Hi all,

I just finished my build of the Centuri Photon Probe. It was very rewarding. It was the first clone I built without purchasing any parts [so much left over in the workshop]. It was fun making centering rings for the first time, as Semroc doesn't show any CR-816 in their store. Iit worked out well considering the available plans were incomplete and I used some ideas extrapolated from the Estes Solar Probe incarnation. I ended up with a 15.75 st-8 tube, 5.25 St-16 main frame, two 1.5 in paper shroud transitions and an available BNC-837 nose. Now Carl and crew have the NC as 4.5 the 845p and I need confirmation before I buy. I thought the overall length of the rocket was 19.2 or thereabouts. Carl's lengths (from the http://www.semroc.com/Store/scripts...arts.asp?ID=554 link) without engine mount come in at 20.2 inches. He has the original Kit [at least I thought I remembered reading that a while ago]. This is getting me crazy. Also I sized my transitions from a scaling of the artwork (I know, I know...) to get the 1.5 inch transition. Thats also where I got the 5.25 St-16 length and that looks about right. The NC should be 3.45 from the math but it looked short and I had a 3.7 available. So, what to do now??????

It looks great and the only change I would make is to get the longer cone and trim the body tube, but it aint necessary. If you guys have any suggestions as to the incongruities, I'm Listening. Primer coat only painted so far.

I also need som color scheme ideas. Never saw the original, and I finished drawing a close decal match in B&W until I get Feedback

Pictures after paint, I promise!!!!!!

Bob

The nose cone I had was supposed to be 4.6" but was less leading me to think it was a Centuri PNC-89. The nose cone in the Proton Probe is 4.62" long and is more pointed. It more closely matches the description in the 1971 catalog. So...

The new replacement for the PNC-89 will be BC-746. Bob, we will send you a prototype when we get one turned.

The shroud is 1.7'. Inner diameter is 4.326", outer diameter is 7.75" and 76.3 degrees of arc. We will send a couple of those as well.

I would not worry about the overall length. Many of them in catalogs and instructions are wrong. In several cases the lengths and weights are based on the prototype. Also in many cases the instructions are also based on the prototypes. The final stage of product engineering changed lengths of tubes, types of nose cones, and even fin design. The Snipe Hunter is a good example of a kit that was kitted with at least three different nose cones and two different payload lengths and the stated weights and lengths did not change or match any combination of parts actually shipped.

We get a lot of questions about why our lengths and weights don't match what they should be. We weighed about 50 kits one time on a triple-beam balance to see if we could detect missing or extra parts by accurately measuring the final kits. The weights varied by up to ten grams. Then we weighed individual pieces and discovered the nose cones, reducers, and fins varied far too much to detect a missing screw eye or engine hook. That also means that all our weights are based on average balsa weight. Our lengths are measured and should reflect the finished model length very closely.

__________________
Carl McLawhorn
NAR#4717 L2
semroc.com

Here's the color scheme from the front of the package!

No, Bob, I haven't managed to get to building this one yet. I have a Tau Zero project to finish first.


Cheers,

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__________________
Jay Goemmer
"Centuri Guy"/"Tau Zero"
YORF Member 28
Semroc SAM #0029
NAR 86131


"I think about organizing things all the time. Never seems to happen. I find something that piques my interest and I'm off on a quest. Or a Centuri. "

--Bill Eichelberger, 02/22/2022


“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014

Thanks for the input friends,

The more I look at the finished model, the more I like it. Jay, the cover art I do remember seeing but fade and/or questionable print veracity makes me wonder if it really was orange. As Carl said, incongruities in the artwork and plans when compared with the actual kit are numerous. Red, a likely suspect, makes it look too much like the Laser-X. Also in the art is a different decal sceme and the cone is way off. The rocket I tried to build was that pictured in the Centuri '75-'76 Winter Rocket Times and I came pretty close. If Carl has that 846 nc ready, It would be near perfect.

I think I'll go with an Orange, simply because I dont have anything with Orange in it.

Thanks again, and if anyone has a Photon-Probe pic to post, please shamelessly post it here.
My pic soon (Paint is ready, but I gotta get some sleep.)

Bob

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Bob, look at models on the launch controller table.

http://www.ninfinger.org/~sven/rock...a/73cen002.html

Edit - The color in that scan looks a little off from the page in my catalog. The red in mine looks a little brighter.

__________________
Quando Omni Flunkus Moritati

Hey, that catalog looks familiar!

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Scott D. Hansen
Ye Olde Rocket Shoppe - Your One Stop BAR Shoppe!
Ye Olde Rocket Plans - OOP Rocket Plans From 38 Companies!
Ye Olde Rocket Forum
WOOSH NAR Section #558

Wow, you are good.

I guess it was red. Now, about that needle I lost in the haystack.....are you busy any time soon!!!

Thanks again,
Bob

What fin shape did it have?

__________________
Quando Omni Flunkus Moritati

Kind'a got sidetracted on a scramjet upscale. (darn you guys for posting pics and making me drool) The Centuri Photon Probe build is finished (decals and all) and although it has been posted that I made some measuring mistakes (minor, I think), it came out pretty good. I will leave it to you to decide if you can tell. Carl has turned the right cone for it and its on its way to me. This one will do for now. Well, only one or two more days left to paint outdoors so I gotta finish the Vector V and scramjet.

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Looks good Bob. Heck I wouldn't have noticed the nose cone if you hadn't mentioned it. Oh so much I wanna do.......

__________________
Don
NAR 53455
"Carpe Diem"