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Power Limitations for rockets

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Burtech

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I'm curious to know if there's any limitations to motor size in rockets and if so what are they beyond physically accepting the motor and build strength. I'm new to HPR and just received my Level 1 with a Public Missiles Quasar, it was a fun rocket to build and I learned a lot. But now I'm contemplating doing a 2.0 version where I use glassed phenolic rather than the quantum tubing and a few other improvements. Their data sheet calls out various recommended motors and advise that with the biggest motors build strength is critical. Yesterday I did a little research and found that it can accommodate some even larger more powerful engines than their suggested motors. I like the idea of pushing it eventually but am wondering what if any are the down sides? I noticed that many rocket manufactures don't even suggest particular motors which leads me to believe choosing them could be part of the fun. Thoughts?

Thanks!

Richard
 

rharshberger

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Pairing a rocket and motor is part of the challenge, along the way you get an idea of the various strengths and weaknesses of different airframe materials and construction techniques.
 

jimn

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The downside is that your rocket shreds, that is comes apart. No more rocket and showering parts over the field.

No expert on this, but the main thing is the speed. The bigger the motor and the higher the thrust the faster the rocket. Breaking the sound barrier is also a major stress.
 

Bat-mite

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Be careful to understand the difference between thrust and impulse. A J motor with twice the total impulse of an I motor might not have sufficient thrust to get the rocket off the pad. Know your thrust curves.
 

Burtech

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Cool guys, thank you. I am going to bone up on the difference between thrust and impulse. I have to say this is really fun!
 

OverTheTop

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Think about impulse being the energy available in the motor. Say you have a particular amount of energy, you can burn it fast or slow (depends on the fuel mix). The impulse energy can be the same, but the long burn will have a lower average thrust, and the short burn will have a higher thrust.

The motors also complicate things by having different burn profiles, so there can be thrust spikes at the start which are designed to get the rocket off the pad and then back off, or they can gradually increase thrust till burnout, and various other varieties.
 

cbrarick

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There's no such thing as too much motor, just enough motor to rekit the rocket
 

markkoelsch

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The real answer is that it is only limited by your budget.
 
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