Calvin&Hobbes 2 Stage High power Rocket for URRF

I am just finishing up my super DX3 build that I will use for my JR. L1 certification this coming June. I was looking around by workshop and decide that I wanted another high power rocket to fly at URRF. I decided I wanted to make an attempt at my first high power 2 stage rocket which I will Calvin&Hobbes. This will be my first High power 2 stage rocket and I will be open to all suggestions and will need some help along the way.

Specifications:

Height: 80''

Diameter: 3''

Booster: 38mm (Calvin)

Sustainer: 29mm or 38mm still deciding (Hobbes)

I plan on placing the electronics for staging in a compartment located between the fins and have a tracker and another altimeter to control deployment using a cable cutter in the nosecone. I will be using 1/4'' birch plywood for the fins and 1/8'' plywood fiber glassed for the centering rings. I am hoping to make this a fast build so I have it done in time for launch. I attached the Open Rocket file below.

View attachment Calvin&Hobbes.ork

I am ordering the tubes today but came across a problem with the coupler I cant find one that is longer than 10'' and I don't want to buy a full length coupler. Does anyone know where I can get a coupler longer than 6'' preferably 9'' and up?? btw it is loc 3'' bodytube.

-Connor

Not sure where to get the tube.. but SUBSCRIBED.... Big Cavin and hobbs fan here!

That's good because I am going to need some vinyl at the end of the build.

Planning on cutting the fins, centering rings and bulkheads out this weekend. I decided that I am going to go with the 29mm motor mount for the sustainer.

Subscribed! I hope to one day do multi stage high power rockets but until then I'll watch this awesome build!

You could join 2 normal length one with a 6" piece of airframe tubing.

Most of the time; PML or Red Arrow phenolic couplers will work with cardboard.
I buy full length couplers (36" or 48" long) as I usually double wall for better strength as well.

JD

conman13 said:

I am ordering the tubes today but came across a problem with the coupler I cant find one that is longer than 10'' and I don't want to buy a full length coupler. Does anyone know where I can get a coupler longer than 6'' preferably 9'' and up?? btw it is loc 3'' bodytube.

-Connor

Click to expand...

Thanks I was thinking about that and that may be the way I go.


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Balsa Machining Service Part # C 300-34 $10.00

I made a 3" prototype rocket using some 3" LOC airframe tubing (3.00" ID). I tried using some 3" PML Phenolic coupler tubing (2.88" OD) that I had, for a coupler. Took some filling and tape to make a good fit. The Balsa machining coupler has an OD of 2.930". LOC couplers appear to be 2.990" OD.

Just be careful mixing and matching various mfg parts. I found them not to be very interchangeable.

Tony

Thanks. I think I am just going to get the two LOC couplers and attach two of them together using a 1'' switch band in the middle.

Connor, I will be watching.

I am doing something along these same lines.

And look what a quick search on Mark's website shows:
https://stickershock23.com/Calvin_and_Hobbs.html

blackbrandt said:

And look what a quick search on Mark's website shows:
https://stickershock23.com/Calvin_and_Hobbs.html

Click to expand...

Yes there are a lot to choose from I am looking forward to your build as well.

I hope to meet you before it flies so I can get some shots on the way up.

Sounds great


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Printed out the fin templates from open rocket. Using a exact I knife I cut out the templates.


I traced the fin template out onto a 1/4" piece of plywood.

I was thinking of cutting these out on my band saw but was wondering if there was any other way of cutting them out to get a straighter an cleaner cut. How do you cut yours out?

Next up is centering rings which I am going to start on now.


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Cut them out in rectangles, put a dowel through the fin tang, and then stack cut and sand them together.

Check out one of qquakes build threads...

ok thanks.

I got the centering ring templates cut out and traced on to the plywood just like with the fins. I had a 38mm circle cutter so I used that to cut out the 38mm holes for the booster centering rings. I only have a 32mm hole cutter and didn't know if I should try it or not. I don't have any 29mm motor tube so I cant really test it out with some scrap wood. Anyone have any experience with this? I am going to try to get some fins cut out tonight and the rest this week. going to order the rest of the stuff tonight.
I

After putting some thought into it I decided that I am going to do 38mm for both stages and I will be able to adapt down to 29mm if I want to. The reason I made this decision is because I will have a larger possibility of motors to choose from when doing this configuration and allows me to fly higher when I am ready.

just ordered the parts minus nosecone. they will be here monday but i am hoping they will get here saturday so i can work on it

Cool! I hope they get here by saturday so we can discuss it on the google hangout...

that was also the reason i wanted them. if not i have another coupler put together i can use.

Sweet. Also, quick tip for setting up avionics bays, cut out a piece of cardboard the size of the bay, and use pins to hold your altimeters on. Nice for figuring out a design...,

blackbrandt said:

Sweet. Also, quick tip for setting up avionics bays, cut out a piece of cardboard the size of the bay, and use pins to hold your altimeters on. Nice for figuring out a design...,

Click to expand...

Thanks I will try that for cutting and sizing the hole for the electronics in the sustainer.

What are your guys thought on using 1/8'' centering on all the motor mounts minus the aft ring on the booster so I can mount a rail button? will the 1/8'' work for the centering rings? I don't want to have the motors fly out the front of the rocket because of improperly sized rings.

-Connor

conman13 said:

What are your guys thought on using 1/8'' centering on all the motor mounts minus the aft ring on the booster so I can mount a rail button? will the 1/8'' work for the centering rings? I don't want to have the motors fly out the front of the rocket because of improperly sized rings.

Click to expand...

The load path for the thrust includes not only the rings but also the root edges of your TTW fins. 1/8" rings will more than suffice!

daveyfire said:

The load path for the thrust includes not only the rings but also the root edges of your TTW fins. 1/8" rings will more than suffice!

Click to expand...

Ok then 1/8" rings it is!!!


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You going to glass the centering rings?