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An S&S Thrust Air Coaster


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#1 X7123M3-256

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Posted 21 May 2017 - 06:32 AM

I thought I would post some images of a launched coaster I'm working on. This is an S&S pneumatic launched coaster inspired mostly by HyperSonic XLC and Dodonpa (but it isn't a recreation of either):
 
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I'm posting this in the construction forum despite the fact that it is already somewhat operational, because there is quite a bit of work still to do on it, mostly around the launch run. The tubing feeding the launch cylinder is narrow and I think it is causing excessive pressure loss that limits the launch power. This was originally meant to run three car trains, but they would not clear the tower. Now that the station is constructed, I will stick with the two cars, but I want to test it with longer cars for future models. There's currently no valve to control the release of air into the system, and the catch car doesn't engage the train automatically, so there's currently a lot of fiddling about with the launch assembly before each run. I hope to automate this at least partially.




#2 IOAgeek

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Posted 21 May 2017 - 09:54 AM

Look at other launch coasters built on the site and build a catch car holder with two pieces of tubing and such, so the catch car smoothly slide down the launch in straight manner without it getting stuck or something. Looks pretty cool though, can we see a video of it running btw? Welcome to SSCoasters as well!



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#3 X7123M3-256

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Posted 21 May 2017 - 11:16 AM

Yeah, I will be working on improving the catch car next. The launch system as it stands was thrown together in about a day to see if it could work (this is a different design to the launches I've built before), and I then added the tower to see how powerful the launch was. I didn't really expect it to clear the tower in the first instance, but it did, so I went ahead and built the rest of the layout. I want to get the launch right this time because most of my previous models have had less than satisfactory launches.

 

I don't have video of it running yet because the handle broke off my air pump broke shortly after the completion of the track, which makes it difficult to reach the required pressure. I have ordered a new one though, so I'll upload a video when I get the system running again.




#4 YolosweggLord

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Posted 21 May 2017 - 01:57 PM

Oh, hey X7123M3-256! Nice seeing you here.
The air-powered launch sounds really intriguing, I can't wait to see a video of it operating.

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#5 X7123M3-256

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Posted 21 May 2017 - 03:06 PM

A small update - I've built a guide to keep the catch car in place on the track. The new system certainly looks better, but as yet, it's completely untested. This has more friction than the original, but it seems to run smoothly. I don't know if it will still perform well when it's under tension.

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The train doesn't have the momentum to engage with the catch car properly (it just barely makes the turn). I considered adding a drive wheel, but there's not the space and the control logic for that would be tricky. What I'm planning to do is leave the catch car at the far end of the launch until the train is in position. The train will pass over a ratchet that prevents it rolling backward, and then the catch car can be wound back under the train. This isn't the way it's supposed to work, but I think it's the most straightforward approach to take.


Edited by X7123M3-256, 21 May 2017 - 03:09 PM.


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#6 IOAgeek

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Posted 21 May 2017 - 03:41 PM

Add some weights to the bottom of the train or smooth out that turn a bit, and it should have enough speed to clear the turn easier. If not make the station higher and add some middle tubing to the turn as well. You don't have those yellow half moons that allow tubing to be clipped onto them like other members have used before, I take it?


Edited by IOAgeek, 21 May 2017 - 03:42 PM.


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#7 X7123M3-256

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Posted 21 May 2017 - 03:51 PM

Weighting the train is probably not a good idea here because it means the launch has to work harder, and it's about maxed out at the moment. The whole track could use some smoothing to be honest, but I don't think I can get enough speed to make the train clear the catch car by itself.

 

You don't have those yellow half moons that allow tubing to be clipped onto them like other members have used before, I take it?

 

I have some, but not nearly enough to build a launch. I think I prefer the look of this version anyway, though the tubing would probably run smoother. At the moment I've not tested this, so I don't know if it'll be a problem.




#8 X7123M3-256

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Posted 23 May 2017 - 12:38 PM

My new pump has arrived so testing has resumed. I've uploaded a short video of the coaster testing. Unfortunately I couldn't get a good angle because the launch still needs to be operated manually, so I can't hold the camera, but the video does show most of the layout.

 

The launch is still super kludgy, but I have at least switched the tubing for a much larger diameter - this has substantially improved the efficiency of the launch, to the point where it can comfortably launch a four car train over the tower with less pressure than was previously required for two.

 

One issue that I still have is that it's quite difficult to get the speed right - the tight radius at the top of the tower means that it ought to crest at a fairly slow speed, but that requires very precise control of the launch that I can't quite achieve with this system. This was a problem with my last launched coaster as well - the obvious solution is not to have a top hat, so my next coaster probably won't.




#9 CW5X

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Posted 23 May 2017 - 01:48 PM

Well, it works. And pretty well too. You seem to get a lot of speed out of this system and consistently. I think if you have more pieces, you could do a lot more with the layout but his works really well as a proper test.

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#10 X7123M3-256

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Posted 24 May 2017 - 04:43 PM

Yeah, this layout was only really meant as a test - I picked an S&S thrust air to model because it goes well with the pneumatic launch, but I intend to use this on something a bit more interesting once I have all the kinks worked out. That said, I can't build a huge model as I don't have nearly as many pieces as some people here. I've already realized that some of the problems I have could be rectified if I'd known about them before building the layout (e.g if I had an inclined launch run, the train would seat itself on the catch car automatically). I may leave this as it is once I've done what I can, and finish perfecting the launch on another model.

 

 

Today, I started looking at ways to reset the catch car to the beginning of the launch automatically. I figured that the easiest way to do that is to apply a constant tension to the launch cable so that it will automatically return to the start of the launch as soon as air supply is turned off. I experimented with using rubber bands to apply the the force, but I found that due to slippage between the cable and the pulley, the rubber band would slowly lose tension, resulting in inconsistent launch speeds.

 

Therefore, I'm currently using a weight to apply tension to the cable. It still slips, but it does not lose tension in the process, so I can now run several launches before the weight has to be reset. I have uploaded a video of the system testing that shows this mechanism in operation.

 

However, this system has it's problems -  the main reason for using a pneumatic launch was to get away from the limitations imposed by the weight drop launch, so having to have a weight anyway is not ideal (though the weight required to reset the catch car is much smaller than what it would take to launch the train). Also, this still needs manual adjustment every now and then - just not after every launch. Also the system is not very reliable (took 14 attempts to capture those two successful runs), nor is it particularly realistic (there does not appear to be any such system on the real thing, and certainly not with a weight).

 

I think in the long run, it would be more productive to make the cylinder double-acting so it can be reset by air pressure. This is conceptually simpler, and I believe this is what the real thing does. However, I won't be trying to do that on this model as I'd need some pneumatic components that I don't have right now.




#11 CW5X

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Posted 29 May 2017 - 06:49 PM

When it works, it looks really nice but it definitely does need some refinement as you said. I'd love to see this with the double acting cylinder working. I did a little bit of pneumatics myself at High School but unfortunately none since then so I can't remember much of what everything does. I recall that it's pretty easy to understand anyway.

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#12 Muzz135

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Posted 30 May 2017 - 05:08 AM

I agree with CW5X - this does look really good, just a shame that it isn't very consistent. I also done some pneumatics, just last year, and would think the double acting cylinder would work really well so hopefully you can get a hold of one of them!

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#13 X7123M3-256

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Posted 10 July 2017 - 03:36 AM

This coaster has now been dismantled. I want the pieces for another project, and I am no closer to figuring out how to make the valves I would need. I'm keeping the launch tube assembled so I can try again in future, but my next coaster probably won't feature a launch.



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#14 sean9782

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Posted 10 July 2017 - 08:22 AM

Well don't forget to make a construction thread for your new coaster. If the shaping and supports are just as good as they were on this one then it'll be a great coaster. Good luck!

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