Tell me how bad an idea this is

[thesnorklemonkey]

So I had this idea way back when. Make a 7 foot tall, 1 foot diameter chemical rocket to launch just for fun. Realizing how hard it was, I've decided to build a prototype of the body just to test it out.

Now here's what I'm wondering. Is it a bad idea to buy a number of premade engines (ie tiny Estes engines) and put them all on one rocket and ignite them at the same time?

I look forward to insults at my intelligence. :tiphat:

 

[n72.75]

On a scale of one to ten, with one being the dumbest and ten being peanut butter; this is about a two.

 

[thesnorklemonkey]

On a scale of one to ten, with one being the dumbest and ten being peanut butter; this is about a two.

Mmkay. What's dangerous and how can I avoid the danger?

 

[n72.75]

Mmkay. What's dangerous and how can I avoid the danger?

I f you're going to get into model rocketry, start small. That way you'll get a feel for what works and what doesn't work. And won't blow your self up.

 

[Mantis]

n72.75 is right....start small, learn the basics with small Estes kits and then move onto HP rockets. Trying to launch a 7 foot tall rocket with a cluster of God only knows how many Estes engines isn't likely to be dangerous - just a noisy and expensive failure. For starters, how certain are you that you've constructed a rocket that is capable of reasonable straight flight? Do you know how much it weighs in order to calculate the impulse required from the engies so that you'll know which type and how many Estes engies you'd need? How do you plan to simultaneiously ignite this cluster of engines? If they don't ignite simultaneously there may not be enough thrust to get your rocket off the ground or there might be just enough to lift it but not enough for it to remain in control. In terms of danger it's pretty low unless your huge engine cluster starts a grass fire or it manages to leave the ground and go out of control and someone catches it between their eyes but it's not very viable without doing a lot of homework before hand.

 

[Ghostrider]

Well... Igniting ALL the engines at the same time will result in a nice KA-BOOM which is all nice and fun until someone loses a leg. Estes rockets like all model rocket engines have - if I remember correctly - the ability to ignite in sequence with each engine being fired by the one underneath it.
The problem is that you might not be able to lift off the rocket's mass with the power of the first engines so it will only stay there and puff a lot or jump up, fall down and skid along the ground like an oversized firecracker.
Keep in mind you're dealing with EXPLOSIVES there. Explosives may be fun but they're not toys. They can hurt you a lot.
Just like cars, guns and girls. Oops...

 

[Rtyh-12]

Mmkay. What's dangerous and how can I avoid the danger?

The dangerous part is the engines. The easiest way to avoid the danger is to buy Hitler's bunker.

 

[jinglesassy]

It would be cheaper safer and better if you used a big engine.The problems with many tiny engines is less thrust and some will ignite fractions of a second later meaning it will become a flying missle possibly hitting you or an person watching. Remember these are real explosives not little water rockets meaning they can kill you if you are not careful and do it right or not at all.

 

[T.Neo]

The dangerous part is the engines.

I beg to differ. I bet you wouldn't like 100 tons of propellant to land on your head.

The problems with many tiny engines is less thrust

I'm pretty sure the fact that they have less thrust is why you have a large amount of them...

 

[Ghostrider]

Feasible to do a bench test?

 

[thesnorklemonkey]

Do you know how much it weighs in order to calculate the impulse required from the engies so that you'll know which type and how many Estes engies you'd need? How do you plan to simultaneiously ignite this cluster of engines? If they don't ignite simultaneously there may not be enough thrust to get your rocket off the ground or there might be just enough to lift it but not enough for it to remain in control.

Well that just sounds like application of Newton's second law, on the bit about impulse to lift off the rocket.

if I remember correctly - the ability to ignite in sequence with each engine being fired by the one underneath it.
The problem is that you might not be able to lift off the rocket's mass with the power of the first engines

It's not too difficult to calculate how many N's of thrust the engine needs. I'll look into the idea of starting in sequence like you mentioned.


Thanks for the advice everyone! I'll start off with small rockets and work my way up.

 

[walsjona]

How do you plan to simultaneiously ignite this cluster of engines?

This is certainly a big question, even trying to get 2 engines to fire is tricky.

I saw a model rocket once with 3 engines in the first stage, 1 fired normaly, 1 got lodged inside the rocket and the other didn't fire at all and was torn out and left on the lauch pad. Interestingly the rocket did still go quite far even if it was not nessarrily in the right direction :lol:

 

[Carmen A]

Trying to launch a 7 foot tall rocket with a cluster of God only knows how many Estes engines isn't likely to be dangerous - just a noisy and expensive failure.

We can learn from the N-1, not to have something that has like, 36 engines in the first stage :3