO, take a look at it at about 1:55 in the video).
Another, much simpler example using only 5 helium-balloons and a 9V-motor: youtube-video
Conclusion: Flying lego is possible when you add some none-lego-parts - building a zeppelin seems to be really easy using some helium-balloons while building an aircraft without suspension is not possible (or at least: not if you plan to use LEGO-motors as they simply don't have enough power).
Some family built a LEGO quad-copter. Unsurprisingly, it uses non-LEGO parts. Also, the design might seem a bit weird and worst of all, it's glued (uuurrrgh).
But it does work and appears to be very stable, enough to provide a nice remote camera view.
The Brick Experiment Channel on Youtube shows a Lego Drone that flies. It's built with a combination of Lego propellors, Lego Power Functions L motors, a Lego frame, and some non-Lego flight-control computer, radio receiver, and batteries.
This is a truly amazing feat, showing how deep knowledge of the Lego motors and technic gear ratios can lead to tricks nobody believed possible, such as flight or breaking steel. I didn't think it was possible until I saw this video. A pure Lego solution would have to replace the flight controller, RF recveiver, and batteries with something like a Control+ Powered Up hub, which has a tilt sensor, bluetooth, and batteries, but is so much larger it would almost certainly be too heavy to fly, not to mention not well suited to the task of maintaining level flight for a drone (I doubt it's possible with a stock Powered Up solution to control motor power levels quickly enough in order to correct flight direction, but I've been wrong before).
Try Using Foam wings, and if you have the money, you could probably add motors, you would just need a Fast motor and the smallest battery box. I have a science fair and I'm going to use foam wings, Check it out!!!
I'm surprised to see that nobody has yet mentioned Peter Sripol's functional RC airplane constructed from LEGO!
It's not a "pure" solution - the powertrain, electronics, and control linkages are all constructed from hobby-grade products, not official LEGO, some pieces were cut to size, and some non-LEGO components were glued or taped in order to secure them to the LEGO components, but the airframe itself was otherwise constructed from LEGO using legal techniques.
For those who might not be able to watch the video or are uninterested in viewing the whole thing, the fuselage is mostly Technic and 1xN plates, with Technic beams supporting the wings and control surfaces, which are constructed from baseplates, except for the vertical stabilizer, which is constructed from bricks. The plane itself uses a 3-channel control scheme (power, pitch, yaw) controlled by traditional RC hobby-quality servos, receiver, battery, ESC, brushless motor, and propellor. The dimensions of the aircraft appear to be roughly one meter wingspan by one meter fuselage length. The wings and control surfaces, being constructed of baseplates, are not true airfoils, and instead generate lift and pitch/yawing moments by airflow deflection, aided by the ample thrust of the powerful motor and large propellor. The plane appears to be very difficult to control and prone to stalls, spins, and fluttering, but it does fly, if only for a couple minutes.
I made a 100% LEGO flying machine. It's built from three parts:
- Propeller number 30333,
- An axle (female end) Technic pin (male end two spaces),
- A three inch axle.
To fly it you hold it in your hands and slide them past each other spinning the contraption. The highest it's flown is about six feet, I've made other ones similar with different pieces but now this seems the most comfortable to spin.
no joke, this video is a flying pure lego helicopter.
he just uses a nxt/mindstorms motor
and the blades do have pitch so it makes sense for it to fly