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ANTI-VIRUS Build Thread

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H. Craig Miller

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54mm Powered ANTI-VIRUS
01.00.Anti-Virus..jpg
PREFACE

With the onset of COVID-19 and its fallout, the interrupting supply chains and size limiting or outright cancellation of launches and other rocketry events, how can its spread be stopped? Wearing masks, social distancing, vaccines? No... with an injection... with the... ANTI-VIRUS.

INSPIRATION

And, how are vaccines and the like administered... injected in a syringe.
01.01.Anti-Virus.Syringe.gif
And, what’s the most distinctive (and memorable) part of a syringe... it’s needle. So too must be the nosecone of this design be.

DESIGN

In formulating the design, the syringe was divided into three corresponding rocket sections, the nosecone, the body, and the fin section. And, in order to maintain a reasonable resemblance to the syringe finger flanges, the fins would need to be different, they would need to be grid fins.

With the design reasonably formulated in my mind, I went to work with OpenRocket.

NOSECONE

The nosecone corresponds to several parts of the syringe: the needle, needle hub, and the syringe tip and barrel top.
01.02.Anti-Virus.Nosecone.gif
A significant concern in the development of the nosecone was the susceptibility of the needle to damage from hard landings. To allow a damaged needle to be easily and readily replaced, the nosecone was divided into three subsections, the needle, needle hub, and syringe tip and barrel top.
01.03.Anti-Virus.Needle.gif

Needle

01.04.Anti-Virus.Needle Hub.gif

Needle Hub
01.05.Anti-Virus.Syringe Tip.gif

Syringe Tip / Barrel Top
But how to actually construct each subsection... and engineer the components to lock together... that came next.

01.06.Anti-Virus.Needle.Dwg.jpg

01.07.Anti-Virus.Nosecone.Dwg.jpg
The eyebolt in the Syringe Tip/Barrel Top Section screws into the T-nut in the aft end of the needle, squeezing the Needle Hub Section against the needle centering stop, mechanically locking the three sections together. The .ork file for the nosecone is attached.

[Construction coming soon...]
 

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Tim51

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Cool! Is there a way to model grid fins in Open Rocket ?
Good luck with the build. Hopefully the RSO isn't an anti-vaxxer...😊
 

neil_w

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Woohoo, been looking forward to this.
Version 15.03 will not model grid fins, but... the new version will.
Clarification: there is no "grid fin" object in the new OR; Craig built those grid fins out of a zillion pods and individual fins. I'm not really convinced it will do so accurately, but it should be giving at least a vague approximation.

If nothing else I salute your perseverance! :)
 

dhbarr

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Woohoo, been looking forward to this.

Clarification: there is no "grid fin" object in the new OR; Craig built those grid fins out of a zillion pods and individual fins. I'm not really convinced it will do so accurately, but it should be giving at least a vague approximation.

If nothing else I salute your perseverance! :)
A reasonable approximation could be possible with appropriately stacked tubefins, but I'm not invested.
 

cwbullet

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I love the design. Do you plan to do 3d file or an orK file uploaded?
 

H. Craig Miller

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I love the design. Do you plan to do 3d file or an orK file uploaded?
A version 15.03 .ork file for each section will be uploaded with the presentation of that section, except for the grid fins. But, the full design utilizes features of the new version of OpenRocket not available in version 15.03. The full .ork will be uploaded when the new version of OpenRocket is released.
 
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H. Craig Miller

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NEEDLE

With the stresses the nosecone and needle shaft would likely be exposed to while descending tip first into a less than hospitable landing zone (a dry lake bed can be extremely hard), fiberglass was selected for the nosecone itself, with a carbon fiber needle shaft, and Blue Tube 2.0 for the needle hub and syringe tip/barrel top; Blue Tube 2.0 is much less expensive and has much greater flexibility than fiberglass tubing on a hard landing(one of the down sides will come later).

A Semroc conical balsa nosecone [BT-20 2.3" SEM-BNC-20SU] was purchased from eRockets and a 20mm OD X 18mm ID X 500MM roll wrapped carbon fiber tube was purchased on eBay. With minimal sanding, the two fit nicely together.

Nosecone.01.Balsa.gif
But, that balsa nosecone, and the pointed tip was never going to survive even a soft landing. So, it was blunted, molded, cast in fiberglass, and duplicated as a friction fit disposable component.

Nosecone.03.Cast.gif
It’s amazing how detailed silicone mold and fiberglass can be when you have a vacuum pump that can literally boil water at room temperature.

The needle centering stop (centering ring) was cut from 1/4" aircraft plywood to fit the inside diameter of 29mm Blue Tube 2.0, and epoxied in place.

Needle Shaft.Ring.gif
The outside diameter of a 1/4" - 20 T-nut was then ground down to fit the 18mm inside diameter of the needle shaft and epoxied in place with JB Weld. The carbon fiber tube was washed with soap and water, sanded in the appropriate places, and cleaned with acetone and then alcohol before the epoxy was applied.

Needle Shaft.T-Nut.gif
The final steps were to sand and then paint the nosecone and needle shaft with Dupli-Color Automotive Metallic Series Chrome High Gloss, insert the nosecone into the needle shaft, and put two teardrop shaped vinyl decals on the nosecone (180 degrees apart) to simulate the needle opening.

Needle.Complete.gif
Not the cleanest paint job past the ring, but that part is inside the needle hub and syringe tip anyway. And, the picture does not do the chrome justice.

On to the needle hub.

[More construction coming soon...]
 
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o1d_dude

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Craig is multi-element fin fan so the grid fins are right in his wheelhouse.

I recall one of his birds hanging from a local hobby shop ceiling that was a ring fin with internal fin support elements in the geometric shape of a Celtic symbol. Remember that one, Craig?

As a toob dood myself I was impressed with the project and I have a bit of Scottish in my family tree so there’s that.
 

Nytrunner

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Very creative!

(I iust hope those aluminum fly swatters dont land on a car or a cow on the way down)
 

Idunno

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Can someone explain to me a bit of the theory on how grid fins work? How much extra cross sectioal area are you getting with a bunch of tiny fins in way of each other? Intuitively it seems like the CP would be pretty far forward. Are the grids just for show? Does the area stack somehow?
 

David_Stack

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Can someone explain to me a bit of the theory on how grid fins work? How much extra cross sectioal area are you getting with a bunch of tiny fins in way of each other? Intuitively it seems like the CP would be pretty far forward. Are the grids just for show? Does the area stack somehow?
Not an aeronautical engineer, but I would think much of the stabilizing effect on the airframe from grid fins is a result of the drag that they impart...
 

H. Craig Miller

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NEEDLE HUB – SYRINGE TIP / BARREL TOP

With all of the varying tube and centering rings sizes, I decided to cut the parts for the needle hub and the syringe tip and barrel top at the same time. The centering rings were cut with drill press mounted hole cutter, one for inside diameters and one for outside diameters, both with cobalt steel cutting tips (razor sharp).

This is an example of one of the rings:
0002.Needle Hub.01.Ring.gif
After the tubes and rings were cut to size, when dry fitting the parts, I realized that the syringe tip and barrel top would need to be constructed first so that the needle hub tubes would be properly aligned (straight instead of potentially crooked).

The centering ring for the syringe barrel top was drilled for 1/4" - 20 T-nuts, and the T-nuts were glued in place with JB Weld. The end of the syringe tip tube (long coupler tube) was then glued inside that centering ring, and the syringe tip spacer (body tube) was glued to the bottom of that, abutting the centering ring, all with epoxy. That is the first of three parts of the syringe tip and barrel top.
0002.Needle Hub.02.Syringe Top.gif
Because I wasn’t thinking about doing a build thread when I began, I don’t have pictures of each step, but I think I have enough to follow this part. To begin the syringe barrel construction, T-nuts (with JB Weld) were pressed into a centering ring identical to the one above. And, the centering ring was then epoxied into a short 4" body tube, and the coupler tube was epoxied into the other end. After that, a body tube spacer was epoxied to the top of the ring using the syringe tip as a guide (the syringe tip is NOT glued to the syringe barrel, it is removable).
0003.Needle Hub.02.Syringe Top.gif
Next, the needle retention bulkhead was constructed with a 4" bulkhead and smaller centering ring. (See, the .ork file for dimensions) As can be seen, the 1/4" - 20 eyebolt passes through the bulkhead and screws into the end of the carbon fiber needle. The three bolts that bass through the bulkhead screw into the centering ring T-nuts shown above, locking the syringe tip in place. This function will be described in more detail later.
0003.Needle Retention.02.Bulkhead.gif
With the syringe tip nearly complete, the needle hub is next. This subsection is composed of three different sizes of body tube, with inner and outer centering rings.
0002.Needle Hub.01.Syringe Top.gif
The, the three pieces were nested inside each other, bottom to top, bottom to top. This is where the three subsections had to be assembled for gluing so that the pieces of the needle hub would be properly aligned.
0002.Needle.Pre-Micro.gif
At this point, you can see that the transitions are square edged. All of the nosecone transitions are made from 30 minute epoxy and micro balloons mixed to the consistency of thick toothpaste, so that there was no slump when pulled up in the mixing cup. Blades were made from basswood of different slopes to draw the mixture around the tubes. This was repeated no less than three times for each transition, until there were no visible defects.
0002.Needle.01.Post-Micro.gif
The three subsections were disassembled and the tube spirals filled using Elmer’s All-Purpose Repair System (a two-part epoxy putty). After that, the Blue Tube 2.0 and plywood elements were sealed with Old Master’s Sanding Sealer (oil based), sanded is steps to 320 grit, then primed. The needle was then painted with Dupli-Color chrome, the needle hub with blue, and the syringe top and barrel with white.
0002.Needle.Post-Micro.gif


0001.02.00.Anti-Virus.Construction.Nosecone.Complete.gif
So, screw the three subsections together and what do you get? The completed ANTI-VIRUS nosecone. Oh, by the way, the blue tape on the syringe tip acts as a spacer so the white paint doesn’t get scratched when you screw the subsections together, it is completely concealed inside the needle hub.
0001.02.Anti-Virus.Construction.Nosecone.Complete.gif
Wow, that took some engineering and construction time.

So, how close did I come to the original OpenRocket design?
 
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JoePfeiffer

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Wow, this is just an awesome project.

On the grid fins, just downloaded that paper. Thanks! It looks interesting. I expect a real analysis of the fins vs. what OR tells you will likely be pretty different.... without looking at your design, my guess (and I do mean little more than totally blind guess) is OR will be most accurate if you model the fins using a bunch of 0-diameter pods, each with four fins, and the fins from adjacent pods butting up against each other.
 
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H. Craig Miller

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OR will be most accurate if you model the fins using a bunch of 0-diameter pods, each with four fins, and the fins from adjacent pods butting up against each other.
Thanks for the suggestion... that is basically the same approach I used, but with fewer pods and crossing fins. I will create a version using your method as well and test both versions against actual collected data. Thanks again.
 

JoePfeiffer

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Thanks for the suggestion... that is basically the same approach I used, but with fewer pods and crossing fins. I will create a version using your method as well and test both versions against actual collected data. Thanks again.
I'll be really curious to see your results!
 

H. Craig Miller

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MAIN BODY

I unpacked and inspected the 48" long 4" diameter Blue Tube 2.0 main body tube and its coupler (for the AV Bay), and everything looked great. But, when I attempted to slide the coupler through the body tube, it got stuck about a third the way down... really stuck. Eventually, after carefully applying pressure from the opposite direction, I was able to extract the coupler without damage.

Concerned, I contacted David Ebersole at Always Ready Rocketry and discussed the issue with him. Even though Dave was willing to do whatever was necessary to remedy my concerns, in light of the high overall cost of the build, and the need for exacting body diameter consistency for the full body wrap decal (when applied and over time, with changing temperatures and humilities), I decided to switch to fiberglass for the main air frame and AV Bay. After comparing inner and outer fiberglass tubing diameters from several vendors, I chose Wildman Rocketry and placed my order.

The characteristics of Blue Tube 2.0 were still more desirable than fiberglass for the Grid Fin Section, however.

So, the Grid Fin Section will be the next part of the build... coming soon.
 
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H. Craig Miller

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GRID FIN SECTION

The Grid Fin Section is actually a sleeve that slides over the motor tube and bolts to the booster airframe. The OpenRocket 15.03 ork file for this section is attached, but is not capable of displaying the grid fins.
OpenRocket.15.03.02.Grid Fin Section.gif
So that you can see what the end result is intended to look like, I have also included screen shots from the version of OpenRocket under development.
OpenRocket.20.11.02.Grid Fin Section.gif
In this version of OpenRocket, you can also simply turn the other stages off (without deleting all of the preceding stages) if you want to see one stage by itself; I divided the design into stages only so that the build could be presented more clearly.
OpenRocket.20.11.02.Grid Fin Section.02.gif
So, that’s the build objective for the Grid Fin Section construction.

Construction pictures coming soon...
 

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Tobor

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@ H. Craig Miller
Thank you for sharing your Ork files and for the detailed build thread. Very inspiring!
 

H. Craig Miller

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SYRINGE BOTTOM / PLUNGER

Because of uniqueness of the grid fin design, and considering that the base of the plunger would likely take the full brunt of the descent impact, followed by a folding force on the grid fins themselves, I decided that it would be best if both the individual grid fins and the syringe bottom and plunger were readily replaceable (not disposable, just replaceable). So, this section is a sleeve that slides over the motor tube and bolts to the booster airframe.

To increase the plunger bottom impact resistance, the plunger base is made of two 1/4" thick aircraft plywood centering rings. But, where the weight of the plunger base will significantly affect the position of the CG, the plunger base was made hollow, with an outer skin to be overlaid on eight triangular supports.
04.Plunger.Base Supports.Assembly.gif
The upper portion, the syringe bottom, was then laid out and assembled.
07.Syringe Bottom.Assembly.gif
The upper centering ring is the platform against which the grid fins will be mounted, after openings are cut through the side of the airframe and coupler.
08.Grid Fin Platform.Drw.gif
Shaping tools were then made from 1/16" wood to shape the upper and lower transition areas, essentially to scape of the excess epoxy-micro balloon filler. With the shaping tools in hand, plates were glued in place on the plunger, and the top and bottom transitions were molded.
12.Syringe Bottom-Plunger.Transitions.gif
Sounds fairly straight forward, but each transition is comprised of no less than 6 coats of epoxy and micro balloons, with the consistency thinning each time, until a smooth finish was achieved. By the way, in the center picture, the tape just below the syringe bottom transition is to keep the transition edge sharp and clean, the lower tape is for spacing to keep the scraper parallel to the tube (the same was done when shaping the plunger transition).

And, guess what arrived...
13.Grid.gif
...I’ll bet you can guess what comes next.

More coming soon...
 
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