Below is a photo of a double-track helix that is part of my friend Andre's layout that is now the centerpiece of the model railroad portion of my site. The layout will have about 600' of main line track; trains will take at least 16 minutes to complete one circuit! Andre has just completed construction of the helix. I will be adding many more photos of his layout within the next few weeks. <img SRC=http://www.trainweb.org/cnotp/model/helix/helix-01.jpg> ------------------ Jeff Norfolk Southern CNO&TP Home Page
Very interesting. I'll look forward to more posts on this. ------------------ Ship It On The FRISCO! | IAMOKA.com
<BLOCKQUOTE>quote:</font><HR>Originally posted by Chessie_SD50_8563: Awsome. On avarage what radius and percent grade should you use <HR></BLOCKQUOTE> That truely depends on the type of trains you're planning on running. For example, the above helix was designed for 50-car trains that included autoracks and double-stacks. Therefore, the inside track's radius is about 36 or 37 inches. The outside track's radius is about 1-1/2 inches wider. The grade is about 1.5%. If you go with a tighter radius, you're faced with a dual problem for longer trains: 1) A tighter radius will require a steeper grade in order to allow the track to get above the previous level of track within on complete turn of the helix. A steeper grade means fewer cars can be pulled up the grade with "normal" power on the head end. 2) With the tighter radius AND the steeper grade, you will be able to pull far fewer cars due to the lateral forces that will cause your cars to tip inwards. This can be especially deadly with the autoracks and double-stacks.
<font color="336633">Very impressive I would love to have a helix on my railroad (when it ever gets built) but with my track laying skills i think it might be best if i dont </font> ------------------ Matthew wheres all the C636's???? stickymonk.com Matts Photo gallery TrainBoard member #257
Great helix! But I have a question for those that are in the know.Instead of doing a wide circle helix,has anyone ever thought of doing a smaller radius but instead of a circle using a stretched oval.The advantage (I think!)would be to keep from using up aisle space.I'm kinda imagineering the idea of say 18-20" radii but with a 6'(or longer) staights between curves.Of course this design wouldn't be necessary on every layout but perhaps in a long garage or narrow basement it might prove do-able or even required where length is not as important as aisle space. Just a thought, Gene ------------------ Cisco & Northeastern Ry.Co. is spoken here!
<BLOCKQUOTE>quote:</font><HR>Originally posted by Stepchld: has anyone ever thought of doing a smaller radius but instead of a circle using a stretched oval. <HR></BLOCKQUOTE> I'm faced with a a similar problem. I "need" a helix in one section of my dream layout for an under-table staging area, but I don't have the space to do a round one. You still need the larger radius curves to properly handle the trains. I'm planning on between 22" and 24" minimum radius curves as a design limit, and 1" in 3' for my grades, which works out to 2.8%. My proposed helix design actually looks more egg-shaped to get it to fit into the available area. Messy, but it looks like it'll work. To climb up to an upper level I'm going to have it climb up the wall. It's nicer looking than a helix and takes up no space at all. Mark P.S. I just got some maxi-cars, and with a stacked load it's 3 1/2" tall above the track. Higher than the NMRA maximum of 3". Now it looks like I have to check the vertical clearances all around my track again! [This message has been edited by Mark_Athay (edited 29 January 2001).] [This message has been edited by Mark_Athay (edited 29 January 2001).]
<BLOCKQUOTE>quote:</font><HR>Originally posted by Stepchld: aisle space.I'm kinda imagineering the idea of say 18-20" radii but with a 6'(or longer) staights between curves. <HR></BLOCKQUOTE> The problem with this is that you will be limited to extremely short trains and shorter cars (no 86' or 89' freight or passenger cars, no double-stack cars due to their high center of gravity). For a layout that uses small four-axle locomotives and a few freight cars, this would indeed be an interesting concept. ------------------ Jeff Norfolk Southern CNO&TP Home Page
Oops...I kinda forgot to tell you guys that I model a shortline in 1930 and thus doublestacks and longer than 50' cars don't exist for my railroad.Also maximum train length was prototypically less than 10 cars.Therefore I believe that I can get away with the smaller radii...I guess I'll find out when (and IF) I build it! Gene Jackson ------------------ Cisco & Northeastern Ry.Co. is spoken here!
<BLOCKQUOTE>quote:</font><HR>Originally posted by Stepchld: Oops...I kinda forgot to tell you guys that I model a shortline in 1930 and thus doublestacks and longer than 50' cars don't exist for my railroad.Also maximum train length was prototypically less than 10 cars.Therefore I believe that I can get away with the smaller radii...I guess I'll find out when (and IF) I build it! Gene Jackson <HR></BLOCKQUOTE> Under those conditions, you should be fine! ------------------ Jeff Norfolk Southern CNO&TP Home Page
Obviously I'm having trouble getting this photo in. If anyone can help?? [This message has been edited by ChrisDante (edited 01 February 2001).]
Hey Chris. Something happened to your link. I hope you don't mind--I took the liberty of reposting your link above because I wanted to see your photo. That's a heck of a work in progress!!! --I removed the photo after Chris reposted in order to save viewers the download time.-- ------------------ Jeff Norfolk Southern CNO&TP Home Page [This message has been edited by CNO&TP (edited 01 February 2001).] [This message has been edited by CNO&TP (edited 01 February 2001).]
Jeff thanks a lot. I'm going to post the picture again so I can see how it's done. This is my helix under construction. The ruling grade will be 2.3% and the radius of the track is 28.75". The helix will make 4 revolutions and rise around 15in.(I don't want to go downstairs and measure again). We are keeping a 2.75in clearence off the rails. The vertical rods allow us to adjust both grade and level. <img src=http://albums.photopoint.com/j/View?u=1500639&a=11324151&p=39750935&Sequence=0> This is a closeup of the first riser of the helix, as you can see we had to use 1/2 size nuts to fit the space. We went with the rod system so we could lay track and sub roadbed as we went along then adjust each level as we install it. Actually we built the entire helix, without track, then took it apart and are now laying track as we go up. <img src=http://albums.photopoint.com/j/View?u=1500639&a=11324151&p=39750923&Sequence=0> This is the last riser we've completed, it's still being adjusted. By varying the hight of each nut on the rods we can insure the track is either totally level or have a super-elevation and using a transit we can keep the grade constant. <img src=http://albums.photopoint.com/j/View?u=1500639&a=11324151&p=39750932&Sequence=0> The layout uses code 70 rail but for ease of operation the helix is code 100. ------------------ When in doubt, empty your magazine. Member #33 [This message has been edited by ChrisDante (edited 01 February 2001).]
