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REV 2.4 - Sat Mar 22 17:29:54 2014

Semroc
Iris
Box 1271
Knightdale, NC 27545
(919) 266-1977
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SPECS: 23.8" x 1.17" - 1.9 oz
ROCKSIM FILE: Right Click to Download
SpaceCAD FILE: MISSING - please submit here
REC'D MOTORS: A8-3, B6-4, C6-5

Rating
(Contributed - by Ron Wirth [Who's Who Page] - 09/17/09)

Brief:
Semroc has recently started a new line of Deci-ScaleTM rocket kits that are 1/10 semi-scale models of the originals. The IRIS is one of the first in the Deci-ScaleTM line which is a semi-scale model of the real Iris designed by Atlantic Research Corporation in the early 1960s. This model is a 4 fin rocket with some added details that give a true scale appearance to the finished rocket.

Construction:
I ordered my IRIS from the Semroc website and got the usual prompt and outstanding service that I have always experienced from them. The kit comes delivered in a sealed bag with the front of the instructions displaying a color picture and specification for the rocket. In the kit you will find:

  • 1 Balsa Nose Cone
  • 1 Body Tube
  • 1 Engine Tube
  • 1 Set of Laser Cut Fins
  • 1 Ring Set (with Fin Mounts included in sheet)
  • 1 Chute Pak (12” plastic)
  • 1 Kevlar® Cord
  • 1 Elastic Cord
  • 1 Screw Eye
  • 2 Launch Lugs
  • 1 Engine Hook
  • 1 Thrust Ring
  • 2 Decals Sheets
  • 2 Bands (to wrap around the body tube for detail)
  • The quality of the materials supplied was of a high grade as is normal with a Semroc kit. At a cost of $16.50, this kit is well worth the price for what you get.

The Semroc instructions for the IRIS consist of 25 steps not including finishing. They are written as concise and easy to understand instruction with accompanying diagrams with each step. You begin with some light fin preparation sanding then start on the engine mount. The rocket uses a Kevlar® cord looped onto one end of the engine hook to act as an anchor point for the shock cord. The rest of the engine mount is glued together using the centering rings and engine thrust ring. A piece of masking tape is used around the engine tube to hold the engine hook in place. While the glue is drying, it is time to mark the body tube with the fin guide. This kit uses the standard marking method for Semroc kits by placing the body tube upright on the instruction page to mark the fin locations. I am not a fan of this method at all. After the tube is marked, you glue the engine mount into the body tube.

Now it is time to start working on the fins. I attached the small fin mounts in the small notches in the fins as instructed to do so by using a small amount of white glue. Since this is a scale model, the laser cut fins have an additional notch along the root side to accommodate a band that wraps around the body tube. Because of this I choose to paper the fins so I would not get Fill ‘N Finish into the small notch or have build up near the small fin mounts. I also decided that I would paint the fins and body tube before attaching them to the body tube. More on this will be described in the Finishing section of this review. After I had painted my part as I wanted, I attached the bands as described in the instructions. Then you need to attach the fins. There are no fin fillets on this rocket since it is meant to be a semi-scale model.

The final steps are to attach the launch lugs, glue the screw eye into the nose cone, attach the shock cord, and assemble the parachute. With those final steps completed, finishing is listed as the next step in the instructions. Since I had already painted the parts for my rocket separately before assembly, I should have only needed to apply the decals but things changed as you will find out.

Finishing:
I believe the success of building a scale model resides in the care that is taken in prepping and painting the rocket. As such, I decided to paint the rocket parts prior to assemble with the exception of the engine mount. To paint the fins, I put some double sided tape down on a pan and situated the fins with the root side down. Since they were papered I decided to paint them with no primer coat. My fear was that I would get paint build up on the small fin mounts joints taking away from the appearance of the rocket. After I had painted them with several coats of red, I realized that a couple of light coats of white primer would have helped. You just need to make sure that you are applying the paint in several light coats. An issue with the fins that I didn’t count on came when I removed them from the double sided tape. The tape was sticky enough to remove a couple of layers of paper from the fin mounts. The fins still fit and glued nicely to the body tube.

For the body tube I filled the spiral with watered down Fill ‘n Finish. I did the same for the nose cone after sanding it with 400 grit sandpaper. After sanding, I used 1/8” pin stripe masking tape to mask where the fins and body wraps were to be located on the rocket. I then painted the body tube with a coat of Kilz Original white spray primer. After sanding, I removed the tape to and attached the bands at the instructed positions. I re-masked the fin positions and coated the body tube with a couple of light coats of white primer. After that I used a gloss white paint to finish it off. Be certain to use light coats with some light sanding to make sure that the bands that wrap around the keep their definition. For the nose cone, I primed it with Kilz and a couple of coats of white primer. I used Rustoleum Silver Metallic spray paint for the final color.

At some point in this process I decided that would not paint the body tube with black for the roll pattern. My plan was to create some black decals and use those. My logic for doing so was based on the assumption that the Atlantic Research Corporation decal was the required width of the roll pattern and that the lettering was created with a clear decal sheet. It is actually white printed on black which is probably why there are two small decal sheets for this kit. It was also smaller than the required roll pattern width. This meant that I needed to paint the black roll pattern onto the body tube. Since I had already attached the fins to the body tube, I carefully masked around the fin mounts to achieve the scale look I was aiming for. This is much easier to do if the roll pattern is painted with the fins off the body.

Once the paint had dried for a couple of days, I positioned the decals on the rocket. I have never had any problems with Semroc decals but I put a clear coat on them before they went onto the rocket. The final step in the finishing process was to apply a coat of Future Floor Wax to the entire rocket. The finished weight of the rocket is suppose to be 1.3 ounces as listed in the instructions but mine weighted in at 1.9 ounces.

Construction Rating: 5 out of 5

Flight:

The first flight of the IRIS was on a B6-4 at a launch hosted by the Oregon Rocketry Enthusiast Organization (OREO). The rocket moved quickly off the pad to an altitude from 300’ to 400’ feet. From the roll pattern on the rocket, I could tell there was some minor spin during the flight. There was also a slight arc in the flight that was likely caused from the steady breeze on the field. The ejection happened while the rocket was still moving upward. It is a nice looking rocket as it moves upward in the sky.

Recovery:
This rocket uses a standard Semroc 12” plastic parachute. I believe that this is the proper size but cannot confirm this since my parachute did not unfurl during decent. I was partial to blame for this since I loaded it the night before and should have repacked the parachute before launch. The rocket landed on one of the softer spots on the field with no damage. The shock cord that is supplied with the kit is about 24” long. I added an addition length of cord to this to help insure that no dents would occur from snap back at ejection.

Flight Rating: 5 out of 5

Summary:
The IRIS is absolutely a beautiful semi-scale rocket from Semroc. The kit is interesting enough that keep the advanced rocket modeler engaged in the building process and not too complicated that a modeler new to the hobby would feel lost during the kit’s construction. With the introduction of the Deci-ScaleTM line, I believe that Semroc will bring more people into the hobby that have an interest in semi-scale models that fly. I look forward to future releases and have already picked up the Semroc IQSY Tomahawk for my next build.

PRO’s: Semi-scale look with parts for detailing, good price point for the quality of the kit

CON’s: Maybe the shock cord length

Overall Rating: 5 out of 5

Other:
Be sure to paint the rocket parts prior to assembly and to keep paint from the spots where you need to glue.


Rating
(Contributed - by Chan Stevens [Who's Who Page] - 09/20/09)

Brief:
The Iris is one of the first of a new sport scale line by Semroc called the Deci-Scale, each roughly 1/10th the size of the real thing. This model is based upon the Atlantic Research Corporation's sounding rocket. The kit is just for the upper stage, as the real sounding rocket flew off of different booster configurations, never on its own, so this model would not qualify for entry in an NAR competition. Still, it is a cool looking rocket and a bit more complex a build than the typical 3 or 4 fin fare that's the majority of the commercial rocketry fleet.

Construction:
Components are all excellent quality, as usual:

  • Balsa nose cone (8 inches long, 1/3 of the total rocket length!)
  • Series 11 body tube (1.17" OD)
  • BT-20 motor tube
  • Centering rings, motor block, metal hook
  • Laser-cut balsa fins (4)
  • Laser-cut fin mounts (8)
  • Laser-cut tube bands (2)
  • Kevlar®/elastic shock cord
  • Plastic parachute
  • Waterslide decals

While this is a relatively easy scale model, I'd probably rate the skill level a 2 on the 1-5 scale, simply because the paint/finishing pattern is a little tricky. I'd estimate I spent about 5 hours on this plus finishing, and the finishing was strung out over the better part of a week.

The instructions follow Semroc's newer format, designed to fit in a 3-ring binder which can be spread open while building. It struck me as a little hokey at first, but I have to admit with several hundred sets of kit instructions stuffed into a milk crate for a file, I'm starting to overflow a bit and using 3-ring binders is a pretty good idea. The instructions overall are about 3 letter-sized pages.

The motor mount is typical tube, block, metal hook and centering rings combo, with the Kevlar® shock cord anchored around the forward ring. Mark the body tube for 4-fin pattern using a template on the instruction page, then insert the completed motor mount assembly into the main body tube.

Prior to mounting the fins, though, comes a little scale realism. First, there's a nifty pair of wrap-around bands that just fit under cutouts in the fins. Pay careful attention to the instructions, as there's a glue side and a shiny/don't glue side. The bands are a very precise fit, so I went extremely thin on the glue so that they would make it all the way around twice--the first trip puts down a wide band, then the wrap gets narrower for the second trip around, for the smaller band. One of the bands goes under the fins (before bonding, of course)and the other goes flush with the forward end of the body tube.

The fins themselves get a couple small cardboard mounting plates tacked on underneath them, also in laser-cut notches. Realizing that the fins would be red, mounted on a line where white and black zones meet up, I felt that trying to mask and paint around the plates would be difficult, so I bonded them to the fins and painted the fins offline, mating up to the black/white/silver painted main body later.

The nose cones gets a screw eye anchor, and a pair of 1/8" lugs are tacked on, wrapping up construction. One note on lug placement, keeping the finish paint scheme in mind. There are 8 rectangles alternating black and white (2 rows of 4) on the main body tube. The lower black rectangles and upper white rectangles get decals in the middle, so you want to avoid these areas for lugs. That leaves half the body, but Murphy says if you don't plan it out up front, you'll find yourself trying to apply a beautiful scale decal around a lug.

Finishing:
As noted, I did a fair amount of the finishing before/during construction. For the main tube, with bands applied, I applied a couple thin coats of gray primer, then 2 coats of gloss white, sanding after primer and finish coats. I then drew 4 fin lines with a black Sharpie, which I then used for marking and masking off the rectangular regions, covering up the white. I hit everything with 2 quick coats of gloss black, then masked off the body tube from the aft band forward, shooting the lower section with silver.

The fins, as noted, were painted red offline then tacked onto the main body with CA, and really thin white glue fillets (applied with a syringe).

 

I had previously confirmed that the white on black Atlantic Research Corp decals were white ink, as opposed to clear printed on white-backed paper, so applying them over the black region was fine, though the gloss wasn't quite an exact match. The black Iris decals went on the upper white rectangles.

 

Construction Rating: 4 out of 5

Flight:
For the first flight, I had a chance to enjoy a magnificent late summer day at the field, winds around 6-8 mph, temperatures a perfect 76, clear skies, etc. Since it was such a nice day for a walk, I put this up on a C6-5. It flew straight as an arrow, though it seemed my delay was a hair longer than -5, so ejection was slightly past apogee, which I estimated to be about 600-700 feet.

Recovery:
I certainly did have a bit of a walk, though not too bad. The 12" plastic chute brought it down at a modest but not slow speed, and I recovered everything fine about 400 yards away.

Flight Rating: 5 out of 5

Summary:
Pros--nice scale detail, especially the fins, wraps, and black on white decals.

Cons--none.

Overall, this is a very good scale-like kit for the money.

Overall Rating: 4 ½ out of 5


Rating
(Contributed - by John Venable - 10/17/09)
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Brief:
This is another TIGHT repro from Semroc. Very Sleek and FAST.Semroc supplied me with a 24mm mount for free.

Construction:
The Kit consists of:

  • 1 Balsa Nosecone,
  • 1 Body tube,
  • Motor tube,
  • 4 Balsa fins,
  • 1 screw eye,
  • 1 thrust ring,
  • chute pak,
  • kevlar shock cord,
  • launch lugs,
  • engine hook,
  • a set of decals.

The only con about this Rocket is the Engine Hook. The pro's about this Rocket is everything else, especially the decals don't change a thing. Construction was a snap and the directions are awesome. Every thing went without a hitch. But anyone who knows me realizes that I am going to Pump up this bird to handle the extremes. I added a 24mm mount and the 18mm an Estes D engine hook, 1/8th inch woven Kevlar® shockcord, 3/16th inch balsa fins and constructed this Bird completely with Epoxy. I did not use the ring set for the fins or the set of bands for the body tube. One of my biggest peeves is disruption of airflow.

Finishing:
No cons here, only pros. After assembly I coated the nosecone and the fins with a product called Restore-it. It turns wood to stone, literally. after sanding I applied a coat of Zinsser cover-stain primer. The next day I gave her a light sand, masked off one wing and applied 3 coats of blue to to one wing. After 2 days I masked off the blue wing and applied 2 coat white finish to the body and 3 wings. Then I applied 3 coat chrome finish to the nosecone. After 1 day I applied the decals. For the best finish I suggest Rustoleum High Performance Enamel, trust me!!

Construction Rating: 5 out of 5

Flight:
All 3 flights were on a C6-5, for now. I used wadding until I can figure a something better. I used an Estes D Hook for retention. All 3 flights were super fast and straight.

Recovery:
There are no cons because I pimped it. 1/8th inch Kevlar® shockcord wrapped around the inside of the upper thrust ring and a 12" thin-mil nylon chute. Perfect recovery, no issues at all.

Flight Rating: 5 out of 5

Summary:
This is one Sexy bird. She flies like an Eagle. I am sure with the quality of Semroc products this kit it would fly flawlessly without any alterations. One more thing the people at Semroc build an awesome product and there customer service is a 10.

Overall Rating: 5 out of 5

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[Enter Flight Log]
Date Name Motor Ejection/
Altitude
Wind Notes
09-19-2009 Chan Stevens Est SU C6-5 Just Past (1-2sec) 5-10 mph winds -
09-19-2009 John Venable Est SU C6-5 Apogee - NC Down 5-10 mph winds Event: moffet field
- Maiden Voyage. Fast and straight to 900'. Flawless flight on my beefed up Iris
09-19-2009 John Venable Est SU C6-5 Apogee - NC Down 0-5 mph winds Event: moffet field
- Another perfect flight. This is a perfect motor for this Bird,for now.
09-19-2009 John Venable Est SU C11-5 Apogee - Perfect 0-5 mph winds Event: moffet field
- Holy Cow !!! This was the best flight for this bird.Easily 1200' absolutely flawless. Good thing the RSO didnt see it due to the 1000' Limit. I,m thinking Composites ! CUL8R

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