add weight or not to add weight?

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rabidsheeep

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im sorta cloning an estes phoenix with a tube from a banged up rocket i ripped apart

the bt has a 3x18mmt, so the engines will be heavier than the stock engine

the thing that might balance this off is that i bought a balsa nosecone... im not sure if it is actually heavier than the stock estes plastic...

do you think i need to add nose weight to the nosecone to even out the heavier engines?

also, to make an estes be able to handle E power motors should i add nc weight?

thanks

--sheeepy
 

DynaSoar

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Originally posted by rabidsheeep
im sorta cloning an estes phoenix with a tube from a banged up rocket i ripped apart

the bt has a 3x18mmt, so the engines will be heavier than the stock engine

the thing that might balance this off is that i bought a balsa nosecone... im not sure if it is actually heavier than the stock estes plastic...

do you think i need to add nose weight to the nosecone to even out the heavier engines?

also, to make an estes be able to handle E power motors should i add nc weight?

thanks

--sheeepy
Shouldn't need it just because of E motors.

Where'd you get the balsa nose? Do they have the weight of it?
 

sandman

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rabidsheep,

Don't decide yet!

Go here:

https://www.rocketreviews.com/cgi-bin/rocksim/cp.cgi?Estes%Industries&&bymanf

It has the CP (Center of Pressure) for the Estes Pheonix and that should interpolate to the the same general area for the upscale.

Just miltiply the upscale factor by the CP distance and your center of gravity should be at least one caiper (body diameter) ahead of that. More or less.

There is room in the cone to add weight if needed.

Don't add weight until you know it's needed which would be after painting (those big fins take a LOT of paint!).

Add the parachute and motor(s) and check the center of gravity then.

Adding nose weight is the LAST thing to do. After the painting, fillets, decals...etc.

It may not need any.

P.S. I made the nose cone.
 

rabidsheeep

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i got the nosecone off balsamaching services... i can get the weight once i can find the scale around here

(sandman, its not the upscale phoenix, is a 3x18 mmt, i still have to order some more shtuff for the upscale but i finally got the mmt's:D )
 

sandman

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(sandman, its not the upscale phoenix, is a 3x18 mmt, i still have to order some more shtuff for the upscale but i finally got the mmt's )
I gotcha!

The EMRR CP chart will help you out easily but wait until the model is finished before you decide what to add to the cone.

So with the model finished and painted install the 3 motors and the center of gravity should be at least 10.12 or more inches from the rear.

Add weight to the nose until you get it there.

Generally balsa is just a little heavier than plastic.
 

JRThro

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sandman,

Do you mean that solid balsa is just a little heavier than solid plastic?

Or that a solid balsa nosecone is a little heavier than a hollow plastic one?

I really don't know, so I thought I'd ask.
 

powderburner

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I am certain that he meant: as compared to a hollow plastic NC.

If there was such a thing as a solid plastic NC it would weigh a ton (figuratively speaking). I guess a cast resin NC would come close?
 

sandman

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OK let me clarify.

A balsa nose cone is a little heavier than a hollow plastic nose cone.

Not much...just a little.
 

rabidsheeep

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done and done, just needs some paint... and uhh, anyone know where i could get decals?



 

sandman

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Call Estes @ 800-525-7561x 216

Tell Christine what you want and she can fix you up.

Or get ahold of Astronboy and have him make you up a set.
 

hokkyokusei

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Since you already have a phoenix, load it up with the motor you regularly fly it on and find the CG. Once you have finished your new phoenix, load it up with the motor you want to fly it on and measuer that CG for that.

If the CG of the new phoenix is in the same place or closer to the nose then your old phoenix, then you are good to go. If it is further to the rear then add nose weight until it moves the CG to the same place as on the old phoenix.
 
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