R4 and R6

[tjkopena]

More MMX action this past weekend.

R6, designed and painted by my 5-year old. She chose the basic parameters (number & shape of fins, nosecone, etc.), and we worked together to tune them in OpenRocket to get the dynamics right.



We also made a little kit of R4 for a friend of ours.



I literally ran it over to his house and 2 hours later he showed up at our planned launch with this nice little bit of work.


Both of these flew very well. My copy of R4 unfortunately took a hard hit on some asphalt but has since been repaired.

 

[BABAR]

That R6 paint job belongs in a modern art museum! Sort of looks a lot like a feminine version of Saturn’s cloud cover.

nice birds!

 

[user 13]

Now I want an R4!

How high did R4 go? How many grams is Brett?

 

[BABAR]

Okay, we got R3, R4, and R6. So the numbers refer to the number of fins? Why R? (“Rocket”?)

 

[mooffle]

Yeah that R6 is rad, nice 'starry night' vibe.
Little kid designs are always fun.

 

[tjkopena]

Thanks all!

I laughed, BABAR, I hadn't even noticed the designations were lining up with the number of fins. "R" is indeed for Rocket. When my daughter started showing a real interest in rockets (in general, not just models) a few months ago I built my first rocket in ~25 years and I just started thinking of it as "Rocket 1" or "R1". From there the convention has just kind of stuck.

mach7, R4 weighs 5.6g empty and should be good for about 150ft. It's a bit heavier than it could be. I'm iterating on a simple kit framework such that I can have a couple of my daughter's (kindergarten aged) friends join us at a launch on a neighborhood field to assemble & fly rockets on the spot. To do that it's got to be easy & cheap for me to make a bunch, super easy to build with just a little parent help, ideally easily colored with Sharpies or similar so it's dry almost immediately, and robust enough for rough handling and flying (bad streamer packing, etc). So R4 and R6 have a couple features that add some weight and drag, like:

• A one-piece tail block with slots to hold & align the fins, the motor mount, and a tie down for the shock cord;
• Pre-papered fins;
• A conformal launch lug so it helps align itself to the long axis.

 

[BABAR]

Thanks all!

I laughed, BABAR, I hadn't even noticed the designations were lining up with the number of fins. "R" is indeed for Rocket. When my daughter started showing a real interest in rockets (in general, not just models) a few months ago I built my first rocket in ~25 years and I just started thinking of it as "Rocket 1" or "R1". From there the convention has just kind of stuck.

in that case, what happened to R1, R2, and R5?
Any chance of a two stage R2-D2?

 

[BABAR]

Thanks all!

I laughed, BABAR, I hadn't even noticed the designations were lining up with the number of fins. "R" is indeed for Rocket. When my daughter started showing a real interest in rockets (in general, not just models) a few months ago I built my first rocket in ~25 years and I just started thinking of it as "Rocket 1" or "R1". From there the convention has just kind of stuck.

mach7, R4 weighs 5.6g empty and should be good for about 150ft. It's a bit heavier than it could be. I'm iterating on a simple kit framework such that I can have a couple of my daughter's (kindergarten aged) friends join us at a launch on a neighborhood field to assemble & fly rockets on the spot. To do that it's got to be easy & cheap for me to make a bunch, super easy to build with just a little parent help, ideally easily colored with Sharpies or similar so it's dry almost immediately, and robust enough for rough handling and flying (bad streamer packing, etc). So R4 and R6 have a couple features that add some weight and drag, like:

• A one-piece tail block with slots to hold & align the fins, the motor mount, and a tie down for the shock cord;
• Pre-papered fins;
• A conformal launch lug so it helps align itself to the long axis.

View attachment 455525

hmmmm, easy build that you want low to medium altitude?

I don’t know how much personal 3D printers cost to operate.

what about a one piece motor/fin/launch lug can that slides on OVER the outside of the rocket body. Automatic perfect alignment.

Think FlisKit DooDad
https://www.fliskits.com/WPRESS/product/doodad/ Adds a ton of drag and a bit of weight, keeps the altitude down which in this case is a plus, as these puppies are likely hard to find in un own grass!

pre-colored label paper to decorate the body, pick a pretty blue or green or red or pink or purple for the plastic.

nose blow recovery (no chute or streamer needed.)

 

[tjkopena]

Usable 3D printers these days are cheap. I also worked out the electricity costs at one point and it was negligible even for much larger prints. The tail block, nosecone, and launch lug on these is 3D printed.

The over-the-tube fin canister is a good idea. I'm trying to strike a balance between being super easy to assemble and actually requiring some assembly. Toward that I'm not eager to dispense even with glueing fins on, same reason the launch lug's not integral with the tail block. But it's definitely an option and would simplify things a lot.

 

[BABAR]

Usable 3D printers these days are cheap. I also worked out the electricity costs at one point and it was negligible even for much larger prints. The tail block, nosecone, and launch lug on these is 3D printed.

The over-the-tube fin canister is a good idea. I'm trying to strike a balance between being super easy to assemble and actually requiring some assembly. Toward that I'm not eager to dispense even with glueing fins on, same reason the launch lug's not integral with the tail block. But it's definitely an option and would simplify things a lot.

I think you already have it on your model, but a fin can could include fin placement guides that could provide the satisfaction of having the kids put the fins on with the assurance that the fins would be on straight, and probably even hold them in place while drying, thus adding making it easier. Might even be able to put in a screw in motor retainer (ignorance of how 3D printers work can be an advantage in imagining possibilities which may be prematurely eliminated due to preconceived ideas. OTOH, can also suggest rabbit holes with no exits!)

cool project, would be nice to have something to bring kids into a hobby that gets them outside and thinking.

 

[tjkopena]

My final iteration on R4, the photo shoot model.





View attachment R4-slow-cut.mp4

 

[mikewrt]

Ok quit teasing and just take my money.