Wednesday, January 12, 2011

Mega Review of Micro Projects: Six MicroMaxx Rockets

I decided these little things were too small to warrant their own posts, so I grouped a bunch of them together, including the Quest Tomahawk Starter Set, Heller 1/300 X-15 PMC, and several scratch builds (My Little Cupcake, Micro Slam Dunk, Micro Darmok, and the MicroMech-X).  I've got more and will group them into several more themed posts.


Quest MicroMaxx Tomahawk Starter Set

I can't believe it. I actually bought a Micro Maxx starter set and a bunch of engines. I guess the desire to launch more than once a month (twice at best), and without traveling 45 minutes or more, got the better of me!

I got my set, with a single Tomahawk Cruise Missile, at Wal-Mart for $9.99 + tax, as I remember. They only had this and a couple of 4FNC rockets available at the time and I wasn't too interested in those. The set included three Micro Maxx-II engines and four igniters. These engines have 150% the total impulse of the originals (0.3 vs. 0.2 N-sec). The launcher appears to be as described in earlier reviews and includes the base unit with integral controller, a three-piece interlocking shell, launch rod, safety interlock/launch rod cap, and a display stand for the Tomahawk.

Flight Report:
I am impressed with the launcher. It is well engineered and houses all launch components in a nice self-contained package. So far, I have launched five rockets with no ignition problems. I was worried about the launcher mating with non-Quest kits, but have not had a problem so far. My launches off this controller have included:

1. Tomahawk - successful
2. Tomahawk - successful
3. Mini105 (a converted 10.5mm rocket) - successful
4. MM-CTV (Micro Maxx Cluster Test Vehicle) on 3 engines - successful
5. Apogee Micro-V2 - too heavy for this engine

Even with the heftier MMX-II motors, the Tomahawk proved to be barely stable. That is, it kept a generally upward trajectory while it wobbled around. The piston ejection worked fine, but the streamer did not deploy. The performance was not that great either but it landed close by, then I bought the set for the launcher anyway.

Update: I used the Quest launcher for a while but for 'solo' launches I now just use the rod in my drill chuck-based LPR pad. Ignition is performed with my Pratt GO-Box, which plugs into a car lighter receptacle.  The new MicroMaxx motors have an upgraded bridge wire igniter with exposed leads.  These work a lot better and are easier to deal with than the original plastic-cased igniters..

Heller - 1/300 X-15 PMC

This is a plastic model conversion (PMC) of the Heller 1/130 X-15, using MicroMaxx motors. I got the kit on-line from Model Expo. Model Expo provided email confirmations of the purchase and of shipment, and their service was prompt.

Construction:
Parts:

* One Heller 1/130 X-15
* LOC ¼" launch lug ~3" long
* LOC ¼" launch lug ~ 3/16" long
* One spent MMX casing
* Section of the ink tube from a BiC pen
* Kevlar® twine
* Teflon plumber's tape
* #9 lead shot

The instructions provided with this kit consisted of step-by-step diagrams. No text description is provided. In general, this was sufficient, but this presentation omitted some details, such as the slight downward cant of the rear wings. The kit consists of 35 pieces, 10 of which weren't required due to the PMC.

The LOC ¼" launch lug is heavier than a standard MMX tube and is a skosh larger. However, it works fine for those of us who haven't gotten around to buying 'real' 6mm tubes. However, with some minor trimming of flashing and other bumps inside the fuselage, this tube fits nicely. There is a recess, just inside of the tail end of the main body, which accommodates the tube well. I measured the distance from this recess to the point just ahead of the side fairings, and cut my tube to fit. Contrary to other guidance, I used this tube as a guide to cut the nose section off the main body with a razor saw. I glued the tube inside the body with black rubberized CA, and the body halves together with liquid plastic cement. I added the back nozzle cap, and then installed a section of a spent MMX casing to serve as a motor block. The Kevlar® twine was tied around the block before its installation.

I assembled the plastic nose cone using plastic cement. I then filled the cone most of the way with lead shot, epoxied in a small piece of the ¼" lug and the remaining part of the spent MMX motor. I inserted the end of the Kevlar® twine, filled the MMX motor section with more shot, and capped it all with epoxy. This works nicely as a shoulder, but requires wrap of masking tape to fit snugly. The CG is 2 1/8" from the nose cone tip (minus the needle nose). It was suggested that the CG should be about 2.032 from the tip (from a known stable conversion of this kit), but no more #9 shot will fit, so I'll try it as is. Oh, and I decided to leave the needle off until I have assessed the rocket's stability. I wouldn't want to poke anyone, plus it will most likely break anyway.

The large front fin comes in one piece and must be cut to accommodate the tube. One end of this fin conveniently has a notch that almost fit the tube, so I used this as a guide and sanded to fit. I used the black rubberized CA on the root end of these through the wall fins, and plastic cement on the outside. The remaining fins were assembled per the instructions using plastic cement. I did add some really small epoxy fillets on the back fins using epoxy left over from the nose cone. The launch lug is my standard BiC ink tube


Finishing:
The whole thing was painted black using brush on enamel.  The kit comes with a raft of decals, which went on nicely.  After a day of drying, I laid on some clear enamel. Since I couldn't get all the paint off of the fin joints, I retouched it. The finish looks bad up close, but there is not much that I can do without ruining the decals.

Flight:
I used Teflon plumber's tape for the wadding and the streamer (12"). I flew the model on a MMX-II motor and used a bit of masking tape to retain the motor. I used my Pratt GO-BOX and a stock igniter that was removed from its plastic shell. The wind was perfectly calm. The flight was a little wobbly and the X-15 flew to about 25 feet. Since the CP-CG is marginal, I wouldn't fly this rocket except in the lightest of winds. Unloaded weight: 0.42oz/12.0g

Summary:
This small X-15 was only my second PMC and was straightforward. The rocket looks great and seems to fly fine. My only recommendation to others building this kit is to use lighter tubing. With the heavier tubing, most of which is behind the desired CG, it is difficult to balance the model properly. Mine is probably just barely stable with the whole nose filled with lead shot. Another option might be to have the rocket separate further back, thus allowing more room for nose weight.

My Little Cupcake

This is a very simple "flying saucer" style rocket for Micro Maxx motors. Its main component is a 2 ½" paper baking cup.


Construction:
The materials used include: one 2 ½"paper baking cup, one Styrofoam picnic plate, one piece of note paper, masking tape, and a 2 ½" long Estes launch lug.

To make the motor tube, I applied a thin layer of white glue on some paper and wrapped it tightly around the tube from an Aerotech Copperhead. After it dried for a while, I cut off a 7/8" section. Next, I cut 1.875" and 2.375" rings from a Styrofoam plate. I made the holes for the motor tube a little big (oops), so I built-up the motor tube with masking tape until it fit snugly. The smaller ring was placed at the end of the motor tube and set into the baking cup. The second ring was slipped down until it just touched the sides of the cup. This assembly was removed, and the rings were glued in place with white glue.

After the glue set, I made notches for the launch lug and slid it through the rings. It fit snugly and I decided not to glue it in.

Finally, the motor mount assembly was glued into the baking cup. While this dried, I set the cup back into the package on top of other cups, in order to provide even support around its circumference. I was originally going to cut the lug flush with the front ring, but decided to leave it as is. The only finishing step was the application of an American flag sticker.

Flight:
The MMX motor is held in with a wrap of masking tape. In order to mate with the launcher, I had to let the motor overhang the motor tube by ~1/4". The saucer flew straight to an altitude of maybe 25 feet and floated down nose first. Using a launch lug that is considerably wider than the Micro Maxx launch rod didn't seem to impact the flight profile. After the first flight, there was a little scorching of the paper near the motor mount. This did not get any worse after the subsequent flights, so I assume it was because I did not fully remove the paper covering the end of the motor mount.

Summary:
This simple rocket flies well and can be easily built while watching TV, cooking, or performing other non-rocket activities. Gee, am I obsessed or what? You can easily substitute different materials; I just used what I could easily grab.

Micro Slam Dunk


The Micro Slam Dunk is a Sputnik style Micro-Maxx rocket. Its major components include a basketball-shaped shoe deodorizer and four bamboo skewers.

Construction:
While cleaning up the basement, I ran across an old shoe deodorizer that looked like a basketball. I stuffed it away in my junk box thinking "nose cone". When trying to decide on my next Micro-Maxx project, however, I looked at this orange and black orb and immediately thought, Sputnik!

After disassembling the ball, I found that two integral plastic tubes held it together. These can be seen in the first photograph. For the motor mount, I drilled a 6mm hole, approximately 3/8" deep in the half with the larger tube. I also cut off about 1/4" of the thinner tube to allow the halves to separate more easily. Thus, the two internal plastic tubes form an ejection piston of sorts. A small section of Kevlar® twine holds it all together. I also drilled a small hole in each half for the launch rod, and four slightly larger holes for the legs. The legs consist of bamboo skewers, which are glued in with Liquid Nails.

Flight:
Although I test-fit the rocket on the launcher, I needed to elevate the launcher slightly on the grass at the launch site. I flew the Micro Slam Dunk three times. Each flight rose to a mere 20 feet or so. Not an impressive altitude but it was fun to watch. On the first two flights, the two halves did not separate and the motor ejected with a loud pop. For the third try, I loosened the halves to they were barely connected, and separation did occur. After all three flights, it landed back on its legs.

Summary:
The Micro Slam Dunk is yet another easy to build Micro-Maxx rocket. It is a bit heavy but is still stable and ejects well before landing. Before it flies again, I will work on loosening up the two halves so it will separate when the two halves are completely together.

Micro Darmok

I ran across some teardrop-shaped plastic Christmas ornaments that I intended to use as wing-tip pods. However, I quickly saw the similarity to Rocket Team Vatsaas' Darmok and Jilad at Tenagra. I love their bulbous rocket designs so I just had to build one.

Construction:

* Plastic ornament
* 6mm tube
* 1/64” ply
* Thin Kevlar®
* Lead shot
* Section of a spent Estes motor spacing tube
* 6mm-10mm centering ring (Totally Tubular)
* Piece of an ink tube from a ball point pen

The build was simple. To prep the ornament, I removed the hanger and cut that section off. I then cut the ornament in half just above the mid-point. I mounted a MicroMaxx motor tube using 6mm-10.6mm centering ring and a chunk of an Estes motor spacing tube. The latter also served as a ‘reverse shoulder' for the cone. 5-minute epoxy was used throughout. I added thin Kevlar® to keep the pieces together and added nose weight per the RockSim file. The fins were eyeballed based on the Vatsaas design and were cut from 1/64” ply using scissors.

Finishing:
I painted the fins using Testors silver model paint (brush-on).

Flight:
There wasn't much prep for this little rocket since it uses break-apart recovery. I've flown it twice. It was stable, unlike its bigger relative. However, due to its weight and diameter, it isn't much of a performer. On the first flight the body didn't separate and it lawn darted, but the second flight went as planned.

Summary:
I love plastic doohickies and this was a quick way to make a micro, ‘retro-style' rocket. The ornaments are useful for pods and cockpits too!

MicroMech-X

Design Concept
This was my entry into r.m.r. DesCon-12, whose complex theme was: Comedy, Sci-Fi, Multiple MicroMaxx, Grissom Kitbash. You had to hit all of these themes to score the maximum number of points. My entry only satisfied the Sci-Fi and Multiple MicroMaxx criteria.

I wanted to pick a theme that I thought would be somewhat unique. I didn't think I could come up with a suitable comedy sci-fi ship that hadn't already been mentioned on r.m.r., so I looked elsewhere for inspiration. I roughly patterned this rocket after a robot model that I resurrected from the depths of our basement (a.k.a. The Rocket Dungeon). I had scoured the web, and had even thought of doing a conversion of a paper model robot, but decided to just start building and see where it went. This model started as a prototype, but I ran out of time.

Development Methodology
I used a tried and true procedure known as "real-time design". In this design methodology, the design is performed as you go, without the benefit of plans, diagrams, or specifications. Documentation is performed at the end, and is kept to a minimum.

Construction
I started by cutting two MMX tubes that would extend from the bottom of the robot's foot up into its body cavity. I then started at the bottom and built my way up. The plastic robot's foot was traced onto foam poster board. I cut the feet, beveled their edges, and cut holes for the MMX tubes. Next came the upper layer of the feet, followed by the front and rear leg sections. At this point, I began to think about weight, so the sides of the legs were made from card stock. The body was started with a foam board plate, with holes cut for the motor tubes. As with the leg sections, the three front and one rear section of the body are foam board and the sides are cardstock. To provide better support for the shoulders/head (i.e. the nose cone), I added a small section of BT-20 in the body cavity. A long Estes lug was inserted laterally through the BT-20 to provide an attachment point for the arms. The shoulder/head assembly started with a foam board plate. Attached to this is a sliver of BT-20 coupler and two pieces of foam board, which were trimmed to mate with the body opening. The head itself was carved/sanded from pink foam. The arms consist of two layers of foam board.

Now that the robot looked like a robot, I had to add more rocket stuff. For recovery, a piece of thin Kevlar twine was tied around the launch lug that supports the arms and was epoxied to the shoulder/head assembly. A launch lug was glued midway up the back. And finally, I scrounged some thin clear plastic for fins. The four fins were glued to the bottom of the leg above the feet.

Finishing was performed with a combination of simple water colors and some card stock cutouts. I painted the robot before permanently attaching the legs, arms, and fins so I'd have better access to its nooks and crannies.

Flight
Ater some miscues, I finally got both motors to light. M.M.X. reached a whopping altitude of 4ft. The second photo below shows it on the way down, just before ejection.

Conclusion
Although the rocket flew, to have a mature model I'd have to build lighter. I might also opt for a lug that is closer to the axis of the motors and a different ejection method. Such conclusions are the point of a prototyping effort. I didn't find time to build V2.0, so that was it for the contest.