Estes Gemini-Titan Questions
Kurt D. Schachner
Hi,
I have been working on building the old Estes Gemini-Titan kit. However,
I've run into a few problems with the construction, and I wondered if
anybody out there would help.
1. First off, the width of the clear plastic fin ring is 2 7/16" wide.
This cannot be any wider because of the launch lug that is in the way.
HOWEVER, the length of the fin root is considerably longer than 2 7/16".
SO, either the fin pattern is wrong, or the leading or trailing edge of
the fin is supposed to stick out beyond the ring. Any ideas?
2. If you use 7/16" for the length of JT-50B stage couplers (on the
engine tubes), then all the dimensions given for the wooden struts are
wrong. I made the struts longer to fit, but I wondered if I used the
wrong lengths for the tube couplers?
3. If you use the engine shrouds given in the plans, they are way too
big, and bump into each other at the trailing ends. I redesigned them so
the bells are smaller and don't interfere with each other.
Also, if anyone needs the patterns for the engine tube centering rings
(they are canted inward), I have those. Plus vector drawings for decals,
both the body tube and the shroud. A friend suggested using the Revell
decals for the capsule, which I did. This decal has white which I cannot
duplicate.
One more thing--this model goes together much better if you do NOT build
the upper shroud like the instructions show. Instead, build it like the
Centuri Saturn V, with body tube separating at the bottom of the shroud.
Use a JT-70 to support the trailing edge of the shroud, and glue the
nose cone in place. I found it impossible to glue that bottom edge onto
the very edge of the BT-70 and still keep a nice form to the shroud.
I realize this may be hard to understand ;-), e-mail me if you want to
discuss it.
Thanks!
Kurt Schachner
Bill Spadafora
Kurt D. Schachner wrote:
>
> Hi,
>
> I have been working on building the old Estes Gemini-Titan kit. However,
> I've run into a few problems with the construction, and I wondered if
> anybody out there would help.
>
> 1. First off, the width of the clear plastic fin ring is 2 7/16" wide.
> This cannot be any wider because of the launch lug that is in the way.
> HOWEVER, the length of the fin root is considerably longer than 2 7/16".
> SO, either the fin pattern is wrong, or the leading or trailing edge of
> the fin is supposed to stick out beyond the ring. Any ideas?
Are you sure you have the fin going in the right direction? I have one
here that I built many ears ago and the root edge of the fin is the same
length as the ring. Would you like measurements from my fins?
> 2. If you use 7/16" for the length of JT-50B stage couplers (on the
> engine tubes), then all the dimensions given for the wooden struts are
> wrong. I made the struts longer to fit, but I wondered if I used the
> wrong lengths for the tube couplers?
The coupler without the centering rings is a little under 3/8". With the
rings it's a little unter 7/16".
>
> 3. If you use the engine shrouds given in the plans, they are way too
> big, and bump into each other at the trailing ends. I redesigned them so
> the bells are smaller and don't interfere with each other.
The bottom if the bell is reinforced with a 20-50 centering ring so
that't the diameter you should have. They just touch on mine.
>
>
--
Bill Spadafora http://users.aol.com/billspad/mypage.htm or
NARTS http://www.nar.org/NARTS/cat.html
bill...@worldnet.att.net 73320...@compuserve.com
Bill...@aol.com
Wayne Hortensius
Bill Spadafora <bill...@postoffice.worldnet.att.net> wrote:
>Kurt D. Schachner wrote:
>> 1. First off, the width of the clear plastic fin ring is 2 7/16" wide.
>> This cannot be any wider because of the launch lug that is in the way.
>> HOWEVER, the length of the fin root is considerably longer than 2 7/16".
>> SO, either the fin pattern is wrong, or the leading or trailing edge of
>> the fin is supposed to stick out beyond the ring. Any ideas?
>
>Are you sure you have the fin going in the right direction? I have one
>here that I built many ears ago and the root edge of the fin is the same
>length as the ring. Would you like measurements from my fins?
I double checked the instructions, which do indicate in step #25 that
the height of the clear plastic fin ring should be 2-7/16". I think the
instructions are wrong here. Here's why: the parts list shows the fin
ring material to be CFS-20 and that's listed in the parts catalog as
3" x 9" x .02"; second, if you measure the length of what I'm taking to
be the root edge in the fin pattern, it comes out to 3". I think the
2-7/16" height a mistaken reference to the length of the fin positioning
guide. Bill, please take a ruler to it and put us all out of our misery,
okay? :-)
>> 2. If you use 7/16" for the length of JT-50B stage couplers (on the
>> engine tubes), then all the dimensions given for the wooden struts are
>> wrong. I made the struts longer to fit, but I wondered if I used the
>> wrong lengths for the tube couplers?
>
>The coupler without the centering rings is a little under 3/8". With the
>rings it's a little unter 7/16".
And here is where part of my argument above falls to pieces. That same
parts list shows the coupler as a JT-50B, and the parts catalog says it's
1" long, and even a quick eyeball look at the drawings in the instructions
shows that to be absurdly long. But it would explain why the struts were
so short...
Wayne
Kurt D. Schachner
Wayne Hortensius wrote:
>
> Bill Spadafora <bill...@postoffice.worldnet.att.net> wrote:
>
> >Kurt D. Schachner wrote:
>
> >> 1. First off, the width of the clear plastic fin ring is 2 7/16" wide.
> >> This cannot be any wider because of the launch lug that is in the way.
> >> HOWEVER, the length of the fin root is considerably longer than 2 7/16".
> >> SO, either the fin pattern is wrong, or the leading or trailing edge of
> >> the fin is supposed to stick out beyond the ring. Any ideas?
> >
> >Are you sure you have the fin going in the right direction? I have one
> >here that I built many ears ago and the root edge of the fin is the same
> >length as the ring. Would you like measurements from my fins?
>
> I double checked the instructions, which do indicate in step #25 that
> the height of the clear plastic fin ring should be 2-7/16". I think the
> instructions are wrong here. Here's why: the parts list shows the fin
> ring material to be CFS-20 and that's listed in the parts catalog as
> 3" x 9" x .02"; second, if you measure the length of what I'm taking to
> be the root edge in the fin pattern, it comes out to 3". I think the
> 2-7/16" height a mistaken reference to the length of the fin positioning
> guide. Bill, please take a ruler to it and put us all out of our misery,
> okay? :-)
Indeed. Bill e-mailed me, and it appears that there are *two* patterns
"out there" for this kit. Bill's fins have the following dimensions:
Root edge: 2 7/16"
Leading edge: 3 9/16"
Leading tip: 1 3/4"
Trailing tip: 1"
Trailing edge: 2 5/16"
And, he says it flys stable with this geometry. Anybody know about why
there might be two patterns?
> >> 2. If you use 7/16" for the length of JT-50B stage couplers (on the
> >> engine tubes), then all the dimensions given for the wooden struts are
> >> wrong. I made the struts longer to fit, but I wondered if I used the
> >> wrong lengths for the tube couplers?
> >
> >The coupler without the centering rings is a little under 3/8". With the
> >rings it's a little unter 7/16".
>
> And here is where part of my argument above falls to pieces. That same
> parts list shows the coupler as a JT-50B, and the parts catalog says it's
> 1" long, and even a quick eyeball look at the drawings in the instructions
> shows that to be absurdly long. But it would explain why the struts were
> so short...
There are numerous discrepancies in the instructions, both in the words
and especially in the illustrations. When I'm done building it (and I
almost am), I'll try and post an eratta sheet.
Kurt
Bill Spadafora
Wayne Hortensius wrote:
>
> Bill Spadafora <bill...@postoffice.worldnet.att.net> wrote:
>
> >Kurt D. Schachner wrote:
>
> >> 1. First off, the width of the clear plastic fin ring is 2 7/16" wide.
> >> This cannot be any wider because of the launch lug that is in the way.
> >> HOWEVER, the length of the fin root is considerably longer than 2 7/16".
> >> SO, either the fin pattern is wrong, or the leading or trailing edge of
> >> the fin is supposed to stick out beyond the ring. Any ideas?
> >
> >Are you sure you have the fin going in the right direction? I have one
> >here that I built many ears ago and the root edge of the fin is the same
> >length as the ring. Would you like measurements from my fins?
>
> I double checked the instructions, which do indicate in step #25 that
> the height of the clear plastic fin ring should be 2-7/16". I think the
> instructions are wrong here. Here's why: the parts list shows the fin
> ring material to be CFS-20 and that's listed in the parts catalog as
> 3" x 9" x .02"; second, if you measure the length of what I'm taking to
> be the root edge in the fin pattern, it comes out to 3". I think the
> 2-7/16" height a mistaken reference to the length of the fin positioning
> guide. Bill, please take a ruler to it and put us all out of our misery,
> okay? :-)
The root edge of the fin and the ring height is 2 7/16". Keep in mind
that these dimensions come from a model I built 30 years ago. I don't
have the original fin patterns.
tropda...@gmail.com
> Hi,
>
> I have been working on building the old Estes Gemini-Titan kit. However,
> I've run into a few problems with the construction, and I wondered if
> anybody out there would help.
>
> This cannot be any wider because of the launch lug that is in the way.
> HOWEVER, the length of the fin root is considerably longer than 2 7/16".
> SO, either the fin pattern is wrong, or the leading or trailing edge of
> the fin is supposed to stick out beyond the ring. Any ideas?
>
> engine tubes), then all the dimensions given for the wooden struts are
> wrong. I made the struts longer to fit, but I wondered if I used the
> wrong lengths for the tube couplers?
>
> big, and bump into each other at the trailing ends. I redesigned them so
> the bells are smaller and don't interfere with each other.
>
> (they are canted inward), I have those. Plus vector drawings for decals,
> both the body tube and the shroud. A friend suggested using the Revell
> decals for the capsule, which I did. This decal has white which I cannot
> duplicate.
>
> One more thing--this model goes together much better if you do NOT build
> the upper shroud like the instructions show. Instead, build it like the
> Centuri Saturn V, with body tube separating at the bottom of the shroud.
> Use a JT-70 to support the trailing edge of the shroud, and glue the
> nose cone in place. I found it impossible to glue that bottom edge onto
> the very edge of the BT-70 and still keep a nice form to the shroud.
>
> I realize this may be hard to understand ;-), e-mail me if you want to
> discuss it.
>
> Thanks!
>
> Kurt Schachner