Jeroen Ottens

I know for a fact that this RCX mod is not an official LEGO mod. In fact at the time I saw it on the internet and wanted to show it to my colleagues in the LEGO Technic design department. They wouldn't believe it (I had even a hard time explaining that there were AFOL's at all). Unfortunately I couldn't find the pictures anymore. The only official model that I know of that had the option to couple two engines hardcoupled was the 8457 Power puller that I designed together with Markus. It did come with one motor in the set, but we had put everything in place so that you could add a second motor for more power. We even had to adapt the design so that it would not eat the gears when you drove it into a wall. But to @1974's point, that were also these old 9V motors.

I like it! Both the original post + the build upon each other's ideas thart follows. I see more optimizations possible in the size of the assy by flipping one of Andy's differentials and then moving it one stud sideways. You then can use just 3 16T gear to go from the drive axle to the sensing axle.

That is indeed the case. At the moment even this simplified gearbox is suffering from high friction , but I am unsure whether that is due to insufficient bracing, too much upgearing or too many gears engaged.

The advantage of the new gear ratios is that the blue 20T gears can be used to make the b,c and e ratios in a very compact manner. So the total gearbox is now even smaller than the previous version: Next step: build it in real life again...

I built the gearbox for real and what you and I already feared happened. When I tested the left gearbox the reverse gear completely locked up (even without the engine connected). I then also made the right gearbox and there the 1st gear also locked up... So it is back to the drawing board. I will have to reduce the gear ratios b, c and e from 3 to something between 3 and 5/3 (=1.6667) (the lower the better). A 16/20 * 24/12 combination gives 8/5 (=1.6) so that is just not enough, a 20/16 * 24/12 gives 5/2 (=2.5) which is still a bit too close for comfort to 3. Hmmm... edit 1: A 16/12 * 20/12 gives 20/9 (=2.22), but that will give a one stud offset somehwere between the axles... but if another 16/20 is added the gear ratio becomes 16/9 (=1.7778) and the extra stud is gone. Now the question is whether this still is compact enough (and what the ratio of d must be to still have a good switch between the even and odd gears, this could become ugly as well). edit 2: Yeah, this is cutting it too close, d has to be now between 1 and 16/15... edit 3: Another route is to make a and f bigger, say 4/5. It is now possible to lower b, c and e to 5/3. d now has to be between 1 and 5/4, something like 10/9... Which I suspect brings me close to the gearbox of @Rudivdk, right? Ratios then will be: R = -50/27 = -1.85 1 = 50/27 = 1.85 2 = 40/27 = 1.48 3 = 36/27 = 1.33 4 = 30/27 = 1.11 5 = 27/27 = 1.00 6 = 40/45 = 0.89 7 = 36/45 = 0.80 This brings the total range down from 5 to 2.3, so the engine RPM will not change a lot when changing gears, but hopefully this one doesn't stall. @Pvdb: I'll have to check the 3rd and 7th gear. thanks for pointing this out.

It was a productive day today Here is the first digital version of the gearbox: It is almost identical to the schematic, only the reverse is the 20% slower than originally envisioned. So that is now 1.5x slower than 1st gear. It was quite a puzzle to get it all packed in between the engine, the frames, the rear suspension and the monococue: It'll probably still will collide with some bodywork mounting structures, but all in all I am pretty happy. The only thing I couldn't avoid was one idlegear on a rotating axle. There is one 20T blue gear for the reverse that is on a rotating axle. Which is probably the worst one as it has a worst case rotation speed difference of -3.6 with respect to that axle, which is the biggest differential speed there is in this gearbox I think... But I just couldn't find a better way to connect that reverse gear.

Ah, that gap. That is not a bug, but a feature. The real car has quite extreme ventilation gaps there (albeit this one is even more extreme maybe).

Wow, thanks Please do not get discouraged from sharing your progress. We were all starters at some point. My first models were also not at this level. I hadn't considered the bionicle teeth, but I fear they are too short to add a meaningful curve. The gap between rear panel and roof is on my todo list. I am not sure which weird gap you are refering to? Those 50 shades of lime are annoying indeed. Thanks. I do not have a specific build order, that varies from model to model.Most of the time I also start with the inside, but in this case I could fit two big frames behind the monococue, so I figured that would give me enough space for the gearbox, so I skipped that until now. Thx. I started working on the gearbox. Since this car has 7+R manual-automatic sequential gearbox I thought I would put that in. Over the years I have developed my own little schematics to design gearboxes: The red lines are the axles for the waveselectors (the selectors themselves are the slanted red lines). The blue lines are the gears themselves. The small horizontal blue lines are gears, while the vertical lines are the connecting axles. The letters indicate that there is a gear ratio between the gears they connect to. b,c,e are on input axles, while a,d,f are on output axles. Finding a gear ratio is now simply done by following the shortest path from the wheels to the engine through the gear you want to know the ratio of. You start with a gearratio of 1 and every time you encounter a letter you multiply the gear ratio with that letter. For instance reverse: You start at the bottom, go left-left-left, then up-up, then left along c, up to R, right, up-up, right along d, and up to the engine. This gives than a gear ratio of 1*c*d. So this gearbox consists of three gearboxes, the upper left one for the even plus reverse gears, the upper right one for the odd gears and the middle bottom one is used to select which of the two gearboxes is used. That one will cycle continuously, while the other two will only shift every other cycle (asynchronously). As you can see the left and right gearboxes are nearly identical with the same ratios (a=f, b=e), only the reverse gear is different. The connecting gear ratio d will put the gearratios of the left box nicely inbetween the ratios of the right box. The only disadvantage I see so far is that by using a gear ratio of 3 for b,c and e I will be using a lot of 24T-8T gear combinations. That may give some headaches when fitting everything in these big frames. Well, I hope this made any sense and was helpful to anybody. I'll be off trying to convert this schematic into an actual gearbox.

Thanks everybody for the nice comments and helpful tips. That is much appreciated. I'll change that once I have the big panels in black. In which direction do you miss the curvature? From top to bottom or from side to side? In the meantime I have rebuilt the 'hip' section. Here are two pics of the whole car as it is now: I am not completely sold on the front of the roof, I would like to get a forward curve on it as well, but I haven't figured out a way to do that. The side intakes are still a bit extreme, but at least I have a first attempt at the front lights: And a final shot from the back to show those rear lights (yeah I really like them ): Almost all bodywork is now securely fixed in place. So it is time to work on the inside again. I still have to add a gearbox, find a place to operate it, invent the mechanism to open the doors and do the whole detailing of the interior and engine(bay).

Time for another update: I have redone the roof to make it more curved and less wide. I also added the paneling that goes over the motor. It is DBG at the moment, but I may change that to black. I also made the rear. It is now one stud further to the back which gave room for a stronger structure behind it, so it is much more solid now. The paneling on top behind the door is nice and smooth, but does not resemble the real car at all, so I will tear that all apart and start over again (maybe even including the top part of the door). It is always a balance to find the lines with LEGO parts that give a clean look, versus following the lines of the real car to the millimeter, but I feel that in this case I have strayed too far from the real thing. So next attempt will be to try to create that sharp line between the side and the top from flexaxles. Leg godt

It has the yellow tracks and some new triangular panel (3x9 or 3x11?) on the top of the hood, so it would be a really good fake... Normally I reserve judgement until I've seen reviews, but this model really does not seem to match the price. So hopefully that gets corrected before the release

No, then I would make the whole car red.

You may have point there... Of course the big green fenders do eat more away because they have such a wide spacing around the wheels. With the red mudguards I would have a stud extra space. But even than I might be a bit too short.

Hi, Another update. Here is a first attempt at the side view. As you can see I am running out of lime parts here and there . This is still a very crude version. Things to improve: - Get a mechanism to 'lock' the door in position when closed - Get rid of that gap between the two 5x7 panels at the end of the door - Get a better orientation of the 5x7 panel before the fender - In general get all panels fixed in a proper way I also don't like the gap between the fender and the 3x13 panel above it and finally the roof is too wide and too high at the sides. So the monococue will need a redesign as well. So it is one step forward, two steps back at this point. I am also still on the fence with the colour vs the fender size... I may have to build both

I understand where you are coming from with the connectors. Unfortunately there is very little room to work with to attach anything in the back. I only have 2-3 studs depth to work with. The nice thing about the connectors is that they don't require any force to stay in place. So the supporting structure can be simpler. Whereas bending flexaxles in shape at these curvatures requires a lot of force that requires a much stronger and stiffer supportstructure. I may make a red version as well, but for now the lime colour advantage outweighs the larger gaps around the wheels.

That is indeed the version I am modeling

After a lot of tinkering I've managed to find a way to have those rearlights in a relatively clean way in the rear together with all the curved serpentine lines:

Very cool looking crane . Packed with functions as well.

Very clever mechanism and a nice evolution of the previous gearbox!

Thx. You have a point, I'll see if I can make it more curved when I go back to this area later. It is . Interesting idea, but I'll first try to make it in lime Thx, it is nice to do a WIP topic. The feedback helps with seeing what I don't see anymore. I haven't decided yet whether the model will become publicly available. The interior will be black/white I think. So far I only used 2 different elements and that already restricts the colourpalette to white, DBG or some very bright coloured interiors. I'm not sure yet whether the weight of the car will collapse the front suspension, so I first want to check that before I commit to the ride height adjustment method I have now. Here is today's update: I changed the bodycolour to lime as per the original idea. The wheel arches are wider now because of that. I also designed a door with hinge. It doesn't have a spring loaded mechanism in yet and the space is really small, so that will be a challenge. Also there is still some volume conflict at the back end of the door when it is being opened, but I am quite pleased with the looks (and sturdyness) so far. What I am especially pleased about is that I was able to build a hinge that is strong, stiff and keeps the door exactly in system despite the angled hinge.

Hi, Time for an update again. First a picture of the rolling chassis. Both the front and the rear axle assembly are modular, so they can be attached to the monococue with a just few pins and axles. The gears that you see in the front are part of the ride height adjustment system. I haven't decided yet whether there will be a similar system in the back. In the rear I have tried to replicate the beams and struts of the original car: I am not sure that the black diagonal beams will do much given the amount of play that LEGO has, but the grey diagonals are in system and really add bending stiffness to the whole frame. Finally I have been experimenting with the front bodywork. I was intending to use lime as the colour for the car, but I realized that with the smaller red mudguards I can make a wheel well that hugs the wheel more. It is tight (so tight in fact that I had to use axle- and pin-connectors to shave just a few millimeters of the edge of the wheel well), but the tires don't rub. I am quite pleased with how the new triangle panels could be used to create those high rising mounts above the wheels. Red ones are on order, but LEGO B&P is not so fast these days. It makes it a bit difficult to judge how the lines will look when all the DBG is replaced with red. Maybe I'll need some more flexaxles to get better defined edges. At the moment the front suspension is just a single hard shock per wheel. With the current bodywork that is still enough, but it does not feel very sporty now... I used some big 5x11curved panels to get a closed floor behind the curve, but maybe I should make those black instead. Comments and critique are welcome as ever.

Actually there is a 7x11 frame below the 3x13 panels. That frame is connected to the backplane with 11.5 double bent liftarms. I use this element to connect the 9L links with: This fits inside a normal friction pin (at least until this year it did). So the 3x13 panels are mounted with friction pins. The roof with the links is definitely stiffer in bending than without the links, it is only in torsion (around any axis) that the links offer no added stiffness at all. As for the 3x11 frame in the center: yes I have thought of it (I even started with that despite the annoying asymmetry of it), but one I had the dashboard in place I realized, that even if I would route an axle through, there would be no space behind the dash to do anything useful with that axle (although I now realize that I could use it for rideheight adjustment on both axles... hmm...). The 5x7 frames were my very first idea, but they are so oversized that that idea was very quickly abandoned.

Thanks guys. Modularity is on the wishlist. I was about to write that the front suspension would be difficult to build as a separate unit, but I just realized a way to do that anyway . So thanks for the nudge in that direction Colourscheme will be lime on the outside, black and white in the interior and maybe some red accents. Functions will be pretty standard: - independent suspension - steering via steeringwheel (maybe also removeable HoG) - sequential gearbox (operated through a lever or knob in the back) - butterfly doors (manual, hopefully with a springloaded mechanism inside the door) Bonus function would be ride height adjustment This design will be more than usual focused on replicating the shapes and structures on the inside of the bodywork. One of the downsides of that is that it is virtually impossible to route an axle from front to back. The central column of the monocoque is so thin that even a single axle is difficult.

Hi, I'd like to present my first steps in the design of a 1:8 scale replica of the Hennessey Venom F5. This time I've started with the carban fiber chassis: The plan is to try to stick to the original structure as much as possible. As is often the case I found that by following the original structure the LEGO equivalent is also stiff and sturdy. The combination of panels and frames make such stiff boxes that even the loss of the torsional strength of the A-pillars is not a problem. The front wheels are really close to the front of this chassis, so the wheel wells are functional. They are a bit deeper than the real counterpart because of the ridiculous width of the LEGO wheels (then on the other hand, the steering angle in the LEGO model is probably a bit smaller than in the real car). The dashboard is already detailed as well. With two big screens, and the double ventilators in the middle. I plan on using this part for the steeringwheel: I even made a short video to show it from all sides : Comments, critique and questions are appreciated as always

Another great Koeningsegg from your hand . The body work is smooth (if I nitpick maybe a bit on the cluttered side), it looks solid and sturdy and it has an interesting gearbox concept. Great model