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Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Unread postAuthor: MaxuS the 2nd » Mon May 26, 2008 3:04 am

I get that runtime error when I attempt to input points for the perfect hybrid.
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Unread postAuthor: jimmy101 » Mon May 26, 2008 12:03 pm

Not sure if the new version has this problem but 0.4 did strange things when the "init position" was set to a small value. This was modeling 1x gun without any burst disk (burst pressure=0). You get the crazy graph and HGDT crashes.

There also seemed to be some strange interaction with "init position" and other parts of the model. With "init position" set to 0.1", and using an oversized chamber (CB 2.7) I get "Barrel unnecessarily long" warning and "Proj never cleared barrel" error. That doesn't make sense for an oversized chamber. If "Init Position" changed back to the default 0.5" then the errors go away.
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Unread postAuthor: D_Hall » Mon May 26, 2008 12:52 pm

jimmy101 wrote:Not sure if the new version has this problem but 0.4 did strange things when the "init position" was set to a small value. This was modeling 1x gun without any burst disk (burst pressure=0). You get the crazy graph and HGDT crashes.

There also seemed to be some strange interaction with "init position" and other parts of the model. With "init position" set to 0.1", and using an oversized chamber (CB 2.7) I get "Barrel unnecessarily long" warning and "Proj never cleared barrel" error. That doesn't make sense for an oversized chamber. If "Init Position" changed back to the default 0.5" then the errors go away.

Those two problems are directly related to each other. I believe the first one should be gone and the second minimized... But the second may show it's face from time to time.

When the disk bursts and mass is introduced to the barrel, well, a small amount of mass is introduced. The problem is that I use a finite time step and the mass flow is constant throughout that step. At the end of the step, a very small mass flow introduced into a VERY VERY small volume results in a very high pressure: a pressure higher than the chamber (obviously, this wouldn't happen in the real world).

The projectile starts to move forward and...

The next timestep, the flow reverses. We again have the "too much mass moved in too much time" problem and now the pressure in the barrel is VERY low. A vacuum is formed.

The projectile gets pulled backward and...

...The simulation interprets that as a projectile that has run down a very long barrel, stopped, and is now being pulled back into the chamber.
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Unread postAuthor: D_Hall » Mon May 26, 2008 1:40 pm

Larda, can you download the latest executable and try it one more time?

Maxus, uh... Perfect hybrid? Can you be a bit more specific?
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Unread postAuthor: Larda » Mon May 26, 2008 1:56 pm

Now it works, almost.
Everything seems to be fine except that some of the text is in the wrong place.
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Unread postAuthor: SpudFarm » Mon May 26, 2008 2:00 pm

just change on the "Main" file.. i got mine Norwegian that way
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Unread postAuthor: D_Hall » Mon May 26, 2008 2:03 pm

Larda wrote:Now it works, almost.
Everything seems to be fine except that some of the text is in the wrong place.

Looks like you're using the old language pack. Did you reinstall the language packs with 0.5 (yes they changed).

If you don't want to do that, as Spudfarm says just edit the main.txt file in the Language directory.
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Unread postAuthor: Larda » Mon May 26, 2008 2:12 pm

Ohh, sorry m my fault.
I used another computer yesterday.
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Unread postAuthor: SpudFarm » Mon May 26, 2008 2:17 pm

if someone want to know this is how it looked after i changed on it.
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Unread postAuthor: D_Hall » Mon May 26, 2008 2:44 pm

Hey, if you've put together another language pack... mind forwarding it my way for inclusion into the distribution?
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Unread postAuthor: SpudFarm » Mon May 26, 2008 3:12 pm

i am going to do some more adjustments to it and then you can :)
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Unread postAuthor: Lentamentalisk » Thu May 29, 2008 11:56 pm

I just DLed the latest version of HGDT today, and several oddities occurred

Not sure how these things happened...

also, any chance you could add the option of using pure O2, rather than just air?
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Unread postAuthor: drex » Fri May 30, 2008 1:10 am

i to am giting some funky funky readings, i to would like to use oxy insted of air.
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Unread postAuthor: D_Hall » Fri May 30, 2008 1:14 am

Lentamentalisk wrote:I just DLed the latest version of HGDT today, and several oddities occurred

Not sure how these things happened...

also, any chance you could add the option of using pure O2, rather than just air?


Regarding the "cold barrel": You set your burst diaphram to go almost the moment combustion started. In essence, your gun was running as a straight up pneumatic. The only reason why the chamber burned out so quickly is because most of the unburned fuel/air had already left the chamber and was in the barrel. The rise of the barrel temp towards the end was when the gases in the barrel started to burn.

Regarding the plot/text mismatch: The plots only show one in every 25 data points. There's just tooo damned much to plot otherwise. If things are happening very fast, it's totally possible for the plot to miss things. Notice how the plot in your case is very spikey (ie, not a smooth curve)? That's a good indicator that it wasn't keeping up. This is WHY the text is there.

Regarding oxygen: Nope. I figure anybody who's smart enough to intelligently play around with enrichment stuff is sharp enough that he/she doesn't need my help. And if he DOES need my help? Sorry, I'm not gonna get involved in those sorts of games. DDT becomes much more likely and the last thing I need is somebody coming after me because my sim didn't warn them. No way no how do I help anybody play that game.
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Unread postAuthor: drex » Fri May 30, 2008 1:20 am

fair enuff about the oxygen, but what about black powder.


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