flyingguitar
TS Member
It isnt impossible, although more common on B&M floorless but objects can get stuck in the wheels, it happened the other week at sea world with a boot.
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Dave
TS Founding Member
I’m not saying it’s impossible for a B&M to stall (though rarer than many manufacturers). I have seen Air nearly stall once during freezing temperatures. I’m saying it would take an extreme event for oblivion to stall due to the height different between the drop, turn and brakes. It would need to lose a lot of speed to do so which would require a catastrophic failure of some description.
DistortAMG
TS Member
This is true, the trains carry a hell of alot of speed and momentum into the break run. Something creating a huge amount of friction would be needed to prevent the train from reaching the final breaks.
I don't think a shoe would do it, especially on a dive machine, which have much heavier trains, thus far more momentum.
flyingguitar
TS Member
They do have quite a bit of momentum, but only a (relatively) small drag is required over the entire drop and subsequent turn to allow it to stall, you also have to remember rollercoaster train wheels are extremely low friction, so even the slightest increase (which a boot would not be, as it would be getting stuck it would do quite a few things to dramatically increase the friction in the wheels, such as trying to rase the car, putting more significantly force into the boot and the up-stop wheels) and the momentum an 8 car floorless train is probably not far off a couple car dive machine. I know that ryan the ride mechanic has said his B&M floorless used to get stuck due to capes (the park sold them) getting stuck and wrapped around the wheels (insert incredibles quote)
Secret Weapon
TS Member
It would be good if Alton Towers offered an after-hours VIP experience which allowed people to walk down into the tunnel and see it with the lights on - similar to the lift hill climb, but going downwards instead of upwards. (AT could even write secret messages on the walls, which would normally not be visible!). I'm not sure if the tunnel was ever designed to allow this to be done safely, though, as I'm assuming that VIP packages weren't common back in 1998?
Numaticjoe
TS Member
I'd love for them to add this onto the VIP walk for Oblivion, if not a paid extra still as well.
There is definitely access down there as I have seen in photos ladders and such built in down there in case they ever need to go down for whatever reason.
It's absolutely huge down there so I couldn't see why they wouldn't think about this for the future, unless it's too much of a liability for whatever reason>
If you've been around for a while you may know of the site Alton Towers Almanac, the guy who run it got to go down there for some pictures I'm pretty sure although, I think it was more of a one time thing for him to doccument the park on his site.
DistortAMG
TS Member
Few mis conceptions there, firstly the momentum of an 8 car floor less train could be similar to a dive machine, but a dive machine carries that momentum over much fewer wheel assemblies than a 8 car train, meaning each wheel is carrying much more momentum, thus making it harder to stop. Oblivion carries a hell of alot of speed and momentum into the break run, unless it is something significant, those trains are not going to stop
flyingguitar
TS Member
The wheel point isn't how momentum works, the momentum of the whole object is the momentum, if you have a 1Kg block on 10 wheels, the friction and momentum would be the same as on 4 wheels (simplifying a bit as rolling friction is more complex than sliding).
Infact as there is more load on each wheels, something getting stuck may mean there is more friction generated.
To put it simplifically a 10N force on a set weight will slow it down the same no matter the number of wheels.
The force generated by getting something stuck would be quite large though, larger than you think because the wheel carriers are locked by the up stop wheels, anything that is stuck will try to lift up the wheels putting a very large force into both the blockage and upstop wheels generating a large friction force.
Tbh something getting into the wheels is probably unlikely on oblivion due to the train design (although if they go floorless I could see it happening)
DistortAMG
TS Member
I'm at work so I can't go into this in detail right now, but imagine you have, say a train of 20 tonnes of weight, rolling on four wheels, vs a train of 20 tonnes of weight, rolling on 8 wheels.
Both trains are moving at the same speed, therefor they have roughly the same amount of momentum. A very similar amount of force will be required to stop both trains as they weigh the same and are going the same speed.
Imagine we are using on wheel brakes to stop the trains, similar to something stuck in the wheel, as its increasing friction on the wheel non the less. The similar required force needed can be spred over the 8 wheels on the 8 wheel train, where on the 4 wheel train, the same breaking force is needed, but across 4 wheels, so you would needed larger breaks on the 4 wheel train, even though the stopping force is the same. This is exactly the same as trains, lorry's, busses and everything in between in real life. Exactly the same principles apply to a coaster car, and something getting stuck in the wheels. Less wheels on a similarly sized and weighted train, will be harder / require more force to stop. This is elementary school stuff.
flyingguitar
TS Member
The problem is you are talking about all the wheels braking, but they are not in this scenario, only 1 wheel is braking for both trains meaning it is the same braking required.
In fact there could be an argument that lower number of wheels could brake more due the increased friction between the track and the wheels (reducing the amount of slippage)
DistortAMG
TS Member
It's not so much the wheels breaking, it's the underlying principle, which you seem to have totally missed. Interesting conversation, non the less.
flyingguitar
TS Member
but that principle isn't correct, if you have 4 vs 20 wheels a force of x will act the same no matter the number of wheels, when a wheel gets blocked with will put a resistance force on the train.
If the force is the same both trains should stop in the same amount of time, but due to the reduced number of wheels there may be more normal force through one set, meaning it would be able to have higher friction increasing the force stopping the train
DistortAMG
TS Member
The force is spred between the 20 wheels though, rather than the 4, making it less on each wheel. That's what I was getting at.
It works both ways too, so it would apply to power being transferred through the wheels, or when a wheel is used to stop the trains, such as if one broke.
If the force was the same for each of the 20 smaller wheels as it is for 4 big wheels, the forces would be much, much greater overall, on the 20 wheel train. But they are not, they are the same, so physics being physics spreads the same force across more points.
Edit: why do you think Oblivion has much larger running wheels? It's because the wheels, being fewer of them, have to cope with much larger forces because the heavy train has much less wheels to spread that same force over. Those larger forces will also reduce the likelihood of something minor, such as a shoe, stopping the train.
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flyingguitar
TS Member
I feel like we are confusing our selves, I have said that each wheel will have more normal force through their wheels on oblivion due to the reduced number of wheels.
I think I understand your point now, it is that more tourque is required to stop the larger force from the wheels, which is kinda true as the increased normal force will add more tourque through the wheels through the increased drag.
but we are not trying to stop the wheel, just slow it by applying a drag on the wheels, through lets say a slow down of 10Nm on a wheel on both (assuming the same wheel size) it will slow it the same, they have different wheel sizes and oblivions is larger which would reduce the force on the train.
but if the drag is large enough to stop the wheel, IMO more likely depending on how the jam comes about for instance if it is a boot under the wheel, the only option is to stop the wheel and slide with the boot as the wheel can't run up and over the boot, due to the increased normal force Oblivion would have a higher friction force (although I would think the force of trying to lift the train, pushing it into the up stop wheels would increase the force dramatically posibly out weighing the weight of the train, depending on how)
Numaticjoe
TS Member
That's a good point actually.
It's a very steep ladder climb down and by no means a "Nice ladder" it's just little metal bars cemented into the wall.
Would be a royal pain in the arse getting everyone down and up again would probably take forever.
Maybe one you could do after completing a previous lift hill climb or something, although that still doesn't really cover the ladder part of things.
Shame really as that would be awesome to go down.
AltonLover123
TS Member
access to the tunnel is via the tunnel exit, not via the drop end.
If you walk around the pond area by the tunnel exit you can see the gate they enter it and some steps that go into the tunnel.
Dave
TS Founding Member
There are also ladders at the other end of the tunnel.
Fact is they are unlikely to ever approve tours of the tunnel, either end is not particularly accessible and I would assume H&S would state that guests need to be able to exit via either route in the event of an emergency and the drop end of the tunnel would be considered too extreme in that event.