How does the parachute in a model rocket work?
Hi. I'm 14 years old and for a project I have to build a rocket from scratch except for the engine. I was wondering how does the parachute come out if I build one and how do I make it?
First, I should say that I've never built rockets from scratch, so what I'll tell you here is based on my experience with building a few different types of rockets from kits. I think you could pretty much use the same techniques for rockets you design yourself though.
The rocket kits that I've used have two types of parachutes: streamers and actual plastic parachutes. The streamers are just pieces of plastic about an inch wide and about a foot long, and they are best used for rockets that aren't going too high. (Streamers slow down the rocket as it falls, but aren't as effective as parachutes, especially if the rocket has a long way to fall. I've used them for rockets with the least powerful engines.) The streamer is securely taped or tied to one end of a piece of elastic, and the other end of the elastic is glued/taped to the inside of the rocket tube. Then the streamer is rolled up around a pencil and slid into the rocket tube. Then the nose cone of the rocket is then placed on. (The nose cone of rockets should be able to come off the tube, so the parachute/streamer can get out. But, it should also be attached to the tube so it doesn't get lost; for example, tie the end of the nose cone to another piece of elastic that glues to the inside of the tube.)
Parachutes are harder. I don't really have any good ideas of how to make one from scratch since I've used kits before, but basically use something plastic or nylon and attach the strings to the inside of the tube. The parachute gets folded and packed into the tube, and the nose-cone (again, the nose-cone has to come off) gets put on.
There are a couple other things to note:
- The streamers/parachutes get deployed by the rocket engine. The engine has a stage that moves the rocket up, and when that stage is used up, a second stage ignites that blasts a small charge back up the rocket tube, in the direction of the nose-cone. This pushes the stuff in the rocket out.
- Because of this, you need something between the explosive charge and the parachute, or the parachute will just melt. Therefore, before packing the parachute in you should place "recovery wadding" into the rocket. This is stuff that looks like toilet paper, and it will serve as a barrier that will prevent the plastic parts from burning when the charge goes off. It's important to use something nonflammable for this! If you just use toilet paper, then burning bits of paper will be expelled from the rocket tube and will fly down on your audience, which would be bad! You should get recovery wadding from a local hobby store.
- Be sure not to pack your streamer/parachute too tight. If it won't fall out if you hold the tube upside down, then it might be too tight to come out when the charge blows. If it's packed in too tight to move, the parachute won't deploy, and it might be melted despite the recovery wadding. (This has happened to me before, so I know from personal experience!)
I think that's basically what I know. You should definitely be able to use the parachute multiple times if things go right and it's not melted. I also found a couple web sites on this topic.
- Small amount of basic information on rocket recovery systems
- Links to many detailed websites on designing parachutes for model rockets
Have fun with the rockets and please remember to be careful, especially with rockets you build which haven't been tested and refined by a rocket company.
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