TJoling Posted October 21, 2014 Posted October 21, 2014 Hi all, Here's the first moc from my side to present here. As the title says, it's a Trophy Truck, which is a known phenomena by now I guess, seeing all the technic trophy trucks appearing lately Mine however, is supposed to be a little different from the rest, since I like a small technical challenge. I let the pictures speak for themselves first: Trophy truck WIP by Thomas Joling, on Flickr The first mock-up with the initial design ideas visible: pneumatic suspension, 5 RC motors for propulsion. Proportions were out of sinc though; Trophy truck WIP 2 by Thomas Joling, on Flickr Pneumatic suspension discarded to be added again later on. Fixed the proportion issue by shortening the middle part. The front RC unit is now to high up and to much upfront to be properly hidden by any bodywork. The steeringoutput of the unit couldn't be connected to the gearrack either, so a servo had to be put underneath the unit, raising it even more. As it turned out later on, the RC units output wouldn't have been powerfull enough to make the thing steer anyway, due to the combination of the large caster angle on the front wheels and the weight of the unit itself. The large caster angle is achieved by tilting the whole suspension backwards. This was also the reason why the steeringoutput of the rc unit couldn't be connected to the steeringgear. Anxious to try if 2 rc units pack enough punch to power 5 rc motors together, I let the aesthetic issue of the front rc unit for what it was, figuring I could solve that later, and put the thing on the street. Turns out rc units are designed to power 2 rc motors, THAT'S It. The 5 motors caused some unexplainable behaviour from the rc units (sometimes it seemed like one of the units couldn't make up its mind whether it should drive forwards or backwards, regardless of me giving the signal to drive forwards ). This stuttering has caused some broken U-joints in the meantime. This made me try out different driveshaft designs, including springs to keep the darn thing in place; no success either Eventually I found that 2 POOP U-joints together with an extendible axle made of a portal axle hub and wedged belt wheels worked the best without having to use non-lego parts. Now I could definitely see 5 rc motors were really to much for the rc units; the thing could bearly start up without the power shutting down, and once rolling it could only just surpass normal walking pace (instead of ). I decided it would be best to remove 1 rc motor. This would improve reliability, (hopefully) performance and because I could build the middle part more compact, it would improve the aesthetics as well; the front rc unit could be moved backwards and lower down. I put on some unimog tires on 41999 rims for that actual trophy truck feel I turned the units and battery on, put the truck on the ground and slowly moved the joystick forward, and.... nothing! Apparently I already drained two sets of batteries while testing before (i bought them new) so I now have to buy new batteries before continuing.When I've done that, the story will continue Quote
Technyk32231 Posted October 21, 2014 Posted October 21, 2014 Wow, looks really badass and fun to drive! For pneumatic suspension, will you modify the cylinders by putting springs inside them, or will you just use air pressure? This guy approves of your u-joints: Quote
lukeandahalf Posted October 21, 2014 Posted October 21, 2014 I've been dreaming lately of buying one rc motor... What an investment! I'm guessing you bought sets vs. individual parts on BL? Looking forward to seeing this "flying"! Quote
TJoling Posted October 21, 2014 Author Posted October 21, 2014 Wow, looks really badass and fun to drive! For pneumatic suspension, will you modify the cylinders by putting springs inside them, or will you just use air pressure? This guy approves of your u-joints: The original idea actually was to put springs along a central pneumatic cilinder, which would keep the whole system under vacuum. The principle should work, although in practice it requires some more finetuning unfortunately. I probably should switch to first gen pneumatic components... @lukeandahalf: Thankfully I got a 8366 as a birthday present when they were still on sale. Lucky me found another one on Ebay a while back for about €30. The seller rendered it worthless since the remote didn't work anymore, and the set itself missed some parts and the booklet. The important bits still worked like a charm though Quote
timslegos Posted October 21, 2014 Posted October 21, 2014 The reason you're having trouble with 5 rc motors is because each rc unit was meant to handle 2 rc motors each, any more than that and you risk seriously damaging the rc unit! tim Quote
Black-Build Posted October 21, 2014 Posted October 21, 2014 Looks interesting! But don't make it too heavy like sariel did with his Dakar Truck... Quote
z3_2drive Posted October 21, 2014 Posted October 21, 2014 This looks awesome! Good luck with it, I'm liking the use of dampers and I hope the rear suspension holds up at full speed. Right now I'm torn between making a trophy truck, muscle car, or crawler with my 4 motors... Quote
Technyk32231 Posted October 21, 2014 Posted October 21, 2014 This looks awesome! Good luck with it, I'm liking the use of dampers and I hope the rear suspension holds up at full speed. Right now I'm torn between making a trophy truck, muscle car, or crawler with my 4 motors... Make a King of the Hammers buggy or a rock bouncer. Quote
AndyCW Posted October 21, 2014 Posted October 21, 2014 Looks entertaining. I hope those drive shafts hold together. I had a problem with the torque forcing, a similar design, to twist apart with shock loads. I had to redesign the geometry to avoid the need for telescoping drive shafts. The weight of the two RC modules and their batteries is going to put a hurt on your drivetrain. Good luck. v/r Andy Quote
Rishab N Posted October 22, 2014 Posted October 22, 2014 5 RC motors wow. I think your idea of using 4 is much more feasible and it should do well Quote
TJoling Posted October 22, 2014 Author Posted October 22, 2014 Looks interesting! But don't make it too heavy like sariel did with his Dakar Truck... That's a good point. I hope to keep the weight below 2 kg actually. This looks awesome! Good luck with it, I'm liking the use of dampers and I hope the rear suspension holds up at full speed. Right now I'm torn between making a trophy truck, muscle car, or crawler with my 4 motors... Thanks! The rear suspension holds up pretty well, I only had to make some reinforcements on the dampermounts to the trailing arms. I'd like to see what you would make out of 4 rc motors in a trophy truck! Looks entertaining. I hope those drive shafts hold together. I had a problem with the torque forcing, a similar design, to twist apart with shock loads. I had to redesign the geometry to avoid the need for telescoping drive shafts. The weight of the two RC modules and their batteries is going to put a hurt on your drivetrain. Good luck. I experienced the same at first, so I made a different design of U-joint which you can see on the last picture (bearly). These are a lot stronger, and don't suffer from torque twisting. Quote
Epic Technic Posted November 9, 2014 Posted November 9, 2014 You better hurry up, I wanna see more. Quote
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