Delta-4 Heavy 1/75 scale model rocket project
(by Bob Supak: Phase 1 – Making the nose cones)
|
|
|
|
|
|
Oak hardwood glue-up. |
|
|
|
Nose cone masters will be turned from this block. |
|
|
|
Turning first nose cone master. |
|
|
|
Starts to take shape. |
|
|
|
Master cone turned for 2.56" body tube. |
|
|
|
Turned cone received 2 coats of red putty and several coats of filler primer and plenty sanding to produce slick finish. |
|
|
|
Part is finally cut from turnstock. |
|
|
|
Fits like a glove. J |
|
|
|
Now turning inner part of cone. |
|
|
|
Part cut to maintain about 2 mm final wall thickness for nose cone. |
|
|
|
Again, Red putty, sanding and filler primer to get slick finish. |
|
|
|
Final coat of lacquer for RTV barrier. |
|
|
|
Starting to make first mold box using large paper tube. |
|
|
|
Using other stuff to complete mold box. |
|
|
|
Just poured about 2 lbs of Alumilite quick-set RTV into mold box. |
|
|
|
Finished RTV mold next day with master cone (on the right) removed. |
|
|
|
Starting to build mold box for second half of 2-part mold. |
|
|
|
Again, the mold box is filled with quick-set RTV. |
|
|
|
After making the negative mold on the far left, it was then filled with RTV to produce the positive RTV part shown to the right, which is identical to the black hardwood part. |
|
|
|
All required masters and molds. |
|
|
|
Finally get to make a plastic nose cone. Liquid Alumilite is poured into the bottom RTV mold. The inner RTV male part is then inserted into the mold and centered. |
|
|
|
Excess plastic is squeezed out. |
|
|
|
20 minutes later, the nose cone is cooked and can be removed with air pressure. |
|
|
|
About 50 lbs of air pressure is required to force nose cone out of RTV mold. |
|
|
|
Voila! Now need to remove male RTV mold from inside of plastic cone. |
|
|
|
Must drill small hole in tip of nose cone to provide place to insert air needle. |
|
|
|
Again using air pressure to force male RTV mold out of the plastic nose cone. |
|
|
|
It pops right out. J Still need to clean up flashing and sand bottom nice & flat on startionary electric disk sander. |
|
|
|
Result – Three 1/75 scale Delta-4 Heavy nose cones. A little Red putty & sanding and the hole at the tip disappears. |
|
|
|
Yep, they’re hollow. |
|
|
|
Quick mock-up to see give an idea of what they will look like on finished model. |
|
|
|
The cones do have a nice smooth finish. |
|
|
|
Here’s the Alumilite product, the liquid plastic on the left and the quick-set RTV on the right. |
|
Sources for Alumilite products: When I first used this stuff years back, I purchased it from "Texas Art Supply" on Voss, off Westheimer. And as a matter of fact, I have been back down there in the past month to purchase more. You should first call to make sure they have the product in stock. They have another location somewhere in the Montrose, but they never have the Alumilite product. At the beginning of this project, I searched high & low and finally found an online hobby shop that carried all Alumilite products and ordered some from them. Great service – no complaints. The name of the place is called hobbyengineering – nifty site. Look for the building materials section – you will see Alumilite. http://www.hobbyengineering.com http://www.hobbyengineering.com/SectionBM.htm It appears that Alumilite does not sell the stuff themselves, but only sell via distributors. Their site does however describe all the products, show how to make molds and also have specs. Their site is: |
Delta-4 Heavy website
http://www.boeing.com/defense-space/space/bls/d4heavy/flash.html
Boeing Delta-4 Heavy photo gallery
http://www.boeing.com/companyoffices/gallery/images/space/delta_iv/deltafour.htm
