Alien Invader 4x Upscale Build

[PhlAsh]

As reconstruction on UFO Invader x4 was winding down, I began scoping the Next Big Project. The loss of one of my favourite rockets to bay-effect winds clinched the deal. I would upscale Estes Alien Invader.

4x was a no-brainer scale for me – plenty of room and plentiful components. The real decision lay in the version. Should I build the 1281 version (which ran from 1976-81) or the 3003 version (which ran from 2010 to 2013)? The most obvious difference is that the pod tubes of the latter are 5/16” further aft than they are on the former. The sticks are ¼” further fwd on the 3003 too. I’d build the 1281 in ’78 and flew it for a number of years. It, along with all my other rockets (except the X-Wings) were relegated to the dumpster by my parents. Once the kids had become interested, I build the 3003, which ended up in a neighborhood between the launch site and the Chesapeake Bay. I like the look the further-aft pods give it, so I went with the 3003.

The kit presented a number of challenges; a cock-eyed pod could send it spinning, misaligned fins would stand out like a sore thumb, and getting some strength into those buttress fins was something not covered in the instructions.

My first goal was to create a virtual 1:1 Alien Invader. I took the RockSim file from RocketReviews and rebuilt it based on the 3003 instructions. At the same time, I dropped the instructions into AutoCAD and digitized the wood pattern. That gave me more accurate dimensions to send back to RockSim. Once the sim was done, I could use RockSim’s Scale function (why is there a separate flyoff for ‘By Scale Factor’? It’s not like there’s another choice.) and take it up to 4x. The projected mass was 44 ounces. That would probably triple by the time all was said and done.

I chose to use a 54mm motor mount largely because, apparently if you’re a SEVRA member and you don’t, your manhood falls into question. I thought I was approaching a deal on 4” Blue Tube. That didn’t pan out, so I got two sticks, a coupler, a stick of LOC 54mm tube and a 54mm AeroPack.

Once I CAD’d up the wood, determined centering ring locations and TTW sizes/locations, I picked up 3 pieces of ¼” aircraft plywood. I figured that cladding the fins in 7oz fiberglass would get them near the 3/8” scale thinckness without going overboard. I also CAD’d up the slots for the TTW fins, dialed in the Sim using the actual components and modeled the rest of the rocket in AutoCAD. That resulted in DWGs that could be sent off to fellow SEVRA rocketeer and upscaler extraordinaire, Joe Zawodny. Joe’s slotting jig and CNC table made short work of producing parts.

 

[judo]

Sub-scribed. I love me a 4" upscale thread.

 

[Cl(VII)]

Ooooooohhhhhhh! I like this very much.

 

[CRC]

Cool upscale choice, I like my invader rocket, I left out 2 fins on the tube pods and it always gets an awesome spiral for every flight.

 

[mainer]

What do you think about this upscale?

 

[PhlAsh]

Having built it virtually – twice, it was time to begin in earnest. All the wood was removed from its parent sheets, sanded and test fit. All the tube slots were finished with a dental bit in a Dremel and sanded. All fins and Rings were test fit to ensure that there wouldn’t be any surprises as epoxy was curing.

JB Weld was used to secure the AeroPack retainer to the LOC tube and also to secure the lower two of five centering rings in place. With the bottom one cured in place, the second was located, adhered a little short of the marking then slid into the airframe. This allowed me to put the fins into place and push the centering ring into seated position with a dowel. The third ring also got JB Weld and was fitted in a manner similar to the second. The positioning of this ring was critical because, unlike the others which butt the TTW tabs, this ring was slotted to interface with the slot on the two buttress fins.


Pretty soon, someone is going to say, “Hey dummy, didn’t you glue your shock cord the length of the motor mount?”

No, I did not. I decided to try a large-scale version of something Hans "Chris" Michielssen posted on his blog. It was the citation of an article in Apogee’s Peak of Flight newsletter. In my version, rather than running a plastic q-tip straw between holes punched in cardboard centering rings, I ran a 3/8” Teflon hose through holes drilled in each centering ring, then epoxied it in place. This allows me to run a Kevlar cord in through the bottom and secure it with a loop around the exposed motor mount.


Once the last two rings were seated, again aligning the rings, slots and canard fins, I cut the aforementioned Teflon tube and motor mount tube to length, 1/4” forward of the forward centering ring. This left me with 10 1/2" of clear space in the airframe, some of which would be consumed by the AVbay which is housed inside the coupler.

 

[PhlAsh]

What do you think about this upscale?

That Rocks!!

 

[gerbs4me]

Coming along nicely!

That is one big upscale!

 

[PhlAsh]

Once the motor mount was cured, it was epoxied into the airframe. Half a run of West System along with a tablespoon of West System 404 High Density Adhesive filler was used for the upper fillet as well as the intermediate and bottom bonding. Once those had cured, a full run with the same (with two tbs of 404) was used on the bottom fillet and injected into the fin slots. Scrap plywood covered in wax paper kept the fin slots clear. I stood it at an angle and rotated it every couple of minutes until it looked like it was setting up. The next day, the tube was flipped and the process repeated with a half-run through the slots.

Once everything was set, the scraps and wax paper bits removed and the fins test-fit again (and some Dremeling of slop), I tacked the main wings in with Bob Smith 30 minute epoxy and used a nylon-band clamp to hold them true. Then came the dorsal and ventral fins, also tacked with 30min.

Some old Dremel cutting disks made for ‘down and dirty’ biscuit joints to provide a bit of strength and alignment while the buttress fins were tacked in.



The canard fins were mounted in the same manner. Two lengths of 2” x 2” x ¼” aluminum angle ensured that they stayed true to the main and buttress fins.

Once all the fins (except for the inner and outer wing fins) were tacked in, blue tape was laid across the joints, holes were drilled in the airframe and an similar mix of West System was injected at about 1ml/linear inch.

Upon completion of the internal fillets, 7oz fiberglass was cut and laid, once again using West System. Each of the four pieces, laid over the course of four days, ran from wing-tip to fin-tip. In retrospect, I should’ve found a way to vacuum-bag each application, but that’s not something I’ve done before and I thought it a rather daunting task. There were only two spots where the fiberglass didn’t bond to the wood, but later sanding, coating and capillary action resolved the issue. The fiberglassed area had another run of West System (with 404) brushed with over and sanded.

Between the fiberglass application, I tacked the pod fins to the pods, clamped, taped and ran internal fillets on each. After the brushed on West and sanding, the pods were epoxied in place and given the same internal fillets as the rest. The nylon-band clamp was used to pull everything together while the judicious use of a spirit-level ensured proper alignment.

 

[mainer]

Looking pretty sweet!

 

[PhlAsh]

We're at the pretty boring part right now: spiral-filling, external fillets (done much the same as the internals), priming, sanding, the odd bit of Bondo, more priming, more sanding... ad nauseum

 

[PhlAsh]

I had acquired a yard of 1/4” carbon fiber tube and, despite breaking the scale, had committed to using it on this rocket. Both versions of the kit called for 3-3/4” dowels. The 1281 kit had you glue the dowel 1” from the front of the pod. The 3003 kit called for 2” of the dowel to be glued to the pod – effectively 3/4” from the front of the pod. After much discussion with my SEVRA cohorts, it was decided that I would “stick it to the man” by cutting my tubes to 16” (4” x 4) and gluing them 3” from the front of the pod.



More later about how that decision came back to bite me in the butt.
The tubes were attached with 30-minute epoxy and filleted with the same ratio West / 404 Filler as discussed previously.

Because I’m housing the AVbay inside the coupler, I decided that I didn’t want to drill later to accommodate a switch. That led to the design of a “switch port”. I hadn’t seen anyone do this before, so I’m either a trendsetter or an inattentive schmuck. I marked the midpoint of the coupler then traced a circle using the pipe that would become the port coaming. In order to preserve strength, you want to put back at least what is removed. That meant I needed at least 0.2528” of pipe. After the initial drilling, I used the sanding barrel bit in the Dremel to widen the hole. Once the hole was sufficient, the pipe, 1/2” Sch 40 PVC, was epoxied into place.



From there, half-circles were traced onto the upper and lower body tubes and were sanded to suit. When everything fit together, the pipe was cut and sanded flush to the body.



Somewhere in there, I glued the wing fins into their notches and, because the fins were a few mils thicker than designed due to the fiberglass, I had to fill the cavities on the opposite sides of the wings.

 

[conman13]

That is huge!!!!!!!!!!


Sent from my iPod touch using Rocketry Forum

 

[PhlAsh]

Next came the work on the nosecone. I’d received a 4” x 19-1/2” ogive nose, the Pinnacle from Giant Leap Rocketry The page claims 19.8” length. I measured 19 1/2” and only needed 19.2” for scale purposes. At 10 feet, it doesn’t make much difference.

My long-time rocketry accomplice, Doug Lucy, still had his 1281 nose cone and was kind enough to provide dimensions of the nares. TRF’s Sandman, demonstrated a method for making the nares out of wood and I’d even contacted him about making me a nosecone.

Side note: If your wife sees the price tag and has just bought you a lathe, she will shoot you down in a New York Minute.​

Needless to say, I had to do it myself. I glued two pieces of 2” Styrofoam together and tacked some 1/4” plywood scraps to the ends so that the floating centers on my lathe didn’t crush the foam. Turning large-bead Styrofoam on a lathe is a messy endeavour and will greatly contribute to the wife consenting to future nose cone purchases. Careful handling of a vacuum cleaner and a chisel simultaneously was successful in reducing the amount of cleanup. I eventually ended up with a 7-1/2” x 3-3/8” ‘teardrop’.



Despite my efforts, the joint was not coincidental to the centers of the form. It had to be cut. Enter another of the SEVRA partners-in-crime, Pat Harden. Pat built a hot-wire foam cutter a year or so back based on plans from Rocket Team Vaatsas site but never hooked up a power supply to it. I had an old Lionel Train transformer which we connected and made short shrift of the task. As an added bonus, Pat let me keep the cutter!



With the nares cut, several attempts were made to mount the nosecone into the lathe, mount 150 sandpaper to the nose and to take the lazy approach, but Reality wasn’t putting up with that nonsense. I ended up holding the sandpaper taut around the nose cone and inching the foam into contour. After a minute or so, I got the Dremel out again and hollowed out each nare in order to ease the sanding burden.



When I got them to shape, I tacked them to the nosecone with spray adhesive and applied 7oz fiberglass to the foam with about a 1/4” overlap onto the nosecone. This was followed with more sanding and filling in the areas where the fiberglass didn’t want to meet the contour of the foam. Looking back, a lighter fiberglass cloth, perhaps in multiple layers may have been more prudent. A 25” planter and playground sand was bought with the intention of casting this thing in plaster so that it can be molded for replacement or for builds of other birds that share the nose cone.

 

[PhlAsh]

Once all the sanding and filling were done, it was time to paint. First came the red for the inside of the wing pods
I used Rustoleum Grey Auto Primer for all the undercoating and Krylon Fusion over for the finish coats. Once the inside of the pods’ red was dried, I had to mask them so that the black would not enter.



Rather than paint yellow, mask and paint black, I masked off the ‘to be yellow’ section and knocked out the black in three coats, wet-sanding between the first two. When the black was done, out and off came the masks.



The payload section, nose cone and sustainer forward of the canard fins got three coats of yellow with wet-sanding between the first two.



I’d contacted Mark at Stickershock early in the project and had received the stickers about midway through the build. We’d discussed the possibility of adding some detail to enhance the upscale but, in the end, decided against it. Because I didn’t use the ‘wet method’, I ended up with a bit of wrinkling in the transition between black and yellow. There’s a funky little detail on the aft end of the wrap that always gets lost in the black-on-black. The instructions of both the 1281 and 3003 kits don’t address it, so, like my builds of both kits, I cut it off.



Once the wrap/forward sticker was applied, it had to be cut to allow for ejection separation and to allow the switch port to be open.

Remember how I said the that the choice I made in mounting the sticks would come back to bite me? I haven’t yet, but I’m going to touch up the end of each stick with some white.

 

[JMZawodny]

Very nice! I can't wait to see it fly.

 

[PhlAsh]

I launched this past weekend at Beach Blast. It flew on a J380SS to 1978' with an event at apogee. It came down nicely but at 500' nothing appeared to happen. I ended up with a 9" core sample. The sticks popped off, the nares popped off the nose and the nose split at the shoulder and the allthread I'd epoxied down there popped out. Post-mortem suggests that the ejection caused the nosecone to break at the shoulder. Giant Leap recommends filling the cone with foam - I didn't *and* I cut the bottom of the shoulder off to give me the extra room. For the impact, the Blue Tube only took about a 3" split (which might not have happened if the 1.5" rock hadn't been there). All in all, I estimate about 2 weeks to repair.

In the process, I'll rethink the avbay. One of our younger members had a successful Jr Level 1 attempt using a heat activated cable cutter. I may go that route so the avionics aren't in a fixed location.

Pictures are forthcoming.

 

[stickershock23]

BUMMER MAN.. but I cant wait to see what the up part looked like!

DOnt forget replacement decals at 50% off! just send me a picture of the damage...

Good luck on the rebuild!

 

[PhlAsh]

The wrap sticker was in the zipper-like split but, depending on how the fix goes, it may not need replacing.

I'll let you know and will be in touch anyway because of UFO Invader, which I'm about to write about - once I find the thread again!

 

[PhlAsh]

The nosecone was messed up, but not destroyed. It's been laying in a 36" planter, half buried in playground sand. About a week ago, the exposed portion was smothered in plaster of paris. Once that cured, it was pulled from the sand. I cleaned the sand off the plaster, pulled the nosecone out, rasped down the edge, put the nosecone back in and Vaseline'd the face that had been in the sand. I smothered the exposed nosecone in more plaster of paris. I didn't like that way that one came out, so, using the last plaster of paris, I smothered it again. I'll post pics once they're taken.