Estes Der V-3 Build Thread - My L3 Project

My first "D" rocket was an Estes Der V-3. It was my favorite rocket for decades. About 2 years ago, using it to test an onboard video camera, I lost it in the highest bough of a tree. Gone forever I was sadly disappointed because I had that rocket for over 25 years. I certified L1 on a LOC Canadian Arrow, and L2 on a LOC Nuke Pro Maxx, but for my L3 I wanted to challenge myself to upscale a rocket instead of building a kit. So I decided the best project would be to reincarnate my favorite rocket as a 3x upscale.

The original Der V-3 was built with a BT80 and a V-2 Nose Cone to fit. Fins were 1/8" balsa and the rocket stood 2' tall.



My upscale will use a glass-covered PML 7.5" airframe and fiberglass V-2 nose cone from Performance Hobbies, and a CNC cut set of 1/2" plywood fins from Upscale CNC that are interlocking to add strength to the fin can. The airframe will be a little longer than scale, although not too noticeably longer, so that I can have a little better stability and also load larger motors. The finished design shows the rocket to be 6' 4.25" tall with a 30" fin span.



If everything works as planned, I will certify with an M1770.

Unfortunately parts are not all in for the obligatory kit shot, but I have enough to get started. Stick around for some photos. After I get the rest of the pieces in a couple weeks, I will post a dry-fit shot.

First thing was to mount the retainer on the 4" centering rings. The original design had the motor tube extending aft, so I wanted to recreate that, but also ensure that the motor was retained well. Since the 4" rings are real narrow, I opted to hold the retainer in place with #6 x .75" stainless sheet metal screws. I hand drilled the first two, using a 3" coupler tube as my guide, then once the ring was attached, used my drill press to finish the remaining screws with the flange in place. After this was done I slid together to dry fit the fin can. Fits like a glove.

That's some nice woodwork there.

op:

Love my V3. Still fly it from time to time. I've flown the heck out of mine, just have more to choose from now so it doesn't always make it to the air.

VonMises said:

That's some nice woodwork there.

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The woodwork is courtesy of UpscaleCNC. If you notice, the centering rings have notches in them and the fins have tabs that fit into the notches. The whole fincan assembly has interlocking parts that both keep everything together and distrubute the load of the rocket thrust.

EeebeeE said:

The woodwork is courtesy of UpscaleCNC. If you notice, the centering rings have notches in them and the fins have tabs that fit into the notches. The whole fincan assembly has interlocking parts that both keep everything together and distrubute the load of the rocket thrust.

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I did notice that. Now I'll be paying a visit to Upscale CNC.

Perhaps i won't visit Upscale CNC after all. Couldn't find them on bing.

VonMises-

A website is in the works, along with a dozen other things!! I'm UpscaleCNC, and made the parts to Evan's specification and design. I won't clutter up his thread with advertising except to say that there is a thread in the Vendors forum ("The latest from UpscaleCNC") that shows some of the different projects I've been involved with and, for now, feel free to send me a PM and we can discuss your projects.

Nat Kinsey
UpscaleCNC

It has been a while since I did work on this project, but it is time to do so. I want to have the fin assembly done so I can show it to my L3 coach. First step in doing that is to sand the fins. I had debated whether or not to round them or airfoil them, so I chose for kinda sorta the latter. I marked a line 1/2" away from the edges of the fin and sanded them so that they tapered to the center of the ply. Being 1/2" ply that gives me a 30-degree angle which will give me some airfoil capability, but still retain structural integrity around the edges.

Sanding involved using discs on my drill. I used 40-grit sandpaper and rough-sanded everything. The 40-grit is dangerous to use because you can gouge the wood pretty quickly, but it makes the work fast. I had done this method before making a daggerboard for a sailboat so I knew to take it slow. End result was a set of uniformly shaped fins. I had a couple minor gouges but I should be able to compensate for that when I add a layer of FG to them.

Time to FG the fins. I chose a more old-school route of glassing the fins, then compressing them under weight to smooth out the FG. The process causes the heat to be a little more intense and that slightly melted the plastic used to prevent the fins from sticking to the fiberboard, but the finish was still relatively smooth.

Once the epoxy set, it was a matter of sanding down again to go back to the shape before FG. First was 80-grit sandpaper on a disc sander to take off the excess epoxy. Next was 150-grit sandpaper on an orbital sander to smooth everything out. Next step will be to use bondo filler to even everything out.

The nose cone arrived yesterday so I sanded the shoulder to the point I could get a fit and sized it up to my car to gauge how big this thing will be.

It's been a while since I worked on this project. Finances dictated that this be postponed until 2014. But I had to make a repair to another rocket and it occurred to me that I could treat my fins with the same material. To smooth the further, I coated with bondo short-strand fiberglass infused filler. Makes a nice smooth and very strong surface.

Very cool like building from scratch . Maga Hi flyer .6x up scale going to mwp11 doing L1&2. Best of luck.

:clap:I too am quite impressed by that method of Centering Ring and Fin Integration. It's Beautiful!:clap:

TopRamen said:

:clap:I too am quite impressed by that method of Centering Ring and Fin Integration. It's Beautiful!:clap:

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It may be a challenge to get the loose epoxy off the tabs and out of the slots, but once it goes together, it isn't going to come apart. Upscale CNC had been doing these assemblies with all the slots on the rings toward the airframe. My thought was that with the slots toward the motor tube, the centering ring itself holds the fins in place. You aren't solely dependent on a good glue bond.

2 downsides to this.

First, if you commit to doing your fins this way you cannot slide the fins through the airframe slots. The entire fin assembly has to be slid into place. If you have a design with a significant distance from the trailing finroot to the aft end of the airframe, this technique won't work.

Second, Your main chute had better come out. I do not see how a fin can be replaced and be held in as strongly as the original. Plus the impact is going to be disbursed throughout the entire assembly so the likelihood is that the damage will be also. Hopefully this assembly will be so strong that the damage will be minimal because if it is significant the entire assembly including the airframe will most likely be toast.

On the upside though, the should not be very prone to shredding as long as I don't try to Chuck Yeager the thing.

Waited about 3 days for the filler to completely set. With the fiberglass infused into it, this stuff is pretty hard. I used 80-grit sandpaper on a drill pad to take off most of the excess, then used my orbiting sander with 220 grit sandpaper. That gets me to about 95% completed. The remainder will be sanded after the fins are attached to the airframe.

When it comes down to it, 60-70% of build time is spent on the fins. Lots of sanding today and I am finally (mostly) finished with the fins. Nice and smooth. After a little scraping and sanding of the slots, I dry fit it together to make sure there would be no issues. I am pretty pleased. Starting to look like a rocket. It should be a little over 6' tall when finished. Airframe is 7.5" in diameter.



For those who are curious, the Scotch bottle is Johnny Walker Blue.

It's been a while since I posted on this build, but there has been work on the project, primarily on the fin can. The fins and rings were glued together, using West-Systems G-Flex Epoxy. It takes about 45 min for this stuff to set, so there is ample work time, and it is exceptionally good at bonding this type of material.

I debated for some time how to reinforce the fins at the motor tube and settled on fiberglassing them instead of filleting. So I cut 16 strips of 3" x 7" glass cloth and epoxied them into place. Between the interlocking fin assembly and glassing the roots, these fins aren't going anywhere.

It has been drilled into me that I need a strong mount for the Rail Buttons, so I thought of a way to add a little more structural support, reinforce the CR holding the shock cord mount, as well as providing a base for the rail buttons to be mounted to. I cut six pieces of 1" x 1" ash and glued them in between the CR's (3 on each side). There is a 4th CR that holds the shock cord mount as well as provide a base for the upper rail button. The other purpose of the 4th CR is to reduce the volume of the space between the DD CR's and the airframe CR's, which will reduce the amount of BP needed to separate the rocket.

After all the glue has set, I will use a 10" x 5/16" drill bit to create holes for dowel rod to go through. This will add more structural support, and also remove obstacles for the rail button mounts.

Fincan is finished! So I cut the slots in the airframe for the fins and dryfit everything. Looks good, I think.

I concur ... looking gooood !

How are you going to do the electronics and deployment ?

Kenny

Forward 10" of airframe is cut off. a 12" coupler holds the two pieces together. The e-bay is 3" deep and tucks up into the coupler behind recessed bulkheads to allow room for a 75mm CTI 6-grain motor.

Recovery components are:
2 Perfecct Flite Stratologgers. Both completely independent of each other. I will have 4 BP charges. Debating on whether or not to power them with a 9V battery or 6x AA batteries. Weight is not an issue.
Crossfire 120" main chute tucked into a Nomex Chute bag
PML 54" drogue chute

Below is the configuration. Chutes are red, the bold dotted and dashed line surrounds the e-bay.

At the suggestion of my L3 CC, I added a couple threaded rods to better secure the upper CR. Since the lower 3 rings and fins are interlocking, the rods did not have to go all the way to the aft end.

EeebeeE said:

It's been a while since I worked on this project. Finances dictated that this be postponed until 2014. But I had to make a repair to another rocket and it occurred to me that I could treat my fins with the same material. To smooth the further, I coated with bondo short-strand fiberglass infused filler. Makes a nice smooth and very strong surface.

View attachment 146908

Click to expand...

What is the working time on that? The thing I always hated about Bondo was the short working time. In about 2 minutes it was starting to set up and get stiff.

Fortunately, I had worked with this stuff beforehand and knew it cured quickly. I did it in the evening, opened the garage door and made sure the temp outside was in the 40s-50s. That slowed down the curing process. I was able to do one side of the fins with one batch.

This stuff is real strong because of the fiberglass that is in it. I am going to use it for my fillets.

More work today and this time it looks like real progress was made. I cut the airframe. 10" for the main chute bay and 38" for the booster section. Two holes drilled for the switches. I drill the holes first, then cut the airframe so it bisects the holes. That eliminates the need for a switch band.

I installed T-Nuts into the support structure for the rail buttons. This anchors the rail buttons to the back of the support beams so that they are very unlikely to come out as the rocket is being set up on the rail. This was done by drilling holes into the support beams, affixing JB Weld to the T-nut, then tightening into place using an eyebolt.




Now I was finally ready to glue the airframe to the fincan. Using West Systems G-Flex Epoxy which soaks in very well to the material and also has a long cure time. That allowed me the time to use wood screws to hold everything in place until the glue cures. Then the screws will be removed and the holes filled.



And this is what she looks like. It's on to the electronics bay.

Why are the threaded rods there again?
On top of the wooden struts you have already.
Maybe some quick set mortar to round things off?

Just a pinch of overkill here.

JD

Just doing what my L3 CC asked. The threaded rods are only attached to the two forward rings. The thought was that there were no interlocking components to this ring other than the struts and that ring was going to bear the brunt of the recovery.

Couldn't you use forged eyebolts on the forward closure of your motor as a recovery anchor?

Mike

Not enough room. The forged eyebolt would come in contact with the U-bolt on the AV Bay. Funny how so many people seem to hyperfocus on one particular element of a build.

To ensure that my AV bay stays together in the event of a less than desirable apogee deployment, my L3 CC wanted me to make some plates that tie all bolts together with steel. So I bought some 22 ga. galvanized steel, cut the plates with tin-snips, washed off the galvanizing with vinegar, then epoxied the plates to the bulkheads. I drilled through the plates by using existing bulkhead holes as a guide. Then I drilled holes through the plate and bulkhead for the U-bolts.