Sunday, January 23, 2011

Mega Review: A Semroc Flood!

This post covers several from my Semroc Fleet:

Gee'hod
SLS Sky Hook
Recruiter Space Probe
LAUNCH Missile

Gee'hod


This is the latest in Semroc's line of Groonies (Grown-up Goonies). Inspired by the "insanity of 9/11 and its aftermath", the Gee'hod is a parody on fanaticism. It has lots of fin area, lots of decals, and flies on 18mm motors. Mine is production #10.

Construction:
For a small kit, this one has a lot of parts. It has two balsa nose cones: the main elliptical cone and the small one for the 'RPG' mounted on the dorsal fin. When I bought the kit, I thought the RPG nose would be cut from flat fin stock. The cone makes this kit look so much cooler. It has 8 fin components. There are 4 main fins, 2 simulated wheels, and 2 pieces that give the lower fin its 'bomb' look. Recovery includes a Kevlar® leader, an elastic strap, plastic chute and a hook eye. The nose cone assembly includes the latter, a plywood plug, and clay nose weight. The main cone is pre-drilled for the clay. The motor mount is typical rings, tube, block, and hook.

As for parts quality, the cones are good and the laser cut fins are precise. However, the fin stock was the most flexible that I have ever seen. More about that below.

Assembling the nose cone involves packing the clay and capping it with the plywood plug. I packed the clay in three pieces but didn't glue in the clay right away. That was a good decision as I added about 10g of extra weight. I usually use epoxy to help hold screw eyes in plywood plates, but decided to use wood glue as directed.

The motor mount is typical, however, the instructions don't say exactly where to place the motor hook on the mount. Luckily, Semroc's instructions have excellent illustrations. I placed it so the motor block just fits in the top of the mount. This gives maybe 1/8 of an inch clearance at the business end. The Kevlar® leader is attached under the motor hook. I've never done this before but it seems like a good method.

As I mentioned above, the fin stock was terrible. Since the lower fin is short and has a bomb-shaped piece glued to either side, it seemed OK. The wheels are small so they seemed OK. However, the side and top fins just seemed way too flimsy. I added a 2nd layer to each with the grain running the opposite direction. I weighed the before and after and added lead shot to the nose cone clay to compensate. Thus, my model comes in at about 0.7 oz over the stock model.

There were no detailed dimensions for the placement of the 'wheels', but again the detailed drawings got you pretty close.

Finishing:
Filling was done with Elmer's Fill 'n' Finish and primer. The base coat is Model Masters Modern Desert Tan. I painted the RPG with a brush-on Testor's. It's a pretty red but is a bit too dark for the black decals. The decals--there are a bunch of them! Most can be positioned based on the cover art and I punted with the rest. These were great quality. I'm famous for destroying waterslide decals but all of these survived. Semroc included a decal spec sheet with the kit's serial number and I also used it. I used Testor's Dull Coat to cover the decals. Finally, I used a black Sharpie to color the edged of the wheels between the black decals. All in all, this model actually looks great up close!

I think the kit's design is cool in a goony sort of way. However, I have to think about the balsa stock. I rate it 3 points and an extra 1/2 for the coolness factor.

Flight/Recovery:
The space available for the recovery components is fairly small since the motor mount is offset up into the body. This also means the plastic chute will be very close to the ejection gases. I started by packing dog barf wadding into the top of the motor tube. I then used a section of Estes wadding stuffed with dog barf and finally wrapped the chute in another piece of wadding. There isn't any extra room but it all fit fine.

I loaded it up with a C6-3 given the weight I added. It flew great but passed the sun so I missed where it ejected.  The chute didn't open fully but it landed fairly slowly. You can see compression damage on the RPG tube atop of the dorsal fin. It's still stiff but the paint cracked.

For the second flight, also on a C6-3, I changed pilots!







SLS Sky Hook

This upscale of an old Estes kit is one of Semroc's new Semroc Large-Scale (SLS) line. It flies on 24mm and 29mm motors in the C to F range. The kit features thick walled body tubes, laser cut basswood fins, nylon chutes, a laser slotted tube, and a Kevlar recovery leader.

Construction:
The kit from BRS Hobbies came nicely packed with a colorful insert, which also holds the instructions. As you can see in the photos, individual parts such as the motor mount, chute, fins, and miscellaneous small parts are all individually packaged. No more dropping some small item followed by the associated searching. The parts themselves are of outstanding quality. The fins are flat and identical, the body tubes are very thick, the balsa nose cone is smooth and hard. The instructions are short but clear and include plenty of diagrams. There is even a brief history of Estes and of the kit itself. If you should be unhappy with the kit, no problemo as Semroc has a 100% satisfaction guarantee!



The parts included:
* one 1.34" diameter body tube, 12.25" long
* one 29mm motor tube
* one balsa nose cone, 4.75" long (exposed)
* three laser cut, basswood, through the wall fins
* one 3/16" lug
* one thrust ring
* one screw eye
* one elastic cord
* one Kevlar® thread
* one 18" nylon chute
* one 24mm engine mount adapter kit, consisting of
  o one motor tube
  o two centering rings
  o one engine block
  o one engine hook (for long 24mm motors)
  o one spacer tube (to adapt short 24mm motors)
* one large waterslide decal
* one small specification decal, including the s/n (mine is #00040)

To build the kit, you require all the normal tools and supplies: white or wood glue, filler, paint, sandpaper, etc. I used wood glue throughout.

This was a simple kit to build and I followed the order of the instructions. I started with the 24mm motor mount, which had its own instructions. The slot for the motor clip was pre-cut and from there you glue in the motor block and the two wide and thick centering rings. These were actually pieces of tube that telescoped over the 24mm tube.

From there I proceeded to glue the motor block in the 29mm tube. You first tie the Kevlar® twine around the block. My first impulse was to go for the epoxy, but I decided to keep with the recommended wood glue.

The next step was to round the edges of the fins and test their fit. They required a few swipes of sandpaper along their tabs. As you can see, since the motor tube fits directly into the body tube, there isn't much of a tab. You weren't asked to fill the grain at this point, so I didn't. On the EMRR review of another SLS kit, I noticed a fin popped off. I decided to see how this kit fared. If I have to make repairs, I'll try the epoxy.

To install the motor mount, you swab a liberal amount of glue just ahead of the fin tabs and push in the mount. The fit of the tube is a little loose and you immediately glue on the fins. I set the tube fins up to dry and noticed the motor tube was sliding further into the body. Glad I caught that one! The TTW fins, despite being shallow, should add a lot of strength and made fin alignment trivial. Up to this point, everything was done in one sitting. I then paused to let the motor mount and fins dry. I went back later and added an internal fillet above the motor mount.

Next came fillets, adding the eye hook to the cone, and completing the recovery system. I didn't tie on the chute but instead added a snap swivel and added it to my stable of reusable chutes. After it was all together, I went to slide on the nose cone and found the shoulder was too large. Being balsa, sanding it down wasn't a problem and the result is a nice snug fit.

So far the PROs are: Great parts, clear instructions, straightforward build, very sturdy.

The one CON is that you have to make sure the motor tube doesn't slide out of place. This could be avoided if you let the glue set first, but the instructions say to proceed. Some sanding on the fins and cone was required, but this not a big deal and was discussed in the instructions. As a result, I don't really consider them CONs.

Finishing:
There are finishing instructions and they are typical. Minimal filling is required due to the fine grain of the cone and basswood fins. I painted the body white, nose black, and fins red, just like the cover drawing. The main decal sheet includes one large wrap that covers the top half of the body tube and a blue strip to go just below the fins. There is also a small specs decal. On the plus side, the decals are thick and easy to work with. This is a very good thing since it took me a month of Sundays to get the large decal positioned. I also swabbed the bubbles forever, and there are still a few. Anyway, I shot a clear coat to help the decals stay put. The decal color is reasonably good, especially if the background is white.

Flight/Recovery:
The recommended motors include a C11-5, D12-7, E9-8, and F25-9. I suspect it will fly well on any other motor in this range, such a 24mm F21 or a 29mm F20. As built, mine weighs in at 3.46oz without the adapter and 4.12oz with. This is heavier than the specified 3.0 oz.

For its maiden flight, I loaded it with the 24mm adapter and a C11-7. This is a longer delay than recommended but it's what I had. Plus I had added a strip of 'anti-zipper' cloth tape where the Kevlar® meets the top of the body tube, so I went for it. I held the adapter in with a lot of masking tape. The wadding was dog barf wrapped in Quest wadding. The flight was nice but ejection was late as predicted. Recovery was good on the largish chute. When I got to the rocket I found the eye-hook had pulled out of the cone, which was gone, and it also spat the adapter. I will split the blame on the cone since I used the wrong delay and the adapter was probably user error. All parts were recovered.

I CAed the eye hook back in, reseated the adapter, and swapped the chute for a 12 incher--there was a bit of wind early and I didn't want to feed the trees. The motor choice was a D12-5. This time the delay was shorter than recommended, but I angled the rod some to keep it from the tree line. It tore off like a bat and I didn't see where it ejected. However, recovery was 100% good this time. It was a grass landing and there were no cracked fillets even with the smaller chute.

I increased the thrust level again with an E9-8 flight.  The flight was really up there and recovered about 40 yards from the pad.  On the 2nd E9-8 launch, I lost it the sun and never saw it again.

Summary:
The materials in this kit were as good as I've ever seen and it was a pleasure to build. The only build issue is to make sure the motor tube doesn't slip while the fins dry. This could be fixed by a piece of tape or a watchful eye, but it is a potential major "gotcha". I had to deduct a construction point here.

This is a very sturdy kit and would be a great choice for someone who wants to move on from Estes kits to mid power. With the bigger motors, you better have a nice sized field!

My thanks to Brian at BRS Hobbies for sponsoring this review!

Recruiter Space Probe

The Recruiter Space Probe, kit # KV-22, is a 'RetroRepro' version of the original Centuri kit (KC-30, circa 1967). It features a "Gemini-styled" capsule and six "Redstone type" fins. The fins thickness was increased to 3/32", the 'chute was downsized to reduce drift, and the rubber shock cord was replaced with a Kevlar and elastic combo. This limited edition kit was provided as a 'thank you' to people who have reviewed Semroc's products or otherwise promoted the company. Very classy!

Construction:
The kit came nicely packed with a colorful insert, which also holds the instructions. As you can see in the photos, individual parts such as the motor mount, chute, fins, and miscellaneous small parts are all individually packaged. The instructions are clear and include plenty of diagrams. There is even a brief history of Centuri and of the kit itself. As with other Semroc kits, this one comes with a 100% satisfaction guarantee.

So the parts include (roughly from stem to stern):

* 1 balsa nose cone, 3.75" long (exposed)
* 1 0.908" diameter body tube, 5.5" long
* 1 balsa transition, 1.625" long
* 1 1.34" diameter body tube, 8" long
* 1 screw eye
* 1 elastic cord
* 1 Kevlar® thread
* Semroc Recruiter
* 1 12" plastic chute (including tape discs and shroud lines)
* 2 1/8" lugs
* 6 laser cut balsa fins
* 1 thrust ring
* 1 engine hook
* 1 18mm motor tube
* 1 fiber retainer ring
* 2 centering rings
* 1 fiber coupler
* 1 waterslide decal sheet
* 1 small 'specification decal', including the s/n (mine is #00033)

To build the kit, you require all the normal tools and supplies: white or wood glue, filler, paint, sandpaper, etc. I used wood glue throughout. This is a straightforward build and these are the highlights:

* The Recruiter sports a cool capsule-style balsa nosecone. The thin neck got some reinforcement with thin CA.
* The motor mount features both a hook and thrust ring. The Kevlar® leader is tied to the motor hook, and both are retained with a fiber ring. The centering rings are thick and a fiber coupler, which fits between the rings, further strengthens the mount.
* The six laser-cut fins are perfect. I'm now a big fan of lasers.

PROs: Great parts, clear instructions, cool spacecraft styling, strong motor mount, Kevlar®/elastic shock cord.

CONs: The thrust ring was missing. It probably isn't really necessary, but I replaced it with an Apogee 18mm-13mm centering ring.


Finishing:
Finishing started with Fill 'n' Finish and Plasticote white primer. I couldn't resist making this look more 'Mercury Redstone-like' than the cover art. I painted the body of the cone and fin roll patterns black (Testor's brush-on), and the tip of the cone red (Painter's Touch spray).

Semroc Recruiter The decals are nice and thick. They were generally placed as shown on the cover art. The thin stripe on the cone was left off since the whole cone portion was black and I added the Semroc logo to one of the white fins. I also left off the specification decal as it seemed too big for the rocket.

I finished the recruiter off with a coat of Krylon clear coat. ARGH! Another case of not testing for compatibility! The clear coat made the black paint run slightly. The black both rolled down and wicked upward along the border of the white and black patterns. Very odd--this was a first for me. Maybe the black paint was not fully dry? I scraped and retouched and have it looking OK.

The kit was easy to finish and the decals are nice. The clear coat problem was mine and not a fault of the kit.

Flight/Recovery:
The recommended motors include the A8-3 (200'), B6-4 (500'), and C6-5 (950'). So far, I only have tried the B6-4. The flight was nice with ejection just past apogee. I used dog barf wadding and a square of Estes paper to wrap the chute. The 12" parachute was perfect for this sized model.

Summary:
This is cool looking limited edition rendition of a Centuri classic. The materials are great and the finished product is solid. My thanks again to Carl and Sheryl at Semroc!

LAUNCH Missile

Not long before they closed shop, LAUNCH Magazine commissioned Semroc to produce a kit based on the missile depicted in their logo. The result is the LAUNCH Missile (i.e. The Rocket that Launched a Magazine). The first 300 kits were reserved for LAUNCH subscribers. As you can see, I got one.

The LAUNCH Missile is a 4FNC kit that flies on 18mm motors and is recovered by parachute. The main distinguishing feature is a ribbed tail section and the custom decal set.

Construction:
The kit consists of 1.34" diameter main body and a 0.759" diameter payload. The nose cone and transition are balsa and were very smooth. The balsa fins, centering rings, and tail cone vanes are all precision laser-cut. The nominally 18mm motor mount includes both a spring hook and cardboard block. Recovery is handled with a Kevlar® leader, a elastic cord, and a plastic chute. These are connected to the transition with a hefty screw eye, which undoubtedly also is used for nose weight.

The motor mount assembly is assembled like any other mount. The slit for the spring hook was pre-cut in the mount. Semroc instructs you to tie a loop in the Kevlar® cord and hook it under the motor hook. The cardboard block sits in the end of the motor tube and abuts the tab on the motor hook. The motor hook is held down with a pair of centering rings. The rear ring is slotted to mate with tabs on the laser-cut vanes. I am so happy they invented lasers! These tabs fit nicely and made the installation of the vanes a snap. The only 'extra' I did was to wick some thin CA into the thin tips of the vanes once they were attached. Once dry, the mount is easily inserted into the main tube,

The four fins and launch lug are positioned via a marking guide in the instructions. The elastic is then tied to the Kevlar® cord and the screw eye.

Finishing:
I 'painted' mine with white primer covered with a clear coat to make a semi-gloss finish. The kit comes with decals, which I also coated with a clear coat before application. These went on fine except for the inverted-U shaped decals that were to fit over the root of each fin. It appears that I am not alone here. The edge of a couple of these flipped on themselves and it was difficult to straighten them out. As a result, I removed them all.

Flight/Recovery:
I used a piece of Quest wadding crumpled into a ball and some dog barf. Unlike many of my models, I decided to use the stock chute. Since the wind was brisk, I decided to fly the Launch Missile on a B6-4. The boost was quick and straight considering the wind. Eject appeared to be at apogee and the stock chute did its job. A C6-5 really got this little rocket moving and, because of a tangle 'chute, didn't require too much of a walk.