That's awesome. If you send your real name in email I will credit you of course. info@usrockets.com.

So I guess the 12" Trident pattern might be a bit bigger?

Epoxied the second ducted tube. No new pix - basically the same look as the last one.

While waiting, I decided to paper the fins. My "press system" is not big enough for all 3 - I can't do more than 2 at a time. Did the first 2 last night. Last one is drying tonight.

First level trim and second level.

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What kind of paper?

I use plain copy paper with Elmer's Glue all.
Some glue on the paper - squeegee to a thin film - apply paper to fin - use squeegee on paper to "burnish" - then place under weights and allow to dry overnight.
I have 2 flat boards that I protect with wax paper and put a couple of cases of water on as weights. The size of my boards is what limited me to only 2 fins at a time

Once glued on to the tubes I will also seal the edges with thin CA

Here is my paper press setup.....

I tried placing the cone on the Motor pod - it was a little difficult with two of the pod tubes in place. I decided to permanently install the motor mount and nose cone before I installed the third, last, UN-ducted pod.

First drilled and installed wood insert into the target block

I applied epoxy in the tube and on the leading edges of the internal rings, slid the mount into place, re-installed the rail button screw to ensure the holes were aligned, and then hung it by the jigs so the epoxy would flow downhill.

After waiting a few hours, I turned the rocket over and applies epoxy to the top and installed the nose cone. Then I applied some Elmer's F&F to the nose cone/body joint

Final step for the day - I won't say I rounded the fins but I did break the edges of the "chunky" 1/4" thick balsa fins.

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Sorry for the long silence - a multitude of issues

Jerry kindly sent me a kit that will allow me to make the rocket dual deploy. But I've already ducted two of the tubes. I need to make a decision....

On the one hand, the ducted ejection is what a Trident is all about, right?
But.....let's do some math.

What is the ejection charge going to do to the motor pod? For the first look, I'm going to ignore the ports.
If I consider the diameter of the tube (2.25) and the length between the top CR for the actual motor tube and the nose cone (4.5), and the 1.2g of ejection charge ...... the calculations show there will be about 130psi in the motor pod.... that seems high - this is only cardboard!

But the pressure will try to vent through the ports. Just how big are they? The width (0.125) and length (2.5) for two ports is a whopping 0.625 sq in. This is 2% of the surface area of the tube, and about 15% of the surface area of the nose cone.. Not a lot of open space. Unlike a plain tube where the ejection charge has the full diameter to push the cone off here the pressure just has the narrow slots to pass through. I get the feeling the motor pod is going to rapidly vent to the atmosphere (blow up) instead of pushing a chute out of the passenger compartment.

What if I removed the supplied powder and replace it with something less. Then I am back into the total volume of the motor pod, side pods, and passenger pod. Anything less may get too wimpy to actually get the chute to deploy.

It appears that the safest bet is going to make use of the dual deploy.

Comments/thoughts? Please! Thanks

The stock config is 3 tubes ejection bypass. The dual deploy is a payload tube, a PP-22-C plate that fits inside the coupler, a screw eye and a screw eye anchor. That is the drogue deploy section below that with plenty of space. The payload tube is only 5" long less 1/2 the 2" coupler and <1" nose cone shoulder. The top of the coupler is hollow so that space can be used for the electronics and charge and the entire 4" x 2.25" space for the main. The kit comes with a 30" chute IIRC. Our 16" with "slide ring"-tm is an excellent drogue despite being plastic. Adding a 15% spill hole would almost eliminate chute rocking with almost no drag penalty.

Tech Jerry

The v0.2 instructions state:

1. Ejection ducting cutting. The lower ducts cut into the outside of the BT-22-9 tube should be about 1” long and about ¾” wide. Mark the tube for 3 fins to establish placement of the ducts. The top of the duct should be at the base of the nose cone or close to it or about 1” from the top of the BT-22-9 lower main airframe assembly.

So I don't know where you get 1/8 x 2.5" unless it is some massive typo somewhere.

Jerry

Attached Files

Trident Instructions 2-19.pd.pdf (63.3 KB, 15 views)

Here is the corrections page for the v0.2 instructions which could be considered v0.3. The next version will be 1.0 and will ship with the released kit post beta. I still have one remaining beta kit for $80+$12 with the added parts and you have the v0.3 instructions and thread now to make assembly without v1.0 instructions practical.

Jerry

Attached Files

Trident Instructions 2-19.2.pd.pdf (64.6 KB, 19 views)

Mine must have been one of the earlier beta kits. My "instructions" consisted of a parts list, upscaled fin template, and a copy of the Estes Trident instructions. I have been scaling everything off the Estes instructions myself using the 2.25 scale factor. And as I previously stated, this caused some confusion as the parts actually ranged from 1.55x to 3.28x. Some of those I made closer to scale by substitution and modifications to the cones and pod tubes.

In terms of the 3/4" wide ducts - that seems large. No matter the diameter of the tubes, there are still two tubes that fit tangentially. That is why I stayed with the Estes 3/32", but then enlarged to 1/8".
Since the pod tubes are about 1.223 in OD, their circumference is 3.84". A 0.75" wide duct is almost 20% of the total circumference of the tube. There will be a large gap (a bit less than 0.2") that will need to be sealed while not getting glue into the slots themselves. I did a very quick sketch below. Realistically, the gap will be a slight bit smaller as the 0.75 line I drew is straight and not following the curve of the tube....

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