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Old 08-24-2011, 06:30 PM
luke strawwalker's Avatar
luke strawwalker luke strawwalker is offline
Join Date: Dec 2007
Location: Needville and Shiner, TX
Posts: 5,871

These fairings are using the same method Dr. Zooch uses in his kits for external half-round fairings-- gluing "skins" onto an appropriately sized tube, and then cutting them out of the tube wall. Once dry, carefully cut around the skins and liberate the fairings from the parent BT-55 tube. The curvature of the tube has to be "corrected", as if you put the fairing on a flat surface, you'll quickly see that it touches at three points-- the two rear ones and the very front tip, with the sides off the surface. Using an old ballpoint pen inside the fairing for support, gently "recurve" the fairing to a tighter diameter, getting tighter and tighter as you move toward the tip. The tip should basically roll right around the point of the pen. Work slowly to avoid creases. Next, measuring up from the base of the fairing the appropriate amount (since the fairings extend past the back end of the tube a certain amount, and are NOT flush with it) mark the fairings at the appropriate place and measure the width there. This will be the "outside diameter" of the "half-moons" that will go inside the fairings to shore them up and give a place to mount the F-1 engines later on. Using a drafting compass, lay these out, cut them out, and test fit for correctness. I traced around a BT-80 to get the "inner diameter" of the half-moons, and then traces the test fit patterns (which looked like a "D" at that point) onto cardstock and cut the "half moons" out of the cardstock and glued them onto a sheet of 1/8 balsa. These are then cut out when the glue is dry, and sanded to shape, and then glued inside the fairings at the proper place (recessed from the end of the fairing so they're flush with the end of the BT-80 when the fairing is glued on the rocket body-- measure up the inside of the fairing and put a line there to guide the glue-up). Once dry, the fairings are then custom fitted to the tube before being glued in place.

The fairings are custom fitted to the tube by installing a coupler or two inside a spare piece of tubing to shore it up, and then wrapping the tube with sandpaper, and holding the fairing at the proper angle, it's sanded up and down the length of the tube until it conforms snugly to the tube. This will sand the outer edges and the "half moons" at the same time (I did SOME pre-fit sanding to the half moons after cutting them out to get them to conform fairly closely to both the fairing and the tubing to minimize the final custom fit sanding).

I decided after getting the fairings done for the Saturn V, to go ahead and do a second project at the same time that I had in mind a couple years ago when I bought the parts for the nosecones of these rockets-- the "Saturn I-F" that was proposed to replace the "Cluster's Last Stand" amalgamation of Jupiter and Redstone missile-derived fuel/oxidizer tanks used to build the Saturn I/IB first stage. These made the development of the Saturn I first stage easier (and cheaper) but it also meant that the stage weighed a LOT more than necessary structurally (which of course hurts payload-- it's not QUITE as critical on a first stage, which has to save around 10-11 pounds to add a single pound to ultimate orbital payload, but still, the added weight and complexity also increased the cost of materials and manufacturing of the stages, which drove up operational costs for Saturn I/IB and ultimately helped, with other factors, to doom the program). The proposed solution was to create a new first stage, similar to the S-IC first stage of Saturn V, using a single LOX tank above a single kerosene tank separated by an intertank ring. This proposed stage would dispense with the 8 engine cluster of H-1's, and replace them with a pair of F-1 engines like Saturn V, and incorporating the F-1A improvements when they came online. This new stage could also be strapped onto the sides of a Saturn V (using two or four) as Liquid Rocket Boosters, or LRB's (though the term hadn't been coined when it was proposed-- they were called "pods" back then!) Such "dual use" would have really helped the Saturn program and would have most likely been incorporated had the shuttle not happened and the Saturn program kept going (in some form) and was "evolved" over time. This proposal is also quite close to the "Saturn C-3" proposal from the early days of the Saturn program. To replace the Saturn IB, this twin F-1 powered first stage would have been topped with a regular Saturn IB S-IVB stage, IU, SLA panels, CSM, and LAS tower. (See the Saturn Studies Summaries in the scale area for more information on all this).

SO, after re-reading the relevant studies and diagrams, doing a little "comparative anatomy" on the "booster pod" diagram, Saturn IB diagram in "Rockets of the World", and doing some careful measurement and calculation, I came up with the necessary figures to construct the 260 inch Saturn I-F first stage, and mate it to the 260 inch S-IVB second stage of a standard Saturn I-B. Next, the BT-60 is laid out with a reference line and the appropriate measurements to delineate the various tanks, intertanks, forward and aft skirts, and interstages needed. Then the fairings are glued on at the appropriate points. The "half moons" are lined up with the aft ends of the main body tube (BT-80 for the Saturn V, BT-60 for the Saturn I-F)
Once glued on and lightly filleted to ensure no gaps in the bond, the fairings are trimmed and lightly sanded until they're parallel with the aft end of the main rocket body tube. (the difference in curvature means they'll be slightly "out of plane" with the rear of the tube-- this effect is most pronounced on the smaller diameter Saturn I-F, but noticeable on the Saturn V as well). A slight trim with the hobby knife followed by a good sanding with 220 grit really gets everything trued up...

Next everything's test fitted... The Saturn V will have a tube coupler at the S-IC/S-II cylindrical interstage (might make it a baffle-- haven't decided yet, nor on what I'll use to power this (single D/E with outboards for a five cluster most likely) or the Saturn I-F (pair of 18mm's or 13mm's perhaps). Here's the final layup of the fairings on the S-IC on the Saturn V.

And here's the Saturn V S-II stage, conical transition interstage, S-IVB, SLA balsa transition, and CSM cones.

More later! OL JR
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