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PostMon Feb 07, 2011 6:19 pm » by Punjedi


funnyman46 wrote:
nilm33 wrote:Oh and as of today... You are engineers.
Today.... I am the lawyer

Tommorow... We will be liberators of the human race! :lol:

Now if they only paid us as such!

Of the three most invested people in this project so far, I'd say we have confirmed two flights coming out of the states. I haven't heard from or been told of any others willing to try this in any other country so far. Could there be others planning this somewhere else while trying to stay under the radar? Only time will tell. :mrcool:


Morning everyone! I finally got paid!!!

So, today (possibly) tomorrow, I will be going to pick up the stuff I need on my end for CaliTest Alpha.

I will be setting up the webpage for us as well so we have a repository of all our stuff and a placeholder for the future implimentations.

I have looked up some good electronics kits for various things and I feel comfortable I can solder together some components once I find the right documentation.

So, in a nutshell, (help....I'm trapped in a nutshell)


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By the end of the week I hope to be on par with Funny and his work and go from there.

You get those cams yet?
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PostMon Feb 07, 2011 7:03 pm » by Funnyman46


Just got them ordered Sunday afternoon Punjedi. They should be here this week.
When they do I can see a major redesign of my craft to lighten it even more. The PVC tube to launch the rocket can be replaced for a lighter heavy cardboard tube. I just need to configure the parachute attachment to go somewhere so it doesn’t impede the flight of the rocket. I’m thinking about placing it underneath in such a way to inflate once the craft starts free falling back to earth.
In most cases, the parachute is located between the craft and the balloon. As the craft falls, the parachute inflates automatically. This presents a problem for the rockets path (unless it flies off from a different angle to avoid the parachute and balloon) A pin placed at the tip of the nose cone should pop the balloon but getting around the parachute is the current problem to be solved on my end.
Don’t worry, when the cameras get here you and the57ironman (along with the forum) will be the first to know.


EDIT:What if the parachute was loaded into the underside of the rocket tube? I could make little scoops that allow air to enter the tube/chute on the way down inflating and pulling the chute out during re-entry?
I’ll have to run some tests on that idea. I’ll also need to figure the size of the chute based on the final weight of the craft as well.

A nice place to start: http://www.hsl.org.au/articles/parachutes.pdf
Sometimes, simple is better

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PostMon Feb 07, 2011 7:34 pm » by Punjedi


funnyman46 wrote:Just got them ordered Sunday afternoon Punjedi. They should be here this week.
When they do I can see a major redesign of my craft to lighten it even more. The PVC tube to launch the rocket can be replaced for a lighter heavy cardboard tube. I just need to configure the parachute attachment to go somewhere so it doesn’t impede the flight of the rocket. I’m thinking about placing it underneath in such a way to inflate once the craft starts free falling back to earth.
In most cases, the parachute is located between the craft and the balloon. As the craft falls, the parachute inflates automatically. This presents a problem for the rockets path (unless it flies off from a different angle to avoid the parachute and balloon) A pin placed at the tip of the nose cone should pop the balloon but getting around the parachute is the current problem to be solved on my end.
Don’t worry, when the cameras get here you and the57ironman (along with the forum) will be the first to know.


EDIT:What if the parachute was loaded into the underside of the rocket tube? I could make little scoops that allow air to enter the tube/chute on the way down inflating and pulling the chute out during re-entry?
I’ll have to run some tests on that idea. I’ll also need to figure the size of the chute based on the final weight of the craft as well.

A nice place to start: http://www.hsl.org.au/articles/parachutes.pdf


Weight vs. velocity vs. drag.

My concern would be that the package itself wouldn't weigh enough that at the point it reach terminal velocity, there wouldn't be enough drag to push the parachute up and out.

Did some math....I know right?

On Earth, with a payload weight of 6 lbs. assuming 2 square foot cross section and assume a drag coeficient of .7 we have a terminal velocity of 69 feet per second at 10,000 feet.

At 30,000 = 98 feet per second

at 100,000 = 518 feet per second.

So what we see is that in a thinner environment we have faster terminal velocity, but I believe we have less drag as well.... I need to look up the determination for drag coefficiency.

and I need to know what the force necessary to open your chute is required.


ps. I cheated

http://www.grc.nasa.gov/WWW/K-12/airplane/termv.html

Is that enough force to open a chute?
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PostMon Feb 07, 2011 8:45 pm » by Funnyman46


Maybe a less complicated approach for the parachute is needed?
How about the standard parachute pack design (see photo) with a tension based release pin set up? If the rising balloon keeps tension on the release the chute stays put for upward flight. When the balloon pops and falls, the tension is released allowing the chute to deploy on the way down.

Image
Image
Image

In the above drawing I’m concerned with the left side only. I think I can use a variation of this to release the chute retaining ring to deploy once the POP happens and the pressure securing the retention ring is released

Edit: Drawings didn't turn out well so here's the links
First & Second drawings http://www.xs4all.nl/~pdj/chutfold.htm

Third http://www.ict.griffith.edu.au/anthony/ ... messenger/


Edit 2: Pun, I think I will do some experiments on the chute design, construction and flight tests in the meantime. I’d hate to see it crash and burn but I also don’t want it to fly over Cleveland before landing as well. Maybe an altimeter release of some kind might help it fall straighter before chute deployment?
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PostMon Feb 07, 2011 9:24 pm » by Punjedi


funnyman46 wrote:Maybe a less complicated approach for the parachute is needed?
How about the standard parachute pack design (see photo) with a tension based release pin set up? If the rising balloon keeps tension on the release the chute stays put for upward flight. When the balloon pops and falls, the tension is released allowing the chute to deploy on the way down.

Image
Image
Image

In the above drawing I’m concerned with the left side only. I think I can use a variation of this to release the chute retaining ring to deploy once the POP happens and the pressure securing the retention ring is released

Edit: Drawings didn't turn out well so here's the links
First & Second drawings http://www.xs4all.nl/~pdj/chutfold.htm

Third http://www.ict.griffith.edu.au/anthony/ ... messenger/


Edit 2: Pun, I think I will do some experiments on the chute design, construction and flight tests in the meantime. I’d hate to see it crash and burn but I also don’t want it to fly over Cleveland before landing as well. Maybe an altimeter release of some kind might help it fall straighter before chute deployment?


Aye, I am thinking. We may need to work this out of course, but how about this?

Have the altimeter set so it doesn't pop the chute until say, 500 feet over the ground, that way we don't have high-alt' deployment and risk losing our equipment or any manner of things that can happen. Granted it's going to be a jolt at that height and speed, but considering what we would be putting it through anyways, that may not be an issue.

I'll check the link you provided after a bit. Gotta finalize some stuff for now.


Oh, and clear this up for me? Are we having seperate recovery plans for the rocket AND the platform?

So we would need a chute system for the LP, and one for the Rocket eh?
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PostMon Feb 07, 2011 9:36 pm » by Funnyman46


Yes, we need to recovery systems. Neither can be allowed to free fall from the sky. (What were you thinking?)
Now, I guess we’ll need GPS trackers for both?
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PostMon Feb 07, 2011 11:06 pm » by Funnyman46


Scientific American circa 1957

The modern hobby was initiated in Germany in 1927, with the formation of a group which included Willy Ley, Max Valier ond Johannes Winkler. By 1931 the German amateurs had built liquid-fuel rocket that could rise to a height of about a mile.

Wemher von Braun, Hermann Oberth and many others joined the group; at one time it had nearly 1,000 members. When the Nazjs came to power, the society was disbanded and its equipment and experimental results were seized.
It goes on to say that somw were using a zinc and sulfer mixture to launch. A 1 second burn gave them 300' in the air. If you want to read the whole pdf file click here http://www.rocketryplanet.com/images/st ... e-1957.pdf

Zinc-sulfur fuel can be used with relative safety even in large rockets. Its burning rate is high-on the order of five linear feet per serond regardless /of tube diameter. Its density is also high, yet danger from explosive pressure is low. Our society purchases Zinc Dust, Technical
Grade, from the American Smelting and Refining Company, We do not specify grain size. Flowers-of-sulfur is inexpensive and available locally in most communities from hardware
stores and dealers in farm and garden supplies.

Maybe we could use this zinc / sulfur mixture for the last stage?
:banana:
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PostTue Feb 08, 2011 7:51 am » by Elmajiko


Attach a balloon to the platform that is roped down so it air born then launch a test to see what your working with.

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PostTue Feb 08, 2011 7:56 am » by Roadkill


Science will fly you into the Cosmos


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Religion will fly you into Buildings

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PostTue Feb 08, 2011 5:38 pm » by Funnyman46


roadkill wrote:


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Roadkill, nice video, thanks. I wonder if this kid ever realized the cost of those bags were more expensive than a weather balloon? But it gave me an idea to try this with my little grandkids as they would get a blast out of sending something up. :flop:

It's nice to know there are always options to the more costly approaches.
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