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 Posted: Sat Jun 14, 2008 9:42 pm
Alright, so I'm building a rocket over the summer, and into my next school year, and I've been trying to figure out a way to predict where my rocket will land with in a set of limits (a mrgreen
So my main problem is I haven't really figured out how a fluid, (the air in this case) transfers it's force to a rocket in flight, or rather tilts the rocket so that it affects it's angle in respect to the ground.(thus pushing it further in the xy-direction, and less high in the z-direction.)
Does any one have any thought in this?
Also, does anybody have any chemistry resources, or taken chemistry classes and could tell me the heat of formation for Pottassium hydroxide? I've searched the net and I can't find it, not even the Wikipedia has it! Maybe someone has a chem book that has this info. in it?
Also, for other discussion, do you like Physics? Why or why not? And did anyone understand the Poll question?
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Posted: Mon Jun 23, 2008 12:06 pm
 Jesus... Well, I really don't understand what you just said o-o But... Like, for the rocket, when you launch it, are you trying to shoot it up high? Or like, get it to go far away from the starting point? ...My Lord, Savior, and Friend
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Posted: Mon Jun 23, 2008 7:43 pm
You said that the fluid would push it in the x/y position, but unless there was displacement of fluid in the rocket, wouldn't the x and y scale stay the same as the z scale changed?
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Posted: Sat Jul 05, 2008 6:22 pm
no.....imagine a 3 dimensional cartesian co-ordinate plane with the z-direction going up. So what I'm saying is that if air is blowing against the rocket in a certain direction it will fly a little furthur in that direction while taking out height possibility. So if wind were to blow along the x-direction, then the rocket would travel a little further in the x-direction.
It will be a solid fuel rocket anyway so......
Although I finally found out the Competition requirements so I've already figured that with only 60.43 lbs of thrust on a 3.3 lb rocket, I can get the rocket up to the target height of 750 ft in about 18 seconds....So now my friend Blake and I are trying to find out to do about bringing it back down in 27 seconds....
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Posted: Tue Jul 08, 2008 7:06 pm
Oh, I didn't know you were taking wind into account. One more question, I understand that it would push it more in the X direction but you said without changing the height. Wouldn't it change the height from air friction being a factor? Because if the rocket was aero-dynamic it would travel farther up without wind than up plus the factor of the x or y scale. I don't know if that made much sense... sweatdrop
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Posted: Sun Jul 13, 2008 1:45 pm
uhm....here, if I throw the equations out would it make more sense?
Let's just imagine a 2-D cartesian Co-ordinate graph, with x in the horizontal and y in the vertical.
The displacement of an object in projectile motion (rocket/ball being thrown/cannon fireing) horizontally/in the x-direction is x=vi(t)cos(theta)
Where vi is initial velocity, t is time, and theta is the angle at which the projectile was fired. The vertical displacement is then y=vi(t)sin(theta)+1/2(g)t^2. Where g is acceleration due to gravity. So if we fire a rocket at a 90deg angle, we find that horizontal displacement is zero because cos(90) is zero.(not accounting wind) And sin(90) is 1. So our vertical displacement will be at maximum. But the problem with a real rocket is that wind changes the the angle of the rocket in respect to the ground in mid flight, and so sin(theta) would become some kind of decimal which would reduce our whole vertical displacement.
Hopefully that made sense, I don't know what level math you have taken, but hopefully that made sense....
As for the rocket competion, when my friend Blake gets back from camp we are gonna' work out the specific impulse we'll need out of the engine, and then we'll start building our design for the rocket.
I really hope that we win this competition though, the grand prize is 60,000 dollars. I'm going to CU boulder, and just a third of that would alomst cover my entire tuition, which would be effing awesome.
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