|
Framework V2 - Cover |
Several experiments were done with various covering treatments. I didn't want the ribs to show, want to present the "hammered" look, and want it to be fairly light. I ruled out model airplane covers because of the likelyhood of the ribs showing, and because I couldn't think of a way to get the hammered surface in that medium. Very lightweight fiberglass would be light enough, but I wasn't sure I could get the "hammered" look in that, so I began experimenting with newsprint and paper mache. The experiments were to find out:
The newsprint I used was from an artist's newsprint sketch pad rather than actual newspaper to avoid having to deal with the ink. I did a litte web surfing to find paper mache recipes. It turns out there is quite a bit of variety in how paper mache can be mixed, and trace ingredients that help prevent mold and make the paste easier to work with.
In this experiment, a simple frame was covered with newsprint. The one on the left was entirely coated with flour/water paste on the back side. The one on the right had paste applied only to the frame.
The full coating actually caused the paper to shrink enough to warp the frame. While the shrinkage is unacceptable, the added stiffness makes the frame fairly invisible. Using paste only on the frame caused some wrinkiling of the paper at the frame, making it look pretty much exactly like paper glued to a wooden frame - not the desired effect. See the Experiment 1 photos below.
For the second experiment, I decided that I needed something that isn't wet, but I didn't know what it might be. Contact cement comes to mind, but I didn't want to go through the trouble of trying to cover with an instant-stick adhesive. A few days later at Home Depot,I ran across some GE Silicone II in a small tube labeled as "Household Glue". That clicked as possibly the "non-wet" adhesive I'd been looking for. I tried a bead around the frame and stuck the paper to it. Sure enough, it spread out nicely but didn't wet the newspaper at all. It didn't make transparent spots, and didn't make the paper wrinkle up at the contact points. Even with oblique lighting, the point where the paper is glued to the frame is almost invisible. See Experient 2 photo below.
 |
 |
 |
| Experiment 1 - Fronts | Experiment 1 - Backs | Experiment 2 - Silicon |
A one foot square of newsprint was painted with the yellow and black colors selected for the rocket. The paint added about 3 grams to the weight of the paper for a single coat, so the paint can be expected to add 35-40 grams to the total weight. Perhaps more if it is necessary to add a final dull-coat.
After thinking about a process for painting and masking, I decided to paint the paper off the rocket as much as possible, then touch up where necessary.
Covering the body was done with one solid wrap and the fins were done with a solid sheet wrapping from one fin, across the tailcone, and up the opposing fin. This made most of the covering go fast, but left all the wrinkles to be worked out in forming the cover around the tailcone, fin trailing edges, and base. The leading edges of the fins are covered with a strip about 1/2 inch wide to close the seam to the airflow. It looks much like the edging on the real V2 fin.
If I did it again, I'd seam the paper at the fin/tailcone joint and glue in a separate sheet to get the "fillet". The paper seams are much less vissible than I expected.
After handling the covered main body and getting a feel for the strength of the paper, I decided that the paper on the nose cone would need some help coping with the aerodynamic pressures of flight. I decided to fill the upper part of the cone with foam. I glued some paper tubes inside the nose to reduce the volume of foam to help curb its tendency to continue expansion over a period of weeks. Ironically, the rest of the rocket is so light that the foam will actually serve to move the CG forward.
 |
 |
 |
| Cardboard tubes to reduce foam volume | The foamed up mess | Shaved and sanded to shape |
Last updated: