10 replies to this topic

[Exo]

Discs are interesting ammo. If they are fired perfectly level, as determined by a bubble level attached to the tacrail, they will fly just like any dart will. When angled just enough to tip the bubble, they will float miraculously. HERE is a video demonstrating this concept. This probably isn't that surprising to most people, but I thought I'd start a discussion on discs and their flight characteristics.

Edited by Exo, 09 November 2012 - 09:16 PM.

[Mully]

The're really accurate too.
It's annoying

Edited by Mully, 10 November 2012 - 12:39 AM.

[Exo]

I'm a little confused as to what you mean by that.

[Mully]

It means that I'm trying to hit my opponent with streamlines, and he's losing me with vortex discs

[hamoidar]

I'm a little confused as to what you mean by that.

I think that he means it is annoying to be hit by them all the time because they are so accurate.

On topic: I use a vortex Praxis at all my wars. Of course, it is an indoor war, with no wind or super-long range blasters. I have found that they are not only long-ranged and accurate but also extremely reliable. It may be interesting to note that the higher the power of the blaster, a more level/strait flight path is observed. This may be due to the discs design, which is quite similar to a Frisbee, with the disc basically acting as a wing. So, when the disc is propelled at a higher velocity, it goes further, possibly straighter.

[Exo]

Got it. I wasn't sure if you were being sarcastic or not. Yes, I agree, they can be accurate under windless conditions.

[Mully]

Thanks hamoidar, I didn't meen it sarcastically.
Anyway, with a lot of wind, these things are terrible, but in indoor wars, the're really good.
One of the people I have wars with has a praxis, so whenever I hear a click, I duck, and a disc appears where my head was.

Mully

[Doom]

Nice video Exo.

There are probably two effects here. The disks certainly have much more lift than regular darts. I'm not going to even check the drag forces here. So that explains part of the range increase. But, even for darts a small angle increases range substantially, as Beaver showed with some experiments.

A year and a half ago I posted about disks somewhere else. Disks have a low drag coefficient compared against darts and they can resist gravity better than other darts due to their lift. There are some disadvantages (wind, moving to one side from the Magnus effect) that can be mitigated with weighted disks and potentially other changes. So, they make some sense from an external ballistic (after the dart leaves the gun) standpoint. How to shoot them in a typical gun (the internal ballistic standpoint) is an entire other question. I'm not sure what the best way would be.

Has anyone seen a disk launcher that did not use some sort of "pusher"? Maybe I'm ignorant of what's out there, but the disk guns I've seen either were motorized or used a pusher.

When I get the time I'm going to do some experiments and engineering analysis with different types of ammo (standard, ball, and disk types) and see what I can figure out about the advantages and disadvantages of each type and which offers the most promise. Disks have interesting properties, and the disadvantages might not be so bad with the right type of disks.

[hamoidar]

Has anyone seen a disk launcher that did not use some sort of "pusher"? Maybe I'm ignorant of what's out there, but the disk guns I've seen either were motorized or used a pusher.

I started to experiment with an air powered disc gun, but quickly realized that making a barrel for the discs was going to be a pain, if not impossible. This difficulty is mostly due to the curved upper edges of the discs, which makes a good disc/barrel seal very hard to achieve.

I suppose you could make a springer which had only a small section of tight fitting barrel material, with the rest of the barrel a looser fit. I believe Nerf has one of the best mechanisms for firing the discs, with one good feature being that you get a mechanical advantage when priming. Their design is also extremely quiet to operate. (no motors) I think that if one was to make a homemade disc launcher, he/she would need to expand on Nerf's design, instead of making a new system. That’s not to say a new design isn't feasible, simply that we should use the good, well-tested technology already available.

Edited by hamoidar, 10 November 2012 - 02:13 PM.

[Meaker VI]

Has anyone seen a disk launcher that did not use some sort of "pusher"? Maybe I'm ignorant of what's out there, but the disk guns I've seen either were motorized or used a pusher.

No, but I have seen very different approaches to pushers - Nerf's approach seems to work very well. Clay pigeon throwers might provide some inspiration as well.

I started to experiment with an air powered disc gun, but quickly realized that making a barrel for the discs was going to be a pain, if not impossible. This difficulty is mostly due to the curved upper edges of the discs, which makes a good disc/barrel seal very hard to achieve.

Using homemade discs with no upper curvature might make this possible, but I don't think it's a worthwhile endeavor. The mechanical systems already get good ranges, and getting the disk to seal against a rectangular barrel consistently would be a ton of work.

[Exo]

Thanks for the physics input, Doom. I think that the wingish cross-section of the disc is too nice to get rid of by using a symmetrical barrel and the mechanical system is just too simple to even consider air-based disc launchers. Nerf's baby is good as is.