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rocksim

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Unread postAuthor: POLAND_SPUD » Sat Jun 21, 2008 12:54 pm

I've found this programme for designing and simulating rockets - http://www.apogeerockets.com/RockSim.asp

The programme has some functions that may be interesting for spudgunners:
+it allows to design a rocket from basic parts such as nose cone, main tube etc. and specify what material they are made of...
+ it calculates stablility of a given 'rocket' and its cd value

I think it might be useful for designing ammo... esspecially long range ammo

what do you think ?

BTW before you ask - I don't want to design ammo with a rocket engine strapped to it - I am talking about using this program to experiment with the shape of a projectile that gives the lowest cd possilbe and is stable in flight
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Unread postAuthor: TurboSuper » Sat Jun 21, 2008 1:05 pm

It costs 108 bloody beans! I may as well just roll up a wad of cash and use that as ammo.
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Unread postAuthor: POLAND_SPUD » Sat Jun 21, 2008 2:51 pm

you can download a trial version like I did....

EDIT
pic added - something tells me that you don't really get the idea of what I am talking about

it toke me 1 minute to design a projectile that has a cd of 0.179 and is drag stabilized (well at least according to this programme)
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Unread postAuthor: sandman » Sat Jun 21, 2008 5:14 pm

i have rocksim, and use it semi frequently, and to do what your asking you would have to also make a custom engine (which i havent done yet due to im to young for high power rocketry) to simulate a gun firing
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Unread postAuthor: POLAND_SPUD » Sat Jun 21, 2008 5:50 pm

no you don't need to add engine to a rocket body to test its drag coeficient or stability... I am thinking of using the programme only for designing low drag ammo... hte rest can be done using the inbuilt balistic calculator in GGDT or any other programme

Lol I am suprised that there are hardly any responses to this...
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Unread postAuthor: sandman » Sat Jun 21, 2008 6:00 pm

ok i see what your doing, nvm then

carry on :)
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Unread postAuthor: POLAND_SPUD » Sat Jun 21, 2008 7:08 pm

anyone has any idea how accurate is this programme ?

I've manged to design several types of ammo with drag coeficients as low as 0.1 so these things would be ideal for anyone who wants to shoot something over 1 mile

:D
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Unread postAuthor: sandman » Sat Jun 21, 2008 7:14 pm

it is fairly accurate with the rocket launches as it is a "3 degrees of freedom" statistical modeler, so i would say that its Cd measures would be very accurate

make sure your are also moving the velocity up from 0 when you are checking the Cd
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Unread postAuthor: D_Hall » Sat Jun 21, 2008 11:11 pm

ROTLMAO.....



I'll give you three guesses who wrote the 6DOF package for RockSim Pro.

Hint: It used to be called "Splash." Then the source code was sold for a nice little sum and rolled into RockSim to become RockSim Pro.



....That said, yeah, it oughta work nicely for the design of low drag projectiles.



(And now ya'll know why I won't write a detailed external ballistics package for GGDT/HGDT... Been there. Done that. Don't feel like doing it again.)
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Unread postAuthor: psycix » Sun Jun 22, 2008 6:45 am

The program looks very awesome to me! Nice find, I will try it out soon.
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Unread postAuthor: sandman » Sun Jun 22, 2008 5:50 pm

D_Hall wrote:ROTLMAO.....



I'll give you three guesses who wrote the 6DOF package for RockSim Pro.

Hint: It used to be called "Splash." Then the source code was sold for a nice little sum and rolled into RockSim to become RockSim Pro.



....That said, yeah, it oughta work nicely for the design of low drag projectiles.



(And now ya'll know why I won't write a detailed external ballistics package for GGDT/HGDT... Been there. Done that. Don't feel like doing it again.)


Damn u (but gives u props for making it in the first place), i wish they just kept updating Splash casue i would have got it, but no, now they have to roll it into Rocksim and make uber amounts of money off of it. It angers me, but i dont think it will matter much as by the time i get into high power rocketry ill be pursuing a degree in aerospace engineering.


And ps its ROFLMAO, not ROTLMAO :wink:
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Unread postAuthor: D_Hall » Sun Jun 22, 2008 8:15 pm

sandman wrote:Damn u (but gives u props for making it in the first place), i wish they just kept updating Splash casue i would have got it, but no, now they have to roll it into Rocksim and make uber amounts of money off of it.

Upgrades are actually the reason why I sold it.

Splash was originally written as an academic excercise for myself. I'd seen what similar software packages sold for and I thought it was highway robbery for no more difficult than it would be to write the program. After thinking this for a couple years I finally said, "Self, you keep saying that it wouldn't be tough... Prove it." So I wrote Splash. It really didn't even take that long; a few months is all (admittedly, due to my day job at the time I had a huge head start).

In any event, once I wrote it I had very little interest in supporting it. There were a few bugs. I knew about them but since I knew their cause and how to fix them I was utterly unmotivated to actually DO anything about it.

Apogee kept asking me for the bug fixes and they wanted me to work on some features to allow it to import a RockSim file. I agreed that it would be a good idea but it seemed like grunt work to me. Once again, I simply wasn't interested as I'd proven what I'd set out to prove.

So when they offered me a nice sum for the source code? Yeah, I took it. 8)

It does offend me that they're charging so much for the new version, but I suppose I should have seen that coming since they WANTED to charge that much for the original Splash (but I vetoed that on principal).
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Unread postAuthor: POLAND_SPUD » Mon Jun 23, 2008 1:31 am

I've managed to create several designs of low drag drag stabilized ammo. According to GGDT I could increase the max range by a factor of 2.5 and more with these. If this does not sound good for you then what does ?

@D_hall now I understand what you meant when you said that cd value changes with speed and I realizied that spherical projectiles are not the best shape you can get.

it would be great if you could implement something like this into GGDT but I realize that the inbuilt ballistic calculator is not as good as it could be in the forst place and that you may not be willing to spend hours implementing this stuff into GGDT:wink:

now as far as GGDT itself is concerned I have one suggestion - it would be great if there was an option to fire projectiles smaller than the diameter of a barrel - so in other words saboted rounds... I always wonder how much more range I'd get if I reduce the diameter of ammo a little bit...
something that would make GGDT calculate as usually but then it would put smaller (user defined) diameter of a projectile in the ballistic calculator
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Unread postAuthor: Ragnarok » Mon Jun 23, 2008 6:09 am

POLAND_SPUD wrote:now as far as GGDT itself is concerned I have one suggestion - it would be great if there was an option to fire projectiles smaller than the diameter of a barrel - so in other words saboted rounds... I always wonder how much more range I'd get if I reduce the diameter of ammo a little bit...

Well, if I got my butt in gear, that's the kind of thing the range calculator I'm working on is supposed to do.
Unfortunately, I seem to be constantly short on time, and eating up what spare time I have for coding is seldom appealing.
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Unread postAuthor: D_Hall » Mon Jun 23, 2008 8:27 am

POLAND_SPUD wrote:@D_hall now I understand what you meant when you said that cd value changes with speed

And believe it or not, GGDT's ballistic calculator does make some (very crude) changes to CD as a projectile goes through transonic into supersonic. But there's just not much point in going nuts on it since most folks are using unstabilized projectiles. Heck, if they can't even say for sure what direction the projectile is facing worrying about gnat's assing the CD is a joke.

now as far as GGDT itself is concerned I have one suggestion - it would be great if there was an option to fire projectiles smaller than the diameter of a barrel - so in other words saboted rounds...

Now THAT is a good idea....
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