Egg Launch and Recover-I need NASA level help

[clinresga]

Egg Launch and Recover--I need NASA level help!

Homework Statement

Another variation on the classic Egg Launch and Egg Drop Science projects, only this 9th grade science teacher believes in upping the ante. Goals are to launch a raw egg, achieving at least 30 feet of vertical height, using a parabolic flight path (i.e. not just straight up), and then having the egg land intact. Combining these two problems seems almost insurmountable to us (my son and I).

Additional constraints: launcher must be a compound machine (uses at least two simple machines). No catching or landing pad devices: all egg protection must travel with the egg during the entire flight.

Homework Equations

The usual motion equations, but this is really an engineering problem--they are not asking for any mathematical modelling.

The Attempt at a Solution

OK, this is where we are to date. As far as I can tell, the simplest launcher design, a slingshot, is not eligible (not a "compound machine"). Similar problems with propelled devices like a water rocket, which would work well I suspect. No rockets.

We are looking at a Trebuchet made out of PVC pipe (I suspect y'all know what a Trebuchet is, but it is a catapult like device that uses a heavy counterweight to throw the arm). I think I can scale it up to the point where it would throw hard enough--but that's absent the real challenge in my mind, which is egg protection.

I'd love to use a parachute, but I cannot get past the deployment problem. I just don't think there is any reasonable way to reliably deploy a parachute. You'd have to use some kind of rocket like device with fins and a nose cone to do this, and that would be near impossible to launch with a Trebuchet.

So we are thinking of a protective device. Here, another problem. The bigger, and more protective the device, the harder it will be to throw 30 feet up. So our working idea is to construct an open wire cage, to minimize air resistance, and then suspend the egg inside. Twisted pantyhose appears to be the simplest material to suspend egg, though we might fool around rubber bands.

OK: is this desperately stupid? Does anyone have a (preferably much simpler) suggestion? This is TOUGH! (unless I'm missing some "Gotcha" trick to solve this).

Thanks!

 

[Mindscrape]

Hah, quite the project. You definitely want to launch up as straight up as possible, and also have the launcher be consistent. Trebuchet is a good idea because it is nice and simple, but it may give the egg too much horizontal velocity. What is the definition of simple machine? Could you use something like a pinball launcher: a spring and an egg fitting cushion?

Yeah, you definitely want a parachute, which probably involves making a contraption around the egg. You'll want it to be light in that case, maybe a simple foam that contours the egg. For the landing you just want something that will distribute pressure evenly as it slows down because eggs won't break given even pressure (try to break an egg by squeezing it in your palm :p). You also want the landing to be really slow to minimize the impulse. A vat of crisco with a temperature gradient could be good :).

Good luck, do it over a weekend so that you've lots of trial and error, and have fun!

 

[clinresga]

Great comments. Hadn't thought about the horizontal vs vertical flight issue with Trebuchet. I agree that there are better ways to launch--slingshot, spring loaded plunger, compressed air cannon, or water rocket. I had assumed that since "spring" is not included in the list of simple machines (lever, wheel and axle, screw, pulley, inclined plane) so had written that off, but sounds like clarification from teacher may be in order.

Landing is tough too. One problem is that teacher will provide egg right at the time of launch, so no time to build egg into something. We will be messing around all weekend. I have to admit, as nutty as the problem is, this teacher is making my son and I think hard! Good stuff.