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Do B&M hypers produce actual negative g-forces?

Matt N

Strata Poster
Hi guys. B&M hypers are an incredibly popular coaster type among parks across the world, and for some, they are among the ride types you think of when you think “airtime machine”. But on the subject of airtime, I have a question about B&M hypers; do they actually produce any negative g-forces?

I’ll admit that this has always confused me, as I’ve heard and seen differing things that offer different answers to this question.

When reading through threads about B&M hypers, one of the most common things you hear about them is that they focus almost primarily on floater airtime as opposed to ejector airtime. Further to this point, I’ve heard from numerous people that B&M hypers are designed to exert a perfect 0G over their hills, so in that sense, many argue that they don’t have any actual “airtime”, as no forces supposedly act to push the rider out of their seat.

However, I’ll admit that this notion confused me somewhat whenever I watched a ridercam video of people on a B&M hyper coaster, because when the train passes over the first drop or the parabolic hills in those videos, the riders seem to fly out of their seats as though an actual g-force is pushing them up out of their seat. From the Physics knowledge I have, I’d guess that 0G is more of a sensation produced by the lack of gravitational forces, and 0G in itself cannot actually push a rider up out of their seat, so surely these rides must have negative g-forces if the riders can actually been seen coming up out of their seats in ridercam videos? With gravity acting downwards, a negative g-force surely needs to act for you to fly upwards, no? Also, from anecdotal experience, I’d say that the airtime on Mako, the one B&M hyper I’ve done, felt equally as strong as, if not stronger than, the airtime on rides like Icon, which is said by Blackpool Pleasure Beach to exert -1.2G. Further to this point, I’ve also heard some sources say that rides like Mako and Shambhala go right up to -1G at parts of their layouts, and I wouldn’t be too surprised if a ride like Fury 325 goes well below 0G in that ending section.

So my basic question is; do B&M hyper coasters actually produce any negative g-force, or “actual airtime”, if you like? Are my theories based on what I know from A Level Physics correct, or is there more to it?
EDIT: Whoops, just realised I posted this in Polls as opposed to the Q&A section like I meant to; sorry! Could a mod please move this thread to Q&A, if they wouldn’t mind?
 

cookie

Hyper Poster
All I know is that dropping off the MCBR on Silver Star in the back row definitely forces you out of your seat and feels as strong if not stronger than some coasters I’ve ridden that I know exert negative forces. It’s a conditional example, but it always springs to mind when I hear people talking about airtime on hypers.
 

VikingParrot

Roller Poster
Raging Bull gets a lot of hate, but that first drop in the back seat is worth the drive to Chicago. 13 hours give or take.
 

Hixee

Flojector
Staff member
Administrator
Moderator
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Moved the thread for you, mate. :)

I think there's some important things to consider which, whilst your A-level physics isn't wrong, is stuff where "physics" becomes "engineering".

Yes, in theory when B&M design their parabolic hills they calculate the curve for the 'perfect' zero-g experience. And yes, in theory that would mean you wouldn't see riders being pushed against the restraint.

However, what they're actually doing is calculating the path for a 'perfect' coaster train. This train is likely modelled as some point at the centre of gravity of the train, likely with an ideal weight, rider distribution, wind direction, air resistance, etc. Of course, B&M can't control most of those factors, so there will always be some variation in those parameters in real life.

B&M will probably run a series of scenarios, considering first the "ideal" then testing that solution against a range of scenarios where they tweak some of those inputs. They'll make sure their coaster will still work (and be comfortable/safe) with an empty train on a cold day and a full train on a hot day and probably a few other 'extremes' to build an area of tolerance into their model. If they can get between +0.5G and -0.5G across a hill in their 'worst case' scenarios, they can be reasonably sure that in the real world the coaster will always land somewhere in that bracket.

So if you're in the front row on a hot day and the train enters the hill 5% faster than B&M's "perfect" speed, then you'll probably get a little pop of ejector as the train begins to crest the hill. Conversely, on a cold day with a partially empty train you may find all the hills feel very lacklustre because the train is running slowly. People with lots of laps on specific B&M hypers (or even comparing different people's experiences of the same ride) will be able to speak to this well.

It's probably worth also saying that B&M probably try to aim on the faster side than slower, as it's easier to trim speed off than it is to boost it.

This is all conjecture, because I don't work for B&M, but this is the basic essence of engineering.

Of course, I should add there's lots of additional factors also coming into play that B&M themselves would have even more difficulty factoring in:
  • Is the rider trying to influence the forces? Throwing your arms up in the air as the train hits near weightlessness is going to pull you out of your seat.
  • Has the park turned off (or dialled back) the trims? Maybe the train is running faster than B&M intended it to.
  • Are you in the back row? The forces experienced are different in every seat.
  • How loose is the restraint? A looser restraint would allow someone to gather a little more upward momentum before being brought to a stop than someone who'd been stapled. This could give the impression of more forceful airtime.
Engineering is not an exact science, and B&M aren't wrong or bad at what they do, it's just that they're working with something that has an almost infinite level of complexity. The closer you look, the more factors you find, and it would be impossible for them to somehow engineer out all of them. At some point, as engineers (and I speak from practice) you say "close enough".
 

Howie

Giga Poster
B&M hyper trains are really long though, right? So no matter how accurate the parabolic curve of the airtime hill may be, there can only one specific part of the train that experiences the perfect 0g. I'm no engineer, but I would assume the calculation point would be somewhere near the middle of the train, right? Therefore any point on the train either in front or behind that 'sweet spot' would either be subjected to slightly more or slightly less negative g-forces. I dunno, is that how it works? Hence the first drop on B&M hypers is always more forceful in the back seat. And that's before you take into account things like weight distribution, atmospheric conditions, wheel and bearing temperatures etc.. etc..
With all those variables, I would say it's almost certainly possible for B&M hypers to produce actual negative g forces.
Anecdotally though, even with the best examples of the model (Shambhala and Behemoth for me), I can't say I've ever felt like I'm being truly ejected from the seat, not in the way Taron or the RMC's do, it feels more like the seat drops away from underneath you, and if it wasn't for the clamshell pulling you down with it you'd be left 'floating' up in the air somewhere.
Floater, see?

*Edit Hixee you bah-stud. 🤣

Or in other words, guys, what Hixee said.
 

Benni

Roller Poster
Okay, as soon as themeparks are allowed to open again, we'll try to measure the g-forces of a B&M Hyper. The nearest one would be Silver Star. ;)
But I'd also say, as long as the tracks are designed to barely hit the 0 g, they'll probably get under 0 g, if you're sitting further from the center of mass - assuming they use the center of mass as reference point for calculations.
 

Pokemaniac

Mountain monkey
Staff member
Administrator
Moderator
I think there's some important things to consider which, whilst your A-level physics isn't wrong, is stuff where "physics" becomes "engineering".
The classic definition of this question is: "Physics is math, constrained by the limitations of nature. Engineering is physics, constrained by a schedule and a budget".
 

Niles

Hyper Poster
With CoasterStats/@Benni video of Fenix, when it goes over its air time hill it hits a negative Gforce of -0.63g. I would be surprised if this is the highest negative Gforce on any B&M so I would assume there is a hyper that would hit a higher negative g. To anyone that has ridden Fenix how does it compare to any hypers?


There work is great and looks well made, It would be interesting to see the stats of a B&M hyper. After riding Shambhala I would say that it easily goes into negative g.

 

Gazza

Giga Poster
I thought that Swedish bloke who used to be a member here did G force logs and they tended to be around the -0.3 mark.
 

Pokemaniac

Mountain monkey
Staff member
Administrator
Moderator
I thought that Swedish bloke who used to be a member here did G force logs and they tended to be around the -0.3 mark.
I guess we could tag him and ask. He's not around very often, but it might be worth a shot: @lond still has an account on here, although sadly his brother left a few years back and even his second account appears to be deleted.
 

Trax

Mega Poster
There work is great and looks well made, It would be interesting to see the stats of a B&M hyper. After riding Shambhala I would say that it easily goes into negative g.
I know the topic is a little bit old, but I think you deserve a reply.
1. Thanks, it really means a lot to us to see that our hard work is apreciated. It's not only money, but dozens of hours to get the project where we are today.
2. Once parks in germany are allowed to open up again, we are hoping to get a measurement of Silver Star. I know this is often considered one of the weakest B&Ms, but it is quite easy for us to reach.

There is i slight chance that I will make it to Port Aventura this year (but as mentioned, slight), in this case I would also try to measure Shambala.

Unfortunately, Covid still causes quite a lot restrictments in europe, so every plan we make can be easily undone with a single governmental descision. We are hoping for the best, but can give no guarantees for now.
 
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