Finished CWBullet PortaPot Shot Clone

[BABAR]

Chuck (@cwbullet ) was kind enough to send me one of his 3D print builds, I have been thinking through it and with NARAM coming up, figure it is time to build it.

The design (like it’s Estes namesake) had some challenges. I plan a free mods, we’ll see how it goes.

The parts fit together great, I am debating whether I even NEED to glue the fins in, they are rock solid just dry fitting them.

I sanded the nose-“roof” a a touch, it fits perfectly AND slides out easily.

The chute was an unexpected gift, extremely well made of nylon.

There are two shock cords, not sure exactly how that is gonna work

 

[BABAR]

What ISN’T Included is the same thing the Estes didn’t have: SPACE.

Getting a chute and wadding in this is gonna be a trick,

At 192 + grams, it also simulates a brick in weight as well as shape.

So I think I will need to steal emulate something from @lakeroadster , the SPOOL.

I’d like to make it rear eject, but that’s gonna be more surgery than I want.

 

[BABAR]

Whether or not I glue fins on, I think this one will recover best with the body coming down fins up.

So a notch in back side (opposite the door) and an extension of the notch in the nose-roof

Prec
Precut


Post cut

 

[BABAR]

 

[cwbullet]

I ended up replacing my chute with a thin mil alternative. It is tough to pack that chute.

 

[lakeroadster]

What ISN’T Included is the same thing the Estes didn’t have: SPACE.

Getting a chute and wadding in this is gonna be a trick,

At 192 + grams, it also simulates a brick in weight as well as shape.

So I think I will need to steal emulate something from @lakeroadster , the SPOOL.

I’d like to make it rear eject, but that’s gonna be more surgery than I want.

Perfect candidate for a square rear spool. I mean what makes more sense than rear eject for a shitter porta potty ?

A couple squared cardboard centering rings glued to the cardboard motor tube, and some Kevlar.... done. Lots of room for a chute and maybe even an altimeter to track the apogee of your stool spool.

What "surgery" are you referring too?

​

 

[BABAR]

.

What "surgery" are you referring too?

View attachment 589773
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the body is one rock solid piece of plastic, with perfectly fitted slots for the equally perfectly fitted fins.

Technically not Through-The-Wall fins, as there is a central contiguous thick walled cylinder about an inch high which perfectly positions (gonna need an abbreviation for that, the major pieces here fit extremely well) a BT-50 motor tube (supplied with kit.)


There is no good way in my opinion to rear eject without taking the fins with it. And while I can see designs dong that, this isn’t one of them.

But we are close to the same wavelength. I found some nearly used up micropore 3M tape at work, the core is moderately thick tube that fits just perfectly around the central motor mount (snug but slides easily).

This is the core or hub of the spool.

It will be glued solidly (probably with gorilla glue inside, maybe epoxy fillets outside) to the nose-roof, which will be the forward end of the spool. A plastic key card is cut with a central hole and will make the rear end of the spool.

The chute and cord are wrapped around the spool, with the cord exiting the side hole at the top in back, routed behind the rocket (the launch lug is also glued into the back) and will attach to the bottom externally.

It’s Semantic as to whether at ejection the spool (nose, core, rear key card end, laundry and shock cord ) are ejected out the front or the body of the rocket with attached fins and motor mount are forcibly slid off the back.

 

[lakeroadster]

the body is one rock solid piece of plastic, with perfectly fitted slots for the equally perfectly fitted fins.

Technically not Through-The-Wall fins, as there is a central contiguous thick walled cylinder about an inch high which perfectly positions (gonna need an abbreviation for that, the major pieces here fit extremely well) a BT-50 motor tube (supplied with kit.)


There is no good way in my opinion to rear eject without taking the fins with it. And while I can see designs dong that, this isn’t one of them.

But we are close to the same wavelength. I found some nearly used up micropore 3M tape at work, the core is moderately thick tube that fits just perfectly around the central motor mount (snug but slides easily).

This is the core or hub of the spool.

It will be glued solidly (probably with gorilla glue inside, maybe epoxy fillets outside) to the nose-roof, which will be the forward end of the spool. A plastic key card is cut with a central hole and will make the rear end of the spool.

The chute and cord are wrapped around the spool, with the cord exiting the side hole at the top in back, routed behind the rocket (the launch lug is also glued into the back) and will attach to the bottom externally.

It’s Semantic as to whether at ejection the spool (nose, core, rear key card end, laundry and shock cord ) are ejected out the front or the body of the rocket with attached fins and motor mount are forcibly slid off the back.

Thanks for the 411.

Front eject almost never makes sense IMO.... with the rocket flying through the chute. I know it's been used pretty much forever, but that doesn't really mean much.

 

[BABAR]

I am a bit concerned about stability, yeah this has a ton of base drag, but it is square, the sides are contoured with moderately deep defining depressions so flow ain’t gonna be laminar, and I would challenge @neil_w , @k’tesh, and @lakeroadster to model the roof nose cone in OR!

So I am thinking to fix the motor mount so the motor is as far FORWARD as it can get. So tell me I am crazy, but I think I will actually recess the motor 1/2 a motor diameter (and more any I play games with Uncle Krushnic). I will have a screw and washer slightly overlapping the plastic base hole to keep motor from ejecting.

Question: will the washer overlapping say 1/8 inch of the outlet significantly deviate the thrust? It will be 12 mm below the base of the motor.

 

[cwbullet]

I have designed one that is rear ejection. I just have not printed it yet. To be honest, I am not sure it would work without getting hung up on the fin slots.

 

[lakeroadster]

I am a bit concerned about stability, yeah this has a ton of base drag, but it is square, the sides are contoured with moderately deep defining depressions so flow ain’t gonna be laminar, and I would challenge @neil_w , @k’tesh, and @lakeroadster to model the roof nose cone in OR!

So I am thinking to fix the motor mount so the motor is as far FORWARD as it can get. So tell me I am crazy, but I think I will actually recess the motor 1/2 a motor diameter (and more any I play games with Uncle Krushnic). I will have a screw and washer slightly overlapping the plastic base hole to keep motor from ejecting.

Question: will the washer overlapping say 1/8 inch of the outlet significantly deviate the thrust? It will be 12 mm below the base of the motor.

Why not just take an old motor casing, cut it to the appropriate length, and stick it at the nozzle end of the motor? Then you can use masking tape to secure it?

You wouldn't really need a motor casing though... just a piece of the motor tube, cut longitudinally and inserted behind the motor.

 

[BABAR]

Why not just take an old motor casing, cut it to the appropriate length, and stick it at the nozzle end of the motor? Then you can use masking tape to secure it?

You wouldn't really need a motor casing though... just a piece of the motor tube, cut longitudinally and inserted behind the motor.

Great minds….

Thought of both, then thought maybe I don’t need it.

Motor block setting will determine how far Forward the motor goes. You are talking a BACKSTOP, which I thought of too.

But do I NEED it? If I have a washer which edges over the lip of the back of the rocket, the motor WILL indeed slide back the 12 mm it is recessed, but should stop when it hits the washer. In traveling 12 mm I doubt it will pick up that much kinetic energy, so washer should stop it.

 

[lakeroadster]

Great minds….

Thought of both, then thought maybe I don’t need it.

Motor block setting will determine how far Forward the motor goes. You are talking a BACKSTOP, which I thought of too.

But do I NEED it? If I have a washer which edges over the lip of the back of the rocket, the motor WILL indeed slide back the 12 mm it is recessed, but should stop when it hits the washer. In traveling 12 mm I doubt it will pick up that much kinetic energy, so washer should stop it.

A steel washer and a steel setscrew? That's weight exactly where you don't want weight.

 

[cwbullet]

I am a bit concerned about stability, yeah this has a ton of base drag, but it is square, the sides are contoured with moderately deep defining depressions so flow ain’t gonna be laminar, and I would challenge @neil_w , @k’tesh, and @lakeroadster to model the roof nose cone in OR!

I have flown it with Estes D12, E12, AT E35, and one AT F32—no issues with stability.

I upscaled it to 2 times the size and have flown it with a 38mm one grain.

 

[BABAR]

I have flown it with Estes D12, E12, AT E35, and one AT F32—no issues with stability.

I upscaled it to 2 times the size and have flown it with a 38mm one grain.

How far can the motor hang out the back?

Anybody recommend good source and price for a thin mil chute?

 

[BABAR]

I have designed one that is rear ejection. I just have not printed it yet. To be honest, I am not sure it would work without getting hung up on the fin slots.

Take the fins with it.
see SR-73 Raven
https://www.rocketryforum.com/threa...n-glider-and-new-gyskelion.38883/#post-361971

 

[cwbullet]

Take the fins with it.
see SR-73 Raven
https://www.rocketryforum.com/threa...n-glider-and-new-gyskelion.38883/#post-361971

Maybe. I will work on the rear rejection.

In the current version, I did not even do fillets. I just glued them in the slots.

 

[BABAR]

Okay, need some help on color scheme.

one of these blues for the body, I am partial to the darker shade on the right.

but what about the FINS?

the original had clear fins, which was part of the problem cuz the were fragile.

these are black plastic, unfortunately I don’t think black works.

?green (like bushes)?

white? yellow (caution tape?)

 

[BABAR]

Boring stuff.

Motor mount.

The Mylar tape is on the tail is the tail (Chuck convinced me on stability.). The Mylar let’s me apply and remove tape motor retention without delaminating the tube.

I’ve always felt for low power using heavy motor blocks (usually centering rings) is overkill. Just a cut piece of tube, cut out a segment, and glue in.

Paper glue, (cheap school glue) gives nice work time so I don’t lock the motor casing.

 

[lakeroadster]

I am a bit concerned about stability, yeah this has a ton of base drag, but it is square, the sides are contoured with moderately deep defining depressions so flow ain’t gonna be laminar, and I would challenge @neil_w , @k’tesh, and @lakeroadster to model the roof nose cone in OR!

Square is not possible for an Open Rocket body tube or nose cone if you are wanting a reliable simulation... but I don't think using round instead is a problem as long as the frontal area is about the same.

Has anybody made one of these with a conical base? That looks more realistic, IMO, and it looks to be a stable option. Although the cone does hurt the apogee.

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[BABAR]

 

[BABAR]

Except will need thin mil chute.

Many thanks to @cwbullet !

 

[Daddyisabar]

A rear eject, 3d printed brick s-house would be cool. Especially if it flew on a poopy clay motor.

 

[cwbullet]

A rear eject, 3d printed brick s-house would be cool. Especially if it flew on a poopy clay motor.

I will add that to my todo list. Currently, I am working on a Silver Comet file and a 4-inch V2.

 

[Daddyisabar]

I will add that to my todo list. Currently, I am working on a Silver Comet file and a 4-inch V2.

Potty humor rockets are the best with the cub scouts. Soooo funny! TP roll wadding. A real big one Dad can build with a built in liquid payload bay containing yellow Gatorade and mini Tootsie Rolls. A delicious treat awaits upon recovery! Gross out mom! Yeah!

 

[Nate G]

What a hoot. Thanks CW for the work and inspiration. I just retired and may have to get my printer up and running and try something like this.

I have seen some portajohns with a base below the inlaid panel sides. might attach fins to that feature and have it rear eject as a unit. How many outer layers and what percent infil did u use?

 

[lakeroadster]

What a hoot. Thanks CW for the work and inspiration. I just retired and may have to get my printer up and running and try something like this.

I have seen some portajohns with a base below the inlaid panel sides. might attach fins to that feature and have it rear eject as a unit. How many outer layers and what percent infil did u use?

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[CoolRockets]

Is there a 3D print file for this?

 

[cwbullet]

Is there a 3D print file for this?

I printed one for my son. I might be able to make it for a 24mm motor mount.

 

[Nate G]

found the other thread and posted files. thanks for sharing CW.