Improved smooth curves by AshiValkoinen

[Ashi Valkoinen]

I was just driving LEGO trains on a LEGO-exhibiton here in Budapest when an idea came to my mind, I really would like to share it with the Train Tech community. I've read Holger Matthes' smooth curves article in Railbricks 1 long time ago, today I played with some straight track segments, building the well-known smooth curve using jumper plate, 1×2 plate and 1×4 plate. Then I looked at a really useful part in the display, this one:

Bracket 1*2 - 2*2

And built it's narrower part between the track segments:

The studs of the 4 LDU wide part perfectly holds the plate of the track segment (okay, it's illegal connection, but works perfectly), between the 1×2 plate part of the bracket and the other track segment you have to place a single 1×1 or 1×2 plate. The inner side of the curve can be connected with a single 1×2 plate below the track plates, or below and above them, too.

Doing some math, calculating the theoretical radius:

We have an isosceles triangle, equal sides with 140 LDU distance (LEGO Digital Unit, 1 stud = 20 LDU, 1 brick = 24 LDU, one plate = 8 LDU), the shortest side is 4 LDU long. (Please note, that the bracket brick is inserted by stud 2, not 1 between the tracks, counting studs from outer side of the curve).

The half of the isosceles triangle described above is a right triangle, with hypotenuse 140 LDU long and a shorter leg 2 LDU (half of 4 LDUs). The angle opposite of the 2 LDU side is the half of the angle between the tracks, let's name it a.

sin a = 2 LDU/140 LDU

sin a = 0,0142857

a = 0.8185 degrees

2*a = 1.637 degrees, this is the angle between the two segments. For 90 degress you need 54,97, so 55 connections, which means 56 straight tracks.

Lenght of 56 straight tracks is approx. 718 cm (including connections), so the radius is:

716 cm = ( 2*r*PI ) / 4 (it is only a quarter of a full loop)

r = 456 cm

It could be quite impressive, if you have enough space for a curve like this. If anybody has enough straight and parts to make a try, please do it, my train tracks are reserved for two more weeks. Please discuss!

[Darthluke824]

That would be very smooth! Since I don't have room I can't try it but it may work with large amounts of track for even bigger displays.

[Haddock51]

When discussing smooth curves, I think you first of all need to answer the question: why? We probably all agree that the standard geometry of the Lego 9V/PF tracks in general, and the curve diameter in particular, have several disadvantages and limitations - most of them related to issues and problems when operating trains at high speed (or using long MOC-wagons).

The main disadvantage with smooth curves - and particularly the one that you are proposing - is the need for a lot of space (and for a lot of tracks ...). I guess the only time you can seriously consider to build such kind of smooth curves with multimeter radius - indoors - is at exhibitions in very large halls.

I am currently starting to build a huge display at my home in Sweden (see topic "9V Extreme"). The entire track will be approximately 150 - 160 m long with inclinations and several levels. Even though this room has an area of 40 sqm, there is no way to consider any kind of smooth curves. I think that the space trade-off is simply too high taking the pros and cons into consideration.

For me, speed has always been of essence (at least when it comes to Lego trains) and part of that huge 9V Extreme display will be a high-speed track 2m above floor level, with standard 90 degree curves. In order to prevent derailments at high speed, I will build lateral curve inclinations by using 1x2 plates along the outside of the 90 degree curves (1-2-3-2-1 plates high). I have tested this concept on the testtrack with my extended 4 engine powered (9V) HE at almost maximum speed and it works very well.

Laterally inclined curves could indeed be an alternative to smooth curves if the primary issue is to overcome centrifugal forces at high speed - and to optimize space for other Lego (train) purposes.

When running long and heavy trains at medium/high speed, you experience strong centrifugal forces in the curves which put pressure on the track connections. In order to strenghthen these connections between curve-tracks, I am using 2x4 plates at the track connections.

The weakness/disadvantage of your proposal with the Bracket 1x2 - 2x2 as a space builder is that the connection between tracks becomes weak/loose. It might eventually open due to the forces I mentionned - particularly if you plan to build a smooth half-circle curve (180 degrees). So these connections need to be strenghthened one way or another.

I need to ask you: what are your reasons to consider/build curves with such dimensions - if it's not just about speed? 56 straight tracks and 57 brackets for a 7,3 m long smooth 90 degree curve ....!?

Looking at your pictures, it appears that you are using PF. Based on what I have seen so far, I have hard to believe that trains using PF can come up to such speed that it would require smooth curves with multimeter radius.

Edited May 12, 2014 by Haddock51

[UrbanErwin]

@ Haddock51: I don't think the main purpose of the smooth curves is the speed, but realism. If I'm correct Ashi Valkoinen builds his trains at 8-wide which means these curves are much closer to a real curve.

Edit:

To make my point more clear: here is a sample (not mine)

IMG_7695 by Cale Leiphart, on Flickr

This train would look ridiculous on regular curves.

Edited May 10, 2014 by UrbanErwin

[Haddock51]

I guess there are different "schools". For some, modelling, design and similarity to original objects and environments are most important, sometimes maybe the only thing that matters. For others - like me - functionality, performance and safety when operating trains comes first. The pleasure, excitement and satisfaction you experience when running multiple beautiful and powerful Lego trains in sophisticated displays - including inclinations! - for me is second to none, at least when it comes to Lego trains! This includes of course the challenge to design and build such displays.

This is not about either or - it's about both. The challenge is to combine and to prioritize.

I am not the right person to judge what is adequate and what is ridiculous. I recently built the Dm3 (see separate topic) which is 8 studs wide and which will haul an iron ore train with some 20 wagons - also 8 studs wide. From an operating point of view, the issue of standard curves vs smooth curves is not the 8 studs whidth but rather the lenghth of - and distance between - the various train segments (if we disregard speed for a moment). In the case of the Dm3, I had to adjust the distance between the 3 locomotive segments from 2 studs to 3 studs. Now it works perfectly even with standard - and inclined - curves.

From a design/realism point of view, you could of course debate. But then I think you need to be consistent when using smooth curves which means that you also should modify standard points (to halfcurve points - or eventually to crossover points in order to avoid the so-called S-curve). I could also argue that smooth curves with modified straight tracks - e.g. half-straight tracks - look more realistic compared to such curves using standard straight tracks. (It will be interesting to see - and compare with - the results of LeifSpangbergs project to build smooth curves with modified tracks and points).

"Track realism and beauty" yes - but at what prize/trade-off and to what benefit?

As Duq said - each to their own.

Edited May 12, 2014 by Haddock51

[ZueriHB]

I'm for the large and very large radi not because of speed (seldom use a setting above 4), but because it just looks better.

Also this technique seems to be great to built curved stations.

[Andy Glascott]

If I had the space and track I'd love to have long smooth curves, it does look so much more realistic. That said, I've grown up with and used Lego track for over 30 years and it does work well in confined space; a 3 to 4 metre by 1 to 2 metre table/board doesn't leave much room for longer/non-standard curves so L gauge curves are fine by me.

[Redimus]

I like that smooth curves are a thing that *can* be done. That said, I've done the whole railway modelling thing, and would like to do so again at some point, but the great advantage for me with the Lego trains is that a lot of the limitations that apply to a good model railway don't have to apply to the Lego. It's less fragile, much easier to fix if you do break it, infinity variable and, for it's size, really doesn't have to take all that much space (I currently have a nice little layout set up on a spare dinner table that isn't *that* large which has more than enough play value).

Still a clever way to improve the smooth curve method.

[Aaron]

The first problem I see with this technique is that the brackets make the track difficult to ballast in an aesthetically pleasing way.

[Ashi Valkoinen]

I've posted this a week ago, then I had no time to reply.

So my motivation of using and redesigning smooth curves is to make my display more close to reality. I really hate those sharp curves we got for the LEGO train track geometry, however, okay, it was invented as toy for kids and not for modelling railway. Creating homemade, larger radius switches are non-LEGO solutions, for stations I think original LEGO-switches are good enough, however, if you want to add more reality and playability to your layout you have to build your own track geometry from non-LEGO pieces. For me it's enough compromise to cut original LEGO-switches to make some new connections, but no non-LEGO parts.

Aaron: it isn't harder to ballast this design than Holger's one, you just have to know, at which points you place only an 1×2 or 2×2 tile on the baseplate, insted of the two plates + 1 tile combination.

[cgarison]

@ Haddock51: I don't think the main purpose of the smooth curves is the speed, but realism. If I'm correct Ashi Valkoinen builds his trains at 8-wide which means these curves are much closer to a real curve.

We run an 8 wide locomotive with long cars on our moonbase layout with standard Lego 90 degree turns and our poor locomotive cries to be run on the big long sweeping turns of the PennLUG layout shown above. Our train cars also had to be modified to set about 2 plates higher off the trucks so they would clear our turns on the layout. As much as I like those long sweeping turns, we do not have the space on our layout because of our hanging monorail and supports for the moonbase modules.

[BricksMcgee]

I guess there are different "schools". For some, modelling, design and similarity to original objects and environments are most important, sometimes maybe the only thing that matters. For others - like me - functionality, performance and safety when operating trains comes first.

Absolutely. I'd love the space to build out larger radius curves but the the space I have contains me to smaller radii and I'd rather have more loops of track than realistic curves for now, to let me run multiple trains at the same time.

Fully understand the desire for larger radius curves if you have the space available though!