What's the recommended radius for the Athearn Dash 9s and Sd40-2?? Donald [ October 13, 2005, 02:55 PM: Message edited by: Donald ]
Well I have an Athearn Dash-9 too and after a test, the model could take 18 radius curves without a problem even if it looks unrealistic do. It ran very fine on 22 radius but 24 and up will be better. If the dash-9 goes well and look realistic, the SD40-2 should be able to take those curves without problems.
Donald - are you asking in terms of aesthetics or performance? Some of the other posts answer the performance question. I've recently dismantled a temporary layout that I set up, at least in part, to determine what minimum radius I'd be happy with on a long-term basis for a layout from an appearance perspective. Many of the locos I'll be running are large steam, and I couldn't get happy with anything less than 42" min radius for myself, but some of the larger diesels looked fine to me on much smaller curves (the smallest I set up was a little over 33"). If you've got a way to set up such a test for yourself, I'd give it a shot. I was surprised as I thought I'd surely be happy with 36" min, so it was worth my time. A. P.
This is something that comes up often. 18" radius looks ok with 4 axle gps, or small steam, and 40' cars. Once you go beyond that, it's really up to you to determine what looks right. I think it can go on a 18" radius curve, but it will look like lionel trains on O27 track. Way too much overhang. Imagine long cars 50'+ on 18" radius curves. NOT PRETTY. Recently, I took some european passenger cars and tried running them on 18" radius curves. The overhang was killing me. I have no idea how I could stand it when I was younger, ok a lot younger, like thirty years ago. I guess my tastes have matured.
18" radius curves were designed for the toy trade, and was never changed since the manufacturing of radius-ed track was pretty much automated to keep cost down, (for the manufacturer, not us). As the hew and cry called for more scale realism, it was directed only toward the engines and rolling stock. Space has dictated track from the start, so only the velvety few have the palace space to enjoy realistic (large) radius or parabolic curves. There is no "Radius" curves in real life except like on a horse shoe or climb-over curve. All non-tangent trackage has easements leading into and out of tangency, which are always calculated on a parabola. To get an idea of size, the Big Boy steam engine was designed to go around a torturous 20 degree curve and not tip over. Take a protractor from school and make a dot on your driveway or a very large sheet of cardboard, or a 4x8' plywood sheet. (Put the dot down in the lower left corner of the sheet.) Measure 100 scale feet from dot 1 straight up and make dot 2. Now align the protractor so it is centered of dot 2 and the right hand 90 degree mark is on the line between dot 1 and 2. Now lay a foot ruler at dot 2 and swing the ruler around the protractor clockwise until you come to a stop at the 20 degree mark, and draw a line from dot 2 out to the end of the rule. Measure 100 scale feet along this line and extend the line out to the 100 foot mark and draw dot 3. Continue drawing 20 degree dots a few times and connecting the dots with lines between them. Do 6 or more for accuracy. Now go back to the first 100 foot line and make a dot at the 50 foot location. Do the same thing on the last line you drew. Use the protractor to start at the 50 foot mark and draw a long line at 90 degrees in relation to the first line, off toward your right. Now go to the last line and at its 50 foot mark, draw a line at 90 degree relation to it, off in the left direction. Where these two lines cross is the center of a radius equal to all the dots, hence the radius of a 20 degree curve. The distance from any one dot to the point where the two long lines crossed, is the true radius. Where ever the Big Boys ran, there were no curves sharper than this including switches. In HO this will measure over 50 inches! So is it little wonder that anything on an 18" radius looks pretty unreal? So we have to return to our childhood and "Play-Like" our curves are larger, our trains have a combined 14,000 ton load, and our little plastic make believe engine is really 8 snorting beasts clawing this load up hill midst thunderous exhaust, squealing flanges and clouds of black smoke, slipping and sliding all the way while our old growlers are down to no more than maybe 8 miles and hour and we are sweating the over-load shut-offs! Whew, what a pull, but we topped out finally! After a pull like that, I used to have to go get a couple of cookies and slug down a short snort of milk to recover! (Mom just smiled). [ October 17, 2005, 11:33 PM: Message edited by: watash ]
