Pumping

Hi, I'm a nl noob. What is pumping?

[hyyyper]

dunno for sure, but i thought it was getting pretty high G-forces for several secondes, which should be avoided when building coaster,

anybody correct me if i'm wrong

Pumping is basically when there is a flat spot in the middle of a turn or a hill. This means that the radius of curvature is not maintained through a control point. If you want to see it, ride in the back seat of the coaster. If the coaster train bobs up and down a bit in the middle of turns or hills, that is pumping. To avoid pumping, try to make verticies that are a uniform distance apart, and use your "lock" feature when you are adjusting them.

It is a very time-consuming process when you are building tracks by hand, so this is the primary reason why people use Elementary.

Originally posted by hyyyper

dunno for sure, but i thought it was getting pretty high G-forces for several secondes, which should be avoided when building coaster,

anybody correct me if i'm wrong

Not even close


Copied from another topic
=======================================

Banking is the bank of the track. Corners are normally banked (save slow sections and wooden coasters) and straight track isnt.

Heartlining is when the track rotates around the riders heart position in order to reduce laterals.
Example: http://nldc.interfix.net/i1265
Notice how the track moves out and around the path of the riders heart (right around where the camera is)
NoLimits Example: http://www.real-coasters.com/dl/heartline_guide.zip
Inside are 2 examples - one proper one not.

Pumping is a phenomanon where the track radius changes more than twice over a certain element (single turn, single loop, etc). This can be seen by watching from the back of the train. If when it goes through a turn the front of the train seems to wiggle (pump side to side) thats pumping.
For a hill, if the train seems pull more than once while going up and over, thats also a pump.
NoLimits Example: http://www.real-coasters.com/dl/pump.zip
First hill is how it SHOULD look. Second Hill is how it should NOT look.

That should cover those common terms.

^This coaster is the very example that taught me how to reduce pumping... you should definitely check it out if you have any problems.

[hyyyper]

Originally posted by hyyyper

dunno for sure, but i thought it was getting pretty high G-forces for several secondes, which should be avoided when building coaster,

anybody correct me if i'm wrong

what it ^that then?

It doesnt always produce high G's. It can produce normal G's. It can produce low G's too.

Also, if you were building a very old style wooden coaster (before the 1950's) I would expect your hills to pump over the tops.

Some modern day English to help those who may not have understood Real's very proficient explanation:

Another way to check for pumping is ride in the rear seat of the train. When it transitions a turn, the train should look smooth and fluid - like it is all turning together. When it looks like an inchworm, that is a pump. Also, riding in the rear train watch it go over hills, when it yanks that is a pump, as well as in the valleys of hills. If you just felt like you slammed down and had your spine pinned in the seat, same thing, pumping.

Special Note: Some folks will see a loop as pumping but loops have a natural tightening and loosening of vertices so you have to be careful when calling pumping on a loop ... just thought I would mention that.

Yeah some pumping, like single pumps as TConwell described with his note about loops, is ok. I've even seen double pumps on real rides, which, if done correctly is also fine. Medusa has one where the radius flattens out after the dive loop, and from what I've seen in pictures Great Bear has one after it's loop. Roar at SFA and SFMW have a huge pump ontop of their large camelback. Also, SROS SFNE's first drop pullout starts with a small radius, gets large for the bottom, then ends with a small radius again. while that might be able to be classified as pumping, it's used to maintain relatively high g's on the pullout. Instead of having g's slowly build up, reach the max, then decrease slowly, SROS maintains it's g force longer by using that setup. It has a smaller radius higher where the train is going slower, then large where the train is going faster. Makes sense. Also because the time in between the small radii isn't that short, the pullout doesn't seem to have a double pump.

Also, as Real said, some older woodies have serious pumping. Wild One (originally built in 1917) at SFA has a couple spots with a lot of pumping (though several of it's hills are free of pumping.) There are plenty other old rides with a lot of pumping.

Point is... if it's done right, like the B&M's I listed and SROS; or if it's on a older style woodie, then pumping in NL coasters is ok. However, that usually isn't the case with most people, because they have turns and hills with many giant pumps that really take away from the experience. Try to avoid that.