SkyrateShadowStorm

ZBLJ, wouldn't it be easier to give it wheels and put the power pack on it instead of holding it? If the speed of the propeller is enough to make it fly it will be able to do so on its own wheels and with the battery pack.

Can you post an underside pic? It looks like you added two rows of supports. Just want to verify if you did. That is looking pretty good. I like that you put the rods through the bag instead of tying/taping/wrapping them. What is good luck in flight terms? Break a leg? No, that's acting...Hmm..

Yea, definitely need it to be at least twice as long. Have you tried doing 4 blades? I would put as many blades as you can(up to 8) if you're only going to do one rotor. I'm wondering if those panels can generate the right lift though. They don't look like they have any airfoil design. You mean 'do', right? I'm not sure if a biplane design would help any. Does it generate more lift for the same weight? I suppose a biplane would allow for stronger-shorter wings versus a normal plane's longer wings. Has anyone studied on the differences?

Could you post some pics of your panel rotor tries? And was that power to the wheels or propeller for the car?

Wow, this topic has really expanded in just a few hours. My thoughts on the non-Lego material glider wings is that I think they ultimately should be made from LEGOs, likely plates. However for testing I think it is fine to be non LEGO, with further engineering to switch to plates later on. If you are going to use non-Lego material for the wings I would suggest some sort of Tape, like packing, scotch, electrical, or perhaps plumbers/teflon tape. I'm not suggesting Duct/Duck tape because I think it may be too heavy for starters, though perhaps the most hardy. Why exactly did we switch to powered gliders, though? We think it will be easier to get a single, smaller, propeller to spin fast enough and pull the machine? That may be possible with light gearing of one or two 5292 motors. We'll also need a small but sturdy technic axle mounted propeller. Is there a factory one or does it need to be designed? @Piterx, I like your drawing. That framework also allows the addition of flaps to control height and help with landing. The biggest problem I see with a powered glider/plane is it flying beyond PF receiver/NXT range. This of course will depend on what speed we actually need for flight. We may find we can fly fairly slow being so small, or we may need to fly fast. Regarding the questions about controlling the craft, You would need one motor to control the main wing flaps(up/down) and one motor to control the tail flaps(left right). As well as of course your main drive engine motor which would likely be 1 or 2 5292 buggy motor. That puts our weight at around 218.4 grams(M Motor x2, Battery box x1, 5292 x1, Receiver x2), or 275.1 grams(M Motor x2, Battery box x1, 5292 x2, Receiver x2) for the motor system. That's not counting batteries though. I definitely think it would be good to get the propeller and engine system running high before bothering with the wings. That's not to say we shouldn't still discuss the wings here though.

@AVCampos, All depends on what you need to do. For LEGO tests, I would think our current main concern is weight thus we should probably consider mimicking a heavy lift helicopter. LEGO aircraft have to have certain weight(motors & technic pieces) so it would be better to try to design around that weight rather than just reducing the weight. @Blakbird, The Fastest Helicopter ever made uses two 4 bladed rotors in a coaxial design.Turbulent air wake is only an issue when hovering, not during flight. During flight the leading half of the rotor is going through undisturbed air. 8 blades apparently doesn't cause too many problems otherwise the Mil Mi-26 wouldn't have 8. 8 may be a few too many for beginning LEGO flight though. 6, whether on one rotor or tandem is probably the best. More blades do require more torque and induce more drag, which is why speed is not always the most important factor. More RPM will also make the turbulent air wake effect the helicopter more, another thing to consider with high RPM. The white blades depicted are the ones ZBLJ has been using on previous tests. They are not ideal nor the most efficient airfoils but for testing they are a good start. I believe the best LEGO airfoil will have to be carefully designed and use plates. Igor Sikorsky didn't build a successful helicopter in one day nor by himself. I highly doubt it was on the first day, either. As we talk and think about different aspects, concepts, and designs and test them we'll get closer and closer to success.

That would probably work in real life airplanes, but I think if you try to make longer blades with Lego and you're going to turn them very fast, they'll start wobbling. And that would make the whole creation a lot more unstable... I don't think any of us are physicists, if we were we probably wouldn't be discussing this. From my studies, yes, longer blades are more efficient. This is because they have less drag and create less turbulence. A wide blade, while moving more air, will have more drag and creates more turbulence in the air it passes. A helicopter rotor is not designed to move air, it is designed to change the air pressure above and below it. A fan is designed to move air, not to change air pressure. Yes, Helicopters do make quite a downdraft of air, but that is not the intention nor how it stays in flight. LEGO has the advantage that the stud system is very strong. Throw a few 4x8 plates together overlapping some and they aren't coming off unless your blade hits a solid object. The centrifugal forces are naturally pulling the studs together(sideways), not away. Granted, if the blades go haywire uppity downy then the blade could separate. Another thing to consider about longer LEGO blades is this: I forget which helicopter it is (I think it was the Mil Mi-26, heaviest lifter in the world), the blade tips are designed to not provide lift(or very little). This is because if they did they would wobble out of control, like legolijntje mentioned. The middle of those blades provide most of the lift. The Mil Mi-26 has 8 blades, each being about 50 ft(15m) long. One thing we should keep in mind is that not all helicopters have the same number of blades. When most people hear the word 'helicopter' they picture a four bladed machine with a 4 bladed tail rotor. Helicopters can have anywhere from 2 to 8 blades on one rotor. The Chinook uses two 3 bladed rotors, Mil Mi-26 uses one 8 bladed rotor, CH-53 Super Stallion uses one 7 bladed rotor. Most combat helicopters use one 4 or 5 bladed rotor. Usually the more blades a helicopter has, the more weight it can lift. It may be worth us considering using 6 or 8 of those white blades on one rotor. Something like that, perhaps?

Here is a good list of test results from all or most of the LEGO Motors. From it you can choose the best motor based on Torque, RPM, and Mechanical Power. From my research of real world Helicopters, most use a constant, low RPM. H-13 Sioux runs at 333 rpm(source). AH-64 Apache runs at 292 rpm(source). UH-60 Blackhawk runs at 258 rpm(source). CH-47 Chinook runs at 225 rpm(source). Mil Mi-26 runs at 132 rpm(source). Note that on each helicopter, the rotor diameter is lengthened and the rpm required is lessened. If these multi-ton machines can achieve flight at low RPMs, surely a few KG of LEGOs can. Here is another thing to take into consideration. I'm not saying RPM isn't required. But one thing I've noticed in every LEGO flying attempt I've seen (and I've seen a lot) is that they have very high RPM, but the body is either too bulky or the blades have no airfoil design. Here is an interesting thing from NASA on airfoil designs. You need RPM, but you need controlled RPM. If you have a few hundred RPM and good torque you can work on designing good blades. The Mil Mi-26 has a 105 ft diameter, if you figure one stud ~= 1 foot then that's a 105 stud diameter, or 52.5 stud radius. Roughly a 50 stud blade. The other helicopters I listed barely have 60 ft of diameter(most have less). You can see why the Mil Mi-26 is such a heavy lifter, nearly twice the blade length. The Model RC helicopters I've seen operate at 900-18,000 RPM. They also usually have shorter, thinner, blades and only 2 or 4 of them. They also usually don't have pitch control, thus their altitude is based on RPM, not Pitch like a real helicopter. Many also run on gas engines. We may be looking at acquiring our lift the wrong way. Just something to consider. I look forward to more tests.

@CamAudio, You have to have the pitch of the rotor blades be correct. Just reversing one motor would causing it to pull the craft down instead of up. @ZBLJ, Quad may still work, you just may have to use different speeds. I.E. X at 75%, Y at 80%. I've done a fair bit with rotor and gear testing with technic and know what you mean. The 5292 is not hospitable to gearing due to its high rpm but very low torque. I think XLs may be able to drive the driveshaft and then be upgeared or vice-versa. Using round gears you can get a 1:3 ratio with one assembly, using normal(or as I say, 'hard') gears, you can get 1:5. The XL spins at around 146-214 depending on your voltage. That could get 438-642 or 730-1,070 rpm, with decent torque(easily enough for those blades). Do you know your target RPM?

The 5292 Buggy motor? Eesh, good luck. ~$32 at Bricklink (http://www.bricklink.com/search.asp?itemID=37545&colorID=11) Maybe better on ebay. Maybe you could mount one on the top and one on the bottom in the center of your quad and use a driveshaft to have one motor power two rotors, one for each axis?(top spins clockwise, bottom spins counter-clockwise?) Or alternatively try the tandem again until your other two motors arrive.

Oh, right. I remember seeing that picture, just didn't notice the pitching pieces on the left rotor. Make sure your normal rotor has the same basic weight of additional pieces, otherwise your anti-pitched rotor will be heavier and thus will require more lift or will fly lower(or spin slower). Another thing is to make sure you are activating both rotors simultaneously, with the same control. They need to spin at the same speed otherwise the torque of one will knock it off balance. I know you've already done a lot of tests and are probably aware of most of the aspects I'm mentioning but sometimes hearing them again can bring up new ideas or variations.

@ZBLJ, Your tests are pretty awesome. I'm glad to see there are still a few true LEGO Masters out there who know LEGO can fly. I think the Quad-rotor may work. The Tandem won't with those blades because, like you said, you can't get even lift and drag on both rotors. Tandem also requires both motors to be spinning at the same speed(so for Tandem tests you need to have only one power control knob feeding both motors). As for the Quad, it should be more stable, but I'm not sure how well the lift will work. Quads require two sets of counter-rotating rotors perpendicular to each other. Y X-----X Y Y is Clockwise X is Counter-Clockwise The counter rotations, assuming all 4 motors are spinning at the same speed, should negate all torque. The potential problem I see would be the fact that for those rotors to be turned around to counter-rotate, it drastically increases the size of the leading edge of the blade. The counter-rotating blades would have a lot more drag. I just played with those blades in LDD and it's possible to nearly mirror them, the hard part being creating the angle we need with the required strength. EDIT: In re-watching your coaxial video I see that you've angled them like this.