[WIP] Hennessey Venom F5

[Milan]

I seldom like the use of Technic panels and how they look on a vehicle, but this is next level. The bodywork looks like it is a one piece panel. Truly great work. 

[grego18f]

This is not the car brand I like the most but you have already done an awesome job on it. I think I will never present my Porsche 911 when I finish it (one day hopefully) because there are so many awesome MOCs in here!

For the curvature on the roof, have you considered using Bionicle teeth?

[Scoar Sonander]

Could you specify which pieces you mean? 

The bodywork is nice, but I don't like the gap where the rear engine panel connects to the roof, and that weird gap between the door and the "hip part" . Maybe use some panels, or some system parts there. Those are my ideas!

I can also see this so-called " 50 shades of lime" here and there. Not your fault though!

[2GodBDGlory]

It's interesting how you built the bodywork before the mechanical bits! This is the opposite of how I build, which is probably why I spend all my space on functions, and can only really fit a boxy bodywork...

Good job!

[Aleh]

This lime beauty looks very cool!

[Jeroen Ottens]

16 hours ago, Milan said:

I seldom like the use of Technic panels and how they look on a vehicle, but this is next level. The bodywork looks like it is a one piece panel. Truly great work. 

Wow, thanks

16 hours ago, grego18f said:

This is not the car brand I like the most but you have already done an awesome job on it. I think I will never present my Porsche 911 when I finish it (one day hopefully) because there are so many awesome MOCs in here!

For the curvature on the roof, have you considered using Bionicle teeth?

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.

14 hours ago, Scoar Sonander said:

Could you specify which pieces you mean? 

The bodywork is nice, but I don't like the gap where the rear engine panel connects to the roof, and that weird gap between the door and the "hip part" . Maybe use some panels, or some system parts there. Those are my ideas!

I can also see this so-called " 50 shades of lime" here and there. Not your fault though!

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.

13 hours ago, 2GodBDGlory said:

It's interesting how you built the bodywork before the mechanical bits! This is the opposite of how I build, which is probably why I spend all my space on functions, and can only really fit a boxy bodywork...

Good job!

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.

12 hours ago, Aleh said:

This lime beauty looks very cool!

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.

[Rudivdk]

I tried a similar gearbox setup in a 1:10 car, but with two identical gearboxes left and right and a 1/0.9 ratio between them to make it possible to have even and uneven gears separated. Got it to work as POC, but didn't yet succeed in fitting it properly in my car. It would be interesting to see your approach and compared the two. I might post a thread of my gearbox to discuss further.

[Scoar Sonander]

4 hours ago, Jeroen Ottens said:

 

The gap between rear panel and roof is on my todo list.
I am not sure which weird gap you are referring to?
Those 50 shades of lime are annoying indeed.

 

I was referring to that big black gap behind the door. I don't know if that's supposed to be a vent or something. I'll try and edit a pic: Hip Gap correction | Scoar Sonander | Flickr

I still can't upload pics, since the site says that the maximum file size is 103 kb or something...    I'll try to fix it! 

[Milan]

26 minutes ago, Scoar Sonander said:

I still can't upload pics, since the site says that the maximum file size is 103 kb or something...    I'll try to fix it!  

In the site guidelines and FAQ, there are instructions on how to post pictures on the forum. EB is not a hosting site, so you need to use an external hosting site and link them here. 

[Jeroen Ottens]

1 hour ago, Scoar Sonander said:

I was referring to that big black gap behind the door. I don't know if that's supposed to be a vent or something. I'll try and edit a pic: Hip Gap correction | Scoar Sonander | Flickr

I still can't upload pics, since the site says that the maximum file size is 103 kb or something...    I'll try to fix it! 

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).

[Jeroen Ottens]

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.

[Aleh]

OMG! How complex.. I assume that will work smoothly as usual :)

[Scoar Sonander]

4 hours ago, Jeroen Ottens said:

It was a productive day today

I think the reason I am not able to finish my own MOCs is that I am constantly just gaping in amazement at your creations :D

Edited April 5, 2021 by Milan
Do not quote the pictures from the same page.

[Thirdwigg]

Thanks again for including us in your build process. It's great to see how you approach your process, and some of the steps you take. I love the little gearbox schematic that you use, and judging by the gearbox render, this process seems to work great as well.

Bodywork is coming along nicely. I love the DBG over engine part. It looks so clean.

[Pvdb]

Have you tried the gearbox yet?  I am just wondering if 1st gear is going to lock it up, if you know what I mean.  Especially when the engine is mounted.  

adding the 7th gear does make things a lot more complex when working with Lego gears and selectors etc, so interesting solution to that problem.

Having looked closer, I think you have the 12 and 20 tooth gears the wrong way round for 3rd and 7th in the CAD image.  

[Jeroen Ottens]

On 4/5/2021 at 5:13 PM, Aleh said:

OMG! How complex.. I assume that will work smoothly as usual :)

 

On 4/5/2021 at 10:39 AM, Rudivdk said:

I tried a similar gearbox setup in a 1:10 car, but with two identical gearboxes left and right and a 1/0.9 ratio between them to make it possible to have even and uneven gears separated. Got it to work as POC, but didn't yet succeed in fitting it properly in my car. It would be interesting to see your approach and compared the two. I might post a thread of my gearbox to discuss further.

 

20 hours ago, Pvdb said:

Have you tried the gearbox yet?  I am just wondering if 1st gear is going to lock it up, if you know what I mean.  Especially when the engine is mounted.  

adding the 7th gear does make things a lot more complex when working with Lego gears and selectors etc, so interesting solution to that problem.

Having looked closer, I think you have the 12 and 20 tooth gears the wrong way round for 3rd and 7th in the CAD image.  

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.

Edited April 6, 2021 by Jeroen Ottens

[Jeroen Ottens]

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...

[Rudivdk]

Am I correct in assuming that at any given selected gear (say:even), all the gearwheels of the opposite side (uneven) are backdriven through the connecting 'gearbridge'? This was for me the big problem and cause of stalling lower gears. I fixed it by making another left/right selector clutch at the engine side of the gearbox, hardlinked to the one at the differential side. This way one side is totally idle when a gear in the other side is engaged.

[Jeroen Ottens]

1 hour ago, Rudivdk said:

Am I correct in assuming that at any given selected gear (say:even), all the gearwheels of the opposite side (uneven) are backdriven through the connecting 'gearbridge'? This was for me the big problem and cause of stalling lower gears. I fixed it by making another left/right selector clutch at the engine side of the gearbox, hardlinked to the one at the differential side. This way one side is totally idle when a gear in the other side is engaged.

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.

[Rudivdk]

26 minutes ago, Jeroen Ottens said:

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.

Well, I have also learned something from the Defender set: even though I meticulously built that gearbox and it ran smooth, after a few weeks it started cracking and jamming on me, to a point where it is almost unplayable now. Probably dust and some playwear are to blame, but it shows that when you are on the edge of what is possible with Lego gears, time will push it over the edge at some point... So high friction now can very well end up in too much friction in a few weeks. If I were you, I'd first focus on fully separating left and right side to see if that alleviates some of the issues by having less gears engaged. Start simply by just removing one gearwheel from the 'bridge' between left and right and testing that. Should give you some ideas on where to improve further

[Pvdb]

Another thing I did, and you could also use with this set up, is use the new red diff as it will lower the ratio right at the source.   That will give you more scope to play with the range in the actual gearbox.

[Jeroen Ottens]

Time for another update:

This time I mostly worked on the inside, as that was neglected when doing the bodywork. I added a mechanism to operate the doors that is relatively inconspicious in the tub. The gearbox has become a simple 8-speed sequential, but that did give me enough space to make the engine proper with a double turbocharger:

The piping really nicely fits in between all the bracing, so I am quite pleased with it now.

[Aleh]

28 minutes ago, Jeroen Ottens said:

a simple 8-speed sequential,

I probably missed the moment, but when did 8 speed seq gearbox become a simple solution? 

 

[Jeroen Ottens]

1 minute ago, Aleh said:

I probably missed the moment, but when did 8 speed seq gearbox become a simple solution? 

 

I made my first 8 speed sequential gearbox in my DB11 in 2016. This one is in principle the same. I try to to push myself everytime to come up with something new, but I just couldn't make it work/fit with a 7+R this time . So reverting back to a known concept feels simple to me .

[T Lego]

Very nice progress Jeroen, I really like all the engine details!

One question about the gearbox: have you considered using a setup like this to achieve 8 + N + R in stead of the early prototypes shown above? The gearbox shown below is based on a concept presented by Anto a while ago where you're using the two driving rings for high/low for reverse and neutral as well. Reverse has the same ratio as first gear and is realised by bypassing the 4 speed gearbox. I know it's probably too late to change anything and I am unaware about the specific space limitations, however this is a much more compact and simpler solution that could have potential. It's not much bigger than regular 8 speed gearboxes. Maybe not exactly the type of setup you were wishing but just sharing an idea here. 

Good luck and I'm looking forward to the next update!