How heavy should the nose cone be?

Discussions about rockets, construction materials, adhesives, nozzles, nosecones and fin design.
runnin_rocket_maker
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How heavy should the nose cone be?

Post by runnin_rocket_maker »

I understand that a lighter rocket will fly higher. However, when you think about inertia would it be beneficial to add a little weight up front? Any thoughts are appreciated Thanks :mrgreen:
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rockets-in-brighton
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Re: How heavy should the nose cone be?

Post by rockets-in-brighton »

runnin_rocket_maker wrote:I understand that a lighter rocket will fly higher. However, when you think about inertia would it be beneficial to add a little weight up front? Any thoughts are appreciated Thanks :mrgreen:
You should add only as much weight as you need to get the correct relationship between centre of gravity and centre of pressure.
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Steve
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rockets-in-brighton
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Re: How heavy should the nose cone be?

Post by rockets-in-brighton »

runnin_rocket_maker wrote:I understand that a lighter rocket will fly higher. However, when you think about inertia would it be beneficial to add a little weight up front? Any thoughts are appreciated Thanks :mrgreen:
You should add only as much weight as you need to get the correct relationship between centre of gravity and centre of pressure.
Cheers
Steve
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runnin_rocket_maker
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Re: How heavy should the nose cone be?

Post by runnin_rocket_maker »

You should add only as much weight as you need to get the correct relationship between centre of gravity and centre of pressure.[/quote]


I have seen on another thread how to get this correct relationship but i am not sure i fully understand, could you maybe explain?
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rockets-in-brighton
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Re: How heavy should the nose cone be?

Post by rockets-in-brighton »

runnin_rocket_maker wrote:
rockets-in-brighton wrote: You should add only as much weight as you need to get the correct relationship between centre of gravity and centre of pressure
I have seen on another thread how to get this correct relationship but i am not sure i fully understand, could you maybe explain?
For straight flight the centre of gravity of the rocket must be ahead of the centre of pressure so that small deviations are corrected automatically rather than reinforced.

To get the balance right you must determine those two points - there are plenty of sources around for that - but you can make a fair estimate by dangling the rocket by a string to see where it balances level (CG) and make a cardboard silhouette of the shape and dangle in the same way (Centre of Lateral Area = conservative estimate CP under special conditions).
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Steve
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SaskAlex
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Re: How heavy should the nose cone be?

Post by SaskAlex »

Sometimes your rocket will actually go higher if you add weight, even after it's stable. If it's too light, the air resistance becomes too significant. Typically rockets are naturally heavier than ideal, but not always. If you have a light rocket with a lot of drag, it's often beneficial to add weight. When you are starting out and building single bottle rockets (especially without parachute systems) you often have such a rocket; very light and with lots of drag. There are simulators you can use to find the optimum weight, or you can just experiment.
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rockets-in-brighton
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Re: How heavy should the nose cone be?

Post by rockets-in-brighton »

SaskAlex wrote:Sometimes your rocket will actually go higher if you add weight, even after it's stable. If it's too light, the air resistance becomes too significant. Typically rockets are naturally heavier than ideal, but not always. If you have a light rocket with a lot of drag, it's often beneficial to add weight. When you are starting out and building single bottle rockets (especially without parachute systems) you often have such a rocket; very light and with lots of drag. There are simulators you can use to find the optimum weight, or you can just experiment.
I guess what I'm saying is, if your rocket is draggy don't just add dead weight to it because then you have a heavy, draggy rocket. Instead see if you can improve the performance by altering the shape, fins, nosecone etc.
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rockets-in-brighton
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Re: How heavy should the nose cone be?

Post by rockets-in-brighton »

runnin_rocket_maker wrote:You should add only as much weight as you need to get the correct relationship between centre of gravity and centre of pressure.


I have seen on another thread how to get this correct relationship but i am not sure i fully understand, could you maybe explain?
Actually, based on your post about getting more altitude, I think you already have it nailed.
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Steve
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Jelo
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Re: How heavy should the nose cone be?

Post by Jelo »

I dont know if you already read about this thread but it will probably help you with stability and finding the CP or CG :wink: http://www.wra2.org/forum/viewtopic.php?f=3&t=764 hope this helps, ask questions over there if you want help
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runnin_rocket_maker
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Re: How heavy should the nose cone be?

Post by runnin_rocket_maker »

Yes i actually have seen that thread post, thanks.
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Jelo
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Re: How heavy should the nose cone be?

Post by Jelo »

well personaly, i always put blue tac on the very top of the inside of the nosecone, just adds a little weight, not to much
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