Davidz90

Interesting idea. I guess the main design goal would be reduction of rolling resistance, e.g. large, bicycle-like wheels?

Now something a little different. The striking mechanism that chimes 1,2,3... 12 times depending on the hour: The basic idea was to use a little additional clock mechanism, where the swinging pendulum acts as a hammer that hits the bell. The challenge was in counting the swings and stopping the pendulum at the right moment.

In this video, I have something like that at 1:35: The lift is using chain instead of gear rack but otherwise that would be more or less what you describe. Note that here the lift turns on when the weight reaches the bottom, but that's just matter of simple geometry tweak. Also, I needed quite a bit of leverage advantage to actuate the battery box switch because it is quite stiff.

Is the lift intended to be manually operated or repeatedly going up and down? For manual operation, I guess the simplest way is to have two levers to actuate the battery box switch. One manually operated lever that starts the lift and second one that switches the battery box off, actuated by the lift when it reaches top/bottom.

Very impressive build, even if not working perfectly yet. Gear backlash is a huge issue I'm also struggling with when doing calculations in my clocks (like moon phase etc.), controlling it in a build this big is a really hard problem. I'll need more than one view to fully understand all of this mechanism, but it seems like a bit of an overkill for addition/subtraction? I do not mean to criticize, it is certainly an unique and impressive way of doing this.

Small update on my grandfather clock. Made it bigger (mostly wider) and most importantly, portable. Can be disassembled into few large pieces for transport.

Amazingly well optimized geometry. I've never seen lego walker that remains so level. There is almost no vertical motion at all!

Maybe I'm repeating myself a bit here, but I agree 100% with this. One cannot beat solid I-beam. Also, 16x16 plate is as big as Lego bricks go, I-beam with plate-based central section would be pretty much indestructible. Unfortunately I don't have enough bricks to make a meaningful test. Updated, simplified I-beam design: ibeam by David_Z1, on Flickr core is 2 layers of overlapping 16x16 plates. Flanges are 2x16 plates and 1x16 technic bricks. At some (possibly large) intervals, 2x4 plates (orange) stick out from flanges and support secondary beams (orange) that keep perpendicular bricks from popping out. One can also use longer perpendicular beams to connect two I-beams together side by side, forming a box spar.

Nice idea with the ring, definitely good for safety, although it needs to be very close to the propeller tip to provide measurable performance gains.

Wow, these panels make a surprisingly efficient propellers! I wonder how well lego sails (for example from 42074 racing yacht) would work. It's also interesting that the angle of attack seems to be the most efficient for medium speeds - at the start the car is a bit sluggish, but as it picks up some speed, the acceleration improves. At least it looks like it on the video.

Yeah, there is some compromise between column density and column thickness. I'd say the sections could be two metre long, with columns on their ends (so that section connections are the most supported). Main spar could be single piece, with sections slided onto it. I don't think that the columns need to be that thick - lego bricks can survive enormous amounts of pure compression. How about thinner columns (possibly h-beams themselves), cross-braced with heavy fishing line? That could be rather unobtrusive. Or, if you are not against using non-lego outside the ship, then steel columns (again with some cross-bracing) could be really thin. Third option is transparent polycarbonate tubes as columns. Overall, I think that there is little gain from making the columns any thicker than the main spar. Or, if the most weight is near the top, maybe consider hanging it from ceiling with thin steel cables or heavy fishing lines?

Some more engineering ramblings: Executor_schem_A by David_Z1, on Flickr Executor_schem_B by David_Z1, on Flickr In the first one, pillars end on the lower spar and the bottom is parallel to the ground. In the second option, pillars end on the upper spar and the upper surface is parallel to the ground. Again, I couldn't resist putting main spars at an angle, but they are only connected with triangular framework so it should be no issue. Generally, I agree that some real-life tests are definitely needed. At the very least, it would be very useful to test one full-length main spar. Or even 50% model of the spar, holding at least 25% of projected weight on the full one.

I strongly believe that this build is possible without steel frame. However, it is funny how the supposedly "overkill" 40 stud beams look absolutely tiny in your cross-section. One thing I'm not too sure about are the purple spars between columns - it is questionable if they help much there (unless columns are attached to them forward/back from this cross-section). As others said, I think that the first thing that needs to be specified is the number and distribution of columns on which the ship rests; the more the better, but that hurts aesthetics. After all, the only span that needs to be bridged is column-column distance. Also, it is an open question if its better to use parallel spars that end as the ship narrows (easier to build) or side spars coming towards center, forming a large triangle to which all columns are attached (stronger in ideal world, where angled connections are not an issue).

I see. Yes, with three columns side by side, your concept makes a lot more sense than mine, and definitely has less weird angles. For whatever reason, I assumed that the sides need to be fully self-supporting. As for the white secondary spars - indeed the angled connections could be an issue. Again, I guess they could be attached in parallel to the main spar and then bent into submission, but that is not your goal. If we assume that all the side connections come directly from main spar or central columns, then the upper secondary spar could work like cable in suspension bridge - working strictly in tension and keeping main spar straight. In such a case, the angled connection can be even freely rotating without sacrificing any strength and the spar needs no additional supports. The tension could even help holding them straight when supporting some part of the skin weight.

Yes, of course this is actually I-beam. Called it H-beam due to the above-mentioned font issue Thanks for nice feedback! My intuition is that for sides, it would be best to utilize the triangular shape of the ship and use two spars, coming perpendicular from upper/lower parts of the spine (flanges in case of my H-beam) or secondary spars running just under the skin, and meeting at the edge. That would provide a lot more support for the edge strip and also shorter the distance between spars and the skin. Something like this (of course this is only a scale model, and rather rough one): structure2 by David_Z1, on Flickr There is one main spar (red), two sub-spars (white) and side spars (blue). Magenta lines are some minor cross-braces.

As an engineer and a long-time bridge building games veteran, I'd say - arches with equilateral triangles inside

You are right that the flange is weak in tension and could be reinforced with more longitudal beams, the green plate takes space outside already, so running beams along it would take no extra space. Good point with the green plates. There should be enough flexibility to press them into place; alternatively, some different pin/axle setup would be needed to attach the flange as the last part. Or just use one orange plate instead of three - it still should hold just fine, and the central part could use more 16x16 plates instead of smaller ones. [edit] Ok, I'm stupid, the solution is simple. Build whole plate assembly, including green plates. Then use 3l pins that go two studs into the longitudal technic beams. Then attach one layer of transversal beams with 2x6 bricks between them. Then attach second layer of transversal beams to the bricks. Then use 3l pins through the two layers of transversal beams. The sticking out pins can be used for another, outer layer of longitudal beams. Overall, I think that the only weak point is the slight possibility of plates delaminating in the middle; making the beam single 16x16 plate wide would avoid that... but then it is much smaller and weaker.

I agree that "exoskeleton" idea is a good one - that is why the two secondary spars on my (rather poor) drawing are close to the top and bottom. Here's a small render how 40 studs tall H-beam based on 16x16 plates could look like. Central part is 7 layers of plates. Side flanges (red) are bricks, additional small spars (green plates) keep them attached. hbeam by David_Z1, on Flickr Sorry if I'm spamming the topic; I never considered designing something this big, and I'm having a lot of fun doing so

I did some quick prototyping. Not suitable for main spar, but should be fine for secondary beams: spar by David_Z1, on Flickr Of course this can be scaled up. As I imagine it, the sides would be covered by two layers of overlapping 6x16 plates. Grey frames provide some attachment points and keep plates from popping out. The grey frame is slightly stressed (construction is little bit wider than 4 studs), but not enough for permanent deformation. Besides, with larger frame, the bending would be even smaller. EDIT: Taking some lessons from bridges, I got this (just some speculation, no guarantee that this would work): structure by David_Z1, on Flickr There are arches, but done by bending straight sections - at this scale it seems much easier to do. Also, pre-stressed structure sags less under additional weight of panelling. Secondary beams form equilateral triangles.

Very interesting challenge. Some time ago, I've built a Lego electric guitar and it used H-beam for neck. The forces were nowhere near your example, but I had a one metre beam holding 3 kg of string tension. The cental part of H-beam was 2 layers of plates, 4 studs wide. Sides were technic bricks. Overall, the best way to maximize rigidity is to minimize the number of connections; H-beam with central part made of largest possible plates, oriented vertically, seems like a good idea. Another thing that comes to mind are studless technic beams connected by attaching plates to them; this slightly stresses the parts, but creates extremely rigid structure.

Very impressive! I guess this had to take a lot of trial and error, stable walking cycle is a challenge on its own, springs make the dynamics even more complex.

Nice. I think that the problem with the tail rotor is more about the size and thickness of the rotor blades than the size of the mechanism (which seems to be hard to make any more compact); Maybe rotor blade 99012 would be better? I agree that the nose is a bit off; too flat, too long. But overall, very nice job!

Absolutely amazing piece of engineering and coding! Very creative solution with two black background/white background sensors. On the photo, it looks like a giant artillery piece XD

Thank you very much! Indeed, getting proper gear ratios and arranging them in compact enough form was one thing, but then making sure that everything is properly aligned and runs with little friction was another. Very quickly I realized that auto-rewinder is a must here; grandfather clocks and wall-hanging ones have the advantage of large space below, where the hanging weight can drop. With this form, getting more than one hour working time was all but impossible (and having two pendulums to keep in motion instead of one doesn't help the efficiency). Thanks!

Thanks! Frankly, working out the correct gear ratios made my brain hurt too. In the end, I wrote a computer program to find them. Then, I "only" had to scan through a list of about 300 combinations to find the most convenient ones.