[MOD] Koncept Mantis - Free instructions

[astyanax]

3 hours ago, nerdsforprez said:

Oh this is a beautiful build.  Well done!  And given that I have 42056 (which I do not like all that much) I will have to built this. 

But, forgive me, the acceleration footage looks to me that it is all downhill.  Significantly.   Please tell me I am wrong...

You are wrong.  Maybe the camera is being tilted a bit. This short street section is definitely flat.

But for sure it's hard to find any flat surface here in the Italian Alps. Only thing nearby is a basketball court, but it's been locked due to corona. I really want to shoot better racing footage asap...

Anyway, such acceleration shouldn't be hard to believe? We're talking 4 PF Large motors, geared UP 2.142x, powered by 2x BuWizz in Ludicrous mode, in a model of only 1686 grams (see scale above).....

Here's a picture of the drivetrain from @Madoca 1977's Icarus supercar, which I borrowed:

Edited May 9, 2020 by astyanax
Added ref to madoca

[amorti]

I have @Didumos69 greyhound with two buwizz and 4 L motors driving the wheels directly... That's impressively quick and yours has 2* gear up.

Even if it has the same motors as Icarus from @Madoca 1977, it has bigger tyres and a little less weight.

I can definitely believe it's quick!

[nerdsforprez]

5 hours ago, astyanax said:

You are wrong.  Maybe the camera is being tilted a bit. This short street section is definitely flat.

But for sure it's hard to find any flat surface here in the Italian Alps. Only thing nearby is a basketball court, but it's been locked due to corona. I really want to shoot better racing footage asap...

Anyway, such acceleration shouldn't be hard to believe? ................

Oh no.... consider me  a believer.... Just bad optics I guess. 

Great model, one I likely will truly build in the future. 

 

[amorti]

The only thing which surprises me, is that Lego pieces can withstand that :)

For sure it'll be a good thing, that this has such wide tyres.

[astyanax]

4 hours ago, nerdsforprez said:

Oh no.... consider me  a believer.... Just bad optics I guess. 

Great model, one I likely will truly build in the future. 

 

Cheers!

4 hours ago, amorti said:

The only thing which surprises me, is that Lego pieces can withstand that :)

For sure it'll be a good thing, that this has such wide tyres.

Indeed my first attempt was using regular CV-joints (between differential and wheel hubs) but they soon turned to pulp. Or, in more lucky cases, they just disengaged upon full-power acceleration. Then I tried the new CV-joints from set 42099 and they have held up fine. That's the setup that is also used now in the instructions on Rebrickable.

[amorti]

I've used the same parts in place of U joints on didumos greyhound. They're holding up remarkably well so far. I think what wears them in that application is a combination of torque and consistent slight misalignment, as Lego small ball joints are "approximate" at best.

[Didumos69]

4 hours ago, nerdsforprez said:

one I likely will truly build in the future

So if you build it, you will truly build it. That shines a whole new light on building. You can build and you can truly build, like you can drink a hasty coffee and you can sit down and truly drink coffee. 

EDIT: Awesome model btw. I would also truly build it .

Edited May 9, 2020 by Didumos69

[Bony_em]

 

 

Closely resembles my futuristic formula one

 

 

Edited May 10, 2020 by Bony_em

[Merlict]

On 4/24/2020 at 10:42 AM, astyanax said:

"covered in a bunch of the largest Technic panels available, making it (almost) comparable in size to the orange Porsche (set 42056). There is no interior. The only "gimmick" is the airbrake. 

 

 

 

 

Man this comparison is great. It's like you let the pieces available just flow, so you get a super smooth look without all the awful gaps and 'cheating' with flex pieces. 

Good stuff.

[astyanax]

4 hours ago, Merlict said:

Man this comparison is great. It's like you let the pieces available just flow, so you get a super smooth look without all the awful gaps and 'cheating' with flex pieces. 

Good stuff.

My reaction is: "I agree wholeheartedly", not "thanks for the complement", because I did not design the bodywork, R. Skittle did. I only take credit for the effort of reverse-engineering it from his Flickr album and providing y'all with building instructions (in full knowledge & support from R. Skittle).

Indeed, one of the main reasons for me to build it in red was so that I could make this comparison with set 42056 (alas I don't have 2 of them!).

It's striking indeed that they are comparable in size, given that the Mantis contains only 40% as many pieces as the Porsche GT3 RS.

[Merlict]

Oh, guess I should read threads more than just looking at the pretty pictures haha

[astyanax]

On 5/9/2020 at 5:43 AM, nerdsforprez said:

Oh this is a beautiful build.  Well done!  And given that I have 42056 (which I do not like all that much) I will have to built this. 

But, forgive me, the acceleration footage looks to me that it is all downhill.  Significantly.   Please tell me I am wrong...

It accelerates faster than a 3yo girl and here's the proof. Do you believe it now?!

 

[Gray Gear]

Yo this thing is fast! 

Poor little princess has no chance in accelleration or top speed 

[nerdsforprez]

2 hours ago, astyanax said:

It accelerates faster than a 3yo girl and here's the proof. Do you believe it now?!

 

yes, like i said before, i believe you !! 

[Pauls Technic]

Now that is VERY cool.

[amorti]

I've just been flicking through the instructions, wishing I had all the pieces to hand.

The front suspension is interesting for a few reasons:

• It doesn't use the usual wobbly ball joints, but similar to Bruno's P1 a frictionless pin instead.
• It use aerofoil wishbones at the bottom, these should help triangulate the suspension to be a bit less wobbly than usual.
• Because of that, it has unequal length wishbones, so like a real car, the way they're mounted should give a little negative camber through the stroke?
• Does it suffer any bump steer?

The rear is cool too:

• Aerofoils triangulate everything for less wobble
• Did the rear suspension work out OK with the too-short driveshafts? I guess the axle sliding in the wheel hub is enough to take up the slack?

I'll gather up the parts one day soon-ish. I've got a fair bit of it already.

[astyanax]

2 hours ago, amorti said:

I've just been flicking through the instructions, wishing I had all the pieces to hand.

The front suspension is interesting for a few reasons:

• It doesn't use the usual wobbly ball joints, but similar to Bruno's P1 a frictionless pin instead.
• It use aerofoil wishbones at the bottom, these should help triangulate the suspension to be a bit less wobbly than usual.
• Because of that, it has unequal length wishbones, so like a real car, the way they're mounted should give a little negative camber through the stroke?
• Does it suffer any bump steer?

The rear is cool too:

• Aerofoils triangulate everything for less wobble
• Did the rear suspension work out OK with the too-short driveshafts? I guess the axle sliding in the wheel hub is enough to take up the slack?

I'll gather up the parts one day soon-ish. I've got a fair bit of it already.

First of all I have to admit your thoughts go way deeper than mine ever went!

Case in point: your comments made me realize, for the first time, that the front suspension's top and bottom arms are of unequal length...

Anyway, although this thread has become a bit disorganized, the Rebrickable entry clearly explains the model's history, and that its design isn't mine. I made several "improvements" to it, but only insofar as I realized improvements could be made. The original front suspension worked fine for me, so I just left it like that... Note that the front suspension is also really really stiff (alternative viewpoint: the weight of the model on the front is very low), so not much "stroking" is happening...

Regarding the rear driveshafts: indeed the idea is that the axles slide in the wheel hub. I did have some problems with the axle sliding out of the 12-tooth gear inside the differential instead, but only on one side. I guess some gears have a firmer "grasp" than others. I solved it by adding a small white rubber band on the rear axle to prevent any sliding:

3 hours ago, amorti said:

I'll gather up the parts one day soon-ish. I've got a fair bit of it already.

So I built the drivetrain to withstand full-on acceleration from 2x BuWizz in Ludicrous mode... assuming 4 stock PF Large motors. I'm morbidly curious to know what happens when you use instead your Chinese "+30%" motors.... Just promise me you'll test it OUTSIDE...

[amorti]

I still haven't tried my Icarus outside properly. It's such a job to take the two buwizz out of greyhound. And Icarus is so fragile that honestly I'm worried about driving it outside.

But from driving inside I can say it drifts like crazy at ~8 volts, and can snap the head clean off a CV joint.

[astyanax]

1 hour ago, amorti said:

I still haven't tried my Icarus outside properly. It's such a job to take the two buwizz out of greyhound. And Icarus is so fragile that honestly I'm worried about driving it outside.

But from driving inside I can say it drifts like crazy at ~8 volts, and can snap the head clean off a CV joint.

Yeah, definitely find a flat open pedestrian-only area, like a basketball court. A (low-traffic) car road is not advised: often has lots of small stones that'll badly scratch the bottom of a low-clearance Lego model.

[BWGunner]

What a brilliant model. An Lobster shot FTW!

[amorti]

I'm going to build this once my bricklink orders come through :)

Considering Porsche wheels are ridiculously expensive and I don't have any, would it work on swirl wheels, or Landover wheels?

They're the same diameter 81.6mm so ground clearance should be the same. Both have narrower tread, however both still seem to have the offset needed to get the rims at the same overall width?

http://wheels.sariel.pl/

Any others which are (lots) less than 25€ per corner and would be suitable? I actually prefer a higher profile tyre to give a bit more cushioning when driving outside. 

Thanks :)

 

Edited August 16, 2020 by amorti

[astyanax]

 

On 8/16/2020 at 9:33 AM, amorti said:

Considering Porsche wheels are ridiculously expensive and I don't have any, would it work on swirl wheels, or Landover wheels?

They're the same diameter 81.6mm so ground clearance should be the same. Both have narrower tread, however both still seem to have the offset needed to get the rims at the same overall width?

Certainly those would all work, technically speaking. As the wheel arches are open and 5M wide, tires that don't fill this width might compromise the looks somewhat. But if you don't mind, who cares?

Unfortunately I don't have any photos of the Mantis with swirl wheels or Landrover wheels, and my Mantis has been disassembled long ago. Nonetheless here's a photo of the Mantis next to set 8448, maybe that'll help:

Full size photo

 

On 8/16/2020 at 9:33 AM, amorti said:

Any others which are (lots) less than 25€ per corner and would be suitable? I actually prefer a higher profile tyre to give a bit more cushioning when driving outside.

Well, I did try putting on the huge 92912 tires... They actually fit inside the wheel arches; however, you can no longer steer. Could still be an option for straight-line drag racing!

 

[amorti]

Thank you @astyanax that's really a big help!

I think you're right that those swirl tyres will look too skinny, at least on the rear. Also since my Mantis will be white, I think the grey of those wheels won't work.

Those Unimog tyres look amazing. It really changes the character of the car from a Le Mans racer, to something from a Batman movie. I wonder if they could steer if they were fitted on Land Rover rims with the new offset?

Edited August 17, 2020 by amorti

[astyanax]

44 minutes ago, amorti said:

Those Unimog tyres look amazing. It really changes the character of the car from a Le Mans racer, to something from a Batman movie.

Haha I'm imagining now the car in all Black... Yeah that would definitely be Batman-worthy!

44 minutes ago, amorti said:

I wonder if they could steer if they were fitted on Land Rover rims with the new offset?

Currently the Mantis has a very tight turning radius, so perhaps adding some stoppers might help. Or redesign the front to include virtual pivot steering...

[amorti]

Just now, astyanax said:

Currently the Mantis has a very tight turning radius, so perhaps adding some stoppers might help. Or redesign the front to include virtual pivot steering... 

I've never been a fan of artificially-limited steering. You can end up with the servo trying to pull the front of the car apart, which is no good for the chassis or the 30€ motor. I had that problem on Bruno's C63.

Virtual pivot steering is definitely a cool idea. I've watched the series of videos from nicjasno with great interest. On the one hand this would be exactly the car to try that on because it doesn't have a lot of bodywork constraints, but on the other hand, it already has unequal length wishbones, and uses the cool F1 wishbone parts. I'm thinking/hoping that with those F1 wishbones triangulating the front wheel, and no upper/lower ball joints, the front wheels should be pretty solidly mounted and it'd be a shame to spoil that, too.