The WAC Corporal is one of the most popular kits from Aerospace Speciality Products and now comes with the Tiny Tim Booster to make a two-stage, sport-scale rocket. My kit is the 18/18mm version, however, it also comes in a 24/18mm version.
This was really the first scale kit that I have put together. It is approximately 1/12th scale.
The instructions had 11 pages. There is a brief summary about the real WAC Corporal, two pages of interesting "Notes on Adhesives" which you should review since you do use different glues for different assembly steps. The assembly instructions were broken down into three sections: the Tiny Tim Booster, the WAC Corporal upper stage, and final construction. I found the the instructions to be clear with a lot of text explanation and and appropriate number of reference drawings.
The Tiny Tim Booster has a body tube, motor mount, 1/16" dowels to attach to the upper and lower telescoping tubes, 4 strips of styrene and 3 precut fins as its main components.
Assembly required some patience and finesse. Rubber bands (supplied) were needed to hold the dowels in place for gluing and it was necessary to really check for alignment.
The four styrene strips are used to add detail to the Tiny Tim booster and are evenly spaced at the lower end of the booster, all of which go under the three fins. Gluing these on also required rubber bands and CA glue. You also have to mark and groove the to accommodate the strips.
The WAC Corporal's main components are a body tube, motor mount, Kevlar shock cord, elastic shock cord, balsa nose cone with 2 nose weights (washers) and an eye-screw, 3 pre-cut balsa fins, a square balsa stick and a Mylar parachute.
Assembly of the WAC Corporal is relatively easy and doesn't require any special techniques.
The instructions include nice illustrations for the shaping of the fins. I like how the instructions say, "If you want a slightly less scale fin, simply round all edges of the fins except the root edge." I didn't. I worked hard at getting the shape like the illustrations. Shaping is required for both the Tiny Tim and the WAC Corporal.
The launch lugs are mounted on a thin basswood strip before being glued to the body. This little offset is nice to prevent the rod from rubbing the rocket body, however, its functional value is to allow the rod to clear the 4 styrene strips on the booster.
The motor mounts include engine blocks and are set up for stand 18mm motors. They do not have retaining hardware. The WAC Corporal's motor mount has the Kevlar shock cord tied around it and then the upper centering ring placed over the shock cord.
The remaining portion of the recovery system includes a piece of elastic which is tied to the Kevlar shock cord and to the nose cone's eye-screw. A swivel and 12" Mylar parachute finish the recovery system.
I could go on, because there was actually quite a lot to building this kit. I'm not saying anything was too difficult but there are quite a few techniques used that I have not come across in other builds. Aerospace Speciality Products has made the claim that they offer "Kits YOU Build!". I agree and encourage others to give one of their kits a try. If for no other reason but to pick up on some of the various techniques used. You may apply them to other kit builds or for scratch building.
For finishing I always rely on several good coats of Plasti-Kote primer. I then followed the color scheme described in the instructions. I had one issue when my black reacted with my yellow. I had to re-sand and clean it up then repaint. Happens every now and then when you mix brands and types of paint. I guess I should always test . . .
Overall, for CONSTRUCTION I would rate this kit 4 points. Take your time and read all of the text. It would have been good to have some wrap-around type of fin marking guides although this was not a big issue. Motor retention would have been nice but would take some away from the scale look.
The recommended motors for the WAC Corporal as a single-stage are A8-3, B4-4, B6-4, and C6-5 (or 7). The recommended motors for the two-stage are B6-0, C6-0 with an A8-3 (or 5), B6-6, or C6-7.
I first flew my kit as a single stage on an A8-3. Being able to observe the whole flight I was able to see that it was still climbing fast at ejection. At ejection the nose cone separated with the parachute and the main body fell to the ground. Upon inspection the elastic had broke just above where it is tied to the Kevlar.
This doesn't surprise me too much since the nose cone has two heavy washers as nose weight attached to it. This puts a lot of extra mass in motion which in turns puts a lot of stress on the shock cord at the "snap" point. It, no doubt, didn't help that it was still traveling upward. I reassembled everything but had to use a three-fold attachment method since I could no longer reach the Kevlar loop inside the tube.
I then flew it on a B6-0/B6-6 combination. The second stage ignited and took off, while the booster turned and "flew" straight and stable downward into the ground. This impact broke one of the dowels that hold the telescoping tube. It should be repairable.
I didn't see ejection, however, after recovery it was obvious that it wasn't at apogee. My guess is that it was still going upward based on my observation on the A8-3 and a later observation on a C6-7. The obvious indicator was the 1/2" tear (zipper) at the upper section of the WAC Corporal.
After putting a single piece of tape around the top, I flew the WAC Corporal again as a single stage on a C6-7. It was still going up at ejection and upon recovery the upper portion of the body tube was badly damaged.
On the positive side, Aerospace Speciality Products has made an excellent gap-boost design. There is a 6" space between the top of the booster motor and the bottom of the sustainer motor. With the removable staging tube, it can look realistic on the stand and still function in flight.
For FLIGHT/RECOVERY, I would rate this kit 2 points. I think motor selection is critical on this one and I would also recommend doubling or even tripling the length of the shock cord, especially due to the nose cone weights. It was certainly a straight a fast flier, but use the longer delays. I don't know what to say about the Booster coming back down like a rocket but I can not see this as being terribly durable unless it lands in the grass.
Overall, the WAC Corporal with Tiny Tim Booster was a challenging kit to build utilizing many build techniques. It was fun to be able to learn them and see the results in a sharp looking sport-scale model. I give the kit an OVERALL rating of 3 points.