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semroc_errs.txt
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semroc_errs.txt
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SOURCE ERROR: ST-7400 Semroc has aberrant PN ST-7400 for ST-7 4" length, should be ST-740
SOURCE ERROR: INVESTIGATE Modern eRockets/SEMROC site has separate BT-60 and ST-16 listings
but gives ST-16 dimensions for everything. Legacy Semroc site has Centuri ST-16 dimensions of
ID = 1.600, OD = 1.640 and Estes compatible BT-60 dimensions of ID = 1.595, OD = 1.637 ***
Using Estes compatible dimensions for BT-60, i.e. assuming legacy site is correct.
SOURCE ERROR: T-3.0 inconsistent sizes for T-3.0 said to be "same as the Aerotech and LOC 3" tubes"
but lists ID=2.950, OD=3.000, wall 0.050, which are internally inconsistent
LOC tubes are in fact ID 3.000, OD 3.100, wall=0.050, so I use that.
SOURCE ERROR: T-3.0 incorrect mfr attribution for T-3.0: Aerotech has never offered a 3" tube
or kit; in early 2017 I personally confirmed this with Charlie Savoie, GM of Aerotech.
SOURCE ERROR: PST-65 dimension discrepancies ***
Semroc clear tube PST-65 (also called "BT-65 Clear" on the legacy site) and the corresponding BNC-65xx nose
cone dimensions show significant discrepancies. Here is a table (all dimensions in inches)
SOURCE OD ID WALL REMARKS
Estes 1974 CPC 1.641 1.595 (.023) This is known to be an error in the CPC
Estes 1974 cat, PST-65R 1.796 1.750 (.023) Same values appeared in all 1970s print catalogs
Semroc 2017 site, PST-65 (1.799) 1.737 .031 Specifies "diameter" (presumed ID) and wall only
Semroc 2017 site, BNC-65xx NA NA NA Modern site does not give nose cone diameters
Semroc legacy site, PST-65 1.774 1.750 (.012) Likely to be an error
Semroc legacy site, BNC-65xx 1.796 1.750 (.023)
DISCUSSION
The Estes 1974 Custom Parts Catalog values are completely wrong and can be ignored.
The Semroc legacy site values for the BNC-65xx nose cones BNC-65L and BNC-65AF agree exactly with the
Estes values.
The modern Semroc site has PST-65 values that work out to a compatible OD but a discrepant ID.
The legacy Semroc site gives an OD in the tube listings that is likely to be discrepant as it implies a very
thin wall. it is worth noting that the digits "96" are exactly offset 2 keyboard positions from the
"74" seen in the questionable 1.774 value.
At NARAM-58 I had a conversation with Randy Boadway (proprietor of eRockets and modern Semroc) about the
plastic tube sizes. He mentioned that the sizing of the clear tubes was inconsistent from one lot to the next.
This could possibly account for the smaller ID value given on the 2017 site.
For now I am adopting the Estes print catalog values as the most likely to be correct, and so that the PST-65
related parts definitions in this database will all interchange correctly.
SOURCE ERROR: CPT-720 legacy semroc site lists 1.87" length. Should be 2.0"; has been corrected on 2017 site
SOURCE ERROR: CPT-10 ALL Semroc legacy site erroneously replicates the CPT-8 dimensions for the CPT-10.
Semroc/eRockets dimensions from the 2017 site are inconsistent with ID 1.039", OD 1.060", wall .021" ***
Here I have set the dimensions to match up with actual ST-10 (ID of 1.00) and use the likely correct
.021 wall to give an OD of 1.042
SOURCE ERROR: on the legacy Semroc site, PST-55 and PST-55-6 are both listed with 12" length and identical weight ***
SOURCE ERROR: Semroc legacy site gives length of PST-65L as 5.0", same as PST-65R. Should be 12". ***
SOURCE ERROR: Semroc quotes CPL-5-34 OD as 0.516 which is greater than BT-5 ID of .515"
SOURCE ERROR: Semroc site has PN SEM-CPL-5-1.5 but other text giving CPL-5-1.75 and
description says 1.75" so I went with 1.75"
SOURCE ERROR: Semroc lists a CPL-ST10-3" but dimensions are for an ST-20 tube
SOURCE ERROR: eRockets Semroc 2017 listings for CPL-52H-34 give OD=1.140, ID=0.980. The OD is
exactly the same as the ID of the BTH-52 tube, which is virtually impossible. I
offset the ID and OD down by .002 to be more realistic.
SOURCE ERROR: CPL-55-34 here again the quoted OD of the coupler is exactly the ID of the tube.
SOURCE ERROR: HTC-13 1975 Centuri catalog has HTC-13 length = 1.5", legacy Semroc
site erroneously gives 1.75". It's correct again in eRockets/Semroc 2017 site
SOURCE ERROR: legacy Semroc site has JTC-60C length = 1.75", new eRockets/Semroc site has 1.5"
Estes 1980 catalog gives 1.5".
SOURCE ERROR: AER-11804 eRockets/Semroc 2017 web listing for AER-11804 gives internally inconsistent
values of OD 1.804", ID 1.610", wall 0.083". The OD is too big as the primary
tube ID is only 1.80", and the ID doesn't agree with the given wall thickness. I
set the OD to a plausible 1.795", took the wall thickness at face value, and set
the ID to 1.629 accordingly.
SOURCE ERROR: CPL-ST20-4 eRockets/Semroc 2017 listing for CPL-ST20-4 gives internallly inconsistent values
of ID 1.952, OD 1.981, .036 wall. I took the wall thickness as likely to be
correct and used an OD with offset of .005 from the ID of an ST-20.
SOURCE ERROR: (?) CPL-3.0=34 OD quoted of 2.92" is a very sloppy fit if the
intended mating tube is LOC 3.0" tube with its 3.00" ID. LOC couplers are OD
2.99, ID 2.88, wall 0.055; I adopted that for now *** Investigate ***
SOURCE ERROR: CPL-3.0"-6" inconsistent length. PN given as CPL-3.0"-6", but in description
it is CPL-3.0"-4" and describes 4" length. I adopted 6" *** investigate ***
SOURCE ERROR: CPL-100-6 dimensions on eRocokets/Semroc 2017 site are completely wrong, with
OD 2.920", ID 2.900", wall .034". The OD would be appropriate for the
CPL-3.0". I adopted a correct OD to mate with BT-100, and took the wall thickness
as correct
SOURCE ERROR: CPL-101-6 Data missing for BT-101 couplers. I adopted proper mating OD for
BT-101 and took wall .034 as used in other Semroc couplers *** investigate ***
SOURCE ERROR: The 2018 Semroc/e-rockets site does not list masses for any BR-xxx balsa reducers.
Many have masses given on the Semroc legacy site, but the new ones do not.
SOURCE ERROR: BR-5-T20 price listed at $9.99 on new site though all others of similar size are $3 to $3.50.
No drawing shown.
SOURCE ERROR: BR-5-T20A price listed at $9.99 on new site though all others of similar size are $3 to $3.50.
No drawing shown.
SOURCE ERROR: BR-813 correct overall exposed length is unclear.
Semroc legacy site: 1.70" Disagrees significantly with drawing
Scaled drawing (legacy): 1.99" (cyl section 0.34" plus 1.65" conical taper - pixel scale 224/in)
Semroc/e-rockets new site: 1.75" (1 3/8" plus 3/8" straight section)
Scaled drawing (new): 1.87" (cyl section 0.32" plus 1.56" conical taper - different pixel scale 324/in)
The stated length disagrees with the drawing on both the legacy and new sites. There was obviously an attempt
to improve the description on the new site, and the drawing was changed, but they still don't agree.
I'm breaking the tie by using the new drawing value of 1.87
SOURCE ERROR: BR-1118 Legacy Semroc table gives 1.50" length, but drawing scales to 2.0"
New site does not list length, and has same drawing. Adopting the drawing value.
SOURCE ERROR: BR-1320 Legacy Semroc site gives length as 0.75". Drawing scales to 2.0".
Mass listed is 0.28 oz which seems low for a 2" long adapter; it's the same as for the
1.0" long BR-1316M. The drawing also shows a cylinder section. Overall I think the drawing is
more likely to be wrong, so using the spec value of length 0.75", and the usual #13 shoulder of 0.69"
SOURCE ERROR: BR-1620 Semroc legacy site gives 1.5" exposed length, but the drawing scales to 1.75".
Adopted the spec length because this drawing again looks like a special one with cylindrical section
at the larger end
SOURCE ERROR: BR-1820 and BR-1820L are seemingly conflated on the new Semroc/e-rockets site.
For the unit on this page: http://www.erockets.biz/semroc-balsa-reducer-18-to-20-1-7-8-long-sem-br-1820/
Title: SEMROC BALSA REDUCER #18 TO #20, 1 7/8" LONG SEM-BR-1820
Description text: BR-1820L
Drawing caption: BR-1820
Length, specified: 1 7/8"
Length, scaled dwg: 1.78"
The L suffix usually means "long", and this is confirmed by the URL.
The drawing says "BR-1820", but the photo of the product shows a long reducer that generally
matches the drawing.
For the unit on this page: http://www.erockets.biz/semroc-balsa-reducer-18-to-20-sem-br-1820l/
Title: SEMROC BALSA REDUCER #18 TO #20 SEM-BR-1820L
Description text: Semroc Balsa Reducer #18 to #20 SEM-BR-1820L
Drawing caption: BR-1820L
Length, specified: - not given -
Length, scaled dwg: 0.42"
Here the nomenclature is consistent, but the drawing shows a very short exposed length inconsistent
with the L designation.
SOURCE ERROR: BR-085-175 length not specified on new Semroc/e-rockets site
SOURCE ERROR: BR-085-225 length not specified on new Semroc/e-rockets site
SOURCE ERROR: BRS-84-115 (only found on 2018 Semroc/e-rockets site) has no length given.
SOURCE ERROR: BRS-115-16 drawing is captioned "BRS-116-16" on new site
SOURCE ERROR: BR-115-168 "special" has no given dimensions. Description on 2018 site says only
"Semroc Balsa Reducer #115 to #168 SEM-BR-115-168 Special". All dims scaled from drawing:
both shoulders 1.0", len 1.19", ID of rear tube 1.68", OD of rear tube 1.75"
BR-115-168 description doesn't say what a #168 tube is. I have
no record or memory of a "#168" tube anywhere and a Google search turns up nothing useful.
SOURCE ERROR: BR-115-225 no exposed length given on 2018 Semroc/e-rockets site.
SOURCE ERROR: BR-125-175 has no exposed length given, no drawing, and only a very oblique photo.
SOURCE ERROR: BR-125-175L has no exposed length given.
SOURCE ERROR: BR-125-225 has no exposed length given on new site.
SOURCE ERROR: TA-520 drawing on legacy site has incorrect length, scales to 0.6" (should be 0.75").
Drawing on new e-rockets site is correct.
SOURCE ERROR: TA-2058 legacy site scaled drawing gives length 1.8", whereas
specified length is 2.0"
SOURCE ERROR: TA-7080 has length 1.5" in table on legacy site, but View page gives length 2.25".
Scaled drawing gives 2.25", so the table is wrong.
SOURCE ERROR: TA-7080H has length 1.5" in table on legacy site, but View page gives length 1.0".
Scaled drawing also gives 1.0", so legacy site table is wrong.
SOURCE ERROR: EB-5 OD on 2017 eRocket site of .516 is wrong, must be less than 0.515
SOURCE ERROR: FB-20 has an erroneous duplicate listing as NB-20P
SOURCE ERROR: BTC-6 Semroc legacy site gives 0.615 for OD of BTC-6. It can't be that
big; they list ID of ST-6 tube as 0.610
SOURCE ERROR: BTC-115 Semroc legacy site gives OD of BTC-115 as 1.15". ID of Series 115
tube is given as 1.14" by multiple sources
SOURCE ERROR: (?) BC-933 description is identical to BC-932, they both say BNC-50X for ST-9
SOURCE ERROR: BC-943 and BC-944 Semroc legacy and new sites both show length of 4.3" for BC-943 and
4.4" for BC-944. They are supposed to be modeled after the Estes PNC-50Y and
BNC-50Y, respectively. However the official Estes specs for those items have
identical lengths of 4.375".
SOURCE ERROR: BNC-50G3 Semroc legacy and new sites both describe BNC-50G3 as a #9 cone
SOURCE ERROR: BNC-50G4 Semroc legacy and new sites both describe BNC-50G4 as a #9 cone
SOURCE ERROR: BC-1023 given length on legacy site is 2.3", but scaled dwg is 2.25".
Looks like part number length rounding propagated into the description.
SOURCE ERROR: BC-1023C given length on legacy site is 2.3", but scaled dwg is 2.25".
Looks like part number length rounding propagated into the description.
SOURCE ERROR: BC-1028 length on legacy site is 2.8", but scaled dwg is 2.75".
Looks like part number length rounding propagated into the description.
SOURCE ERROR: BC-1038 given length on legacy site is 3.8", but scaled drawing gives 4.13".
SOURCE ERROR: BC-1043 length given on legacy site as 4.3", but drawing scales to 4.46"
SOURCE ERROR: BC-1048 length given on legacy site as 4.8", but drawing scales to 4.98"
SOURCE ERROR: BC-1121 len is given as 2.1" but drawing scales to 2.15"
SOURCE ERROR: BC-1135 len is given as 3.5" but drawing scales to 3.55"
SOURCE ERROR: BC-1159 len is given as 5.9" but drawing scales to 5.81"
SOURCE ERROR: BC-1350 appears in the legacy site table http://www.semroc.com/Store/Products/NoseCones.asp
but does not appear in the All > nose cones > balsa parts product query
SOURCE ERROR: BC-1648 length is supposed to be 4.8" but legacy drawing scales to 4.6" and superposition
shows it to be exactly the same drawing as for BC-1646 but with the label changed to BC-1648. This error
has propagated to the new eRockets site. Are manufactured BC-1648's actually only 4.6" long?
SOURCE ERROR: BNC-70 and BHC-70Hxx are not separated on new Semroc site, but BNC-80 and BNC-80Hxx are
SOURCE ERROR: BC-T2032C legacy site gives length 3.2", but scaled drawing is 3.25". Looks to be a
roundoff error where Carl changed a 3.25" length to a "32" part number suffix.
SOURCE ERROR: BC-T3033 legacy site gives length 3.3" but scaled drawing is 3.35".
Apparently another part number length roundoff.
SOURCE ERROR: BC-T3541B legacy site gives length 4.1" but scaled drawing is 4.05".
Apparently another part number length roundoff.
SOURCE ERROR: Semroc legacy site lists inconsistent thicknesses for the various sizes of
parachutes...I doubt that these are all correct. Here is the list:
12" 1 mil
14" 1.5 mil
16" 1.5 mil
20" 1.1 mil
24" 1.1 mil
32" 1.5 mil
36" no thickness given
For now I have used the stock 1 mil HDPE Estes type material for all of the Semroc
sizes until we get better information.