Divitis

Can we see it moving? Pretty pleaseeeeeee

Somehow I'm only seeing this now, sorry. I think I got a little bored with myself, and also my second son got born, which sort of slowed down progress but now he's on a more decent sleeping routine so I hope I'll find time to make the proper reveal happen - funny how many seemingly basic pieces you realize you miss and have to order. Anyway, bodywork process is boring, you just sort of go through every piece in the color you chose until you find something that matches a curve and then go through every piece that combines with it to complement it. And then repeat until all combinations have been vetted and you can sleep a good sleep. The control base in nearly there too.

#16 Sparse bodywork progress at the beginning of April, so about four and a half months into the making. To ensure progress on the technical side would not impede work on the bodywork later on, but also to break momentarily free from the 'tyranny of gears', I was regularly trying things out. Here are some of the early approaches to making sense of the bodywork, in no particular order. I generally don't like the look of flex axles, but I explored them as the only mean to get some of the curves right. None of these new panels exist in red! (still? yet?) The first clean-ish line I got on the rear mudguard! The best early exploration that probably won't fit in the end is this. Might it inspire someone else. Two dishes back to back held together by a clear transparent Spiderman web (the only bar piece in this color) and a transparent blue round tile (I don't have a yellow one). Here's the effect with and without led lights. So overall not much progress from these early attempts, but a stark discovery: This car has no 'anchor features'. It's not a Porsche that's immediately recognizable as soon as you see the lights, or a Ferrari Monza with its asymmetrical seat. You basically have to nail it all together as one. Thank you! Again, longer post than intended. Studio rant will have to wait. Next up: probably the fight for the real axle.

A good way to look at it is mapping top speed over gear ratio, that gives a feeling of what's reasonable to achieve with the engine running at maximum rpm. The P1 can officially reach 350Km/h, divide it by eleven and you get a 32Km/h top speed in first gear. I bet your city car can do better. With the real ratios, that value is a much more reasonable 85Km/h. The Lego rations are clearly just for show. Not that that's bad, on the contrary in fact as they make the effect of gear shifting much more visible. @danielhstahl these numbers are a great find, thanks!

The grandstand is awesome, gives me old school vibes, from the airport monorail set especially. I also like how it integrates ()while being different) with the rest of the buildings.

Lovely!

#15 The gearbox stick and linkage system This is the initial linkage system to operate the gearbox. I'm reproducing it in full to give a sense of scale respective to the whole chassis - it basically occupies all of the cockpit floor. The ball join allows for surprisingly limited movements, because the axle connected to the ball touches the socket piece. This is especially pronounced for diagonal movements (exactly what you need to put a gear in). The easy solution is to 'multiply' the movement by placing the ball joint higher up and having a longer stick, but in this model it would look funny. Eventually, I figured that one can increase and decrease the sensitivity of the mechanism by putting the pivot point respectively further away and closer to the rotation center of the changeover catch. So, I lowered the ball joint so less horizontal movement is needed to turn it, meaning less movement range is required on the gear lever as well. Also, the mechanism slides on two axles, very smooth. But still the range of movement wasn't enough and I set out to miniaturize things further. In this early design, some of the cockpit flooring also helped with holding the yellow constructions in place. The change to 2L rings meant the catches need to be placed at 1/2 stud offset. Together with securing the sliders, figuring out proper bracing was quite a task and for each test I had to fully disassemble the model. The main drawback of this configuration is that the bar rotates inside the cross axe hole of the joint, making things finnicky to operates - for example, you think you're pushing while in fact your rotating the bar only. And to further complicate things, in the 125S the gearbox is tucked underneath the dashboard and the lever bends towards the driver at a steep angle. Replicating this with bars makes the structure way too weak. After countless prototypes, the lesson learnt was: one thing is what works stand alone, with the mechanism fully exposed so that one can fine tune their movements. Another what works when the mechanism is hidden and the lever hard to reach under the dashboard. And so, finally, it was with a heavy hearth that I reverted back to a more conventional set up. It's hard enough to reach in there with adults fingers, no need to make the mechanics finnicky to operate. I thought those who've kept up with my rambling until now would appreciate a little spoiler - some paneling and the pedals are still missing plus there are details I don't like but I reckon I'm mostly there. Happy to hear your criticism, of course To your points @Lipko I never thought of painting parts before, but I might make an exception for the steering wheel. It'd be so nice to have it in brown. @dantheman12 I'm very happy to hear you're finding my updates useful. And by all means, please put the ball joint idea to good use. You won't be disappointed by it's realistic friction and maneuverability - with enough space allowed. Next up: The post got much longer than I thought, so I'll save the early bodywork ideas for the next one, together with some furious ranting over Studio.

#14 Let's talk gears again! I wasn't in love with the gear ratios and generally the gearbox output being on one side and needing u-joints to be brought back to the middle; I was afraid they'd rub on the cockpit floor - which I intend to cover with plates. Also for realism, I wanted to make the whole gearbox one stud shorter and give more legroom to the cockpit. And so, I bode my farewell to the old solution and worked out something entirely new going backward from the output upstream. To accommodate the output axle, the gears axles must be placed asymmetrically - two on the left and one on the right of the central axle. All three on the same size would mean having the outermost link at an angle, which increases stress. The intuition was using the same axle to both transfer movement between gears and receive their output finally passing it on to the output axle (green). The classic 16/24 diff was also considered but there were no 12t spur at the time to engage the bigger side. Luckily I had some 2L rings available. Blue friction pins work very well to keep them from sliding in and out of gear. Positives: Realistic output. Now the gear lever sits right on top of the axle. Much better gear ratios: R: 0.297 1st: 0.29 2nd: 0.45 3rd: 0.80 4th: 1.25 5th: 1.33 Way less slack than I thought - at most the car needs to roll for about 20cm before the pistons move. Better than I imagined. Negative: The gearing for R. But I guess I'll have to leave with it being slightly faster that the 1st. I reckon if a compromise has to be made in a race car, reverse gear is a tolerable one. I had to abandon the 'modes' system illustrated above. But we already know it's only a temporary setback. Tip: An Excel sheet to calculate gear ratios saved me from a head hake, or two Next up: miniaturizing the gearbox stick, and early bodywork

I was thinking about the angle. I don't own the one with the fin, but it looks comparable to the new one from the images

Could it be the rational version of 87745 (which I don't own)?

#13 This won't be a technical update, but one I hope fellow noobs will find it useful to avoid some of the pitfalls I fell into. Plans are useless. Before this project, I had never used a technic panel in a MOC, and had next to no knowledge of their sizes and availability. So after starting with the 125S, whenever I ordered some pieces, if the store had red panels available at a reasonable price, I would get some just in case. Result: the car is pretty much built while the drawer is still full. but planning is fundamental. I have a habit of purchasing pieces 'just to have them' even when they seem like p.o.o.p.s or useless gimmicks, at least when compared to the simplicity of the parts lineup of my childhood. But without these two, the bodywork would have not been possible, or it would have been rather flimsy. A well assorted drawer of 'what if' bricks makes it much more easy to try out ideas and reduces the frustration of waiting for parts. How many times did you have to put a design on hold waiting for that part to arrive in the mail? It is also cheap enough to maintain, especially if one buys pieces in random (cheapest) colors. Stud.io dependency vs embracing imperfections. To me, working with Studio is less cognitive demanding than the real bricks, maybe because I play late at night. So I often find myself working on, say, a supporting structure and wonder 'will it be sturdy enough'? rather that quickly building it with real bricks. Another bad habit is always building to perfection in Studio, which results in either impossible constructions or very difficult ones that need to be put together in a special way. The 3L pins eventually became my best prototyping friends and now I no longer feel guilty using them when I know a 3L blue pin could theoretically be fit. Next up: Another (the last) gearbox revolution. Because the previous one wasn't accurate enough.

#12 Evolution of the front axle (again) I realize this is the second post on the front axle (see top of the page). Apologies if it gets boring, but the duplication reflects my struggles with it. Steering and suspension need to be developed together and the new challenges are: Offsetting the wishbone arms half a stud towards the center to allow using regular wheel hubs. Shortening the steering arms as much as possible to reduce play in the mechanism. Connecting the two, now that they are unevenly spaced. This literally drove me nuts, just look at that lime mess which was the best I could do after days of trying! Routing the movement back to the steering wheel (in yellow below). It would be much much easier if I could rotate the motor so the output is closer to the cockpit, but then the cable wouldn't reach the hub. Of course, I had to rebuild everything to find out. Minus some bracing, this is about 90% there compared to what's in the final model, where the 'transversal leaf spring' also found a way in. I'll leave it at that for this WIP thread so there's some unknown left for the eventual reveal. Learnings: The right placement of the shock absorber is right on top of the lower arm for sturdiness. When the suspension is pushed hard (In my strive for as good as possible, I'm treating this Ferrari as a Mad Max stunt car) the 5l liftarm connecting the upper and lower arm wasn't enough and the wheel hub popped out, I reckon partly because of the imperfect geometry (one arm longer than the other). Eventually, the weak point proved to be the towball pin connection to the hub. So switching to the Audi one solved the problem entirely. To your points: I am indeed proud of this system, it feels like 'overcomplication with a purpose' since it improves playability a lot. Over the course of the development this actually disappeared but then luckily found a way back in. Next up: Plans are useless, but planning is fundamental. Stud.io dependency vs embracing imperfections.

That chassis is so elegant, it makes all the engineering look simple. And I mean this in the best possible way :)

I really like this bizarre model and how you're 'engineering it on the fly'. I appreciate that it takes great skills to enjoy this sort of freedom with Technic, playing with it with the same joyful spirit of brick stacking Duplo.

On the secret switches With the failed test drive where the car could only go as fast as second gear, I started doubting that I could make it ever go fast through the gearbox, even with better bracing. And so what would it be the point of making it motorized at all? So I devised this solution: #1 Connects the motor output and the gearbox input #2 Connects the gearbox output and the drive axle #3 Directly couples the motor output and the drive axle tot he wheels Then, the following is possible. The car runs through the gearbox (#1 on, #2 on, #3 off) The gearbox is fully excluded from the drivetrain for uncompromised performance (#1 off, #2 off, #3 on) The car becomes a push-along model with fake engine running at constant speed (#1 off, #2 on, #3 off) In theory the M angular model can be back-driven (it can be used as a rotation sensor) so one could even steer the car through the steering wheel, albeit somewhat inconveniently. Watch the fake engine run at different speeds while the car stays still (#1 on, #2 off, #3 off) Unfortunately I couldn't see a way to add levers to operate these switches without compromising the aesthetic. Which sparked the idea of building a base for the model, from where they can be operated, ideally with some mechanical trickery to make it impossible to turn #2 and #3 on simultaneously, which would mean disaster. I'm actually going het started on this tonight (time of writing). On the asymmetry of the car. To my knowledge, two 125s exist today and they are slightly different (one has two windshields and the other one, only one has a parking brake). So when fetching images online I got used to incongruences. But I wasn't expecting this: One of the 125 S' most interesting features was that it had just one conventional door, on the passenger's side. On the driver's side, there was a cutout in the metal panel through which the pilot jumped inside. And it's then that I begun really liking the 125S. A Ferrari made for pilots, not fat millionaires. As a perk, the one door setup should make it easier to reinforce the chassis. Thanks @karmadrome and @Paul B Technic! I means a lot reading that my updates are appreciated. And I hope this thread will help fellow inexperienced builders who want to embark on a similar challenge :) Next up: The evolution of the front axle