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blackshire
01-12-2011, 02:40 AM
Hello All,

Today I received a set of all of the issues of "The Rocketeer Collector's Journal" (RCJ) from Danny Sagstetter. Volume 1, Numbers 9 and 10 (the January 1997 and April 1997 issues) of RCJ contain re-prints of old Semroc Astronautics catalogs (including the Volume 1, Number 1 [March 1970] issue of the Semroc "Astronautic Modeler"). These contain the recommended motors lists (which include the unusual "3/4B" and "3/4C" motors) for Semroc's "first era" model rocket kits, "Retro-Repro" reproductions of most of which are available from Semroc today. These recommended motors lists are reproduced below. Also:

I noticed that the lengths and fin spans given for the original Semroc model rocket kits differ somewhat from those of today's "Retro-Repro" reproductions of those same kits. The specifications for the original kits, which can also be found in the online scan of the Volume 1, Number 2 [May 1970] issue of Semroc's "Astronautic Modeler" (see: www.ninfinger.org/rockets/catalogs/semroc570/570semroc8.html ), are reproduced below (under the original Semroc kits' recommended motors lists), along with the lengths and fin spans (given in parentheses) of today's Semroc "Retro-Repro" model rocket kits. (I've included these *not* as a criticism against Semroc, but simply for historical research purposes).

I have reproduced the original recommended motors lists (and the predicted altitudes, where given) from the old Semroc catalogs so that SAMs can get a better "feel" for the performance capabilities of the unusual motors. (Incidentally, the decor schemes depicted on the Semroc rockets in these catalogs are quite handsome--Carl should include decals for them in the "Retro-Repro" Semroc kits!) Here are the recommended motors lists and the predicted altitudes, followed by the original vs. "Retro-Repro" kits' specifications:


Semroc "Goliath" (cluster model)

Recommended Motors (3 required per flight)

A8-3
3/4B6-3
B6-4
3/4C6-4
C6-5

Expected Altitudes for "Goliath" (dependent on surface finish)

A8............300' - 350'
3/4B6........500' - 600'
B6............625' - 800'
3/4C6.......850' - 1100'
C6..........1100' - 1400'


Semroc "Aphelion" (beginners' sport model)

Recommended Motors

1/2A6-2
A8-3
3/4B6-3
3/4C6-4
B6-4
C6-5

Expected Altitudes for "Aphelion" (dependent on surface finish)

1/2A6........55' - 70'
A8...........210' - 240'
3/4B6.......350' - 400'
B6...........450' - 500'
3/4C6......700' - 900'
C6.........1000' - 1200'


Semroc "XK-23" (sport model with experimental "eject-muffler" [ejection baffle])

Recommended Motors

1/2A6-2
A8-3
3/4B6-3
3/4C6-4
B6-4
C6-5

Expected Altitudes for "XK-23" (dependent on surface finish)

1/2A6.........55' - 70'
A8............210' - 240'
3/4B6........330' - 400'
B6............500' - 600'
3/4C6.......700' - 930'
C6...........950' - 1200'


Semroc "Lune R-1" (large payload model)

Recommended Motors

A8-3
A4-4 (Possibly a typographical error? Perhaps B6-4 was intended instead?)
3/4B6-3
3/4C6-4
B6-4
C6-5

Expected Altitudes for "Lune R-1" (dependent on surface finish)

1/2A6.........55' - 70'
A8............210' - 240'
3/4B6........350' - 400'
B6............450' - 500'
3/4C6.......700' - 900'
C6..........1000' - 1200'


Semroc "Swift" (minimum-diameter beginners' model)

Recommended Motors

A8-3
A8-5
3/4B6-5
3/4C6-6
B6-6
C6-7

Expected Altitudes for "Swift" (dependent on surface finish)

1/2A6........200' - 250'
A8............450' - 600'
3/4B6........600' - 950'
B6............750' - 1200'
3/4C6......1000' - 1750'
C6..........1250' - 2100'


Semroc "Sigma II" (two-stage model)

Recommended Motors (booster motors in left column, sustainer motors in right column)

1/2A6-0.........1/2A6-4
A8-0.............A8-5
3/4B6-0.........3/4B6-5
B6-0.............B6-6
3/4C6-0........3/4C6-6
C6-0.............C6-7


Semroc "Black Brant III" (scale model)

Recommended Motors

1/2A6-2
A8-3
3/4B6-3
3/4C6-4
B6-4
C6-5



ORIGINAL VERSUS "RETRO-REPRO" SEMROC KITS' LENGTHS AND FIN SPANS:


"Goliath": Length: 23.2" (23.9" today), Fin Span: 7.00" (7.0" today)

"Aphelion": Length: 16.0" (14.8" today), Fin Span: 4.50" (4.5" today)

"XK-23": Length: 16.1" (16.1" today), Fin Span: 4.9" (4.9" today)

"Lune R-1": Length: 23.6" (23.3" today), Fin Span: 3.70" (4.0" today)

"Swift": Length: 12.5" (12.0" today), Fin Span: 3.25" (3.2" today)

"Triton": Length: 5.75" (5.4" today), Fin Span: 3" (2.9" today)

"Hydra VII": Length: 32" (30.5" today), Fin Span: 8" (6.9" today)

"Black Brant III": Length: 21.7" (N/A), Fin Span: 3.44" (N/A) [NOT YET AVAILABLE AS A "RETRO-REPRO" KIT]

"Sigma II": Length: 15.0" (N/A), Fin Span: 7.00" (N/A) [NOT YET AVAILABLE AS A "RETRO-REPRO" KIT]


I hope this information will be useful.


-- Jason