Independent Senior Project...

[VH_man]

Well, Its my senior year, and because my school is awesome every once and a while, I am being allowed to spend the last 6 weeks of my senior year pursuing any project I really desire. Most people go make art for 6 weeks or go get an internship, but I have been allowed to construct something instead. I have a few Ideas. Some are spud cannon related, some are not. I have to decide on one by at least January, so here's some of my ideas. I would like peoples views on them, practically. the school will NOT let me construct any kind of cannon or gun for the sake of shooting stuff, it has to have a purpose with learning value. anyway, Ideas:

Break the Sound Barrier:
It has always been a goal of mine to do this. I can see two was to do it: a hybrid cannon (which my parents still will not allow for some depressing reason) and a method involving firing a model rocket out of a cannon vertically and then firing the engine when the rocket leaves the muzzle, effectively pushing itself another 200-400 FPS faster than the muzzle velocity of the cannon.

Motorized rollerskis:
This would probably require far more cost than the sound barrier idea, except it would be far more rewarding and I could use it in college the following year. For those of you who dont know, rollerskis are the skis used by nordic skiers to practice in the summer. it would be a kind of wearable motor-suit, if It works the way I want, which would be decidedly sweet. Anyway, If I were to do this, I would need to find an appropriate gearbox, because I lack the machining facilities to construct such a precise mechanism. I have an Idea of the motors (FIRST CIM motors used in my electric bike project) that will give me ridiculous power.

Guitar:
I have wanted to do this for a long time. I have the money set aside, the tools to do it, plans, ect ect, but have never gotten around to It. This would be relatively straightforward.... as straightforward as guitar building can be at least.

If you have any other ideas to do, I am very open to suggestions.
Thanks!

[jackssmirkingrevenge]

The rocket would be a good idea fired from a combustion if you could get the gasses to ignite the motor.

If you could figure out a way to light the motor while firing it from a pneumatic (and with a bit of thought, this is an achievable goal) you might even make a "hybrid" rocket if the motor burns while in the pressurised atmosphere of the barrel.

If they are opposed to the idea of firing something out of a barrel, why not have a rocket car of some description and make a pneumatic ram to accelerate it further? You're unlikely to reach mach one but it would be an itneresting project nonetheless, and will sound less belligerent than a pure rocket projectile

[jeepkahn]

or you could just build a cannon to be used as "test equipment"(see vera), and use it to launch projectiles at various window materiels to test them against impacts from rocks kicked up by lawnmowers, hail, etc...

The cannon would be a means to an end rather than the end...

[dilweed]

I agree with jsr, from the selection you've presented that would certainly be the least costly(well actually maybe a guitar), and the most technologically impressive(think about it, who else in your school would have ever undertaken such an endeavor, and successfully execute it. Unfortunately, you have to take into account the multitude of paranoid parents who suffer for ignorance and the vastly negative and overbearing bad press. Also, you should probably first receive the "go" for such a project as most principles would burst a vein at the notion of somebody taking a supersonic rocket launching gun with definitely lethal power....and what other students would think of you.

If you would be willing to choose another project, try something like creating a simple program(game), construct a complex circuit that does a little more than make a led pulse rapidly. Another idea of mine would be constructing a rocket or steam engine( on a feesable scale...cant get to carried away can we.....or can we?)

[Technician1002]

I find makezine full of great ideas.

http://makezine.com/

Electronics, arieal photography, animation, steampunk, music (A 2X4 bass electric guitar is one of the current items) and just plain fun.

[Moonbogg]

I had a wacky idea of making water shoes. It would be challenging at best, maybe impossible. What they would do is act like webbed feet that lets you run on the surface of the water. Or maybe be large floaty shoes that will barely let you float as long as you are in motion.

[VH_man]

thanks guys. I think my top choice is going to be breaking the sound barrier (or trying to)

Only thing i'm wondering about is the legality of firing a model rocket engine out of a pneumatic cannon. ATF prohibits the use of Incendiary projectiles, and this most definitely counts as incendiary...

Other thing im wondering is if I need FAA clearance due to the maximum altitude of such a device. (I would calculate this all out. my physics teacher will be my ISP advisor and therefore will help me If i get stuck, as this is VERY important to get right)

Funny thing is my school has a perfect area to do such a test... we have a giant field that is a conglomerate of 2 soccer fields and a baseball field. Its huge.... and on one side of it is a hill that is almost 30-40 feet above everything where one could remotely set off the experiment and record video with a perfect vantage point and no danger if something goes horridly wrong.

[blackhawk13]

try something like this

http://en.wikipedia.org/wiki/Gyrojet

once you get that to work call the us government. tell them that you have a new idea and boom! funding

[Lentamentalisk]

Ok, breaking the sound barrier:

I happen to know a fair bit about this, from my model rocket work.
For starters, a minimum diameter rocket on a high impulse G can get pretty near (if not break) the sound barrier.
Second, with a pneumatic, you have the trouble of igniting the rocket at the right time. Composites (AP) are notoriously slow at igniting, and may "chuff" on the pad for a while before they get up to pressure. Because of that, I would suggest having some sort of sensor in the tube that senses when ignition has started (maybe a pull string attached to the rocket) that then fires the electric solenoid to release the air.
The other option would be to use a combustion, and just have the exhaust gases ignite the propane/air mix.

Your next problem will be figuring out if you actually broke the sound barrier. All barometric altimeters go haywire right around the sound barrier, and from that, you can tell if you at least got close. They have some tiny ones that will fit in the nosecone of your rocket, and not weight it down much. For tips on how to make your rocket "super sonic capable" check out this pdf from Apogee Components. Their is considerable doubt as to whether the rocket actually goes supersonic, but with a boost out of a cannon, I am sure it could.

I must warn you though. If you are trying to break the sound barrier with a rocket, you are looking at altitudes of at least a mile, and without a field of at least a half mile radius, you can kiss your rocket good bye forever.

I will gladly help you out with whatever I can (I have been wanting to do the same thing for ages) but you can also take any further rocket related questions to http://www.rocketryforum.com/ where all of the big name model rocketeers hang out, like George Gassaway an the likes.

[jackssmirkingrevenge]

For tips on how to make your rocket "super sonic capable" check out this pdf from Apogee Components. Their is considerable doubt as to whether the rocket actually goes supersonic, but with a boost out of a cannon, I am sure it could.

Basically some common sense advice on reducing drag, something which spudders should take to heart when developing projectiles aimed at achieving maximum distance.

[Lentamentalisk]

that and the all important strength. Breaking the sound barrier can be very strenuous on a projectile. There is a sharp spike in drag right around there, which can rip off a fin, or worse, separate the body from nose cone, deploying the recovery system, and ripping the rocket to shreds. Read up on your model rocket building, and you will learn all sorts of awesome techniques for improving performance and durability.

[psycix]

If you school lets you, go for the sound barrier. Otherwise I would go for the motorized ski's.


You could simply use a burst disk which is destroyed when the rocket fires.

Or the rocket engine will explode due to the pressure it can build up when the pneumatic pressure comes from behind... increasing burn rate... causing even more pressure..... ehhh... let's just do the rollerski's.

[VH_man]

I am already very good at constructing model rockets. I have been doing so for as long as I can remember. Therefore, I am not afraid of the structural integrity of my rocket. I will be using Basswood fins instead of balsa, and pressure-treating them with primer so they have a glassy smooth finish.

However, I am interested to see what happens when a model rocket reaches the sound barrier.....

Also, Anyone know the legality of such a setup? I'm afraid the rocket may count as an incendiary projectile...

I am writing up my proposal shortly, and I will post it here when it is done.

[D_Hall]

Break the Sound Barrier:
a method involving firing a model rocket out of a cannon vertically and then firing the engine when the rocket leaves the muzzle, effectively pushing itself another 200-400 FPS faster than the muzzle velocity of the cannon.

Won't work.

At least, not if you're talking about Estes rockets. Admittedly, there ARE rockets out there that can break the sound barrier, but they don't need a boost to do it. Thus, I'm assuming you're talking about the basic Estes rocket.

As I said, they won't do it.

Why not? Because the drag on a transonic/supersonic model rocket (even of minimum diameter) is higher than the thrust the rocket produces. Even if you shoot it out of the gun at supersonic speeds, the best the rocket can do is decrease the decelleration. There will be ZERO acceleration.

How do I know?

Because I tried it probably 10 years ago.

[Technician1002]

Most model rocket construction materials won't hold up to supersonic flight. A model rocket built for supersonic flight will need more than the traditional motors.
http://dthrocket-articles.blogspot.com/ ... ocket.html

Getting it light enough to accelerate to the desired speed and strong enough to remain assembled is difficult in smaller sizes.

It will most likely require a multi stage rocket or a very large rocket to contain enough fuel for the high power engine.

In the US this will require a FAA waver;

Also realize that there is a limit to the total impulse you can use without requiring an FAA flight waiver. That limit is 160 Newton-Seconds. That's ONE "G" motor. Your cluster would produce four times the legal limit to launch without an FAA waiver.

From page http://en.allexperts.com/q/Model-Rocket ... rocket.htm

It would make a good senior project. Include all aspects including safety, legal, mechanical, etc.