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B&M Pre-drop

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This may have been discussed before, but I did a search and didn't find the answer.


Anyway, I was just wondering what ever happened to the B&M pre-drop? It seems they're on most B&M coasters made before 2004 or so (with a few exceptions), but they don't seem to be on any newer models, except for the inverts.


The pre-drop is supposed to help alleviate the stress on the lift chains and/or trains, correct? Plus, it prevents the front of the train from crawling down the beginning of the first drop as it waits for the back to clear the lift hill?


Seems like a sound concept, so why do away with it?

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The only thing that I can think of for getting rid of them would be a cost saving measure. Less track at the tallest point of the coaster where it's more expensive to build.


At that point you've got to not only create more track, but also another set of supports and footers. I'd imagine it would be a pretty pricey stretch of track.

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^True, but if having no pre-drop will increase tension and strain on the lift hill and on the trains, then wouldn't the cost of needed repairs eventually match the cost of what a pre-drop would have cost? Maybe?


I think Apollo's Chariot at BGE and Goliath at SFoG both cost approximately $20,000,000.00 each, and the former has a pre-drop while the latter does not, so maybe the difference in cost wouldn't be that great? I know there are a LOT of other factors that go into the cost (terrain, layout, and the like), but just thought I'd throw that example out there anyway.

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I could be wrong, but I think they only did the pre-drop on the 1st two hypers back in '99 and then never did it again.


I don't think it's a cost thing, my theory is that B&M was trying to give the train more speed by not holding it back by the lift chain. But riding Goliath, I don't see much of a difference.

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^I don't think the purpose is necessarily to "increase the speed" on the drop, per se; it just prevents the front half from inching its way down the first hill while the back half is still climbing the lift. By the time the last cars clear the apex, the front cars have already gone down a quarter of the drop at the same slow speed that back cars were climbing the hill.


Am I explaining this well?

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That is an advantage of the pre-drop and you're explaining it well!


I personally don't like the pre-drop. I think it's some kind of signature from B&M.


Just give me a nice drop all the way down: a pre-drop makes my head hurt against the seats and restraints. Silverstar doesn't have one either and that's one of the best B&M drops I know (apart from the vertical drop, of course).

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But riding Goliath, I don't see much of a difference.

man, maybe it's just me, but I thought the air on the first drops of Apollo's and Raging Bull was much better than on Goliath (or Nitro)


You sir are wrong.


Ive been on Bull, Apollo, Goliath, and Nitro. I believe they dont all have the same first drop angles but IMHO I think bull has the most air in the first drop.raging bulls is 65 deg and nitro is 66(?) and nitros drop just felt slow and boring. now if its because of the pre drop or just the angle of decent im not sure.

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Well I think that the B&M pre-drop is an awesome ride element.

It does reduce stress on the chain and it also adds a lot to the ride experience.


Not only does it add suspense, it also allows all parts of the train to hit the edge of that drop at a higher speed. This creates ejector air at that point, instead of that point simply being a downward slope into the drop.

If you are riding in the front, it makes the drop much more fun, and if you're riding in the back, it's even more noticable.


Plus, I always love it when a coaster hangs around at the top - even if for just a few seconds - before a drop.


Kraken is an excellent example of this. So is sheikra.

Mantis's little "swoop" before the drop looks terrifying, especially since I have never been on a stand up.

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I asked this same question to a gentleman that had worked with constructing a a couple B&Ms in the US, and this is what he had to say. There were two main factors in the origin of the B&M pre-drop:


1. Evacuations. Supposing a train crested the hill and balanced prior to going over because the chain stopped, getting people out of those first few cars really is quite inconvenient. If you have a flat area with a catwalk under it, getting those first two rows unloaded becomes much easier, than with the modern straight drops.


2. Perhaps the biggest reason was having to do with chain wear and tear. You'll notice B&Ms all have "feeder" wheels at the base of their lift. This is designed to match the speed of the train with the speed of the lift chain, so that when they engage, it is one fluid motion. The result is less stress on the chain. The pre-drop was implemented at the top of the ride to once again reduce tension and wear on the chain when the train began to disengage. After the first chain dog on the train has disengaged, there still may be one or two more still lodged in place, and the pre-drop made it so that for the most part, all of the chain dogs release from the chain at the same speed. These two features significantly reduce the amount of strain placed on the chain, and as such increases reliability.


(By contrast, I might point out, that most all other coaster companies do not have these design features on their lift hills. Whereas on most coasters, a cracked chain is not unheard of, B&Ms have a stellar reputation- their chains hardly ever break.)


Ok, anyway so why did they get rid of the Pre-Drop?


From what I understand, there is a simple, "duh", solution that solves both of the problems stated above, that was simply looked over in the design of the first B&Ms: Speed up the chain as the train starts to crest over the hill! A proximity sensor detects when the first car has reached just slightly passed the apex of the lift, and signals the lift motor to speed up. The end result is that the dogs release from the chain because the lift hill speeds up to match the speed of the train cresting and falling down the first drop. A keen eye will see on Nitro and Hydra that the chain speeds up as the train starts rolling off the top of the ride.


And because the chain motor is speeding up, it gives that extra little "nudge" to the back cars just in case the power were to suddenly kick out, so that there is enough momentum to push the train all the way over the lift hill, thus preventing any chance of the train balancing before the first drop.


Simply speeding up the lift chain at the right time relieves the necessity of a catwalk for evacuations, and unneeded stress on the chain. So I hope this solves your mystery!

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