[MOC] Rugged supercar - Hammerhead (1:9 scale) - Revisiting

[Didumos69]

1 hour ago, Lipko said:

Hmmm, the only issue I see with steering is that it's maybe hard to perfectly center the steering wheel (the 2L axle not inserted between the U-joints implies I'm right).

For me perfect centering is a must in my designs. I usually try to use Madoca's 12/20*12/20 reduction scheme with the transfer axle rotated 45 degrees. Though I have to admit that in the telehandler the steering wheel is only easy to be centered by luck. But apart from that model, all my models after the V12 Coupe have perfect and easy to align steering wheels and this is a major part in the design process.

 

1 hour ago, Jeroen Ottens said:

You shouldn't make comments like that

You know what kind of perfectionist Didumos is, now he will have the perfect excuse to delay his bodywork designing even further

EDIT: But I do agree, it is definitely a bonus if the steeringwheel is perfectly aligned with the wheels

Haha, I'm affraid you're right Jeroen! But it turns out I'm a lucky guy too. The odd number of 90 degree meshes easily makes you think the steering wheel will always be 1 tooth out of center - in this case 1 tooth of the last 12t gear. That would be true if it wasn't the angle made by the U-joints to align with the tilted dashboard that compensates for that perfectly. Here's a short - unlisted, bad-quality - video in which I fixed the steering wheel in centered position and try to show what I mean. It also shows how the slack in the steering gears averages around the center position. The fact that the 2 U-joints are not correctly aligned and the 2L axle was not inserted was because I didn't want to put in the effort in LDD.

And here's a video showing the HoG in operation. The HoG works the same, but the steering wheel operates with less slack compared to the situation with 3 8t gears. I think this is a more elegant solution:

 

Edited December 14, 2016 by Didumos69

[Paul Boratko]

Don't be surprised if that steering set-up doesn't work as well when you start adding the weight of the car's body.. I used a similar method over a decade ago.. And while it worked, there was a lot of stress on the universal joints because of the weight of the car.. I try to avoid using bevel gears(meshed 90 degrees) as much as possible in the steering..

 

 

[PorkyMonster]

24 minutes ago, Paul Boratko said:

Don't be surprised if that steering set-up doesn't work as well when you start adding the weight of the car's body.. I used a similar method over a decade ago.. And while it worked, there was a lot of stress on the universal joints because of the weight of the car.. I try to avoid using bevel gears(meshed 90 degrees) as much as possible in the steering..

That struck a chord with me! When I started (which wasn't long ago anyway, haha) I used rack/pinion with gear downs of 20/12 or 24/8, and more often than not, with weight added to the model, gears slipped and alignment was gone with the wind... and because I wanted to brace the gears properly in the first place, they ended up at locations rather inaccessible and I had to tear down quite a large portion just to fix that.

 

[PorkyMonster]

9 hours ago, Didumos69 said:

Yeah, you're right. I did exactly the the same in my Steppenwolf. I did need to add an extra half bush to secure the end of the CV-joint inserted into the diff though. Otherwise the CV-joints would eventually get pulled out of the diff because the distance between the CV-joint and the U-joint varied in turns.

I do have a different solution than your half bushing. But I'll leave that for other occasions as I don't want to deviate too far from your main topic...

[Didumos69]

On 14-12-2016 at 11:24 PM, Paul Boratko said:

Don't be surprised if that steering set-up doesn't work as well when you start adding the weight of the car's body.. I used a similar method over a decade ago.. And while it worked, there was a lot of stress on the universal joints because of the weight of the car.. I try to avoid using bevel gears(meshed 90 degrees) as much as possible in the steering..

Okay, thanks for pointing this out. If I understand correctly you're saying that 90 degree bevel gear meshes generate friction when steering gets harder due to increasing weight. I'll see what I can do. This HoG steering is giving me more headaches than the entire build sofar.

Edited December 16, 2016 by Didumos69

[Didumos69]

Over the last 7 days I found some scattered moments to make sure the chassis fully embeds the seats and the H-frames supporting them. In that process I also incorporated several 5x7 angled liftarms to reinforce the way the front and rear modules are connected to the mid-section of the chassis. This reduced longitudinal twist significantly and made the red diagonals (based on Pythagorean quadruples) unnecessary. I did hold on to the ones in the back though, simply because they did not collide with other changes, but I might eventually drop those too.

As for the HoG steering. I decided to leave it the way it is right now. I tested it with an extra kilo of weight and after gearing down by another 12:20, both steering wheel and HoG still worked satisfactory. It remains to be seen how heavy the build will be when it's finished, so I undid the extra gear reduction for now. That simply feels most playable right now and gives me an overall gear reduction of 12:20.

 

A few more images:

LXF-file (with placeholders for the Porsche wheel hubs!) can be found here. Comments and (suggestions for) improvements are welcome.

Edited December 20, 2016 by Didumos69

[Lox Lego]

I am very much looking forward to the body work of this car! Do you have a vehicle in mind? Have you scaled this frame?

[PorkyMonster]

Very sturdy chassis. I will incorporate more 5x7 and 5x11 frames in my next build .

Edited December 21, 2016 by PorkyMonster

[AkiyamaWataru]

4 hours ago, Lox Lego said:

I am very much looking forward to the body work of this car! Do you have a vehicle in mind? Have you scaled this frame?

Didomus stated, he wanted to build the fst anml from zoo mania ;) It's written in the opening post.

[Lipko]

The chassis looks very good and very low profile (reminds me of my latest car chassis). It's nice to see other people so obsessed with rigidity

 

20 hours ago, Didumos69 said:

Comments and (suggestions for) improvements are welcome.

Careful with phrases like that if you ever want to call the chassis finished...

Edited December 21, 2016 by Lipko

[LegoDego]

About Ackermann steering, how does it works in this model? 

[agrof]

21 hours ago, Didumos69 said:

Comments and (suggestions for) improvements are welcome.

Technically I can not add much, optical improvement is needed in my opinion. I would better distuingish the segments by recoloring: I would leave the chassis in DBG-LBG as it is, but would make the seats completely black (except the gears of course), the dashboard as well. Or blue. Or yellow. What You prefer. Now everything melts visually too much together. After that the body should be made also in different color... orange maybe. 

Edited December 21, 2016 by agrof

[Didumos69]

13 hours ago, Lox Lego said:

I am very much looking forward to the body work of this car! Do you have a vehicle in mind? Have you scaled this frame?

12 hours ago, PorkyMonster said:

Very sturdy chassis. I will incorporate more 5x7 and 5x11 frames in my next build .

8 hours ago, AkiyamaWataru said:

Didomus stated, he wanted to build the fst anml from zoo mania ;) It's written in the opening post.

Yes, I did scale this car. To 1:9 to be precise. The car that I used as a reference is 4.5m long and 2.07m wide and has a wheelbase of 2.7m. This scales to a total length of 63 studs, a total width of 29 studs and a wheelbase of 38 studs. The wheelbase and the width is the same as in Paul Boratko's latest model.

It was indeed the red 'FST NML'-car from Zootopia that got me started, but I also mentioned that it might turn out completely different. I simply like to have some design freedom. The point is that where others feel comfortable with bodywork based on 'whatever fits' I have the irrepressible urge to fit everything together legally, preferably on a perfect 1-stud grid. I know we have entered the era of 'closed' bodywork, but somehow I tend to think more in the direction of a minimal body with big holes that show what's inside. Something that captures the essential lines only.

7 hours ago, Lipko said:

The chassis looks very good and very low profile (reminds me of my latest car chassis). It's nice to see other people so obsessed with rigidity

Careful with phrases like that if you ever want to call the chassis finished...

Thanks! I'm afraid it will never be finished ... About it being 'low profile', when I remove dashboard, HoG, seats and engine, it can in fact ride upside-down . Here are some images showing the rigidity. Most of the level difference is anticipated by the suspension, only a small portion by longitudinal twist:

6 hours ago, LegoDego said:

About Ackermann steering, how does it works in this model?

I realized Ackermann steering by off-setting the steering pivots of the (Porsche) wheel hubs by one stud. Like this:

6 hours ago, agrof said:

Technically I can not add much, optical improvement is needed in my opinion. I would better distuingish the segments by recoloring: I would leave the chassis in DBG-LBG as it is, but would make the seats completely black (except the gears of course), the dashboard as well. Or blue. Or yellow. What You prefer. Now everything melts visually too much together. After that the body should be made also in different color... orange maybe. 

I agree. Seats and dashboard should stick out, they are part of the interior. Maybe the cover top side of the mid-console too. Black seems like the most likely candidate.

Edited December 21, 2016 by Didumos69

[DugaldIC]

Looking great!!  Another question,  what's the benefit to the Ackerman steering?  Or offsetting the steering one inward? 

[Didumos69]

28 minutes ago, DugaldIC said:

Looking great!!  Another question,  what's the benefit to the Ackerman steering?  Or offsetting the steering one inward? 

It makes the wheel on the inside of a turn follow a circle with smaller radius than the wheel on the outside. This reduces tire scrub. You can actually feel the difference in playable Technic models. Theoretically the offset I use is a little too much, but it comes far more close to the ideal situation than with no offset at all.

[Lox Lego]

2 hours ago, LvdH said:

Can't wait to see a body on it. Any idea what color you're making it?

+1. It's cool you're modelling a fictional car!

[Meatman]

This has probably been covered already in this thread somewhere, but what are those yellow double perpendicular connectors in the rear and the yellow connectors in the front for?

[emielroumen]

3 hours ago, Meatman said:

This has probably been covered already in this thread somewhere, but what are those yellow double perpendicular connectors in the rear and the yellow connectors in the front for?

Torsion bar suspension :)

[Didumos69]

3 hours ago, Meatman said:

This has probably been covered already in this thread somewhere, but what are those yellow double perpendicular connectors in the rear and the yellow connectors in the front for?

They fix the axles holding the upper wishbones. These axles serve as torsion bars. I deliberately used normal shocks which are too weak to carry the car by themselves. The nice thing about torsion bars is that their resistance starts subtle and increases fast when they get twisted. This makes dropping the car possible without having the bottom of the car touch the ground. And the shocks actually work as absorbers this way. They absorb the jumping spring effect of the torsion bars. They also make it possible to finetune the suspension by adjusting the way each torsion bar is secured. By using different parts for the front and the back I could incorporate a subtle rake angle. The torsion bars in the front have been secured a little more relaxed than in the back.

Here you can see the difference between 'torsion bar attached' (left) and 'torsion bar detached' (right):

Edited December 21, 2016 by Didumos69

[Meatman]

Ok, I can see the difference now. You would think they could carry the weight considering they can carry it on the very heavy Porsche. I guess that it is just in the set-up. Thanks for the clarification.

[Didumos69]

9 hours ago, Meatman said:

Ok, I can see the difference now. You would think they could carry the weight considering they can carry it on the very heavy Porsche. I guess that it is just in the set-up. Thanks for the clarification.

The Porsche has hard springs, this one has normal springs. I started with hard springs, but that was far too rigid. Only after replacing them with normal ones the anti-roll bars and the torsion bars started to make a real contribution to the suspension characteristics.

Edited December 22, 2016 by Didumos69

[Didumos69]

To get started with the body in LDD, I added tires that mimic - and match the exact diameter of - the Porsche tires. This gives a nice render showing how 'low profile' (flat) the whole thing is  (click to enlarge).

Edited December 22, 2016 by Didumos69

[brunojj1]

2 hours ago, Didumos69 said:

The Porsche has hard springs, this one has normal springs. I started with hard springs, but that was far too rigid. Only after replacing them with normal ones the anti-roll bars and the torsion bars started to make a real contribution to the suspension characteristics.

I was actually thinking the red Porsche springs are new unique type (and specified by the red color) which indeed are harder than the "normal" yellow springs . You are using red springs while saying they have the "normal" hardness?...

 

35 minutes ago, Didumos69 said:

...

This gives a nice render showing how 'low profile' (flat) the whole thing is (click to enlarge).

....

Is it good or bad? Does your emoji tell us that you are not completely satisfied with it?..

Another odd question: is it allowed now to embed huge pictures of bigger size than 1000 pixels?

EDIT: it looks great! (although the LDD tires substitus are disgusting)

Edited December 22, 2016 by brunojj1

[Didumos69]

11 minutes ago, brunojj1 said:

I was actually thinking the red Porsche springs are new unique type (and specified by the red color) which indeed are harder than the "normal" yellow springs . You are using red springs while saying they have the "normal" hardness?...

 

Is it good or bad? Does your emoji tell us that you are not completely satisfied with it?..

Another odd question: is it allowed now to embed huge pictures of bigger size than 1000 pixels?

EDIT: it looks great! (although the LDD tires substitus are disgusting)

In my perception the red Porsche springs are as hard as the usual yellow hard springs. I indeed use red springs too, but with normal hardness.

Sorry, wrong emoticon, I'm actually quite content with it .

I only do 'too wide' images when the height is under 500 pixels. I think the main concern is that pages don't get too long to scroll and image sizes in terms of MB don't grow too big. But I downsizes it nevertheless .

I agree, the substitutes are a pain in the eye, but they do add proportional justice to the chassis.

[agrof]

I made some recoloring according my taste, maybe useful as inspiration. 

The chassis is mainly LBG, the swingarms are DBG, the seats and dashboard are black.