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Specter · 06-19-2008, 06:56 PM

OK so I wanted to see the volume of different size PCs for the APH I'm thinking of building.[Total volume- adding volume of # of PCs together] I compared them to the volume of the PCs in Ben's Guide
I was wondering if I could get somewhat equal performance from these calculations. Or if the calculations mean anything at all.
Keep in mind that my PVC is 2" diameter so the radius in the EQ is 1" virtually eliminating that part of the equation essentially making it just PI*height

I used the Cylinder Volume formula V=Pi*r^2*h and my trusty Texas Instruments TI-84+ Silver Calculator

Code:

Volume of Guide APH 1 PC
PI*1.5^2*4 = 28.27433388 cubic inches
Total Volume of both PCs 
Ans*2 = 56.54866776 cubic inches
Possible Choices for my PC(s)
6" length PC 
PI*1^2*6 = 18.84955592cubic inches
I would use 3 PCs with this length PC
Ans*3 = 56.54866776 cubic inches - Equal PC volume to the Guide
8" length PC
PI*1^2*8 = 25.13274123 cubic inches
I would use 3 PCs with this length
Ans*3 = 75.39822369 cubic inches - Larger total volume
10" length PC
PI*1^2*10 = 31.41592654 cubic inches
I would use 2 PCs @ this length
Ans*2 = 62.83185307 cubic inches - Smaller than 3 8" PCs but larger than Guide PCs
3 PCs would yield 
94.24777961 cubic inches

Do these mean anything about having good performance? Could it mean different shot times depending on which configuration I use?
What do you guys suggest?

aEx155 · 06-19-2008, 07:27 PM

There really isn't any configuration that would yield the most performance; it's all about how you put it together. The only thing you'll get from a higher PC volume is longer shot time, as that's the only thing it controls. Performance is based on a lot of factors; PC volume is one of them, but it isn't the only one. If you want higher volume, then go for whatever config you want...but to get performance, you need to watch how you make your gun.

Drenchenator · 06-19-2008, 07:57 PM

aEx155 said it best. I'd just like to add that larger PCs take more time to fill. And that those calculations are for total volume of the chambers; don't expect to put that much water into them because if you did, the pressure would be infinite. Give a good third of the total volume for air; the rest would be water.

Specter · 06-19-2008, 08:03 PM

Quote:

to get performance, you need to watch how you make your gun.

I was going to do the standard setup like in the guide. Except I was thinking of putting the first check valve in line like in the bottom part of this image (don't mind the captions/PC configuration)

Drenchenator · 06-19-2008, 08:06 PM

Performance should be the same then because check valve placement doesn't matter as long as the order's the same. At that point it's a switch-up of the original APH design. It doesn't really matter where the check valves are; it matters in what order they are in. From this your design is completely okay and fine. Performance won't be changed in the slightest.

Ben · 06-19-2008, 08:17 PM

I do these calculations. They're very useful to figure out how long to cut your pipes if you have a certain water capacity or weight in mind. Remember that 1 liter of water weighs 2.2 pounds.

A good approximation for total water volume uses a 1:1 water-air ratio. You should of course have more water than that in your pressure chambers but it gives you an easy rough idea of the capacity. Find the volume of the cylinder, convert it to something more meaningful like liters (the trick to go from cubic inches to liters is to divide by 61), and then multiply it by 0.5 to find the water volume with a 1:1 ratio. If you have a 3:2 ratio you would multiply by 0.6. Other ratios can be figured out with fractions.

Total volume doesn't have much affect on power type performance unless the volume is rather low. If you had 100 mL of water for example, your shot might not be substantial enough to resist drag as much as a longer column of water would, so the range would decrease. Once you have a reasonable amount of water like 500 mL, total volume shouldn't make much of a difference.

Total volume of course would affect shot time, but you already know that.

If it were up to me I'd choose three 8 inch PCs. The water capacity is rather good and the height isn't terrible. 10 inches seems a little too tall to me.

Specter · 06-19-2008, 08:52 PM

Quote:

If it were up to me I'd choose three 8 inch PCs. The water capacity is rather good and the height isn't terrible. 10 inches seems a little too tall to me.

I was thinking the same thing.
From my calculations to me it seems like the 3 8" PCs is be the best configuration

cantab · 06-21-2008, 06:12 PM

I think it was discussed before - it may be better to have each PC coming directly off the main pipe on its own T-junction, rather than them all branching off one. This will also result in a longer but less tall gun.

Silence · 06-21-2008, 09:20 PM

Actually, I don't think the length will change. The width of the pressure chambers, and not the width of the tees, will determine how closely they can be spaced.

Drenchenator · 06-21-2008, 10:32 PM

The length will only really change if we're talking about large tee, 2" or more. They are about 4 to 5 inches in length, so the chambers will fit in between each one nicely, but the gun will get longer from just the size of the tees. But most people just use 1/2" to 1" tees, so this isn't much of a problem. The chambers would be at least 3 inches in total thickness, so extra pipe will be needed to string the chambers together, as showcased in the first photo of the APH article.

Specter · 06-21-2008, 11:06 PM

Quote:

I think it was discussed before - it may be better to have each PC coming directly off the main pipe on its own T-junction, rather than them all branching off one. This will also result in a longer but less tall gun.

I know...
I used the same picture from my other thread and did type this into the post in this thread

Quote:

(don't mind the captions/PC configuration)

So I'm sorry if you missed that part of the post.

Specter · 06-22-2008, 12:36 AM

Couple more questions to ask...
How long typically is the pump made? Or does it matter on how much water I want to be sucked into the PCs each stroke. Which I guess I can figure out with the cylinder volume equation?
What size holes do you drill for the nozzles? Also what ranges and shot times do you typically see from those nozzles?
Is it possible to create a fan type nozzle?

Silence · 06-22-2008, 11:03 AM

The pump length is entirely subjective. I prefer 8 to 10 inches; Ben and Drenchenator use 12 inches, I think. Your length will change the number of strokes it takes, obviously, which is why I prefer "inches of pumping" to "number of pumps", both given a fixed pump diameter. At any rate, it's not really worth worrying about - as long as you're close to a comfortable length, it's either more shorter strokes or fewer longer ones.

1/4" and 3/8" are good sizes to use. From there you can experiment - 3/16", 5/16", 7/16", and 1/2" may work well too. I haven't had much luck in drilling good nozzles, so from now on I'll just use pipe nipples and hose barbs that have suitable inner diameters (which you'll have to guess or measure yourself, as they don't advertise the inner diameter).

To create a fan nozzle, take a very small drill bit, maybe 1/8", and drill as many holes as you want in a single endcap.

aEx155 · 06-22-2008, 08:38 PM

For the pump length, you could always just try whatever you think is best. Since it's not part of the firing path, the only thing the length will affect is the time it takes to pressurize/fill your chambers. The longer you make it, the less pumps it will take; keep in mind, though, it makes the pump easier to break (if you're using wood) to have a long, extended pump handle.

I would have to say that nozzle sizes would vary from gun to gun; it also depends on whether or not you are going for range or output, as the nozzle size controls those two factors. I believe smaller nozzles are for more range, while larger nozzles are for more output (is that right?).

Yes, you can create a fan nozzle, but it might not turn out how you think it will. I believe you should look into buying sprinkler heads (the fixed types) because they already are made and do create a fan-shaped blast; they might not have enough flow though.

cantab · 06-22-2008, 08:48 PM

Every gun should have a nozzle diameter that will give optimum range, with smaller and larger nozzles having reduced ranges. The more powerful the gun, the bigger the optimum range nozzle will be. (In practice, there'll probably be a range of sizes that has very little range variation).

Larger nozzles will certainly be for more output. Smaller nozzles are for saving water or for long shot times. With a big (over 1 litre) PC capacity and a small nozzle, shot times can become very long indeed (into the minutes).

06-19-2008, 06:56 PM	#1
Specter Senior Member Join Date: May 2007 Location: bound brook, NJ -The flood town Posts: 363 UserID: 1090	Speculated APH calculations &questions... OK so I wanted to see the volume of different size PCs for the APH I'm thinking of building.[Total volume- adding volume of # of PCs together] I compared them to the volume of the PCs in Ben's Guide I was wondering if I could get somewhat equal performance from these calculations. Or if the calculations mean anything at all. Keep in mind that my PVC is 2" diameter so the radius in the EQ is 1" virtually eliminating that part of the equation essentially making it just PIheight I used the Cylinder Volume formula V=Pir^2h and my trusty Texas Instruments TI-84+ Silver Calculator Code: Volume of Guide APH 1 PC PI1.5^24 = 28.27433388 cubic inches Total Volume of both PCs Ans2 = 56.54866776 cubic inches Possible Choices for my PC(s) 6" length PC PI1^26 = 18.84955592cubic inches I would use 3 PCs with this length PC Ans3 = 56.54866776 cubic inches - Equal PC volume to the Guide 8" length PC PI1^28 = 25.13274123 cubic inches I would use 3 PCs with this length Ans3 = 75.39822369 cubic inches - Larger total volume 10" length PC PI1^210 = 31.41592654 cubic inches I would use 2 PCs @ this length Ans*2 = 62.83185307 cubic inches - Smaller than 3 8" PCs but larger than Guide PCs 3 PCs would yield 94.24777961 cubic inches Do these mean anything about having good performance? Could it mean different shot times depending on which configuration I use? What do you guys suggest? __________________ My "arsenal": Storm 600 pistol (never finished fixing this), launcher- Model:Afterburner(AB) 1.0(Decommissioned), AB1.5, soon AB 1.1(2"rebuild) maybe ill get something else in the future My site

06-19-2008, 07:27 PM	#2
aEx155 Senior Member Join Date: Apr 2008 Posts: 315 UserID: 1517	Re: Speculated APH calculations &questions... There really isn't any configuration that would yield the most performance; it's all about how you put it together. The only thing you'll get from a higher PC volume is longer shot time, as that's the only thing it controls. Performance is based on a lot of factors; PC volume is one of them, but it isn't the only one. If you want higher volume, then go for whatever config you want...but to get performance, you need to watch how you make your gun. __________________ My homemade

06-19-2008, 07:57 PM	#3
Drenchenator Administrator Join Date: Jun 2004 Location: Maryland Posts: 718 UserID: 320	Re: Speculated APH calculations &questions... aEx155 said it best. I'd just like to add that larger PCs take more time to fill. And that those calculations are for total volume of the chambers; don't expect to put that much water into them because if you did, the pressure would be infinite. Give a good third of the total volume for air; the rest would be water. __________________ The Drenchenator, also known as Lt. Col. Drench.

06-19-2008, 08:06 PM	#5
Drenchenator Administrator Join Date: Jun 2004 Location: Maryland Posts: 718 UserID: 320	Re: Speculated APH calculations &questions... Performance should be the same then because check valve placement doesn't matter as long as the order's the same. At that point it's a switch-up of the original APH design. It doesn't really matter where the check valves are; it matters in what order they are in. From this your design is completely okay and fine. Performance won't be changed in the slightest. __________________ The Drenchenator, also known as Lt. Col. Drench.

06-19-2008, 08:17 PM	#6
Ben Founder Join Date: Mar 2003 Location: College Park, Maryland Posts: 6,054 UserID: 1	Re: Speculated APH calculations &questions... I do these calculations. They're very useful to figure out how long to cut your pipes if you have a certain water capacity or weight in mind. Remember that 1 liter of water weighs 2.2 pounds. A good approximation for total water volume uses a 1:1 water-air ratio. You should of course have more water than that in your pressure chambers but it gives you an easy rough idea of the capacity. Find the volume of the cylinder, convert it to something more meaningful like liters (the trick to go from cubic inches to liters is to divide by 61), and then multiply it by 0.5 to find the water volume with a 1:1 ratio. If you have a 3:2 ratio you would multiply by 0.6. Other ratios can be figured out with fractions. Total volume doesn't have much affect on power type performance unless the volume is rather low. If you had 100 mL of water for example, your shot might not be substantial enough to resist drag as much as a longer column of water would, so the range would decrease. Once you have a reasonable amount of water like 500 mL, total volume shouldn't make much of a difference. Total volume of course would affect shot time, but you already know that. If it were up to me I'd choose three 8 inch PCs. The water capacity is rather good and the height isn't terrible. 10 inches seems a little too tall to me. __________________ email: / Forum rules / Read this page before emailing me. Do not send me a PM or email with a water gun question if someone else could answer the question. Post at the forums. You will get a response from me along with others' views or ideas.

06-21-2008, 06:12 PM	#8
cantab Senior Member Join Date: Oct 2007 Location: England Posts: 539 UserID: 1400	Re: Speculated APH calculations &questions... I think it was discussed before - it may be better to have each PC coming directly off the main pipe on its own T-junction, rather than them all branching off one. This will also result in a longer but less tall gun.

06-21-2008, 09:20 PM	#9
Silence Administrator Join Date: Apr 2006 Location: Virginia Posts: 3,293 UserID: 576	Re: Speculated APH calculations &questions... Actually, I don't think the length will change. The width of the pressure chambers, and not the width of the tees, will determine how closely they can be spaced. __________________ Forum rules

06-21-2008, 10:32 PM	#10
Drenchenator Administrator Join Date: Jun 2004 Location: Maryland Posts: 718 UserID: 320	Re: Speculated APH calculations &questions... The length will only really change if we're talking about large tee, 2" or more. They are about 4 to 5 inches in length, so the chambers will fit in between each one nicely, but the gun will get longer from just the size of the tees. But most people just use 1/2" to 1" tees, so this isn't much of a problem. The chambers would be at least 3 inches in total thickness, so extra pipe will be needed to string the chambers together, as showcased in the first photo of the APH article. __________________ The Drenchenator, also known as Lt. Col. Drench.

06-22-2008, 12:36 AM	#12
Specter Senior Member Join Date: May 2007 Location: bound brook, NJ -The flood town Posts: 363 UserID: 1090	Re: Speculated APH calculations &questions... Couple more questions to ask... How long typically is the pump made? Or does it matter on how much water I want to be sucked into the PCs each stroke. Which I guess I can figure out with the cylinder volume equation? What size holes do you drill for the nozzles? Also what ranges and shot times do you typically see from those nozzles? Is it possible to create a fan type nozzle? __________________ My "arsenal": Storm 600 pistol (never finished fixing this), launcher- Model:Afterburner(AB) 1.0(Decommissioned), AB1.5, soon AB 1.1(2"rebuild) maybe ill get something else in the future My site

06-22-2008, 11:03 AM	#13
Silence Administrator Join Date: Apr 2006 Location: Virginia Posts: 3,293 UserID: 576	Re: Speculated APH calculations &questions... The pump length is entirely subjective. I prefer 8 to 10 inches; Ben and Drenchenator use 12 inches, I think. Your length will change the number of strokes it takes, obviously, which is why I prefer "inches of pumping" to "number of pumps", both given a fixed pump diameter. At any rate, it's not really worth worrying about - as long as you're close to a comfortable length, it's either more shorter strokes or fewer longer ones. 1/4" and 3/8" are good sizes to use. From there you can experiment - 3/16", 5/16", 7/16", and 1/2" may work well too. I haven't had much luck in drilling good nozzles, so from now on I'll just use pipe nipples and hose barbs that have suitable inner diameters (which you'll have to guess or measure yourself, as they don't advertise the inner diameter). To create a fan nozzle, take a very small drill bit, maybe 1/8", and drill as many holes as you want in a single endcap. __________________ Forum rules

06-22-2008, 08:38 PM	#14
aEx155 Senior Member Join Date: Apr 2008 Posts: 315 UserID: 1517	Re: Speculated APH calculations &questions... For the pump length, you could always just try whatever you think is best. Since it's not part of the firing path, the only thing the length will affect is the time it takes to pressurize/fill your chambers. The longer you make it, the less pumps it will take; keep in mind, though, it makes the pump easier to break (if you're using wood) to have a long, extended pump handle. I would have to say that nozzle sizes would vary from gun to gun; it also depends on whether or not you are going for range or output, as the nozzle size controls those two factors. I believe smaller nozzles are for more range, while larger nozzles are for more output (is that right?). Yes, you can create a fan nozzle, but it might not turn out how you think it will. I believe you should look into buying sprinkler heads (the fixed types) because they already are made and do create a fan-shaped blast; they might not have enough flow though. __________________ My homemade

06-22-2008, 08:48 PM	#15
cantab Senior Member Join Date: Oct 2007 Location: England Posts: 539 UserID: 1400	Re: Speculated APH calculations &questions... Every gun should have a nozzle diameter that will give optimum range, with smaller and larger nozzles having reduced ranges. The more powerful the gun, the bigger the optimum range nozzle will be. (In practice, there'll probably be a range of sizes that has very little range variation). Larger nozzles will certainly be for more output. Smaller nozzles are for saving water or for long shot times. With a big (over 1 litre) PC capacity and a small nozzle, shot times can become very long indeed (into the minutes).

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