Tri-Trident - A Very Scratch Build

[les]

I actually started this before the NewWay Quadradent (Quadradent), but since I was attempting to make my own tubes I wanted to make some progress before starting a thread. And again, I will have a "stop work" for 3 weeks effective this Saturday, so it will not be complete by then.

My concept is to cut Matboard and make triangular tubes. I purchased the board and ready for cutting


I started off cutting a length of 2x4 with slots at 30 degrees to use as a jig. You will notice one side is cut a little deeper. The cutout piece is saved for the jig operation.


The concept (this is a dry run) is place a strip of mat board in the "short" side.


Then apply glue on the edge of the second piece and place on other side


To make the tube, a length of wax paper is put into the jig. Side one is installed.
The cutout piece from the jig is also covered with wax paper. I used tape on the ends to hold it on.



Add a bead of glue to the second piece. Place in jig against the first piece. Place the cutout piece on and clamp. Repeat until all three corners are glued.

 

[les]

NOTE - while making these tubes made me wish I had Rick's laser cutter. His tubes are so much better!

Some of the tubes needed repair.


Since my tubes are just butt joints, I wanted to strengthen them. I cut some card stock and bonded it to matboard. I did this as three pieces so I didn't have to worry about the bends lining up. Blue is the matboard, Red is the card stock.



And the real final process.

 

[les]

My one big concern. The three pieces of matboard just have the butt joints and only one layer of card stock in the corners as reinforcement. Suggestions????

Here are the tubes dry fitted (well, rubber banded) together.
Not all the tubes have the card stock applied yet. Meanwhile - how to make the nose cones???
I'm thinking starting with card stock and folding them up similar to the Quadradent

 

[les]

I need to make cones for everything. I made a template for the top. small tube cones.
My first attempt is shown sitting on the template

 

[neil_w]

Neat project. I like the construction of the tubes. Are they strong enough? I have no idea. You could do another layer of cardstock, or even glass them to give extra strength if desired. Ultimately, I would guess that the only way to really know if they're strong enough is.... well, you know.

Are you going to pre-paint the surfaces of the side of the skinny tubes that face inward? Seems like it'll be very difficult to get paint in there post-assembly.

One other small comment: the relative sizes of the skinny and larger tubes is such that there's not a lot of airspace in the middle... might be a bit hard to see the see-through-ness of it all. See what it looks like with all three skinny tubes dry-fitted and be sure you're happy with the proportions. It might be totally fine as-is, just seems worth checking before the glue starts flowing.

 

[les]

The tubes are sized so the expected BT-5, -20, and -50 would fit in them. But I agree, as a triangle they seem stubbier....
My BT-20 size motor tube just barely fits inside the the BT-50 tube

 

[les]

One other small comment: the relative sizes of the skinny and larger tubes is such that there's not a lot of airspace in the middle... might be a bit hard to see the see-through-ness of it all.

Yes - there is a problem. I made a rough internal cone for the drive section.

Up close, it is tight and difficult to see.


From a distance it becomes "what nose cone"


Looking at the tail end, you can see how the motor tube just fits the drive tube.


Bottom line, I am going to redo the main body tubes in the BT60 size vs BT50 to see how they look. I may stretch the length a smidge to compensate for the new width.
I can't shrink the BT5. I had enough issues with their small size....
I may make another jig to speed up the tube building process.

 

[ljwilley]

awesome!!

 

[les]

Made a quick test case - things are just held together with tape and rubber bands



A bit better. Rocket will appear "short" so slightly Goonified....

How an actual Trident looks....

 

[les]

Ya know - to really look right it should be built this way,
But I don't know how to do it and have the vents.....

 

[BABAR]

Made a quick test case - things are just held together with tape and rubber bands

View attachment 590738 View attachment 590741

A bit better. Rocket will appear "short" so slightly Goonified....

How an actual Trident looks....
View attachment 590744

https://www.rocketreviews.com/excelsior-rocketry---gooneydent.html

 

[les]

Yep - used to have one. Until the Rocket Gods decided to keep it
Or perhaps it was that too large chute and thermal that had it drift far, far away.......

 

[les]

CRAZY IDEA........
Although I'm sure it will a bit difficult to achieve

A way to keep the existing tubes and visibility...
Basically, mount the tubes point to point. Cut a slot, and use some plywood (not a popsicle stick) to seal the vent
Think the rest of the joint (where the "joiner" isn't) will need to be reinforced....

 

[neil_w]

I think that will look very good, if you can secure the vents. Is there a way you can dry-fit it to gauge the appearance?

I’m not sure about the venting question at the moment.

 

[kuririn]

Suggestion: Holes instead of a slots.
Short segments of launch lugs for gas conduits between tubes.
For the triangular tubes, instead of butt jointing three flat pieces per tube why not cut one piece of matboard then score the lines of each fold and make the tubes?
One long butt joint instead of three. Paper glue strip on single butt joint for reinforcement.
So score, dry fold, attach glue tab to one side of matboard, unfold and apply glue on each inner fold, refold and apply glue to the other side of the paper glue strip and the single butt joint.
Be aware that the mat board probably has a grain, align the grain with the length of the tube.
Should be a cleaner exterior, stronger joints since it's scored and reinforced with glue instead of cut all the way through, and easier to assemble.
Also you can cut triangular bulkheads to keep the pressure between the inlet and outlet ducts. You don't want to pressurize the small nose cones unnecessarily.
Try browsing the cardstock forum for techniques like these.

 

[BABAR]

Ya know - to really look right it should be built this way,
But I don't know how to do it and have the vents.....

View attachment 590745

Instead of


Does this work cosmetically?

 

[BABAR]

You could to the same thing for the square version.

you need to customize the inside cones anyway, that shouldn’t be that hard.

 

[neil_w]

Does this work cosmetically?
View attachment 591072

I like that idea, although I'd be a bit nervous about joining the triangles at the points like that.

How about positioning them exactly point to point, but joining them with embedded rectangular blocks like this:



Yeah they'd be visible, but I feel like that would provide fairly secure attachment and venting.

 

[neil_w]

The whole assembly would look something like this:

 

[les]

Isn't this what I showed in post 13?

 

[les]

This time used foam board for all three. Nose cone easily visible.

 

[neil_w]

Isn't this what I showed in post 13?

View attachment 591090

Yes, probably... but I didn't fully grasp what you had written then, and it sort of went in one eye and out the other.

So, yeah, 1 vote for post 13.

 

[BABAR]

Isn't this what I showed in post 13?

View attachment 591090

I posted mine without seeing yours, my bad.

there is a sub but potentially significant difference. On mine, the angles are “sunken”, the portion “creates” the vent, which cannot be done with simple point to point contact. while I came up with my idea independently, clearly you had the idea first.

I think the combo of your idea, my “sinking” or “merging” the triangles, and @neil_w ‘s idea of a bracket may be complementary. Yours “opens up” the space to emphasize the open architecture, mine provides the duct connection, and Neil provides ideal alignment and more strength.

Key is, it’s YOUR rocket, so you are the final arbiter!

 

[les]

Meanwhile, While I should be able to access TRF, I will not have access to the rockets for 3 weeks.

But here is a beauty shot of the the three 'dents to date.

 

[les]

I'm BACK!
An 11 day cruise of the inner banks in Alaska, followed by nearly a week in Seattle. Saw whales, eagles, bears, mountain goats, glaciers. Even caught a pix of some minor calving. More luck, but also related to my pix of rocket launches! Did go to the Museum of Flight in Seattle for a "pilgrimage" to the rocket model section (toured the rest of the museum as well).

Now to re-read this thread and figure out where I stopped and what's next........

 

[les]

Continued work on the tubes. While drying, I started working the "motor "rings""
I decided to use the matboard, cut into strips and glued up.

 

[les]

WRT post 18. I'm concerned with trying to make the wood blocks, as they need to be fairly small.
Instead, I'm thinking an external vertical piece, even matboard, and a goop of rocketpoxy. The poxy will adhere to the tubes and the vertical piece. To keep the poxy from filling the slot, I'm going with the idea of some cut launch lugs pre-glued in as vent "pipes"
In the diagram below,
the blue is the 1/8" lugs,
the green is the "vertical piece". This would have its edge sanded to line up instead of the "box" as shown - got lazy drawing the pix.
The reddish in between is the poxy



Thoughts????

 

[BABAR]

WRT post 18. I'm concerned with trying to make the wood blocks, as they need to be fairly small.
Instead, I'm thinking an external vertical piece, even matboard, and a goop of rocketpoxy. The poxy will adhere to the tubes and the vertical piece. To keep the poxy from filling the slot, I'm going with the idea of some cut launch lugs pre-glued in as vent "pipes"
In the diagram below,
the blue is the 1/8" lugs,
the green is the "vertical piece". This would have its edge sanded to line up instead of the "box" as shown - got lazy drawing the pix.
The reddish in between is the poxy

View attachment 595404

Thoughts????

Never built a ‘Dent or a diverting ducting eject system.

I do wonder about the heat durability of the tail end ducts/ports. Those gases start out really hot, and when you “force them” through narrow channels that is a lot of concentrated heat.

The rest of this post provides more detail on my experience, feel free to skip unless really curious.


I have built a number of “chimney” ducted birds, where a DIRECT tube routes the ejection charge up through an extended length motor mount with a forward centering ring. Most commonly used with “wide bodies” to reduce the volume the ejection charge needs to pressurize.

When I started messing with pop pod gliders with rear ejection of the motor and a long tube that held forward nose weight, I started DOWNSIZING the central duct, for example you can greatly increase the packing space for rear eject (glider or otherwise) with a BT-50 model with a long BT-20 motor mount and pod or chimney by downsizing to BT-5. There is a (relatively cheap) price, the narrowed tube just forward of the motor gets far more toasty (same amount of flame concentrated in a smaller volume. Easy solution was to put rolled up aluminum can inside as a liner for the first three inches of tube.

 

[les]

When I was young, I built the original trident
Now as a BAR, I built the Semroc clone, an upscale from Hawks Hobby, and a super upscale from US Rockets. I also built the Goonydent from Excelsior.

And now the Tri-trident and the Quad-dent.

I have not had issues with burn through, but then again most of my rockets have less than 5 flights on them.....

One thing - the hot gasses first hit the bottom of the nosecone of the lower section, and then have to move through the vents. So there is a pseudo-baffle action there.

 

[les]

Added a corner layer inside the tube which you can barely see in the top portion



Started making the "pan pipes" using 1/8" launch lugs. I wonder if the Angry Launch Lug would approve (and am I dating myself)? I made up some extra partial test pieces. Marked and cut notches.