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1/12 Scale Little Joe I (was: Anyone care to ID this component?)

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James Duffy

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Here's a quick update on Little Joe progress. The past few weeks have focused on the transition section, the capsule shroud, and the capsule recovery and antenna sections. There's still a bit of paint work to be done on the transition, but it is essentially complete. (I was too lazy to put the fins on for this shot, sorry.)

I've completed some laser-cut jigs for assembling the escape tower uprights, then assembling them into a completed tower. Stay tuned for that...

James

IMG_1793.jpg
 

James Duffy

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Additional boilerplate Mercury capsules have been detailed and dry-fitted, and fit has been verified against one of the transition assemblies. Rain here in Texas has placed any paint work on hold, so the focus will now shift to assembly of the escape tower lattice assemblies.

IMG_1794.jpg

More later,
James
 

TheAviator

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The detail is incredible, James. Remind me, how many rivets are on this thing? :wink:
 

James Duffy

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motor choice?
Not quite sure yet, and I've been agonizing over that for several months. It will certainly be a cluster of two F impulse motors, but the specific motor is dependent on the final weight of the rocket. Ideally the all-up weight will be less than 36 ounces, allowing the use of a pair of Estes F15-4 BP motors. If it slides beyond 40 ounces I'll need to go with single-use composites, probably AT F42-4s with the blue propellant for ease of ignition. Current weight of the whole assembly less the escape tower, motor tubes, electronics, and recovery is 20.8 ounces, so I remain optimistic that I can keep things light and stick with the easy-to-ignite BP cluster.

The rocket will also use a cluster of four A10-PT motors, but those are for effect more than thrust.

James
 

TheAviator

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Not quite sure yet, and I've been agonizing over that for several months. It will certainly be a cluster of two F impulse motors, but the specific motor is dependent on the final weight of the rocket. Ideally the all-up weight will be less than 36 ounces, allowing the use of a pair of Estes F15-4 BP motors. If it slides beyond 40 ounces I'll need to go with single-use composites, probably AT F42-4s with the blue propellant for ease of ignition. Current weight of the whole assembly less the escape tower, motor tubes, electronics, and recovery is 20.8 ounces, so I remain optimistic that I can keep things light and stick with the easy-to-ignite BP cluster.

The rocket will also use a cluster of four A10-PT motors, but those are for effect more than thrust.

James
Will you be including a motor in the base of the BPC to simulate the escape tower firing?
 

James Duffy

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Will you be including a motor in the base of the BPC to simulate the escape tower firing?
Yes, there will be a B6-2 in the base of the boilerplate Mercury capsule ignited by a Perfectflite MiniTimer 4.

James
 

MaxQ

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Not quite sure yet, and I've been agonizing over that for several months. It will certainly be a cluster of two F impulse motors, but the specific motor is dependent on the final weight of the rocket. Ideally the all-up weight will be less than 36 ounces, allowing the use of a pair of Estes F15-4 BP motors. If it slides beyond 40 ounces I'll need to go with single-use composites, probably AT F42-4s with the blue propellant for ease of ignition. Current weight of the whole assembly less the escape tower, motor tubes, electronics, and recovery is 20.8 ounces, so I remain optimistic that I can keep things light and stick with the easy-to-ignite BP cluster.

The rocket will also use a cluster of four A10-PT motors, but those are for effect more than thrust.

James
Cool. Scale motor locations.

Looks like you have no central MMT so you obviously have the confidence needed in getting the cluster outboards ignited.

Total Respect.
 

James Duffy

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Assembly of the escape tower components has begun, and I thought that some of you might like to see the jigs used to facilitate this process. The towers are constructed from bits of styrene tubing, individually cut, fitted, and glued into place. The first step is to assemble the inverted "V" at the base of each tower upright. This jig was cut from two layers of 1/4"-thick plywood, and holds the two pieces of styrene in place until the adhesive dries. Once the glue has set a razor saw is passed through the upper and lower slots to trim the piece to exactly the right length.

IMG_1797.jpg

Each of the inverted V parts are then placed in a second jig to create the uprights for the tower. A small block of wood is inserted underneath the joint to provide the correct angle for the completed part. While not visible in this photo, the joint is augmented internally by a wire stiffener that connects the V to the upright and provides a bit of additional strength.

IMG_1798.jpg

Each of the three completed tower uprights are then placed in the tower assembly jig. This jig has two plates that have locating holes for the upper and lower points of each upright, and the plates are connected by a square styrene central post that holds each end in alignment. There is also a threaded rod running through the center of the jig holding everything together. Once the horizontal and diagonal pieces have been fitted, glued, and allowed to dry, the end plates can then be removed to allow the completed tower lattice to be removed. The jig can then be reassembled to allow another tower to be built.

IMG_1799.jpg

More later,
James
 
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JumpJet

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Love your jigs for making the tower components. I've been wanting to build an Russian N1 for some time now and seeing your jig has reignited my building goal of this model since those truss assemblies between the stages would be the hardest part of the build.


John Boren
 

James Duffy

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Two tower lattice assemblies have been completed and a third is in process, while parts are in process for a fourth. Once they are all complete they will be lined up and the best two will get tagged for service on completed models, while the laggards will be relegated to boilerplate and replacement duty.

IMG_1803.jpg

James
 

K'Tesh

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Two tower lattice assemblies have been completed and a third is in process, while parts are in process for a fourth. Once they are all complete they will be lined up and the best two will get tagged for service on completed models, while the laggards will be relegated to boilerplate and replacement duty.

View attachment 285474

James
Beautiful Work!

I can't be the only one who is wishing that you'd create a downloadable (3d printable?) template for these jigs. I'd love to see this adapted for the Saturn 1B, Saturn V, and Mercury kits that I have from Estes/Centuri (Read: I was very frustrated in my personal attempts to build them, thus they remain unfinished... for over 2 decades (and counting)).
 
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James Duffy

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A quick update to show some of the paint work currently underway on the boilerplate Mercury capsule components. After the orange/white roll pattern is in place the lower section of each capsule will be masked off and the upper section painted raw aluminum. That will be followed by the installation of the core tube (a section of BT-60), the recovery section will be added, and the hatch bolts and handle details will be attached.

IMG_1808.jpg

More later,
James
 

James Duffy

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Finished the paint work on the capsule components today, and got the urge to stack everything up for the first time. (The escape tower is still incomplete, obviously.) Total weight of the stack at this point is just below 20 ounces, so coming in under the 36 ounce mass budget for the ready-to-fly rocket should be attainable.

IMG_1813.jpg

The bolt details have been added to the capsules, with the hatch handle and decals yet to come.

IMG_1814.jpg

More later,
James
 

James Duffy

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Anyone care to see some more jigs in action? The antenna and recovery sections atop the boilerplate Mercury capsule each feature a series of 48 corrugations around their circumference. This would be pretty tough to freehand, so a pair of jigs were created and pressed into service to simplify the process. A few photos were snapped of the final antenna sections being prepped so that I could share the process here.

First, drawings of the jigs were whipped up in Adobe Illustrator, and the parts were cut from 1/4" plywood on the laser cutter. Here's what the antenna jig looks like assembled and ready to go. Note the notches on each side for locating the corrugation details:

IMG_1819.jpgIMG_1820.jpg

Next, the shroud for the antenna section was cut from .015" thick styrene, rolled into shape, and glued up using medium CA. A tab cut from .020" thick styrene was used to join the two ends of the shroud:

IMG_1815.jpgIMG_1816.jpgIMG_1817.jpgIMG_1818.jpg

Next, the rolled shroud is inserted into the assembly jig. Sections of .060" half-round styrene strip are inserted into place, cut, and glued into place using a mild solvent cement. The very first corrugation covers the outside seam on the shroud, eliminating the need to clean that up later. Once half of the corrugations are in place the assembly is removed from the jig, rotated 180 degrees, and the process continues on the other side of the shroud:

IMG_1822.jpgIMG_1823.jpgIMG_1824.jpgIMG_1825.jpg

More in the next post...
 
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James Duffy

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(Continued from the previous post)

Once the cement has had the opportunity to set the part is removed from the jig. The ragged ends of each corrugation strip are trimmed with a sharp #11 blade. Next, the upper and lower support rings (also laser cut) are glued into place using epoxy.

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After the epoxy has cured a sanding block is used to refine each end of the assembly, and we're done. At this point I couldn't resist the opportunity to dry fit the completed part with the capsule and tower assemblies.

IMG_1827.jpgIMG_1828.jpg

More later,
James
 
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James Duffy

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The current push is to finish up the escape towers in the next couple of weeks. Assembly of the tower lattices and antenna sections was documented in a few previous posts, and now we will paint those bits and assemble them into a complete escape tower. Paint work on the tower lattice is the first step. Take a look at this photo of the Little Joe 1A round, noting the contrasting bands of color on the tower uprights and cross members (you may need to download and zoom in to see the markings):

lj1a-4.jpg

We need to make an intelligent guess as to what these marks might be. Duct/duck/gaffer tape was already in wide use at this point (late '50s-early '60s), having been introduced a couple of decades earlier. It strikes me as highly likely that these marks are bits of duct tape attached to various points on the tower, so we're going to reproduce them with grey paint. The first step is to paint the entire lattice a medium-darkish grey. Next, the duct tape locations are masked with narrow bits of Tamiya masking tape.

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With the masking tape in place the tower is airbrushed with black paint.

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Next, the tape is removed to reveal the grey paint under the black, simulating the bits of duct tape.

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Finally, the orange antenna section, the black "coolie hat" blast deflector, the tower base, and the lattice are glued together. A section of BT-5 tuning aligns with holes located in the former rings for the recovery section, coolie hat, and tower base. Two plywood centering rings will allow the completed tower to fit into the core of the boilerplate Mercury capsule.

IMG_1842.jpgIMG_1843.jpg

More later,
James
 
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Pat_B

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James- do you have your own laser printer? The reason I ask is that some of your jig designs would take some tinkering around with the laser settings. I keep debating amongst myself as to whether or not to get a used laser or to continue using one I have access to. I was wondering if you were outsourcing the laser work, and if so, how easy it has been to fine tune the settings when using someone else's laser.
 

James Duffy

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James- do you have your own laser printer? The reason I ask is that some of your jig designs would take some tinkering around with the laser settings. I keep debating amongst myself as to whether or not to get a used laser or to continue using one I have access to. I was wondering if you were outsourcing the laser work, and if so, how easy it has been to fine tune the settings when using someone else's laser.
Pat,

I have access to a laser cutter through a place called Techshop, which is essentially a country club for nerds:

https://www.techshop.ws

You're right, many of the jig and part designs required multiple iterations to refine, adjusting both the Illustrator drawings used to drive the cutter and the laser settings for various materials. I could not imagine outsourcing a project of this magnitude to a third party due to the iterative process. At Techshop I can sit at the laser for several hours cutting parts, checking the fit, and adjusting the drawing until things come together just right.

Another comment on laser cutters: as flaky, poorly conceived, and inconsistent as the drivers supplied with the Western-sourced industrial laser cutters are, I cannot conceive of the horrors associated with using one of the low-buck Eastern products. You will always be better off with a used laser supported by a real manufacturer than a new one from one of the eBay vendors.

Hope this helps,
James
 

Pat_B

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Yeah, your experience seems similar to mine. When I saw your parts I realized they probably took numerous runs to get things correct.

I've always got my eye out for an older US brand of laser cutter. Been spending too much money on other things lately.
 

James Duffy

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The escape motors have been constructed, painted, and attached to the tower lattices. With that step completed the entire assembly can be stacked for the first time.

IMG_1880.jpg

Fully stacked the whole works stands 48.47" tall (that's a 12" ruler in front for scale). There are still some minor tasks yet to be completed:

*Nozzles for Sergeant, Recuit, escape, and tower jettison motors
*Marman clamps for the capsule/transition interface
*Base spider details
*Transition antennas

A boilerplate version of the rocket is also at this stage, and I hope to fly it within the next couple of weeks.

More later,
James
 

kcobbva

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WOW! Just WOW! amazing detail
 

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Pat,

...

Another comment on laser cutters: as flaky, poorly conceived, and inconsistent as the drivers supplied with the Western-sourced industrial laser cutters are, I cannot conceive of the horrors associated with using one of the low-buck Eastern products. You will always be better off with a used laser supported by a real manufacturer than a new one from one of the eBay vendors.

Hope this helps,
James
Anyone who wants to get effective use out of a Chinese laser cutter will toss the controller and software that comes with it and spend an extra couple of hundred to fit a smoothieboard controller and opensource LaserWeb
 
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