Buzz Bee's Trantula

Threads about water gun modifications.
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Drenchenator
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Re: Buzz Bee's Trantula

Post by Drenchenator » Tue Jul 08, 2008 3:14 pm

Getting more life out of the battery may be a more worthwhile modification, even if you up the voltage. Since you can't always pump in this gun (that's the idea, right?), you'd like to make sure you can last. Replacing the battery with one with an equivalent voltage but higher charge (which is what mAh measures) will make the battery last longer. Plus, if you up the voltage, you'd probably want to do this to last at least the same amount of time as before.
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cantab
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Re: Buzz Bee's Trantula

Post by cantab » Tue Jul 08, 2008 3:43 pm

That said, how long does the stock battery last? Has it been tested.

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StormGlorious
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Re: Buzz Bee's Trantula

Post by StormGlorious » Wed Jul 09, 2008 12:47 am

I bought the Tarantula about one year ago..... The stock battery on mine lasted about 45 minutes before needing a recharge. In my opinion, this gun really isn't worth the time and maybe the money required for this mod. In my wars, this gun could not really survive. I think that the best thing you could do to this gun is a resevoir expansion. So that you can keep upa continous rate of fire for longer.

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cantab
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Re: Buzz Bee's Trantula

Post by cantab » Wed Jul 09, 2008 10:31 am

45 minutes? Was that shot time or just how long it lasted in a battle? If the former, that's pretty impressive. If the latter, not so great.
Also, had the battery been charged recently? NiMH batteries lose a lot of their charge in only a few weeks. So especially if it's been unused for a while, you should put the tarantula on charge the night before you plan on using it.

In what sense did it "not really survive"? What did you find lacking?

Personally I wouldn't use it as a main blaster, but it seems more attractive as a backup, since it needs no pumping. I'd still want a small third weapon just in case the tarantula battery dies.

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Drenchenator
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Re: Buzz Bee's Trantula

Post by Drenchenator » Wed Jul 09, 2008 12:43 pm

I doubt that's the shot time. That's how long the battery lasted, right? Assuming it is, that means it lasts at most .75 hours, making the current at most 800 mA and the effective resistance of the whole thing about 12 ohms.

Overall, I find the fact that you can't just pump it to pressurize it faster manually. As stupid as it sounds, I like to manually (in the Latin sense, meaning by hand) charge my gun because it gives me the freedom to charge it as quickly as I want as frequently as I want. Moreover, the gun's a pressurized reservoir soaker, which limits it more than most other things. Pressurized reservoir guns can't get multiple shots; once you run out of water, you have to depressurize the gun to refill it. That's why having a separate pressure chamber really helps--it just saves a lot of time.
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SSCBen
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Re: Buzz Bee's Trantula

Post by SSCBen » Wed Jul 09, 2008 12:47 pm

I'm looking into the battery replacement with some interesting results. While it's definitely possible, very often these batteries will cost $30 or more so it's not really worthwhile unless you intend to get good use out of it.

I don't know why in particular BBT chose NiCds but I assume that NiCds can be swapped with NiMhs without issue because every charger I've seen can do both. I don't know about lithium ion batteries but I don't imagine they'd be ideal for water wars with their problems. If you use your own charger I guess you can use any battery type you wanted to.

Any battery from places like Tower Hobbies should be good for the Tarantula, given that you replace the connector with BBT's one.

These batteries seem to have the best capacity for their price:

http://www3.towerhobbies.com/cgi-bin/wt ... LXGBM4&P=0
http://www3.towerhobbies.com/cgi-bin/wt ... LXKZC2&P=0
http://www3.towerhobbies.com/cgi-bin/wt ... LXGBM8&P=0
http://www3.towerhobbies.com/cgi-bin/wt ... LXSZW6&P=0
http://www3.towerhobbies.com/cgi-bin/wt ... LXMDK1&P=0

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cantab
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Re: Buzz Bee's Trantula

Post by cantab » Wed Jul 09, 2008 1:21 pm

@Drenchenator: The tarantula's not a pressurised reservoir. Rather, the pump directly forces the water out of the nozzle. There's no pressure chamber at all. The manual equivalent is thus a piston pumper.
The older Scorpion, by contrast, used a hydro power PC, making it rather better, like a motorised version of the blazer.

@Ben: Ah right, it's NiCads actually. Well they have three advantages over NiMH. One is lower self discharge rate, so the battery won't go flat so quickly in store like I mentioned. Another is I believe NiCad has lower internal resistance, making it better able to supply high current, as the motor probably needs. (Internal resistance results in an effective voltage drop under high currents). Consequently, changing to NiMH could actually reduce the performance of the gun.
The third is I think NiCads are a bit cheaper.

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Drenchenator
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Re: Buzz Bee's Trantula

Post by Drenchenator » Wed Jul 09, 2008 1:30 pm

@Drenchenator: The tarantula's not a pressurised reservoir. Rather, the pump directly forces the water out of the nozzle. There's no pressure chamber at all. The manual equivalent is thus a piston pumper.
The older Scorpion, by contrast, used a hydro power PC, making it rather better, like a motorised version of the blazer.
Okay. Doesn't change my mind. Though, it does mean that you may be able to convert this to a more useful kind of gun. Build a pressure chamber out of some PVC and use the electric pump to power it, much like what Ben did here.
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cantab
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Re: Buzz Bee's Trantula

Post by cantab » Wed Jul 09, 2008 1:55 pm

Point. As I mentioned, there's a fair sized dead space behind the nozzle. That could be a good place to fit a PC, though it might be a bit small.
Though whether that works depends on the pressure the pump can produce. It might turn out to be rather low.

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Drenchenator
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Re: Buzz Bee's Trantula

Post by Drenchenator » Wed Jul 09, 2008 2:58 pm

Point. As I mentioned, there's a fair sized dead space behind the nozzle. That could be a good place to fit a PC, though it might be a bit small.
Though whether that works depends on the pressure the pump can produce. It might turn out to be rather low.
Agreed. That dead space could be perfect for a small PC, though I'd imagine that to get any real use out of the gun with a separate chamber, the chamber would have to be made of at least 2" PVC, needing much more room. Perhaps a hole could be made into the casing around the dead space where the chamber could leave the gun, much like in guns like the XP 70, 270, or 310. An external chamber goes with the looks of the gun at the point with the dead space too. Just some thoughts.
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SSCBen
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Re: Buzz Bee's Trantula

Post by SSCBen » Wed Jul 09, 2008 3:25 pm

@Ben: Ah right, it's NiCads actually. Well they have three advantages over NiMH. One is lower self discharge rate, so the battery won't go flat so quickly in store like I mentioned. Another is I believe NiCad has lower internal resistance, making it better able to supply high current, as the motor probably needs. (Internal resistance results in an effective voltage drop under high currents). Consequently, changing to NiMH could actually reduce the performance of the gun.
The third is I think NiCads are a bit cheaper.
That makes sense. There weren't too many high capacity NiCds I could find on Tower Hobbies though. Maybe it would be best to use two NiCds in parallel then to get increase mAh.

Pressurizing the reservoir should increase the power too, though I'm unsure whether it's an advisable idea because the chamber isn't designed to handle pressure and the pump might not be able to handle much of an increase in flow.

zacharious8
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Re: Buzz Bee's Trantula

Post by zacharious8 » Wed Jul 09, 2008 5:24 pm

The current of the diffrent batteries listed will fry the guns motor. You have to keep the AA cell setup to ensure the correct current. The voltage needs to be increased by 1.2v or one cell. This will insure the correct current and only increase the voltage.

Batteries in series = higher voltage
Batteries in parallel = higher current

The current also changes with the use of diffrent size cells. Say C cells vs AA cells.

NIMH vs NICAD. The diffrences are not that great. The NIMH does not have a memory effect. Which means you can charge it at any time no mater if the battery is half charged or completly drained. Most RC trucks/cars us NIMH or LIPOs.

The battery box is big enough for a 9th AA cell. You would just have to dremmel out the battery cover.

Zach

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Silence
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Re: Buzz Bee's Trantula

Post by Silence » Fri Jul 11, 2008 10:02 pm

Ben, lithium batteries don't usually have very high current. Plus there are still occasional reports of the batteries catching fire, as you implied. Not a good choice obviously.

The Scorpion, which came out a year before the Tarantula, did have a pressure chamber, along with three nozzle sizes. The motor could only keep up with the water output on the smallest nozzle. The Tarantula isn't as good in a water war, but it probably targets its audience best - electric water guns aren't really meant for serious use, unlike CPS ones.

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