Lipko

I failed miserably with my 4-speed sequential gearbox, so I'm very curious how you will solve it. According to my experience with about 5 different concepts and 10-15 implementation attempts, I doubt that you can do pure paddle shifting, if you are aiming for playability and reliability. The slack will be too high and the hysteresis (direction-dependancy) of the driving ring clicking is quite big often resulting in two gears being engaged at the same time. Or use 2L connectors without rigdes if you are okay with not fully purists solutions, but I think even with those, the gearbox will be too sensitive for the strenght of rubber-bands (if any), the contidion/friction of other parts, etc. PiterX did a paddle shifting gearbox, but that would be too big for your car. EDIT: or I am just simply not smart enough to design such a system. Anyhoo, do you have pictures of your gear switching mechanism?

With active aerodynamics? Front axle looks very good. I envy you building speed and/or time.

I know but it this case it's locked 100% (if you are not relying on bending parts by design)

Looks very good, but what is that stabilizer thing there (with the push rods)? You effectively locked the left and ride side together, or do I miss something? And won't that one-stud axle connection of the wheels too weak for such a big car?

Not the best but non-RC, non-pneumatic: http://rebrickable.com/mocs/lipko/small-rally-car

Gearing-up means higher friction than with gearing-down with the same ratio. Friction is (simplification) proportional to the contact force between the gears. Sorry, I'm sleepy and both my engineering thinking and English fail me at the same time. I just can't explain it, but it's sure you will have a much higher friction with gearing up and down than with a 1:1 then 1:1 gear train. The friction could be reduced by using bigger gears (smaller contact force needed to transfer the same torque), but most of the times that's not space efficient.

Ever thought of using Duplo pieces for the huge inner structure, or they are not cheap enough (or other reasons)? BTW I also built a very very small motorboat with practically the same SNOT (or rather studs-out) technique, though maybe it's a straightforward way of building ship hulls.

I'm a bit on the opposite side, I was on vacation, I was giving vacation to someone and no building for more than a month, but I'm in business again. Only one vacation left: Transylvania, surveying old houses in small villages and making architectural drawings of them.

I wanted to say that but my English failed.

A larger collection is "unfair" too, because it's not only a question of effort put into your hobby, but it depends on how do you live. In many countries and cities, the prices of apartments and rents are exploding. I, for one, could easily buy a huge collection of Legos because of money. But I can't because I can't afford the space. But this advantage can be greatly decreased by part limits in the contests. There were many contests like that, and they worked, even if you have to trust the contestants since making CAD models can't be expected.

I agree with most of what you say, but I think points 3 and 5 is just a matter of some (really just some hours) of learning and effort (way much less effort that designing a model). The other points are the real factors for me, that's why I prefer contests with part limit (and because sadly in these voting contests the bigger is usually better), and contests with non-generic theme. Though generic themes usually mean much more contestants and virulent contest. So dunno. I'm not really complaining, I just don't like it when some people just modify their existing WIPs/finished models and even go as far as to argue with the contest rules and act like they can't comprehend them. But by far the most annoying thing is the lack of time...

I think you could continue with your WIP. Remember the TC6 contest? Some entries were admittedly very well developed when the theme was announced and I bet many of them only needed to be adapted to the few specific rules. Remember all the higgling about the simple 4 RC function rule? I bet the reason behind most of the higgling was having nearly finished or finished but not announced yet models which did't fit the rules out of the box. So yes, non announced WIPs or even finished models should be allowed. (and yes, I was a bit upset with the very generic theme of TC6)

It would be awesome to enter, but with my building tempo and no part limit in the contest, I can't join...

Same feeling. That chassis is mindblowingly beautiful. It's nice to see doing bigger scale models, I'm really waiting for a 1:9 (super)car from you.

That's pretty cool! I gave up on a Tumbler model* because of the front suspension and steering. Yours seems to work fine and it's visually okay too. Congratulations! *I wanted to build a fully studless, "street" version of it, with gearbox, opening doors and everything else you can find in a Lego supercar.

Or learn to use a Lego modeling tool, such as LDD. It helps a lot because it lets you to have floating panels and other parts to define the looks, and after that you can work out how to fix the panels.

This thread is too lofty for my mind, but I do think/believe that even though the part inventory, topics-to-be-MOCed and the physical constrains of the system limit the number of possible "good" solutions to problems, we still don't see perfect solutions and I believe that it's close to impossible that two persons can come up with the same exact solution and implementation. What I'm trying to say that in the very most of the cases, if two implementations are the same, that one of them was copied. With that said, I think that common sense is enough, no obligations are really needed apart from the obvious reselling issues of MOCs and instructions. It's nice to attribute the direct source of inspiration or actual implementation (attributing the whole idea chain is obviously not necessary). Captain Obvious spoke.

Thanks for the PowerPoint tip! I did the finishing work with Photoshop, I will try it with PowePoint, maybe it's faster.

This is all totally amazing. The idea, the mathematics, the implementation and development, the programming, calculation conditioning (this stuff). This all seem to be a pretty good thesis work material. About how many workhours went into this? (These threads lately make me think that I picked a wrong profession, and this mechanical engineering is just not my thing. It's a bad feeling to feel that I suck at something I love and picked as a profession)

Another problem for me might be the fact that I don't build other's MOCs. I only built Crowkillers' Vampire. And building others' MOCs (because they usually contain more advanced stuff than official sets) is a very important learning process. At least you will learn what's good enough, and that you might be over-engineering and over worrying your build. Maybe if I would have built MOCs with sequential gearboxes, I would have learnt that if a gearbox works 90% of the time, than it's good enough (or not). Building the Vampire taught me that my models are rigid enough, and that the parts of my models (especially the body) are rigid and defined more than enough and that I could be more tolerant towards my models in regards with stiffness. The reason I don't build others' MOCs is simply lack of time and parts. Actually, MOC reviews would also help, so I woluld love to see more of them.

@Cumulonimbus: Do you see fundamental differences (harder/easier) between designing Lego models and "real" machines? Maybe I'm just not a good mechanical designer, but I find it harder in some points to design Lego models than real machines. These points are concept planning and detailed implementation (which are actually the two most main aspects of Lego design...). Or maybe I'm just not patient enough to do proper planning. (and I find Lego and real machine design both significantly harder than programming, maybe I took the wrong profession).

So trial and error design is pretty common. It's somehow very different with real machines. You have a task, you sketch up many concept variants and/or do some benchmarking (look for existing solutions and check if there's an applicable one), you have materials to choose from and usually it's quite straightforward to design the parts needed to achieve those functions in under the given constrains (I'm talking more about special purpose machines than commercial machines, which require tons of optimizations and manufacturing itself is a huge beast). With Lego, you have essentially one material (a pretty weak one), a limited set of parts, and that's it. No matter how simple a real life solution is, if there are simply no suitable parts to reproduce it. A sequential gearbox is a pretty good example. After months of trial and error, something like 4 fundamentally different concepts and 15 final variants, I still couldn't come up with a reliable solution which is compact enough to fit in a 1:10...1:9 scale car, and doesn't rely on the driving ring sliding on a smooth 2L connector, which was considered an illegal technique last time I checked (I tried with the new 3L system, and the force it takes to engage the driving ring and the hysteresis (the point it gets into/out of neutral position is direction dependent) plus the backlash in Lego systems frequently resulted in both driving rings remained in non-neutral position). In real life, you have a selector shaft with properly shaped grooves to guide the arms engaging the driving rings (1 shaft + 2 parts per speed); plus the ratcheting system which is basically some pins at the end of the selector shaft, and a special shaped part to grab the pins, plus a spring (2 parts).

Working out all details just in your head is close to impossible (or at least for me). Anyways, I usually design with LDD and with real parts simultaneously (I usually start in LDD, by defining the sketchy boundaries/wheel positions etc). I usually design smaller modules in LDD and try it with real parts as soon as possible (such as front, or rear suspension, gearbox, some other mechanism). I sometimes start with real parts and improve the design in LDD, sometimes the opposite, depending on where I get stuck (with real parts or in LDD). I usually have several versions of the design in LDD (I make backup copies even in case of small changes), and have 2 (very rarely 3) real builds simultaneously, if my part inventory lets me. My rule of thumb is to never prototype with the final colors, because I surely won't have enough parts in the final color to build the final model. Having no parts to keep to at least one copy means the whole real build have to be precisely modelled in LDD in order to make the final build with the right colors. I rarely design on squared paper too. This all sound nice and all, but I still fail to use some proper design methodology, all of this is just random trial-and-error design. And it's pretty sad because it's very ineffective, and I graduated as a machine designer...

You are the master of mechanisms with differentials.

If a mod made the last reply, and the reply implies the uselessness of the topic, than you can suspect something...