Science Fair Projects

[Disaster_Guy]

It is science fair time for my 5th grader. Since she has been helping me with several rocket projects lately and built a few of her own, I think that she may be leaning toward a rocketry related project for the fair. I am interested in hearing any possible ideas for a project anyone may have.

So far, we have brainstormed the following as possibilities:
-Impact of different shape nose cones on altitude (weight compensated)
-Impact of airframe diameter on altitude (upscale/downscale & weight compensated)
-Impact of steamer length / material on drag / fall rate

 

[gdiscenza]

Apogee has a pre-assembled science fair kit here.

Whichever type of project you choose, I highly recommend the educators bulk pack of motors from Hangar11. You'll burn a ton of motors in any decent scientific experiment, so the bulk packs are the way to go. You might find them at HobbyLobby if there is one near you, and with a 40% discount coupon, it would be much cheaper than HAZMAT.

Have fun!

G.D.

 

[UrbanKnight]

My middle school science fair project was a radio controlled launch pad. The base was MDF with a door hinge screwed into it and the launch rod glued to the other half with JB Weld (sand the hinge first). An RC servo then pulled strong fishing string in a loop around nails to each side of the hinge to make the rod tilt into the wind. A second servo had a wire on the arm which rotated down to touch the other wire, completing the circuit which was powered with a 4xAA battery harness, and launching the rocket.

Other Ideas I've seen include a nose cone altitude experiment. Someone sells a kit that includes 6 differently shaped nose cones (including one blunt one) with a basic rocket.

Another idea would be how the number of fins affect performance. The control would be making all the fins the same size and shape and putting them all on identical rockets except for the fin count.

 

[UrbanKnight]

Oh, and if you'll be launching these from a school field, I'd recommend using the smallest engine the rocket can use.

 

[Zeus-cat]

-Impact of different shape nose cones on altitude (weight compensated)

I actually looked into trying something like this for the fun of it. Before I launched the first rocket I realized the drag coefficients of the standard shaped nose cones just isn't that much different. The difference in altitude from two randomly chosen rocket motors with the same nose cone is far greater than what you will see with the exact same thrust from two motors and different nose cones.

Or in more scientific terms, the variability of the independent variables (thrust from random rocket motors) far exceeds the variability of the dependent variables (drag induced by the shapes of the nose cones). Therefore, the results of the experiment are void.

 

[scsager]

My suggestion for a 5th grade level project - Compare and Contrast Mathematical simulation, Computer Simulation, and real world performance of a model rocket.

- Design and build a model rocket.
- use information such as Estes TN-5 to calculate the speed of your rocket using pencil and paper.
- Next ,use a computer simulation to calculate the speed and altitude of your rocket. (OpenRocket simulation software is free)
- Last is the real world test - fly the rocket several times loaded with an AltimeterTwo from Jolly Logic.

- Draw conclusions about the accuracy of the methods used to project and measure the results.

 

[UrbanKnight]

Before I launched the first rocket I realized the drag coefficients of the standard shaped nose cones just isn't that much different. The difference in altitude from two randomly chosen rocket motors with the same nose cone is far greater than what you will see with the exact same thrust from two motors and different nose cones.

Or in more scientific terms, the variability of the independent variables (thrust from random rocket motors) far exceeds the variability of the dependent variables (drag induced by the shapes of the nose cones). Therefore, the results of the experiment are void.

What if you did extensive launches with each nose? Say, 10 or 20 each, averaged out to reduce the effects of the variability?

I imagine the blunt nose cone would make a noticeable difference there.

 

[edwinshap1]

What if you did extensive launches with each nose? Say, 10 or 20 each, averaged out to reduce the effects of the variability?

I imagine the blunt nose cone would make a noticeable difference there.

at the speeds an estes/quest motor would push the rocket to, you'd see the lowest altitudes in the blunt and very shallow conical nosecone. the ogive and normal conical would be nearly identical.

that being said, for a 5th grade science fair, it would be an amazing experiment. launch each one x number of times (more is better, and more fun:tongue then average. maybe you could explain to her a little about why the blunt nose cone makes the rocket not go as high, and why the sleeker ones will go higher, and she could incorporate that into her explanation.

A friend of mine entered the california science fair to determine which motor would go higher, between a C6 and C11 (in a similarly sized rocket). I think your daughter would have a fun time testing that as well, she could build 2 rockets with different sized motor mounts, and a small amount of nose weight in the C6 to compensate for the increased mass of the C11s casing.

More important than all of this, however, is what she wants to test, the nose cone shape is much more intensive, but will make the teachers turn their heads, an will make her display awesome

 

[GregGleason]

One of the biggest problems with testing rockets "in the wild" is the amount of variables that need to be controlled. There are at least two variables that you cannot do anything about.

The first is wind, as it can affect the altitude by weather-cocking.

The second is the statistical variation between motors.is doing tests like this is the small statistical sample. From the attached chart, the A8 motor may be the best choice but of the low sigma's. The downside is that the A8 may not give you the velocities needed to see the variances between nose cones. In that case, the B6 may be the better choice.

Regardless of what you decide or how you go about it, have fun and please report the findings!

Greg

 

[skip_dye]

1) Do whatever your daughter want to do.
2) Make sure she has fun doing it.
3) Let her do the work, but spend lots of time with her while she is doing the work.
4) The real purpose of a science fair project in 5th grade is to learn how to use the Scientific Method.
5) Make sure she understands what she did for when the teacher asks her questions about it.

A properly graded project should be about applying and using the scientific method (and including all the items on the display the teacher asks for), not the accuracy of the experiment, or how well you accounted for every variable that might affect the results.

Just my $0.02.

Alan

 

[Disaster_Guy]

Thanks for all the replies and input. Alan, I agree with you 100%... Understanding the multitude of variances, one of the reasons that the nose cone idea came to mind was because it would be very simple to apply the scientific method to and also be pretty easy for her teacher to understand. The points regarding the variables are however very valid as I would go broke buying the number of motors required to obtain a representative sample.

I must say though that the idea of comparing a mathematical model and SIM to real-world observations is something that may be a winner. She has been playing with open rocket a bit lately designing her next scratch build LPR project and has a blast with it. It also gives me an excuse to buy a small altimeter as the one I currently have is too large to use in my LPR and most of my MPR projects.

 

[MrGneissGuy]

A properly graded project should be about applying and using the scientific method (and including all the items on the display the teacher asks for), not the accuracy of the experiment, or how well you accounted for every variable that might affect the results.

Just my $0.02.

Alan

I second this (as well as the other items in skip's post). My daughter's school hasn't had the typical science fair for the grades she's been through, but they have had similar grade-wide projects. Two years ago they had the "invention convention" where the students had to come up with an invention, design it, build it, test it, refine it, etc. and then present it. My daughter's actually ended up having to be partially disabled when she took it in, as it nearly caught fire on it's final full scale test the night before it was due (we printed out fire hazard placards and everything for her to take in, along with a note to the teacher to not turn it on). It was about the process, and she actually got very high marks on all categories, even though it wasn't fully operational (well, not safely operational...it did what it was supposed to). In fact, her teacher asked the class if anyone had any "failures" or major setbacks in the process. My daughter was the only one to raise her hand (I'm guessing others had too much parental help). The teacher simply asked if she was able to determine the cause, and what she would do to correct the problem if she were to build a second version of it. My daughter was able to answer those questions well and I think that was a large part of why she got such high scores on it.

I don't know that I would let those uncontrolled variables stop her from doing what she wants. It might be good if she noted those variables, and maybe included information on what she did, if anything, to compensate for them. If I were judging, I would be pretty impressed if a kid pointed out that his/her results had some percentage of error due to the wind or motor variability or whatever. It's important for scientists to remember that there are things that can adversely affect the accuracy of experimental results when they are reaching their conclusions.

 

[RandyT0001]

You could build two "identical" rockets, each about 1" or 1.3" in diameter (BT-50 / BT-55) accounting for the difference in mass of each. In one you put a 12" diameter plastic parachute to serve as the "control" rocket. In the other you can substitute a 12" dia parachute with a 2" diameter hole in it, then a 12" dia parachute with a 4" hole in it, followed by a 12" diameter parachute with the shroud lines reefed about half way up the lines. Use the same sized motors for all flights (try to use small ones) and launch the control rocket simultanously with the test rocket. At apogee start a stopwatch for each rocket and time it's descent. Fly each pairing of rockets (control and test) about ten times for each combination of modified parachute. Now the experiment is testing the differences in the descent rate of the modified parachutes as it relates to a "control" rocket. The variable of wind will now affect the "control" rocket and the "test" rocket in virtually the same way. Using multiple flights the variations of the motors total impule can be averaged out.
:2:

 

[Zeus-cat]

Here are some sample altitudes with various rockets from my fleet. As you can see the altitudes vary dramatically even with the same rocket and same motor. As has been mentioned there are a lot of variables you can't control such as thrust of a particular motor, temperature, wind, humidity, etc. All of these things can add up to drastically effect the maximum altitude.

As has also been stated at a fifth grade level it is not about producing ground breaking results, but more of knowing how to apply the scientific method. However, I would shy away from an experiment that you know is unlikely to produce anything close to the expected results.

Something with descent speeds and different types of recovery devices would work well in my opinion. You might need to get a Perfectflite or Jolly Logic altimeter, but that might be a sacrifice dad is willing to make. :lol:

 

[UrbanKnight]

You could build two "identical" rockets, each about 1" or 1.3" in diameter (BT-50 / BT-55) accounting for the difference in mass of each. In one you put a 12" diameter plastic parachute to serve as the "control" rocket. In the other you can substitute a 12" dia parachute with a 2" diameter hole in it, then a 12" dia parachute with a 4" hole in it, followed by a 12" diameter parachute with the shroud lines reefed about half way up the lines. Use the same sized motors for all flights (try to use small ones) and launch the control rocket simultanously with the test rocket. At apogee start a stopwatch for each rocket and time it's descent. Fly each pairing of rockets (control and test) about ten times for each combination of modified parachute. Now the experiment is testing the differences in the descent rate of the modified parachutes as it relates to a "control" rocket. The variable of wind will now affect the "control" rocket and the "test" rocket in virtually the same way. Using multiple flights the variations of the motors total impule can be averaged out.
:2:

Perhaps to show a more reliable (widely varied) result, instead of using all 12" parachutes, compare the control chute with a 6" chute, a 12" x-form chute, and a 3cm x 50cm streamer. Do the streamer last just in case it descends quickly enough to break something... which would actually make for a great analysis for the experiment.

Also, in order to make the control and test rocket as identical as possible, consider a model with a plastic fin unit.

 

[bjphoenix]

We've had other science fair threads in the past so you might search for those and look for ideas there.

 

[John Beans]

From the attached chart, the A8 motor may be the best choice but of the low sigma's.

Greg

Very cool data. I've always had it in the back of my head that motors "vary by 20%," and some of this data shows that (at least for thrust and burn time). As I was developing the AltimeterTwo I noted some of this.

I'm glad the "total impulse" figures are a lot closer ~4%. I guess that's to be expected as "the amount of stuff" in the motor is easier to control than how it burns.

Thanks for sharing the data!

--John Beans, Jolly Logic

 

[cjl]

at the speeds an estes/quest motor would push the rocket to, you'd see the lowest altitudes in the blunt and very shallow conical nosecone. the ogive and normal conical would be nearly identical.

that being said, for a 5th grade science fair, it would be an amazing experiment. launch each one x number of times (more is better, and more fun:tongue then average. maybe you could explain to her a little about why the blunt nose cone makes the rocket not go as high, and why the sleeker ones will go higher, and she could incorporate that into her explanation.

A friend of mine entered the california science fair to determine which motor would go higher, between a C6 and C11 (in a similarly sized rocket). I think your daughter would have a fun time testing that as well, she could build 2 rockets with different sized motor mounts, and a small amount of nose weight in the C6 to compensate for the increased mass of the C11s casing.

More important than all of this, however, is what she wants to test, the nose cone shape is much more intensive, but will make the teachers turn their heads, an will make her display awesome

The problem with assumptions is that they are frequently wrong.

Interestingly enough, a blunt nose that is elliptical or parabolic in shape will do better on a subsonic flight than a pointy nose. In fact, if you want to see an ideal nose shape for a subsonic rocket, look no farther than the nose of a commercial jetliner. They are actually quite blunt, but due to some quirks of aerodynamics, it turns out to be better than a pointy, sleek looking cone.

 

[UrbanKnight]

I'm pretty sure "blunt" was referring to the nose cone that is completely flat. He's probably quite right that the flat and conical noses - which are not elliptical, parabolic, or ogive - will have the lowest altitudes.

 

[FastCargo]

How about validating something like this:

https://Rocketryforum.com/showpost.php?p=248042&postcount=5

The discussion was about which variable will affect your peak altitude more. The ice thing is that although the altitude variance by weight adjustment only was small (within the error of individual BP motors), the drag effects were more pronounced.

Hardest part of the whole thing would be making nose cones that are all the same length but different diameters.

FC