An "R"-powered rocket build

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Ez2cDave

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new thread later today:
anyone know how to repair router marks in an island before my hot-blooded latin woman gets home?
Hmm . . . Call a local "home improvement store" and order a new countertop ?

LOL !

Dave F.
 

Wallace

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View attachment 368546 Well Chuck,

Guess we better look for some pirate garb.
Tried to tone this beastie down best I could, but this is the best I can do.
There will be slight changes in the design parameters as we go along, but this is pretty much it..
Now THAT'S a motor....Quick question though. Why is nozzle exit and expansion set to "0" ?
 

Rail Dawg

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View attachment 368546 Well Chuck,

Guess we better look for some pirate garb.
Tried to tone this beastie down best I could, but this is the best I can do.
There will be slight changes in the design parameters as we go along, but this is pretty much it..
Darn lucky to have you on this Pat!

Looks great!

Picked up a couple parts today...

Arrrggh!!!

Chuck C.


IMG_4754[1].JPG
 

Rail Dawg

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OK up above is my first crack at getting this rocket onto Open Rocket.

It's going to be currently right at 1000-1100 lbs.

Here's my idea for the build:

(5) 3/4" birch centering rings in the fin can section. Through those rings will go a G-12 tube for the motor. There will also be (3) 3/4" birch centering rings on the bottom acting as a thrust plate.

Fins will bolt onto the 5 centering rings.

The idea is the G-12 motor mount will be epoxied onto all the fin can centering rings and airframe.

Thus all the motor thrust and fin attachments will act together to carry the thrust and aerodynamic loads.

In the upper section there will be more 3/4" centering rings. Not sure yet how many will be needed.

I will then run an 8" or so G-12 tube up through those centering rings and it will act as an internal stringer. All the upper centering rings will be epoxied to that tube and of course to the airframe.

In between all the bulk plates will be 2-part foam. The same foam utility companies use for telephone poles.

The foam will press against the airframe so along with the centering rings we should have a pretty stiff airframe. Of course there will be 2-3 layers of carbon fiber.

Been looking at this pretty hard and this process eliminates the building of a bunch of wooded 2x4 structure.

Also the upper G-12 tube allows the recovery cable to be attached to the eyebolt on top of the motor and run all the way to the nosecone.

There will also be a Schedule 80 conduit run from the altimeter bay near the top of the motor to the upper area where the recovery charges (whatever they may end up being) will be placed.

It's a relatively simple build but one that brings the entire rocket into the load-bearing.

Pat G. is designing the motor to provide the initial 5-6000 lb average thrust needed to get this big guy off the pad.

Glad to have him.

Thoughts and suggestions encouraged.

Chuck C.
 
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dhbarr

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Save a bunch of weight by filling up much of the foamed cavities with balls before foaming?

Note that I haven't seen this tried and may be entirely misunderstanding your description.
 

DAllen

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Here's my idea for the build:

(Mundane tech details deleted)

Thoughts and suggestions encouraged.

Chuck C.
Since you requested it...Forget this pirate crap, the rocket name ought to be the name of the file you have in your screenshot above; "Hot Blooded Latin Woman."
 

boatgeek

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[lots of good stuff snipped]

There will also be a Schedule 80 conduit run from the altimeter bay near the top of the motor to the upper area where the recovery charges (whatever they may end up being) will be placed.

It's a relatively simple build but one that brings the entire rocket into the load-bearing.

...

Thoughts and suggestions encouraged.
Well, since you ASKED... :) Is the conduit supposed to be load-bearing? If not, maybe a simple electrical conduit (steel or plastic) would be better than Sch 80? It would save you a few pounds and maybe some bucks at no significant change in strength.
 

Rail Dawg

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Well, since you ASKED... :) Is the conduit supposed to be load-bearing? If not, maybe a simple electrical conduit (steel or plastic) would be better than Sch 80? It would save you a few pounds and maybe some bucks at no significant change in strength.
Good point of course!

No it's not load bearing but it's important the wiring is completely protected.

Sch 80 is overkill I agree!

Chuck C.
 

boatgeek

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Good point of course!

No it's not load bearing but it's important the wiring is completely protected.

Sch 80 is overkill I agree!

Chuck C.
OK, glad I'm not crazy. Or if I am, this doesn't prove it. I was having flashbacks to a project at work where they put in 8" Sch 80 exhaust pipes.
 

Rail Dawg

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Save a bunch of weight by filling up much of the foamed cavities with balls before foaming?

Note that I haven't seen this tried and may be entirely misunderstanding your description.
I've seen the 2-part foam used for filling in places like the fin can but not for structural strength.

Along with a bunch of barb-wire fencing I laid in about 75 vinyl fence posts a few years ago.

Found out utility companies use the 2-part foam all the time for installing poles up to very large telephone poles. When you look at the data and the testing on foam vs concrete you might be surprised just how effective foam is for strength.

For putting poles in the ground it's not the weight of the cement that does the holding it's the pressure exerted on the dirt on the side of the hole.

I'm going to use that data and testing to fill the open spaces in the rocket with foam so the foam exerts pressure on the airframe. You can choose different weights per cu/ft from 2 lbs to 16 lbs.

Quite frankly this might "revolutionize" the building of bigger amateur rockets where aluminum airframes are costly and heavy. I've filled other cardboard tubes with foam and they are rigid.

Eliminating the time-consuming method of an internal structure in our rockets allows us to build a substantial rocket in half the time. Just make sure the centering rings are in the right place and fill the gaps with 2-part foam.

While many think building a rocket of this size is going to take a long time I can actually do it with just a little help. The most time-consuming part will be creating the centering rings and carbon-fibering the skin.

In fact I almost think there won't be a need to do much carbon-fibering at all. But to play it safe I will.

You balls idea is a good one to save foam space but actually we want that foam in every possible nook and cranny.

Hope my explanation makes sense!

Chuck C.
 

llickteig1

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Is the rocket 3 pieces? Nosecone, mid-body and fin can? What is the weight and dimensions of the heaviest and largest piece?

Large monolithic components are difficult to transport, assemble and hoist to vertical.
 
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Rail Dawg

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Is the rocket 3 pieces? Nosecone, mid-body and fin can? What is the weight and dimensions of the heaviest and largest piece?

Large monolithic components are difficult to transport, assemble and hoist to vertical.
Good question Lance.

It will be transported in 3 pieces. Heaviest is the fin can around 250 lbs without motor.

Chuck C.
 

tomsteve

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raildawg, something with that foam ya may want to think about- something i do on rockets:
i assume you'll be doing TTW fins. you may want to think about drilling some holes through the fins- in the area between the BT and MMT- for the foam to flow through and help lock the fins in. i do that on all rockets i can. only one rocket i believe showed me it helps lock them in- a 1/4 scale PML patroit( phenolic tubing) that came in ballistic from about 1200' into frozen michigan farm field. BT blew into a jillion pieces right up to the forward centering ring. from there back, the exterior fin fillets didnt even crack

by the way:
them sono tubes seriously put into perspective the size of this build!
 

tomsteve

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Save a bunch of weight by filling up much of the foamed cavities with balls before foaming?
them foam balls sold at craft stores might be a good idea. might have to glue them in place before filling- not sure of the foam would try and push them up as the foam expands
 

Rail Dawg

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raildawg, something with that foam ya may want to think about- something i do on rockets:
i assume you'll be doing TTW fins. you may want to think about drilling some holes through the fins- in the area between the BT and MMT- for the foam to flow through and help lock the fins in. i do that on all rockets i can. only one rocket i believe showed me it helps lock them in- a 1/4 scale PML patroit( phenolic tubing) that came in ballistic from about 1200' into frozen michigan farm field. BT blew into a jillion pieces right up to the forward centering ring. from there back, the exterior fin fillets didnt even crack

by the way:
them sono tubes seriously put into perspective the size of this build!
Great input tomsteve!

Picking up those sonotubes certainly drove home just how big this rocket is going to be lol!

Even an "R" motor is going to be tested at these weights/drag.

Totally agree with you about what foam does when used in the fin can. Like I mentioned earlier it wasn't until I studied the foam vs concrete issue that I learned just how strong foam can be laterally.

In this build I'm only going to attach the fins to the airframe and anchor them into the centering rings.

Right now I'm planning on using aluminum angle with bolts in at least 4 maybe 5 centering rings. Weight plays an issue as we know in the lower half of the rocket so the design is still fluid.

But with the build starting soon it's time to hammer down more exactly what needs to be done.

Depending on all of you to look over the design and call out anything that looks sketchy.

Thanks.

Chuck C.
 
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