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Posted: Tue Apr 12, 2011 5:04 pm
by ramses
:shock: :shock:

I'll admit that I had no idea what scale you were working at until you showed the projectile in your hand!!!

The spinning would strictly even out any uneven drag, and not contribute to stability. Basically, if the round tended to drift in one direction relative to itself (say, from a bent fin or something), it would corkscrew, rather than go off on some wild arc. Sure there may be a tiny amount of drag, but that's better than the projectile randomly drifting off course and burying itself in the ocean.

Posted: Tue Apr 12, 2011 5:18 pm
by MrCrowley
@&#* that thing is beautiful :D

...I might cry when I shoot it :wink: :wink:

Posted: Tue Apr 12, 2011 5:21 pm
by LeMaudit
Here's the detail and weight for all the parts, if someone want to compute some optimal gravity center and additional weight in the nose.


Image

Posted: Tue Apr 12, 2011 6:30 pm
by mark.f
Uh, so you're going to shoot this, right Crowley? :shock:

I have an idea of how the "location effects" work, but a PM would be cool? To clarify, it looks like the threaded rod moves back into the rear of the round upon impact...

Very nice work, LeMaudit. This is the nicest object I've ever seen designed to by launched at high velocities...

Posted: Tue Apr 12, 2011 6:39 pm
by LeMaudit
Very nice work, LeMaudit.
Thanks mark.f, and also all you guys for your nice comments. I had a lot of fun coming back to machining again with this fun project. Now the sabot... I'll work on it during next week-end.

Posted: Tue Apr 12, 2011 6:49 pm
by MrCrowley
mark.f wrote:Uh, so you're going to shoot this, right Crowley? :shock:

I have an idea of how the "location effects" work, but a PM would be cool? To clarify, it looks like the threaded rod moves back into the rear of the round upon impact...

Very nice work, LeMaudit. This is the nicest object I've ever seen designed to by launched at high velocities...
Actually, aside from the four holes (in case I decided to use smoke on the off chance it works), there are no "location effects" on this particular round. I believe the rod is just a way to keep it all together.

We ruled out smoke because:

a) it would require a very unique styled sabot that would risk the projectile not being launched properly
and
b) the smoke would only help to get a general idea of the projectile direction, smoke would either run out or be too hard to see by the time it gets out past 2000m or so I imagine.

We ruled out transmitters because:

a) we'd need to use something that operated in the UHF range to keep the antenna short
and
b) would be too expensive to make a reliable one (~$75)

We ruled out LEDs because:

a) no way you'll see an LED past a 1000m or perhaps even less. Like the smoke, it may give a general direction but little else.

We ruled out dye because:

a) on the chance it deployed correctly and left a visible mark above surface, the mark still may be too hard to find due to the low volume of dye.

Think that's all the options we discussed.

I'm thinking I might take my chances and fire at this. It's about 3500m away (if shot from the beach/cliffs), the firing zone is close to my house (2min walk) and the island receives a large amount of visitors at one time of the day yet practically zero at another time of the day.

If I included an email address or phone number waterproofed inside the projectile, there is the slim possibility either a tourist or a DOC (Department Of Conservation) worker would find it and hopefully report it. I could make the note and email address sound official so they are more likely to report it. I wouldn't be worried about someone reporting it to the police though. There are a very small number of 'houses' (~6) on the island but they're all located by the ferry terminal and if I did the shot late in to the evening at an isolated part of the island there wouldn't be a risk of hitting anyone as the last of the day ferry leaves at around 5pm I think and the island isn't suitable for camping.

Anyway, just thinking it might be better than blatantly losing it in the sand up at that beach where the chance of recovery is virtually zero without any "location effects".

Posted: Tue Apr 12, 2011 6:57 pm
by LeMaudit
I believe the rod is just a way to keep it all together.
Correct. It was the simplest way for me, and the sturdiest. In case more space would be needed, the pieces could be glued together... dare I say... with... epoxy :D

Posted: Tue Apr 12, 2011 7:10 pm
by mark.f
Ah, I was thinking the rear of the threaded rod was free to move a very small distance forward or backward, so upon impact a magic cup shaped piece of metal would be struck by the sharpened end of the rod, initiating a special dust which creates a large amount of dry aerosol. :wink:

Posted: Tue Apr 12, 2011 7:12 pm
by POLAND_SPUD
I'll tell you what will happen...

you'll load it and fire... and that's it... no chances of finding it afterwards to confirm the range :?
a) no way you'll see an LED past a 1000m or perhaps even less. Like the smoke, it may give a general direction but little else
As jsr and I pointed out earlier you know more less where it will land (well at least the general direction) so the point of using LEDs is to help you locate the projectile once it has hit the ground
(and if it didn't embed into ground :wink: you only hope is that the terminal velocity will be pretty low)

Posted: Tue Apr 12, 2011 7:31 pm
by mobile chernobyl
I might have missed it but what's being used to shoot this shiny little thing?

Posted: Tue Apr 12, 2011 7:32 pm
by LeMaudit
magic cup shaped piece of metal would be struck by the sharpened end of the rod,
The holes can be used to let stick out a slow magic cord that could be deal with before the loading into the barrel and generate some visible spell in flight or after hitting the ground. :cherry:

I'll tell you what will happen... you'll load it and fire... and that's it..
Have faith! :D

I might have missed it but what's being used to shoot this shiny little thing?
MrCrowley's big gun... using a sabot that I'll build soon

Posted: Tue Apr 12, 2011 7:35 pm
by seeyouinhell2mf
put a cheap cellphone in it before you fire so you can use the gps to find it,jk

Posted: Tue Apr 12, 2011 7:37 pm
by Gun Freak
seeyouinhell2mf wrote:put a cheap cellphone in it before you fire so you can use the gps to find it
Dude how is he gonna fit a cell phone in it? The thing isn't designed for use in VERA... :lol:

Posted: Tue Apr 12, 2011 7:39 pm
by seeyouinhell2mf
he could feed it some of that stuff Alice drank to shrink it but, to post in a non-wibbletacular fashion if you do find it post a before and after pic of it, I would like to see how much damage it takes

Posted: Tue Apr 12, 2011 10:33 pm
by MrCrowley
mobile chernobyl wrote:I might have missed it but what's being used to shoot this shiny little thing?
http://www.spudfiles.com/forums/mjoelln ... 21873.html

:)
POLAND_SPUD wrote: As jsr and I pointed out earlier you know more less where it will land (well at least the general direction) so the point of using LEDs is to help you locate the projectile once it has hit the ground
(and if it didn't embed into ground :wink: you only hope is that the terminal velocity will be pretty low)
General direction but in an area probably around 30mx1000m since plus-minus 0.02 in the Cd could mean the projectile falls within a 1000m area not to mention that the calculator is only giving us a rough guide as "Cd is assumed to be constant. As such, results are going to be very touch and go for projectiles that are either unstable or transonic (or even faster)."

If I do a night shot, I might use LEDs for the sake of it.