Can we save this Estes Pershing 1A?

I've made the 3D files for the nose cone if someone wants to give a 3D print try.

How much weight goes in the nose of this thing? The fin area has always looked grossly inadequate to me, seems like it depends on a really heavy nose.

I know you mentioned it's 5+ oz with the nose installed; how much of that is the added clay (or whatever)?

Leo said:

I've made the 3D files for the nose cone if someone wants to give a 3D print try.
View attachment 373350

Click to expand...

Leo, are the files available on Thingiverse?

I'd like to have the dimensions of the other parts first and then put everything together on Thingiverse.
I also want to print the nose cone to make sure all fits before publishing the all the parts.

Leo said:

I'd like to have the dimensions of the other parts first and then put everything together on Thingiverse.
I also want to print the nose cone to make sure all fits before publishing the all the parts.

Click to expand...

When ready please let us know, and Thank you.

neil_w said:

How much weight goes in the nose of this thing? The fin area has always looked grossly inadequate to me, seems like it depends on a really heavy nose.

I know you mentioned it's 5+ oz with the nose installed; how much of that is the added clay (or whatever)?

Click to expand...

I wish I knew exactly how much nose weight was installed in the nose cone. It was already there when I received the partially-built kit.

Perhaps one of the Estes historians here could let us know how much nose weight clay was provided with the original kit?

James

Needing dimensions for the Pershing is solved. I came across this thread with the data: https://www.rocketryforum.com/threads/scratch-built-5-25-pershing-1a-built-with-foam.120203/

I forgot I had posted that in my thread, keep in mind those drawings may not match the kit, the maxi kit fins may be slightly oversized, i dont remember.

Good point! I'll keep that in mind. I am printing the nose cone right now. I'll open a new thread as not to hijack this one.

Here are the Estes instructions . . .

Dave F.

The rest . . .

Dave F.

It's been a few days since any updates were posted, so here's a quick update...

To make masking and the application of the markings simpler, the airframe tube will be primed and painted before the fins and details are added. The first step in the process, priming, is already underway using Rustoleum grey auto primer.

Additionally, the nose cone has been cleaned up and sanded up to 1200 grit. It will also get a couple of primer coats.

As soon as the laser-cut fin parts arrive we'll get to work on assembly, sanding, filling, and priming.

James

The laser-cut bits arrived today, so we can get to work on the fins and detail parts.



Here's what the sheet for the fin mount pad parts look like:



Assembly of each fin mount pad is pretty simple and quick using medium CA glue.



There is a small gap between parts at the forward end of the assembly. We can fill that in with a small sliver of balsa scrap.



Because CA was used to put this assembly together we'll want to sand the edges immediately.



The next task is to refine the shape of the side that will interface with the airframe tube. To do that, we'll tape a large square of 320 grit sandpaper to a scrap section of BT-101 airframe tube. Each fin mount pad assembly can then be sanded against the sandpaper, yielding the appropriate shape on the back side of the assembly.



We now have six fin mount pads ready for filling, priming, and painting.


More later,
James

Time to start putting the fins together. We'll start with the aft fins, which are triangular in shape. A 1/16"-thick plywood core will be laminated with 1/16"-thick balsa skins on each side. The balsa is attached in two separate triangular sections. When the fins are later sanded into their faceted shape, the joint between the two balsa bits on each side will serve as the "high point." If you've ever built the new BT-60 Honest John kit from Estes, you'll immediately recognize the technique. I freely admit that I stole the idea from that kit.





The forward wedge fins are built up from a plywood structure, over which a balsa skin will be attached.





The balsa skins will get attached sometime tomorrow.

If you've read the old Pershing instructions, you've seen reference to a part called a "charge retainer" Rather than use the fiber bits supplied with the kit, a replacement part will be laminated from two 1/16" laser-cut plywood parts.



I promise that the part is there underneath all of the clamps.

More later,
James

A couple of quick updates on the fins. The aft fins are ready to be sanded into the diamond shape after having their balsa facings attached. This will be a miserable job, and I will probably end up with a sinus infection from the balsa dust. I'm willing to suffer for my art, though.



The forward fins have also had their balsa facings attached, and sanding is already complete as the wedge shape here is much simpler. If I were to do the forward fins again I would use 1/32"-thick balsa instead of 1/16"-thick stock.



More later,
James

The two long cable raceway parts have been cut from 3/16"-thick balsa stock and sanded to shape. If I were to do this project over again,I would have created a built-up replacement for these components and laser cut the parts. If another Pershing 1A kit ever comes into my life I'll make that change.

All of the wood parts for the model are now ready to be finished. From top to bottom, they are:

• three forward wedge fins
• forward fin mount pads
• aft fin mount pads
• three aft triangular fins
• short cable raceway
• long cable raceway
• charge retainer

The parts are all painted with a diluted mixture consisting of a squeeze of Elmer's carpenter's wood filler and a few drops of water, painted on with a cheap 1" brush. Here's what they look like all slathered up and gooey.



Tomorrow will be a busy sanding day, methinks.

More later,
James

James, could you please measure dimensions "a" and "b" on your Estes kit.

Thanks.

Leo said:

James, could you please measure dimensions "a" and "b" on your Estes kit.

Click to expand...

Sorry, I've been distracted by another project and just saw this message.

Dimension A is 55mm, dimension B is 54mm

Hope this helps,
James

P.S. as a general update on the Pershing project, the dry transfers have been ordered and should be here in about a week.

Thanks James.

If I got the scaling right then it looks like Estes made larger fins for it's kit.

Leo said:

Thanks James.

If I got the scaling right then it looks like Estes made larger fins for it's kit.

Click to expand...

That is very likely and common for Estes versions of real rockets and missles, the fins if accurate to scale would make the models difficult to get stable, by increasing the fin sizes a bit its easier to make that happen.

James Duffy said:

The nosecone on this model is very long, ~19.5" of the total 41" on the rocket! Adding mass at the shoulder would place it in the wrong location.

James

Click to expand...

When I rebuilt an old Pershing, I lengthened the shoulder with a piece of BT, and a small epoxy fillet to the NC. Not sure how much weight it added, but it does make the NC much more secure. Rebuilt weight was a bit over a pound, so I fly it on E28/F24/F35 motors.

Any progress on the build?

Leo said:

Any progress on the build?

Click to expand...

Yep! I've stared at the pieces with no progress for the last several months, and with TARC behind me I was able to get back to work on the beastie.

First up was to sand the already-primered nose cone with Tamiya white spray lacquer. No photos, as you all know what spray paint looks like. The body tube assembly has also been primed and sanded a couple of times.

Next, we'll turn our attention to the balsa and ply parts that we've already prepared. I should note that I generally prefer to paint and decal models before final construction takes place, as fins just get in the way when doing those tasks. So, we'll go ahead and paint these bits.

The fins, fin pads, cable raceways, and destruct package are all attached to scrap material to help with handling during the paint process.



Next, three coats of Tamiya Olive Drab 2 spray lacquer are applied.



These will be set to the side, as our last step will be to add these to the model. Our next step will be to mask and paint the black stripes on the nose cone.

More later,
James

Another quick update...

After sanding the primer that was applied to the airframe tube last week, our next task will be to mark the locations for the fins and detail parts on the tube. Unfortunately, time has not been kind to the original marking guide included with the kit, as it has shrunk considerable. I suspect that it did a few decades of hard time in a hot garage or attic.

No problem, though, as we can download an image of the original marking guide from the JimZ site. Accurate sizing can be a problem with JimZ files, so the graphic was pulled into Illustrator, and resized against a simple line of the correct circumference. Amazingly, everything was sized appropriately on the first try! A pdf of the file is attached below, and I also added a 1" reference square to help future users.

Here's a comparison of the original and resized guides wrapped around the tube.



More later,
James

Time to push through and finish this project. The decks have been cleared of all other immediate distractions.

Using the marking guide reprinted a few weeks ago, the airframe tube was marked up for the fins and detail parts. Mounting slots were then cut for the through-the-wall tabs on the fins.



One of the fins was then dry-fit to confirm placement.



More in a bit,
James

The next task is to apply the stage separation band located near the midpoint of the airframe. Rather than use light cardstock as supplied with the original kit, a strip of 4mm-wide styrene strip is instead used. The styrene was placed on a strip of 3M Type 465 double-sided tape, after which the excess was trimmed away using a fresh #11 blade. The strip was then applied to the tube, placing the seam below a fin pad location.


More in a bit,
James

The kit instructions call for three "thrust reversal port covers" to be placed in line with the fins at the forward end of the airframe tube, using decals cut from one of the kit sheets. This won't work, at least not in this dojo.

We're going to cut replacements out of .010"-thick styrene sheet. Measuring the original decals shows that the port cover details are about 33mm tall x 20mm wide. A pattern is drawn in Illustrator, after which the pattern is printed and taped to the styrene sheet. The parts are then cut from the sheet, and the edges lightly sanded.



The finished thrust reverser covers are then applied using 3M #465 double-sided tape.



More in a bit,
James

I should comment on the sequence of planned events before painting begins. I generally prefer to get as much paint and decal work done as possible before adding fins or detail parts. This makes the masking chores much simpler and cleaner, and usually results in a much crisper completed model. The catch is that you have to plan ahead and put marks in place for attaching components later, as the drawn locator marks get obliterated during the painting process.

For the fins on this model that's no problem; they will drop into the locator slots that have already been cut. It's a bit tougher for the cable raceway and charge container details. To locate those down the line, we're going to drill tiny little holes along these centerlines.




The styrene band that simulates the separation plane between the two stages seemed a little stark, so I decided to spice this up just a bit with some simple details, cut from the same stock used for the band. This has the added advantage of covering up the brand/strap seam.



Time to spray some paint. Naturally, it is raining outside.

More later,
James

One of the more notable features of the Estes Pershing 1A kit is the assortment of large bright orange fields, which are created in the kit by decals. Two problems with that: 1) the original kit decals are shot, and 2) if they were still usable, they would look terrible over the dark OD green. So, we're going to use paint instead.

The simplest approach would be to paint the airframe green, mask, and paint the orange areas. That would result in the same problem as #2 above, though, as the orange wouldn't "pop" over the dark undercoat. So, we're going to paint the orange first, mask to protect the orange areas, and then paint the OD green.

Our airframe tube is already primed with Rustoleum auto primer, so we'll spray on a couple of coats of Tamiya white spray primer so the orange will pop.



After the Tamiya white primer dries we sand with 800-grit sanding film, and spray the general locations of the four orange stripes using Tamiya TS-31 Bright Orange spray lacquer.



After the paint dries for a day or so we can mask off the areas that will remain orange and spray the OD green.

More later,
James

While the orange lacquer on the airframe cures, we can turn our attention to the nose cone. The kit is supplied with two templates that are cut out and positioned on the cone to mark the twelve positions where the masking can be applied for the six black stripes. We can cheat and use the mold parting line on the upper cone as a common reference line, helping to make sure that the two templates line up with each other.

Hash marks are placed on pieces of tape placed near the upper and lower limits of the roll pattern, and long pieces of tape are used to connect the hash marks.



With all of the longitudinal tape pieces in place the upper and lower circumferential masking locations are cleaned up with fresh tape.



After some protective plastic is placed to protect the upper and lower areas of the cone from overspray, we'll airbrush the black areas with Tamiya Semi-Gloss Black acrylic.

More later,
James