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  #1  
Old 06-13-2005, 11:19 PM
Vanel Vanel is offline
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Default Looking for info on Centuri Stiletto...

I'm looking to clone a Centuri Stiletto (2 stage, series 7 body tubes) - Unfortunately, the plans on JimZ's site do not have a parts list or fin patterns. Can anyone provide such or give me some measurements?

Thanks in advance...
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  #2  
Old 06-13-2005, 11:51 PM
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CPMcGraw CPMcGraw is offline
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Quote:
Originally Posted by Vanel
I'm looking to clone a Centuri Stiletto (2 stage, series 7 body tubes) - Unfortunately, the plans on JimZ's site do not have a parts list or fin patterns. Can anyone provide such or give me some measurements?

Thanks in advance...


Without having a kit to measure from, I would look at the "typical" body tube lengths used by Centuri, and then compare those with what we now have available through SEMROC.

Example, the booster is almost assuredly 3". Unlike Estes, who used 2.75" tubes for their 18mm motor mounts, Centuri used 3" tubes for their motor mounts.

SEMROC part equivalent is the ST-730. The coupler is called the HTC-7B.

Tricky part is the main body and the nose cone. Let's check the nose cone first...

Moldin' Oldies says their match for that cone is the PNC-76. Checking with the Centuri catalog against the balsa cones, the BC-76 is listed as 3.3" long. Remember that length. If you want a plastic cone (actually a resin cone) instead of a balsa cone, order from Mike.

If you want a balsa nose cone, then the SEMROC part is BC-733. This is a 3.3" ogive cone.

Finally, the sustainer tube. The 1978 catalog says the length was 18.25" for the model. Subtracting 6.3" (or just a tad over 6.25", notice...) from 18.25" (or 18.3") gives us a body tube length of 12". Keep in mind, Centuri was notorius for mis-stating the model lengths in their catalogs.

SEMROC sells this tube as the ST-7120.

With some 1/16" thick balsa sheet for the fins, and a few other odd parts from SEMROC, you'll have as close a clone of this model as you'll find anywhere.

Craig McGraw
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  #3  
Old 06-14-2005, 12:05 AM
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CPMcGraw CPMcGraw is offline
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Additional note...

I called out a single 12" tube for your clone, whereas the original model used two tubes with a coupler to make up the 12" length. Personally, I'd go with the 12" tube and a TB-7 thrust ring internally, with a 24" length of SEMROC's Kevlar thread tied around it for the shock chord mount. I'd dare to say none of us on this forum use the old Estes method for attaching mounts anymore, unless we're in some kind of competition for classic designs where "modern" construction methods are frowned on. We're a very progressive bunch of coconuts on this forum...

If you absolutely insist on staying with the old method, then you want to use another 3" length of tube for the motor mount, and a 9" length forward of that. The SEMROC part number for that tube is ST-790. The internal coupler is the HTC-7.

Go with the 12" tube. It will make the finishing stage much simpler. One less butt joint to sand and fill...

Besides, no one has to know it's not an original kit...

Craig...
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  #4  
Old 06-14-2005, 12:15 AM
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A Fish Named Wallyum A Fish Named Wallyum is offline
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Nice job, Craig. I was trying to put something together, but got frustrated when I realized that there were no fin patterns.
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  #5  
Old 06-14-2005, 12:30 AM
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CPMcGraw CPMcGraw is offline
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Quote:
Originally Posted by A Fish Named Wallyum
Nice job, Craig. I was trying to put something together, but got frustrated when I realized that there were no fin patterns.


Actually, there are, but you have to look really hard to find them...

I'm attaching a copy of the image, so you can see what I mean. You'll have to clean the image up in Photoshop, or some other image program, to get some straighter edges.

I might try to clean this image up and post the results later.

Craig McGraw
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  #6  
Old 06-14-2005, 12:42 AM
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Carl@Semroc Carl@Semroc is offline
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Craig,

Very nice work! It took a little digging, but I found an old one. Before I rip it open, you are right on the tubes. 3,3,9.

The nose cone is 3.0" the PNC-76. Our BC-730 is a balsa equivalent.

I will have to scan the fins and convert them to Corel to laser-cut them.

Carl
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  #7  
Old 06-14-2005, 12:43 AM
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The fins are 3/32"
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  #8  
Old 06-14-2005, 12:45 AM
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Quote:
Originally Posted by CPMcGraw
I might try to clean this image up and post the results later.


...And here they are!

Craig...
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  #9  
Old 06-14-2005, 12:57 AM
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CPMcGraw CPMcGraw is offline
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Quote:
Originally Posted by Carl@Semroc
Craig,

Very nice work! It took a little digging, but I found an old one. Before I rip it open, you are right on the tubes. 3,3,9.

The nose cone is 3.0" the PNC-76. Our BC-730 is a balsa equivalent.

I will have to scan the fins and convert them to Corel to laser-cut them.

Carl


But that's cheating, Carl! You've got an actual kit to measure up, and I've only got a grainy set of images and a tortured mind to work with!

I was right, though, about the measurements being a tad off. I'll bet that 3.0" nose cone in your kit was a grab-what-they-had instead of what it should have been. Was there a length difference between the BC-76 and the PNC-76? I was just following the part number from Mike's list of which cones went to which kit, and interpreted the "76" as a direct carry-over from balsa to plastic.

Thanks for the "heads-up" on the balsa fin thickness. Estes would have used 1/16", but Centuri liked a more conservative, beefier fin.

Craig McGraw
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  #10  
Old 06-14-2005, 01:13 AM
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CPMcGraw CPMcGraw is offline
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Quote:
Originally Posted by Carl@Semroc
The nose cone is 3.0" the PNC-76. Our BC-730 is a balsa equivalent.


Carl,

I went back to the 1978 catalog, and I see what happened. That 3.0" PNC-76 is shorter than the BC-76. But when the kit was originally designed, it was probably with the BC-76. That reference to "grab-what-they-had" is likely more accurate than guesswork.

If I were going to build the model (and I just might), I'd want the 3.3" BC-733 to be used to get it closer to the original length. The original release date was February 1, 1972, so they might have still been using balsa when the model was developed.

Vanel now has an option as to which cone to use...

Decisions, decisions...

Craig...
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