22 radius curves

[jettrainfan]

Well, I'm planning on buying some engines that might be a little too big for 18 radius curves (2-6-6-2 mantua, bachmann 4-8-4, etc.). Would these survive on 18?

If not, I was wondering how many 22 radius curves would it take to make a circle, better yet, i have 12  18 radius curves along the main, how many 22 radius curves (estimated) would i probably need? Last question, how much more distance should i suspect with these curves?

[simkon]

Most 4-8-4s will never make 18 inch radius curves. Each piece is 22.5 degrees, so you need 16 pieces of 22 inch radius to make a full circle.
In comparison, 12 pieces of 18 inch radius make a full circle, each piece is 30 degrees.

[Jim Banner]

If you already have the 18" radius track down and sceniced, you might want to consider a 4-8-4 that can run 18" radius.  I have a couple similar to the IHC ones (sold in Canada under the President's Choice Label) and they run very well on 18" radius.

Jim

[jettrainfan]

its not down for good and the scenery is movable so that's not a problem. I plan on getting this                                ( http://www.hobbylinc.com/htm/bac/bac50804.htm ) for the 4-8-4.

[simkon]

I have one of those, that one will not make 18" radius unfortunately.
But, why not buy this one, it is  the exact same loco down to the road number, brand new with warranty and is only $90 including shipping. You would save $60 after you factor in shipping.
http://cgi.ebay.com/BACHMANN-HO-DCC-4-8-4-TRAIN-LOCO-SANTA-FE-50804-/190468645746?pt=Model_RR_Trains&hash=item2c58d0e372

[jettrainfan]

ok

[jward]

assuming that the ez track curves are the same as the atlas ones.......

18" curves are 30 degrees each, thus you need 12 for a complete circle.
22" and 24" curves are 22 1/2 degrees apiece, thus you'd need 16 for a complete circle.

22" radius will fit  on a 4' wide sheet of plywood, however the track will be close to the edge. if you can add a couple inches on each side of your table it's give you some breathing room.

[Doneldon]

jtf-

I'm with sinkon on this.  $77 for the DCC Bachmann Northern is a fabulous price, and the Favorite Spot is an outstanding merchant.

From what I've read here and in other places over the years, the Bachmann Northerns are funny about 18" radius curves.  Apparently some will make it; others will not.  It's unpredictable whether a particular loco will make it or not, but I've heard about it often enough that I have to assume it's true.

If you can't make your train table any wider for some reason, you can use flex track for your outside loop, going as close as possible to the edges to get maximum dimension.  Just add a piece of wood, metal or Plexiglas (best) along the edges because a fall can be a disaster.  Remember: Vertical distances are in even greater scale than 1:87.  That four-foot fall to the concrete floor scales out to four miles.
                                                                                                                      -- D

[jettrainfan]

Alright, Its already on the edge but, that's because I have a straight on the other side, track can be removed and if worse comes to worse, I'll re-route the main and the yard, it looked like a mess to me anyway (the yard).

[jward]

i'd add an extension along the sides by adding a length of 1x4 secured to the layout with either blocks or L brackets.......

you can gain about 3 1/2 extra per side you add this board to.

[Jim Banner]

jtf-
Vertical distances are in even greater scale than 1:87.  That four-foot fall to the concrete floor scales out to four miles.
                                                                                                                      -- D

Interesting concept.  That would make a scale 10 story building somewhat less than 1/4 actual inch high.  Chad from a round hole paper punch could be models of people.  I am not overly tall in real life but in scale I would be 1/80 actual inches high.  And we could have a scale model of Mount Everest on our layouts.  At 1 foot = 1 mile, our Everest models would be a measly 6 feet high.

On the other hand, this could make my daughter happy.  She has often wished she were taller.  Now the 1:87 scale model of her represents a woman over 300 feet tall.

Jim

[jward]

it could be even better than you think jim. nmra clearances are a thing of the past. all your trains can now fit under that low bridge in the layout.......

[Doneldon]

Hunt-

My use of hyperbole should be obvious, but apparently it's not so I'll explain. 

My comment was a purposeful exaggeration which plays on the idea that dropped toast always lands jelly side down or, less colorfully, even a crumby four-foot fall to concrete is likely to yield disastrous damage.  I apologize for failing to anticipate that any readers might for some imponderable reason take the statement literally or concretely, but it's a good example of how hyperbole works: the wild exaggeration reveals its tongue-in-cheek message in a humorous way which renders it paradoxically clearer, at least to some, and more likely to be recalled.  Again for the less dexterous readers, a real world four-foot fall to concrete is the HO scale equivalent of a fall of exactly 348 feet, barely over one over 72.178 times the stated distance of four miles, but the anticipated results are comparable to the much longer fall, so don't take any chances with model railroad equipment falling to the floor.  (NB: The use of "barely" in the previous sentence is intended to be ironic and should not be interpretted as signifying that this writer does not consider a factor of over 72 to be insignificant.)  Other readers who picked up on my hyperbole obviously understood it and even had some fun with it themselves.  I'm sorry that you weren't able to play with us.

Incidentally, I ignored whether the hardness of the concrete, and consequent damage, might also be scale-equivalent; it is my long-standing belief, admittedly unsupported by empirical evidence, that falling on concrete is just as painful in 1/87 scale as it is in 12 inches to the foot.

I hope this clears things up for you.
                                                                                                                                                    -- D