So,

With my last order from Semroc, I have just about all the parts now for a T-Bird clone. Well, all except the clear payload tube, I'll simply foil cover the payload tube for simulated affect until I can locate one (time to roam the candy aisles during holidays!).

The plans are at jimz: http://www.spacemodeling.org/jimz/kc-9.htm. I'm building it as close to stock as possible, with one more exception. Given the lack of a suitable 18mm booster, I'll build the 1st stage for 24mm, and use a C11-0. The ST-10 tubing makes this work, since an ST-9 motor tube slides right in, complete with aft motor block, and the ST-10 coupler allows inserting the motor from the top, similar to the original design. The only part lacking is a pass-port coupler between the first 2 stages, since it'll be 24mm -> 18mm. The booster should be plenty tough for landings with the combined ST9/10 tube.

Anyhow, when looking through my 1971 Centuri catalog, I noticed what seems to be a discrepancy in the fins. The laser-cut fins from Semroc match the drawing at Jimz: http://www.spacemodeling.org/jimz/centuri/kc-9i.tif , yet the photos from this catalog (see attached), as well as all other catalogs, show a small triangular section at the leading edge of the fins, at least on stages 2 & 3.

Anyone know why they're different?

I'll try to post a bit here as the build progresses. Currently, it's just a bag of parts, while I figure out what to do about the fins. I'm tempted to modify them to match the photos...

Attached Thumbnails

 

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Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

The picture of the model in the 73 catalog - here - does not show the triangular pieces on the lower stages.

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Bill Cooke
NAR #31312
TRA #19705
SAM #0001
Huntsville, AL

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I have wondered about the T-Bird fins for some time. I have two vintage kits from the early 70s and the fins are not like what the 71 and earlier catalogs show.

I also got a copy of the original T-Bird instructions from around '65 when this version of the T-Bird was introduced (there was an earlier version with completely different setup), and THOSE fins do not even match the catalog illustrations.

Conclusion: the T-Bird as we classically know it NEVER had those forward strakes on any of the fins.

The T-Bird as show in the '72 catalog and onward DO show the correct fin design that came with the kit.

Apparently, the T-Bird maybe was originally designed to have those forward strakes and catalog art was drawn up to reflect that, but actual production kits never had them.

The fin sets you got from Semroc are correct (I have a set of their fins too that I planned to use before I got a vintage kit to build).

It took a bit of investigative work to come to this conclusion, but after I got a set of the original instructions and saw that even THOSE did not reflect the fins as shown in the catalog, I concluded that no T-Bird kit EVER came with them.

Look at the 1972 Centuri catalog (one is on Ninfinger) and you'll see they finally revised the catalog art to reflect how the kit fins actually looked.

Earl

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Earl L. Cagle, Jr.
NAR# 29523
TRA# 962
SAM# 73
Owner/Producer
Point 39 Productions

Rocket-Brained Since 1970

I purchased a KC-9 Centuri T-Bird directly from Centuri back in 1968. I built it and flew it a few times. My last flight I lost the 3rd stage (rocket), which drifted out of sight. This kit had the Balsa Nose Cone.
I still have those original plans though.

PaulK's concept of using a 24mm booster for the first stage sounds interesting. Love to see some photos of this if you actually go this route.

And, I do believe that Earl's information re: the Centuri T-Bird is accurate.

Now how about a Centuri T-Bird with the ST-16 Payload section to compete with the Estes Farside-X.

Larry B

There was the KC-9A kit option which came with an ST-13 payload section that was offered in the 1971 catalog, but I have never seen one before, not even a photo of one.

I suspect it was a payload section very similar to that on the Centaur kit. The catalog lists the diameter as 1.34, which is the paper tube diameter (as compared to the plastic tube diameter which is a bit smaller od).

That would be a pretty decent little payload sport flyer, and tricked out with the 24mm booster would probably perform pretty decent.

The T-Bird was probably my most favorite three stager based on looks, because I never had one back in the day, but always wanted one. Didn't have a field to fly it in 'all up' back then either, but did dream about it quite a bit.

Earl

__________________
Earl L. Cagle, Jr.
NAR# 29523
TRA# 962
SAM# 73
Owner/Producer
Point 39 Productions

Rocket-Brained Since 1970

Here's a couple shots (didn't have time for formal scans) of the 1965 version of the T-Bird instructions.

As can be seen in these images, the fins do not feature the forward strakes, even though the catalog art continued to show forward strakes all the way until the 1972 catalog. I do kinda like those Centuri classic strakes.


Earl

Attached Thumbnails

   

__________________
Earl L. Cagle, Jr.
NAR# 29523
TRA# 962
SAM# 73
Owner/Producer
Point 39 Productions

Rocket-Brained Since 1970

Hey Earl,


Are you able to scan those instructions and send them to Scott?


S.

__________________
SAM #0031

I have the exact same plans sheet as Earl. I think my Centuri T-Bird from this era came with the booster and 2nd stage engine mounts pre assembled right in the sealed kit bag.

Larry B

Yes, I believe up until about the 1970 catalog, the kit descriptions on multi-stagers (and Mini Max kits) mention that motor mounts were pre-installed at the factory.

I'll try to get the full sheet scanned and posted here at some point. The entire sheet at once is too big for my scanner bed, so it will have to be a multiple scan deal and pieced together to make one continuous sheet.

Earl

__________________
Earl L. Cagle, Jr.
NAR# 29523
TRA# 962
SAM# 73
Owner/Producer
Point 39 Productions

Rocket-Brained Since 1970

Thanks Bill, I hadn't noticed that, I was looking through all the catalogs up to '71. Notice this '75 catalog shows the strakes again. http://www.ninfinger.org/rockets/ca...75/75cen18.html

I kinda dig that paint scheme from '73, I might just decide to go with it.

Thanks Earl, that's great! Now I just need to decide what fins to use, since I was kind of liking the strakes. Well, I do have enough parts to build 2, so I'll probably go stock on the first one.

__________________
Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org