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Daniel-99 posted a topic in LEGO Technic, Mindstorms, Model Team and Scale ModelingHello everyone! I would like to introduce you my new top-tech mid-scale Trophy Truck "Falcon". This car is a TRUE RC car in Lego clothing. Technical characteristics Full independent suspension with positive caster on all wheels Minimalistic and strong transmission with metal CV-joints 4 - wheel drive 4 Buwizz motors for propulsion (1 motor per wheel) Custom RC controllers adapted for Lego 3S Li-Po 35C 2600 mAh for power GeekServo for steering soft RC wheels 75 mm Custom wheel hubs with metal bearings Light bodywork, 1270 gram of total mass Instructions? Some of you might be interested in instructions. Well, there will be non, I am sorry! Here I will explain why instructions for this car are impossible. Falcon has 4 Buwizz motors for power, which can be easily changed to Buggy motors or Mould King version. Power source and controllers could be replaced with two Buwizz 3.0 units (in theory). But there is no way to replicate both suspension and transmission with lego parts only. Non-Lego solutions: Custom 3D-printed parts, such as wheel hubs, steering arms, suspension arms with 4,5 stud length Modified Lego parts Hand-made parts from plastic bottle ;-) Broken Pythagorean theorem in suspension metal parts, which make the whole car rigid Chassis Falcon has same chassis as a Wilde beast, but with shorter wheel base and suspension arms. So I will not dive into details here. Bodywork I was inspired by a Trophy Truck by Keymaker`s armored Trophy Truck. Though I reduced some details and widen the body by two studs to fit the chassis. Made for outdoor driving This car is not a shelf model. It was made for regular, extensive and extreme driving. Recall, that the elder brother Wilde Beast had a problem with motors: they were not strong enough to translate all the power from Li-Po battery to 90 mm RC wheels. That is why Falcon was made in a smaller scale to fit 75 mm wheels. Now motors does not struggle at all! Enjoy drifting on sandy road? - easilly! Lego Outdoor cars usually struggle from dust and dirt filling the transmission. This car has a minimalistic transmission without Differential, so there is noting to break. The weakest parts of lego cars (wheel hubs with CV joints) have been replaced with custom hubs with metal bearings - no more plastic dust in transmission! And nothing to brake! Massive 3S Li-Po provide an hour-long continuous driving. RC controller with physical buttons is very comfortable to use. After two weeks of tests I added fenders for the front wheels to keep the inside of the car from being filled with stones. 4WD drifting is a fun thing to play with, but I got tired from cleaning the car from small stones after each driving session!
Daniel-99 posted a topic in LEGO Technic, Mindstorms, Model Team and Scale ModelingHello everyone. This is a story of my mid-scale RC baja truck called “Phantom”. The beginning. I always had a strong desire to go fast. For that reason I made my Red Roadster powered by Buwizz motors (See my Profile for dedicated post). But this sport car has one significant disadvantage - it requires a very smooth road! So I decided to build a trophy truck. I learned a lot about trophy trucks made with Lego. Best of them had 2 Buggy motors for propulsion with a direct connection to the rear wheels. So I decided to build myself a similar setup. First trophy truck I designed in big scale (~1:10) but Buwizz motors were struggling with a load from big wheels (and that is not a problem of motors, but a problem of construction). So I made a portal reduction and the problem was solved. After that I build an ultimate dune Buggy “Dragonfly” with independent suspension driven by couple of Buwizz motors. The result was great, Buwizz motors allowed to drive it very fast on 85 mm wheels. So I decided to build a trophy truck with them. Such wheel size is the smallest one which could be used outdoors. Smaller wheels does not provide enough of ground clearance to go full speed on bumpy terrain. Photos. Front axle. I started the build with the front suspension. A technical task was the following: - to use big Lego wheel hubs - double steering rack - positive caster angle - ridged suspension arms I took many ideas from the front suspension of my Dune buggy and tried to make it smaller. Dune buggy used 9,5 L shocks so I decided to change them to 7 L shocks. Also I was able to avoid ball connections, since they struggle a lot at bumpy roads. Here is the result. The steering motors should get connected to the vertical black axe (on the first picture). The key idea was to place steering arms horizontally and in a slight diagonal way. Such placement caused some friction in the steering system, but from the other hand it reduced the wobbling to ZERO! Also there is a 3 studs distance from the connection of steering arms to the wheel hub and the pivot point of the hub (see picture 2). It reduces the maximal steering angle, but strengthen the steering system and make the control smoother! Rear axle. A technical task was the following: - direct mounting of Buwizz motors to the rear axle - Long suspension arms and long travel - Suspension with progressive hardness I decided to make it simple without any articulation, though there was some provided by bending of plastic parts. There are two sets of springs used. Small vibrations of the rear axle get absorbed by a soft 9.5 springs, while hard bumps compress the rear axle stronger, so the set of 7 L springs does their job. Finally, there is a couple of Lego rubber elements which play a role of fenders. So there are three stages of compression. First stage. Soft settings. Second stage. Hard settings. Third stage. Rear axle touches the frame. Frame of the car and bodywork. A technical task was the following: - two layers of frame - use the roof of the car as structural element - minimalistic bodywork The space frame of the car consist of two layers. Roof of the car tighten the upper layer in order to bear the load from the rear springs. The middle compartment is dedicated to power sources. The "new" cross-beams (15L and 11L) were very helped a lot. The bodywork is made with several panels which can be easily detached for servicing the electronics. Electronics. On photos above you can see a custom Lego-compatible RC unit equipped with two high power cells 18650. It provides more power comparing to Buwizz 2.0, but it is not enough for two Buwizz motors. It get overheated quite fast (5-10 mins). One may ask me, why I use it. Actually, the first version of the Phantom was powered by two Buwizz 3.0 units, which provided a plenty of power to the car. But I managed to drown the car at first outdoor driving test! So I bought replacement for them since there was no possibility to purchase new Buwizz units in Russia. Here is the video of an accident: This month I bought a different Lego-compatible RC electronics from a Russian AFOL, it is called "Wixy". It plays a role of the controller for RC motors and allows to power my cars with 3S Lipos! WIth 3S Lipo I forgot about lack of power and was able to ride the Phantom for miles and miles... Conclusion. The car Is made for outdoor driving. It has a decent speed and a good control. Though there are several weak places of Phantom which can not be fixed with plastic Lego parts. The dust is very annoying, especially on county roads! It fills all holes of the car, most importantly plastic wheel hubs. I destroyed all the wheel hubs I own and there is no way of fixing the problem... Also the car has slight problems with ground clearance - it is acceptable for city roads but too small for stony surfaces. Finally, the Truck can not go trough the tall grass with such small wheels and RWD.