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Vallean's Achievements


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  1. No worries about the brakes. All mission-critical roller coaster brakes are failsafe (at least those of modern steel coasters, I don't know every antique woodie around). The pictures of the http://www.coastersandmore.de website are from a simplified test coaster built close to Lucerne in Switzerland.
  2. Unless it's for legitimate purposes serving the park's interests (media etc.) it will be difficult to get an official authorization and even than for liabilitie issue the camera will have to be specially secured and/or one will have to ride alone (or maybe with some park employees). BTW If someone drops a camera while riding at 60 MPH the camera won't hit anyone immediately at that relative speed as initially the camera moves at the same speed as the person who drops it before being slowed down by aerodynamic friction. It's like if one would drop a camera standing on the ground facing a steady 60 MPH wind. The problem is more for persons in following cars and/or if the camera bounces on the structure. That said, roller coasters have predictable accelerations, so some flat rides are more critical. Overall one must be quite stupid to drop a small camera on a roller coaster as accelerations and jerk aren't that important but it's anyway against the safety rules.
  3. From a technical POV a +/- 1 MPH top speed difference is pointless and the top speed cannot even be predicted that precisely. There are design parameters you work with but engineering is not an exact science, kinetic energy losses are evaluated based on model computations and empirical results and that can't be done with an extremely high precision (i.e. leading to speed uncertainities in the MPH range). The only speed you can (more or less) control is a final launch speed but it depends on the launch system perfomance (speed regulation accuracy if applicable).
  4. One should be very careful when comparing claimed accelerations. It's not only about the acceleration itself but also about directions, rate (jerk) and durations. It's not that easy to perform really comparable measurements and the publicized figures are not necessarily true either.
  5. Didn't see the other message as I was writing. The acceleration is regulated, more precisely the speed is regulated. A simplified explanation: Many times each second the speed is computed (indeed based on the position difference based on signals from incremental or absolute rotary encoders) and a digital regulation algorithm issues a signal to drive proportional valves or servovalves which modulate the hydraulic oil flow sent to the hydraulic motors.So if the acceleration is too low somewhat more oil is sent to the motors which increases the power. A fraction of second later the system may accelerate slightly too much and the power will be reduced and so on many times per second. Of course the regulation is so fast that you don't notice oscillations, their frequency is above the one which the system can respond to. What does it mean? That the speed profile (during the launching), and therefore also the acceleration, do not depend e.g. on the weight of the train and friction losses... But it also means that unless the control system adjusts the final launch speed according to parameters like wind or temperature, you need some margin to make sure there will be no rollback. If you don't you just guarantee a constant final launch speed. This is a somewhat simplified explanation, reality is more complex as several regulation loops are nested and you also require multistage valve systems due to the relatively high hydraulic flow rates reached toward the end of the launch procedure. The motors used by Intamin are internal gear motors (therefore obviously with fixed displacement), the accumulators are of the piston type. (Edited to add some text.)
  6. But a few people post about engineering facts, not all are nerds. The 200 lbs difference you mention as example is negligible as you not only have to accelerate the train but also the catch car, the hydraulic motors, the reduction gear, the drive drum as well as the pulleys and the cable. Interesting is the design of the part which locks on the catch car, due to the rollback possibility a failsafe retraction is required as soon as the train leaves the catch car. It's a safety design feature to allow the train to roll back passing over the catch car wherever the catch car has stopped.
  7. From a technical POV it should be remembered that the braking force depends on the permanent magnets, the fin material (and thickness) as well as a lot on the relative speed between the fins and the magnet assemblies as well as slightly on the ambient temperature. For drop towers, a smooth increase of the braking force is achieved by using different fin plate materials along the brake run. The final speed at which the gondola reaches the shock absorbers is about constant and is reached some distance above them to safely compensate variations. Final shock absorbers are required because eddy current brakes have zero force at zero relative speed between magnet assemblies and fins. Of course such brakes are totally failsafe and don't require any sort of active control. As the braking effect is bidirectional, gondolas are lifted relatively slowly in order to not require excessive winch power.
  8. The eddy current brake system of the catch car has not only to slow down the catch car itself but also at least partially the cable and drum system. IIRC it's an Intrasys http://www.intrasys-gmbh.com brake design. The rollback braking section must also be long enough to take in account the possible failure of some brake fins, they're failsafe up and lowered pneumatically. After a fixed delay after the launch command or in case of any control system failure they're automatically raised.
  9. If what is mentioned in that message is true, which is very possible from a formal technical POV, it's another shame for Vekoma engineers and a proof of very serious PLC (Programmable Logic Controller) programming flaws. Roller coaster automation systems should (and new one shall) be designed to meet at least SIL 3 (Safety Integrity Level 3) according to the IEC 61508 standard. Unfortunately many roller coaster control systems, especially those based on dual conventional (i.e. non-stafety) PLCs do not meet SIL 3 requirements. Vekoma designed some restraint monitoring systems which I still wonder how they passed the safety inspections. The most basic safety feature you test is to guarantee that retraint locking and, if applicable, tilt locking can't be affected in ANY way once the train starts to move even while collector brushes haven't left the contact strips in the station.
  10. I'm glad if you're able to perform roller coaster computations because it's not that trivial, although less complex than some would possibly imagine, I mean form an engineer's or physicist's POV.
  11. Acceleration (in m/s2) is defined as the variation of speed vs. time (i.e. 1st derivate of speed, 2nd derivate of position) but the accelerations rate, called jerk, indicated in m/s3 is important too (sorry, I use the metric system as for some engineering purposes it's tough to use imperial units). Those interested can have a look at this PDF file showing accelerometer plots from a B&M roller coaster test (Superman, la Atracción de Acero, Madrid, Spain): www.4emme.it/PDF/ES_Superman.pdf Accelerometer measurements are performed on all new roller coasters to check if the design specifications are met and especially if limits (e.g. per ASTM) are not exceeded. Sorry if it is somewhat off-topic.
  12. The main drive system of the drum is not that exceptional, it's mainly good engineering and a lot can be quite well simulated too with computer models. The whole cable system is more challenging as it's unusual to use cables at such high speeds and accelerations (excepted maybe in the military domain but I don't know details and you don't launch so many times per hour during the whole day). A "falling" counterweight isn't useful as the achievable accelerations are low and limited (even if an infinitely heavy mass would be used). The old Schwarzkopf flywheel solution is still better and could be done for large roller coasters. The most elegant solution are linear motors but unless using one (or several) dynamic generator with a huge storage flywheel it's difficult to go much further due to the electrical peak power (=costs, not technical issues). From the linear drive technology there wouldn't be much limitations. Back to Kindga Ka: The reason many hydraulic motors are used is related to the availability of commercial hydraulic motors. There are very powerful single motors but they run very slowly (see e.g. http://www.hagglunds.com), far too slow for the intended application. All high-displacement-volume hydraulic motors are for low-speed high-torque applications, therefore the only commercially available hydromotors with high enough speeds are relatively small (though not that small as they can typically be in the 500-800 kW range), therefore to reach a very high power several motors are used in parallel. Like in any design, engineers first try to find appropriate off-the-shelf products (COTS) before doing a custom design. In this case the gear made by L. Kissling & Co. AG in Zuerich (see my post above) was a full-custom design based on another custom design also made for Intamin AG. As OT, those interested in huge cable drive systems for mines can visit http://www.siemag.de (click on "English") or have a look at this PDF (a 12.8 MW winder, it's in the range of the Kingda Ka launch power but it's continuous, not just a few seconds): http://www.siemag.de/ti-south-deep.download.6597ee4de29d5b2d74177c543f03d813.pdf.
  13. For those interested in technical details: An article from Kissling & Co. AG, Zürich, Switzerland, the manufacturer of the drive gear (page 4 of this PDF file, the document is also available in German and French): www.kissgear.ch/fileadmin/user_upload/Kissling_Firmenzeitung_80jahre_E.pdf There are also several technical articles in U.S. engineering magazines. Technically there aren't that many options for high power launching systems. Electrically powered linear drives draw a lot of peak power (although generators with very large flywheels would be possible to store most ot the required launching energy), require complex drive power electronics and fast real-time digital regulation systems but are mechanically very simple. From an engineering POV I'd tend to consider the hydraulic launching solution as reliable but the whole drum and cable system is challenging, especially as it's not usual tu use cables at such high speeds. Edit: Those interested in eddy-current brakes and linear drives for roller coasters can visit the website of Intrasys GmbH (mostly in German): www.intrasys-gmbh.com A 17-pages article about linear drives for roller coasters can be found here (in English): www.intrasys-gmbh.com/at/LSM_0205.pdf BTW the patent # indicated in some article linked above is wrong.
  14. Just a small word about the technical safety (mainly probability of mechanical failure, either if a retaining part breaks and/or if the locking mechanism fails). Basically dual independant (=redundant) locking systems are preferred. Worst are probably some older lap bars with worn out ratchets. From the outside it's often hard to tell if a restraint has a redundant locking system. Recent designs found in advanced roller coasters are usually very safe if maintained correctly. Personally I appreciate the quality of Swiss B&M designs.
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