#11
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see: http://www.lulu.com/content/paperba...an-form/8075185 http://www.lulu.com/product/cd/what...of-2%29/6122050 http://www.lulu.com/product/cd/what...of-2%29/6126511 All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com. NAR #54895 SR |
#12
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My PMC building days are pretty much over, but if I were tackling a new project, I'd be doing everything possible to cut mass out of the model. Most PMC builders push the thrust to weight ratio on these birds pretty close to the minimum, and if there's any wind at all, the flight goes south pretty quickly. My $0.02. WMMV.
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A dark night in a city that knows how to keep its secrets. But high above the quiet streets on the 12th floor of the Acme Building, one man is still trying to find the answers to life's persistent questions. Guy Noir, Private Eye. Fox Valley Rocketeers: http://www.foxvalleyrocketeers.org |
#13
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100% agreement with Mark above.
With the C5-3 returning, one should be able to use BP SU power in 18mm PMCs. I definitely would NOT try r/c conversion. It's enough to get one to fly in a stable rocket/chute configuration.
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When in doubt, WHACK the GAS and DITCH the brake !!! Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't ! Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY. ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC ! |
#14
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(flew/fly very stably, so an F-104 PMC model should, with relatively little or possibly even no forward ballast, fly equally well.)
I respectfully disagree. I have built four F104 models and each one if them required a significant amount of ballast to get the CG where it needs to be. I used another modelers CP calculation that was derived from the cardboard cutout method. Each model flew very well. YMMV
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Jim Filler NARHAMS # 139 NAR CB - RCPC |
#15
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__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see: http://www.lulu.com/content/paperba...an-form/8075185 http://www.lulu.com/product/cd/what...of-2%29/6122050 http://www.lulu.com/product/cd/what...of-2%29/6126511 All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com. NAR #54895 SR |
#16
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The version of F-104 that is modeled for PMC flying can also make a difference. For example, the XF-104 and YF-104A, F-104A, and F-104C had/have shorter (from front-to-back; that is, smaller-chord), and thus somewhat lighter, vertical stabilizers than other F-104 variants (and the YF-104A also lacked the centerline ventral strake that later F-104 variants have, which would delete a bit more tail mass, in a YF-104A PMC model). Plus, some F-104 variants (the F-104B, F-104D, TF-104G, etc.) have two seats--and definitely noticeably longer cockpit canopies--which add more mass well ahead of the wings, which would benefit PMC models of these Starfighter variants. Also: The Cox and Estes X-15 RTF models (particularly the latter) flew/fly well, and they didn't/don't need ballast. Their wings' and tail surfaces' relative sizes and locations (with respect to each other, and to their fuselages' widths, lengths, and fineness ratios) were/are similar to those of the F-104. In any event, of course I concur with the wisdom of determining the location of a PMC model's--or *any* non-kit model rocket's--CP (Center of Pressure) with respect to the model's Center of Gravity (CG), and adjusting either (or both) to ensure stability in vertical (or nearly so, for launch angles up to 30 degrees "down" from the local vertical), rocket-powered flight. But as with the RTF X-15 models, F-104 PMC models need not always require added ballast up front.
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see: http://www.lulu.com/content/paperba...an-form/8075185 http://www.lulu.com/product/cd/what...of-2%29/6122050 http://www.lulu.com/product/cd/what...of-2%29/6126511 All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com. NAR #54895 SR |
#17
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Blackshire.
I downsized a Fat Cat F-104 Starfighter in 2011. I included my yorf post. Been flying it for years. Daniel https://forums.rocketshoppe.com/sho...104+starfighter https://www.rocketreviews.com/fat-c...hobbs-2054.html
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If it flies, I can crash it! |
#18
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__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see: http://www.lulu.com/content/paperba...an-form/8075185 http://www.lulu.com/product/cd/what...of-2%29/6122050 http://www.lulu.com/product/cd/what...of-2%29/6126511 All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com. NAR #54895 SR |
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