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rbeckey

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Altitude expirement. Big Bertha/Rhino (BT60 A-B-C power)
Three NCs. One conical, one rounded (from kit), one flat. (Basically a nose block.) Use one body, interchange NCs, use B6 motors and track altitude. Baffle to eliminate wadding variable. Compare NCs and equalize with added weights. Say, 3-4 launches with each NC and make graph(s).

Questions:
1. What color should we use for maximum visibilty in clear or cloudy skies? Black? Blaze orange?

2. What ratio to use for maximum efficiency in the conical NC. (I want the difference to be as obvious as possible.)

Probably not due till spring, but might as well start while the weather is good.

Thanks in advance.
 

DynaSoar

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Originally posted by rbeckey
Altitude expirement. Big Bertha/Rhino (BT60 A-B-C power)
Three NCs. One conical, one rounded (from kit), one flat. (Basically a nose block.) Use one body, interchange NCs, use B6 motors and track altitude. Baffle to eliminate wadding variable. Compare NCs and equalize with added weights. Say, 3-4 launches with each NC and make graph(s).

Questions:
1. What color should we use for maximum visibilty in clear or cloudy skies? Black? Blaze orange?

2. What ratio to use for maximum efficiency in the conical NC. (I want the difference to be as obvious as possible.)

Probably not due till spring, but might as well start while the weather is good.

Thanks in advance.
Mostly black with some orange, say 2 or 3 fins.

Anything over 4:1 is fine. Much more won't add much but weight. It's not going to be the best result anyway.

If you want to prove which was better, you'll need to launch several times each and use a statistical test called "one way ANOVA (analysis of variance)". Look it up, get some help if need be, but doing this will turn it from a demonstration to an experiment. The good part is, if you do this and none are proven to be better, you just need some more samples (flights) to get the proof.
 

rbeckey

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It has been more than 20 years since I even heard the terms population and variance. Probably not going to happen. ;) It is a fourth grade project. A graph will do. I am trying to maximize the altitude difference between the subjects so as to make measurement easier and more obvious.
 

sandman

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Say...is this your sons project or yours?

Check to see if your local school has a copy of Rocsim...or if you do...

Besides the real launches, do the simulations to compare.

Now THAT's SCIENCE!!!:rolleyes:

He's NOT a real doctor..."I have a masters degree IN SCIENCE!"

I miss "Ask Dr. Science" on NPR.

Brought to you by "Duck's Breath".
 

Stymye

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about the nosecones,

the conical cone is only optimum for supersonic speeds , for subsonic a parabolic is the best choice,an ogive is a good compromise between the two, there is an ideal length of cone for every rocket so that can be figured out with something like rocksim. hope that helped a little
 

rbeckey

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Rocsim - Duh! Why didn't I think of that? So I sat down and worked it all out and it seems that, according to my sims, the parabolic nose cone goes higher, the conical next and the flat last. The difference is about two feet between each. I doubt we could reliably measure that with an Estes Altitrak. So much for the Apogee Science Fair project book's statements about a good expirement for kids.
 

DynaSoar

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Originally posted by rbeckey
It has been more than 20 years since I even heard the terms population and variance. Probably not going to happen. ;) It is a fourth grade project. A graph will do. I am trying to maximize the altitude difference between the subjects so as to make measurement easier and more obvious.
That's fine too. Plot each on its own line and see how much they overlap. Nothing wrong with demonstration rather than experiment. Feynman dipping the O ring in ice water was no experiment, but look at the impact it had.
 

teflonrocketry1

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Originally posted by rbeckey
Rocsim - Duh! Why didn't I think of that? So I sat down and worked it all out and it seems that, according to my sims, the parabolic nose cone goes higher, the conical next and the flat last. The difference is about two feet between each. I doubt we could reliably measure that with an Estes Altitrak. So much for the Apogee Science Fair project book's statements about a good expirement for kids.
Got RockSim!? Use the Scientific method for your project! The range for the landing distance from the launch point has never been verified. The hypothesis could be that the simulation software is wrong (or right). Launch the same rocket say three times measure the distance it lands from the pad. Program all the ambient parameters into the software and see how accurate it is. If you have an altimeter you could verify the Tube fin, Ring-tail, side pod, or boost glider simulations that I came up with (these articles are in the old newsletters at the Apogee web site). The hypothesis is that the simulation method is right or wrong and the conclusion would either confirm or refute this.

You could get a nice model rocketry project which is not to complicated that can be done with a minimum of launches using areadily available mesuring device (tape measure or altimeter).

Bruce S. Levison, NAR #69055
 

Rick James

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Originally posted by rbeckey
Rocsim - Duh! Why didn't I think of that? So I sat down and worked it all out and it seems that, according to my sims, the parabolic nose cone goes higher, the conical next and the flat last. The difference is about two feet between each. I doubt we could reliably measure that with an Estes Altitrak. So much for the Apogee Science Fair project book's statements about a good expirement for kids.
My son and I did exactly the same experimant for his science fair one year. We used a Big Bertha. We added a payload section with ballast (marbles) in zip-lock sandwhich bags marked for each nose cone. We used 5 nose cones: conical, ogive, parabolic, flat, and a Mercury capsule.

We flew each nose cone three times (15 flights) on both B and C motors (total 30 flights) and then plotted the results on an Excel spreadsheet.

I also didn't think to use RockSim (doh!) but the results were not really very exciting. But he still got a good grade because we followed the scientific method and his display had a lot of cool stuff on it -- and we had a lot of fun (though he did get pretty tired after 30 flights).

If I were you, I would go ahead and do it, just so he can see how the process works.

We had a couple of other rocket related science fair projects that we did over the years... one of them actually got my son to the state level.

Good Luck
 

sandman

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But he still got a good grade because we followed the scientific method and his display had a lot of cool stuff on it
I've judged science fairs and THAT is the criteria. We aren't looking for a Nobel prize here.

Just sound use of the scientific method.

Go for it but be accurate, show your work, lots of detail and a good display showing your results.

Roc sim would just be another way of showing more data.

Even if it prove there isn't much of a difference you have prove...there isn't much of a difference!

It's still "good science"!
 

powderburner

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Do you still have access to RocSim for some tests?
Maybe if you used a BABY Bertha as your test vehicle you might get more variance in altitudes? I wonder if the Big Bertha has so much mass that it carries itself aloft on momentum, with aero effects minimized. If so, a Baby Bertha might get you more sensitivity to the different NC drags.
OTOH, a Big Bertha is long and stable, flies like an arrow. The shorter Baby Bertha may introduce more 'wobble' into the flight, complicating the comparisons?
 

Stymye

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doesn't the estes educater site have a book on science projects ? you might take a look at some of those for ideas

ok I found it

http://www.esteseducator.com/cfusion/publications.cfm

theres one in there that sounds strange,
you insert an insect into the payload and measure his abdomen to see how fast it breathes before and after a flight, to determine how exceleration effects insects.
 
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