dswp.de
http://www.dswp.de/old/

REMINDER: Buy your arrow air guns before 2020-09-01!
http://www.dswp.de/old/hardware-dreams/reminder-buy-your-arrow-air-guns-before-2020-09-01-t7653-10.html		 Page 2 of 2
Author:  wurst [ 09.22.20 ]
Post subject:  Re: REMINDER: Buy your arrow air guns before 2020-09-01!
natirips wrote:
104 J of energy is a decent amount.


question.

it you take a dick and stick it 30cm deep into a spring which pushes that dick back with 10k newton towards his carrier, when reachin the final spring dick intrusion position.

would he be able to proudly exeed 104 joule?
Author:  Pirat [ 09.22.20 ]
Post subject:  Re: REMINDER: Buy your arrow air guns before 2020-09-01!
wurst wrote:
natirips wrote:
104 J of energy is a decent amount.


question.

it you take a dick and stick it 30cm deep into a spring which pushes that dick back with 10k newton towards his carrier, when reachin the final spring dick intrusion position.

would he be able to proudly exeed 104 joule?

O.o

Pirat, inconspicuously taking notes.
Also inconspicuously getting a ruler.
Author:  wurst [ 09.24.20 ]
Post subject:  Re: REMINDER: Buy your arrow air guns before 2020-09-01!
lets inconspicuously dream of decent amounts of energy.

imagine taking an old piston engine from a car.
the engine itself would be permanently turned @ 6000 rpm by an electric motor.
the exhaust valves should be modified. they would close from outside, very quick flappng to outside under explosion pressure.
(i mean... we dont want to accelerate the crancshaft, pressure MUST be out BEFORE the cylinder starts moving downwards again)
the exhaust gas should be used to decently accelerate our potato.

repeatedly.
Imagine, @ 6K rpm...
with a 4-tact engine we would have 12000 shots per minute on a 4- cylinder!
(one per cylinder every 2 revolutions, using 4 of them)

@joule...
thats difficult, forgive me, I make some assumptions and mistakes...
Lets assume that engine has 300 NM torque.
Lets assume that the crankshaft exceeds its center by 5cm.
--> The push down power of one cylinder would be 6 K newton?!
Lets assume a cylinder of 500ml, having a diameter of 80mm. Think thats kinda typical for cars.
So its A=Pi * radius quadrat = Pi * 4 quadrat = 3,14 * 16 = 50cm2
6000newton on 50cm2 = 120newton/cm2 ==
12bar pressure inside cylinder / We have a volume of 6 liters gas to expand.
[here it becomes difficult. a gas explosion would deliver 6-8 bar maximum. that 12+bar should result from a turbo charged engine, we would need a 5kw+ air pump in our setup... )

now comes traveler potato.
lets say the ideal rocket type potato has a diameter of 5 cm and a length of 8.
that 12 bar would create a certain pressure in newton to our friendly potato.
A=Pi r2 = Pi 2,5cm2 = 7,85 == 8 cm2
8cm2 * 12 bar = 960 newton.
now the pressure sinks while that potato moves in our ideal tube that way, that the gas has 1bar at the end of teh barrel.
the pressure sinks all the time, but we can say that it should be half the maximum pressure from the start.
so, over the time of acceleration, the potato would "feel" an average 480 newton.
now the length of the barrel becomes important.
we want to fill 6 liters of combustion gas in a tube/cylinder with A=8cm2
thats 6000/8 = 750cm. (impressive^^)
so, we have 480 newton * 7,5m = 3600 newton * meter
thats a very interesting 3600 Joule.

if you would shoot now for 1 minute...

1 potato weighs [8cm2 * 8cm] 64 grams.
@12k potatoes per minute firing rate (ppmfr).
--> our minigun would spit 768 Kg potatoes per minute, delivering 43200000 Joule!
--> it would be 10 times stronger then the german MG3.
--> its potato output power [200potatoes/s*3600J] would be 720KW.
[it would have more power as it had before in that shitty car, but we would have to invest some 50KW...]

that would be style.
you could use that gun to dispense large amounts of food or fertilizer in farming.
the further crap flies, the less you would have to drive over your fields (which comresses the ground, takes time, harms plants etc)
ofc ethanol or at least propane driven in order not to poison the food/fields
for a seeding machine its output temperature should be problematic.

for military use it would be to weak in terms of pressure.
the pressure in a rifles barrel is 50-100 times higher, at least i thinkso.
Author:  natirips [ 11.01.20 ]
Post subject:  Re: REMINDER: Buy your arrow air guns before 2020-09-01!
Sorry for late replay. I wish I had more time (both for dswp and for physics) but I'm not working from home despite corona as I make physical objects at my current job.

But in short: if I learned anything in seven years of studying physics, every time you get more power/energy in the output than you put in input - you miscalculated something, or you forgot about some critical detail (i.e. efficiency or something).

In this case, I think problem is: as you push potatoes out they block exhaust gases, and engine can no longer spin at same rpm (same as in engine braking on diesel cars). So you need to invest more energy to keep the rpms stable at 6000. Either that, or you get less rpms and less potatoes per minute and less energy output per minute.
Author:  wurst [ 11.08.20 ]
Post subject:  Re: REMINDER: Buy your arrow air guns before 2020-09-01!
ah, i think i understand what you mean...

you would remove the car, that engine wouldnt have to push a car forward.
that engine would just to have to keep itself rotating.
it should do so since theres still some pressure between piston and potato.
- maybe we should add a modifyed fly wheel
- maybe the electrical starter would have to be better in torque and/or rpm.
- maybe we should invest in a modern (piezo driven) injection system (since the cylinders are kinda open all time)
anyhow, in my original setup, the crancshaft was rotated by an electrical motor.
not cause i think its needed, just to do it minigun-style.


btw.

since trump now finally lost, I think we dont need guns anymore.
how about a machine that bakes 74.000.000 cookies. in one hour.
Author:  RunTMC [ 11.08.20 ]
Post subject:  Re: REMINDER: Buy your arrow air guns before 2020-09-01!
wurst wrote:

how about a machine that bakes 74.000.000 cookies. in one hour.


I am in for this! :)
Author:  wurst [ 11.11.20 ]
Post subject:  Re: REMINDER: Buy your arrow air guns before 2020-09-01!
ok lets say a typical cookie has a baking time of 15 minutes.
the longer our machine gets, the faster that baking conveyor could move.
we should discuss the width of that conveyor, the minimum "inter cookie distances" and ofc the cookie size.
will they be round or can ai help to create tetris-patterned optimized use of baking surface.

74.000.000 / 3600 is 20,5 Kcps
1 cookie in a 1-barrel cookie engine takes ~20 cm, including 8cm cookie and 12 cm space.
this results in ~4000m of conveyor per second.
4 Km/s = 14400 Km/h
Cause the cookies must bake 1/4h, our machine would need to be 3600 Km long.

if we realize now something feasable...
1 Km would be already giant, difficult to find space to build.
the conveyor woud need to run 3600x more slow, which is great since baking cookies at supersonic speeds hasnt been researched yet.
we would have to have 3600 lanes or 720m width.
Author:  RunTMC [ 11.11.20 ]
Post subject:  Re: REMINDER: Buy your arrow air guns before 2020-09-01!
Well...

at Brandenburg we may have enough space for the last alternative. ;)
(Sorry Zottel!)
Author:  wurst [ 11.17.20 ]
Post subject:  Re: REMINDER: Buy your arrow air guns before 2020-09-01!
brandenburg comes out best prepared, zeh musk brings best ngineers. at least.
Page 2 of 2 All times are UTC + 1 hour
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/