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Old 11-05-2017, 08:36 AM
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blackshire blackshire is offline
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Join Date: Jan 2009
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Default Titan IIIA PMC (links)

Hello All,

In the realm of scale model rocketry, kit-bashing—using a non-scale sport kit as the basis (or at least as the source of a few parts) for a scale model rocket—is a fairly common practice. It is less common when an existing scale kit can be used to create another scale model, but below is an example of such an opportunity.

Most if not everyone here is familiar with the MPC 1:100 Scale Titan IIIC kit (see: http://www.google.com/search?source...1.0.0imS1sy8raE ) of the early 1970s, which has been re-issued by Round 2, LLC. This kit—and its "companion" 1:100 Scale Vostok kit (which could also be built to depict Sputnik 1, and interchangeably, too, see: http://www.google.com/search?ei=Bgn...1.0.iGAYMOV4ZOE )—could be built either as display models or as flying scale model rockets. Also:

While the Round 2 re-issues of these kits do not contain all of the parts (or the specific portions of the kit instructions, see [flyable Titan IIIC plans]: http://www.ninfinger.org/models/kitplans/mpc9002.pdf [the Titan IIIC clear fin "patterns" are in Reply #39, see: http://www.oldrocketforum.com/attac...achmentid=36659 in this informative thread: http://www.oldrocketforum.com/showt...IC+instructions ] and [flyable Vostok plans] http://plans.rocketshoppe.com/mpc/m...0/mpc3-0700.pdf ) that were necessary to build them as flying models, both can—if desired—be built to fly without much extra effort. To fly, the Titan IIIC needs a 7.5” length of Quest 25 mm T25 body tube, a 2-3/4” length of Estes BT-20 for the motor mount tube, two Quest centering rings, a motor clip, and a thrust ring. Its fins are made of ~3/32” thick clear styrene or ABS plastic sheet, and:

The Vostok needs a 9” length of Quest 20 mm T20 body tube, a 2-3/4” length of Estes BT-20 to “sleeve-fit” inside it (9” of BT-20 could work by itself, if built up at the top and bottom ends to fit “centered” inside the plastic rocket body), a motor clip, and a thrust ring. Both models need heat protection to keep the ejection charge and—in composite motors—the “ejection charge after-burn” from warping or melting the plastic; stage couplers or Nomex felt glued inside the body tubes provides insulation. Parachute space is limited inside the Vostok model, which used a 20” parachute; a mylar parachute, or multiple smaller ones, would fit more easily. Both models are heavy for their sizes, as is common for all-plastic model rockets, and they fly best on 18 mm composite "D" motors (or on Estes or Centuri C5-3 black powder motors, *if* one has any) rather than on the MPC-recommended 18 mm C6-4 and/or C9-3 black powder motors (or the "closest-match" Estes or Quest motors). The MPC Titan IIIC kit, however, also offers another scale modeling possibility:

Before the Titan IIIC flew, its three-stage liquid propellant core vehicle (Stage 1, Stage 2, and Stage 3 [the restart-able Transtage]) was test-flown by itself in 1964 and 1965, *without* the two huge solid rocket motors that constituted Stage 0, and these four vehicles were called Titan IIIA (see: http://www.google.com/search?source...0.M g_rR98pRVA ). (This "Stage 0, 1, 2, and 3" numbering system was used in order to avoid confusion in the stage designations of the various Titan III versions that did—and did not—use the solid motors; this stage numbering system is also used today, in Orbital ATK's Minotaur family of launch vehicles, for the same reason.) In addition:

The first Titan IIIA fell short of orbit (but it came close; it accomplished 95% of its test objectives), the second placed a large dummy payload into orbit, and the final two vehicles orbited multiple experimental satellites (the third Titan IIIA orbited the LES 1 "ghost" satellite [see: http://www.google.com/search?ei=Ov_...0. VMhtMpNRrwM ], which in 2013 was discovered to be transmitting again, *46 years* after it went off the air in 1967!). These missions—which involved multiple Transtage maneuvers and engine re-starts—were so successful that a fifth planned Titan IIIA flight was cancelled, and that vehicle was modified to fly later as a Titan IIIC core vehicle. A flying scale Titan IIIA model (or a display-only model, if desired) could be made from the MPC Titan IIIC kit, in the following way:

The main difference between the Titan IIIA and the Titan IIIC was the "A's" lack of the tapered "boat-tail" just above the two Stage 1 engines; like the Titan II ICBM and the Gemini-Titan II, the Titan IIIA's Stage 1 engines and their thrust structure were "hanging in the breeze." For a display-only Titan IIIA model, the boat-tail and the Stage 0 solid motors could simply be left off the core vehicle, which could be painted and "decal-ed" to depict one's favorite Titan IIIA round. To create a *flying* Titan IIIA model, the following modifications could be implemented:

In the MPC Titan IIIC kit, the core vehicle is 1.2 " (30.48 mm) in diameter, which is large enough to accommodate two 13 mm (BT-5) motor mount tubes. As in the old BT-70 size Estes Gemini-Titan II kit (see: http://www.spacemodeling.org/jimz/estes/k-21.pdf ), the Titan IIIA's motor mount tubes could be angled slightly inward toward each other. I don't know what this model's weight would be, but I'm confident that two A10-3T motors would provide good performance; so might two 1/2A3-2T motors.

I hope this information will be helpful.
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Last edited by blackshire : 11-05-2017 at 09:29 AM.
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