Calvin&Hobbes 2 Stage High power Rocket for URRF

qquake2k said:

Sounds like a fun build! Here is how I cut my fins on a bandsaw:

https://www.rocketryforum.com/showt...quot-Binary-Effusion-quot&p=693144#post693144

https://www.rocketryforum.com/showt...quot-Binary-Effusion-quot&p=693146#post693146

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I am at school right now so I don't know if I passed it but I couldn't find the post on the fins. I will look later but just for reference what post # is it?


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First one is #29, second one is #31.

conman13 said:

I am at school right now so I don't know if I passed it but I couldn't find the post on the fins. I will look later but just for reference what post # is it?


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No I think I am just goin to use 1/8" for the rings for everything but the aft ring on the booster so there is a place to mount the rail button.


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Well no cutting for me because my band saw blade is dull. I went to cut and it is really rough with a horrible finished cut. I will have to run to the store and get a new one and hopefully get the fins cut by next week.

qquake2k said:

I can't get blades for my bandsaw locally, because they're an unusual size. I get mine here:

https://toolcenter.com/

The last one I ordered was a Lenox Neo-Type 3/8" x 14tpi. I really like it.

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Thanks I am going to check my local lowes to see if they have them and if not I will take a look at the website. First I have to remember what size mine is I think it may somewhere on the machine.


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This is the paint scheme I had in mind



Along with some black Lettering for the names and then the Calvin and Hobbes decals matching the color scheme. (orange for Hobbes and green for Calvin) What do you think I am pretty much set on the white for the tubes and the orange for the sustainer but I don't know about the green. Any color suggestions for the booster?

Well my stuff came today and here is the shot of most of the things need.

I am now a VIR at apogee(very important rocketeer) and earned my honorary certificate

I am going to start marking the tube and getting some ttw fin positions cut into the body tube. Pictures to follow.


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Marked and extended the ttw fin positions.


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Very cool. If it was me I'd paint the booster red and black, and the sustainer orange and black.

I'll be following




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rocketgeek101 said:

Very cool. If it was me I'd paint the booster red and black, and the sustainer orange and black.

I'll be following




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Thanks I will keep that in mind.


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LOVE the theme.

Do the sustainer Orange with black stripes, going to a point and the booster Red with think black rings around the circumference of the tube with black fins.

This might make a cool decal:

Put each on their corresponding area of the rocket.

It might also be cool to write Hobbes quotes all over the sustainer and Calvin quotes all over the booster.

op:

Alex

Thanks I think I will use your idea of the quotes. that would be really cool along with some full color decals.

I have run into a small problem. Originally I planned on using a side AV-bay to mount my staging electronics but now that I look at it I realize that I have no room to make that happen. I don't want to mount them in the nosecone because there are already going to be tracking and deployment electronic mounted in there. Are there any other ways to mount the electronics inside the sustainer? I was talking to BlackBrandt on Sunday about some of these things and he mentioned of doing a removable E-bay inside of the sustainer and not using motor deployment at all. I have never heard of this can someone explain how this is done and held into the airframe?

-Connor

Connor, I meant using the booster avionics bay to control the booster deployment, and having a sustainer avionics bay control staging.

Ok I see.

Well does anyone have any idea of where I could mount the staging electronics. I am trying to avoid running wires from the motor and don't want to get any more couplers for having an E-bay in the sustainer. Thoughts?

Hi Connor. Attached is a pic that shows one of my sustainers. Starting from the left, the fincan has a conduit running to the top of the "zipperless coupler". This link describes the zipperless coupler concept and why it's a good idea to use that design.

https://www.info-central.org/?article=132

You can design a zipperless coupler to allow backup motor ejection or not - your preference - but you must have electronic apogee deployment at a minimum.

From there, the upper airframe is divided into two parts. The lower section is for the drogue and the upper section is for the main. The altimeter bay holds them together. There are probably dozens of ways to do this.

In this particular rocket, the staging electronics are in the electronics bay shown in the picture. The wires running from the bay connect to the wires going to the motor (and the separation charge) via breakwires located at the top of the zipperless coupler.

As an alternative, you can use the space within the zipperless coupler to hold the electronics for staging. Again, there are many variations on the theme, but the easiest way to say this in words is to imagine that the bulkhead on the top of the zipperless coupler can be removed, and that there is a compartment below it where you can put the staging electronics. Obviously, with this approach, you can use motor ejection for backup. And, you would still have an electronics bay as shown for the dual deploy electronics.

Hope this helps.

Jim

Thanks Jim that does help a lot. I think I have it down. I am going to cut the body tube at 16 inches up and then attach an Electronics bay that will hold the staging electronics with rivets on both sides of the coupler. I can then run the wires down to the motor and attach them to the igniter leads. There will also be an eyebolt at the top bulkhead for my shock cord attachment point. I wont be able to use my motor deployment but will run a separation charge at the nosecone at apogee and will use a cable cutter for deployment of the sustainers parachute. I also forgot to mention earlier that I will be making the Inter-stage coupler into a small electronics bay for my timer that will control the separation charge of the booster and sustainer.

conman13 said:

Thanks Jim that does help a lot. I think I have it down. I am going to cut the body tube at 16 inches up and then attach an Electronics bay that will hold the staging electronics with rivets on both sides of the coupler. I can then run the wires down to the motor and attach them to the igniter leads. There will also be an eyebolt at the top bulkhead for my shock cord attachment point. I wont be able to use my motor deployment but will run a separation charge at the nosecone at apogee and will use a cable cutter for deployment of the sustainers parachute. I also forgot to mention earlier that I will be making the Inter-stage coupler into a small electronics bay for my timer that will control the separation charge of the booster and sustainer.



View attachment 170575

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I guess I've never considered what would be the best approach for two-stager electronics using a cable cutter. I'm stumped. Your approach looks as good as any, but what it looks like to me is that you have almost a conventional dual-deploy configuration, but you're not going to use the normal drogue section except to run wires through. The question I would ask is, since you have what is close to a conventional dual deploy configuration, why wouldn't you use that instead of a cable cutter? For several reasons, a conventional configuration will always be more reliable than a cable cutter approach. And, you would be able to use motor backup at apogee.

One downside of the conventional approach is that you would need another tube break (which would appear at the top of the zipperless coupler in my previous pic). I hate tube breaks on two stagers, so what I do now is design so that the electronics bay can just slide into the airframe from above. The new pic shows that approach on a different sustainer. On this one, the electronics bay just slides in to the position shown.

Jim

I guess it would be easier to do conventional dual deployment. I can just move my electronics bay up to the middle and then have the drogue on the bottom half where the wires are run and the main on top. Thanks

I changed up the design a little and extended the sustainer here is the updated openrocket file.






View attachment Calvin&Hobbes.ork

I ordered a 3'' hole saw off of amazon that will be here Friday so I will be able to cut out the centering rings this weekend and hopefully get the motor mounts finished and epoxied in.

conman13 said:

I ordered a 3'' hole saw off of amazon that will be here Friday so I will be able to cut out the centering rings this weekend and hopefully get the motor mounts finished and epoxied in.

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If it's the same type of hole saw that I use, a 3" will cut a 2-3/4" OD disc. For centering rings for 3" or 3.1" body tubes, I use a 3-1/4" hole saw, then trim them to final size on my lathe.

qquake2k said:

If it's the same type of hole saw that I use, a 3" will cut a 2-3/4" OD disc. For centering rings for 3" or 3.1" body tubes, I use a 3-1/4" hole saw, then trim them to final size on my lathe.

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this is the one I got:

https://www.amazon.com/gp/product/B002FYFYW8/?tag=skimlinks_replacement-20

Is it the same?

conman13 said:

this is the one I got:

https://www.amazon.com/gp/product/B002FYFYW8/?tag=skimlinks_replacement-20

Is it the same?

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Yep, that'll cut a 3" ID hole, or a 2-3/4" OD disc. Hole saws like this have a 1/8" kerf, but because it's a circle, you have to subtract 1/4" from the size of the saw.

time to cancel my order

conman13 said:

time to cancel my order

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Don't ask me how I know about this...

qquake2k said:

Don't ask me how I know about this...

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Thanks glad you cought that before I got it and found it out myself I ordered a Lennox 3 1/4'' and it will be here Friday.

conman13 said:

Thanks glad you cought that before I got it and found it out myself I ordered a Lennox 3 1/4'' and it will be here Friday.

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That should work fine.

throughout the last couple of days I have been able to cut the ttw fin slots, cut the sustainer stage at 18", glue together the interstage coupler, apply super glue to the ends of all of the tubes and cut out the motor mount tubes. Unfortunately I couldn't get the arbor out of my 4" hole saw so no cutting the centering rings. I ended up just ordering another one. I still have to get a band saw blade so I can cut out the fins. I am going to place an order tonight for another body tube and coupler. Pictures coming soon.

Started working with mark from sticker shock about some vinyl for this bird.


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