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  #1  
Old 05-31-2015, 07:36 PM
jdbectec jdbectec is offline
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Default Centuri V-2 specs

I've been driving myself nuts trying to figure out the actual length of the Centuri V-2 body tube. I know that Peter Alway's Bt-60 version says 4.88", but I know that that design requires a shorter Estes plastic cone. I recall it being only slightly longer than the Estes tube when I compared them back in the day. Can anyone give me an accurate measurement? I have the proper cones already so all I need is a proper length for the tube.

Thanks in advance,
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  #2  
Old 05-31-2015, 08:28 PM
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I used 4.5" with both the BMS cone and boat-tail and the Semroc cone and boat-tail.

1) On the left the Bumper V-2/WAC
2) Bumper before paint
3) Bumper, Blossom (with an experimental 1.64 inch extension) and stock.

The Bumper had scratch fins; the others had Semroc laser cut fins. Blossom has Semroc nose and boat tail. I need to finish these . . . .
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NAR 79743
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I miss being SAM 062

Awaiting First Launch: Too numerous to count
Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard
Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774
On the Bench: 2650;
Dream Stage: 1/39.37 R-7

Last edited by MarkB. : 05-31-2015 at 10:21 PM.
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  #3  
Old 05-31-2015, 10:53 PM
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K'Tesh K'Tesh is offline
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My V2 built by my band teacher back in the day has a body tube that is 4" exactly (I just measured it). I don't know if he did anything to customize it, but it shows no evidence of having been altered after assembly (say chopping off a damaged section).

https://www.flickr.com/photos/94793...157635127535067

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  #4  
Old 05-31-2015, 11:35 PM
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Guys,

It's a math problem: The real V-2 was 65" in diameter: Series 16 tubing is 1.64 inches in diameter, so your scale is 1/39.6.

From tip of the nose to top of the boat tail was 377.8" on the real thing. Divide by 39.6 yields 9.54" so measure your nose cone and cut your body tube to length.

And the 4" body tube was the correct length for an Estes/ Semroc BT-55 based 1/49 scale V-2 not the larger Series 16 Centuri 1/39.6 model. I'll bet your band teacher model is BT-55.


* Measurements from Rockets of the World, Third ed.
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NAR 79743
NARTrek Silver
I miss being SAM 062

Awaiting First Launch: Too numerous to count
Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard
Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774
On the Bench: 2650;
Dream Stage: 1/39.37 R-7
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  #5  
Old 05-31-2015, 11:47 PM
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K'Tesh K'Tesh is offline
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Quote:
Originally Posted by MarkB.
Guys,

It's a math problem: The real V-2 was 65" in diameter: Series 16 tubing is 1.64 inches in diameter, so your scale is 1/39.6.

From tip of the nose to top of the boat tail was 377.8" on the real thing. Divide by 39.6 yields 9.54" so measure your nose cone and cut your body tube to length.

And the 4" body tube was the correct length for an Estes/ Semroc BT-55 based 1/49 scale V-2 not the larger Series 16 Centuri 1/39.6 model. I'll bet your band teacher model is BT-55.


* Measurements from Rockets of the World, Third ed.


The body tube is a BT-60 (it can easily fit a modern Estes PNC-60L nosecone), it is certainly not BT-55, I'm looking at it right now... The parachute says Centuri Engineering. There are no other markings on the rocket. The shock cord is elastic cord (not a rubber band), and mounted with a tri-fold "teabag". That said, there is evidence that a ring to mount the shock cord was glued in at one time.

The fin details match the instructions I found on JimZ. (http://www.spacemodeling.org/jimz/ks-19.htm)

It also matches the description in the 1971 Centuri catalog I bought at the same time I bought the rocket. It is over 14 1/8" long*, but damage to the nosecone's tip has shortened it some (looks like it would have been less than 14 1/4" long).

*Measurements from actual rocket sitting next to my left elbow
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Dreaming of making the rockets I dreamed of as a kid (and then some).

"The Guide says there is an art to flying", said Ford, "or rather a knack."
"The knack lies in learning how to throw yourself at the ground and miss."


Launching is Optional... Landing? That Depends on Trees.

Last edited by K'Tesh : 06-01-2015 at 12:09 AM.
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  #6  
Old 06-01-2015, 12:25 AM
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Well,

By visiting your Flickr site, your fins look like they are Centuri-style with paper details. So a real V-2 was 552.2" tall, which translates to 13.94" tall at 1/39.6 scale. So yours is in the ball park at just over 14" tall. V-2s are notorious for marginal stability so a little over-length in a commercial kit would not be a bad thing. You win the bet, yours is a Centuri kit.

So back to the math: nose cone + tube should equal 9.54". The boat-tail should be 3.68" long and the fins extend a further .73" for a total of 13.94" at that diameter.

My boat tail from Semroc is exactly 3.69" (to the shoulder); my nose cone is 5.22" long; my fins extend down .70" so my body tube should be 4.33" and is therefore slightly over-length at 4.4875".

So the bottom line is measure. If your balsa pieces are the same length as mine, there's your answer.
__________________
NAR 79743
NARTrek Silver
I miss being SAM 062

Awaiting First Launch: Too numerous to count
Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard
Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774
On the Bench: 2650;
Dream Stage: 1/39.37 R-7
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  #7  
Old 06-01-2015, 12:35 AM
K'Tesh's Avatar
K'Tesh K'Tesh is offline
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Not a problem...

Nosecone shoulder is 9mm long. I can't be 100% on the exposed length due to damage.

My tail cone is 3.5" long (exposed).
Tail cone shoulder length (measured from inside the body tube) is 1/2" .

Bottom edge of fin extends 7/8" below rear of tail cone.
__________________
.
.

Dreaming of making the rockets I dreamed of as a kid (and then some).

"The Guide says there is an art to flying", said Ford, "or rather a knack."
"The knack lies in learning how to throw yourself at the ground and miss."


Launching is Optional... Landing? That Depends on Trees.

Last edited by K'Tesh : 06-04-2015 at 09:32 AM.
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  #8  
Old 06-01-2015, 12:47 AM
MarkB.'s Avatar
MarkB. MarkB. is offline
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So K'Tesh, your nose cone is + or - 4 5/8" (to the shoulder)?

And the remaining question is: what are the dimensions of jdbectec's balsa pieces? Cone + tube + boat tail shoud be just short of 13.25".
__________________
NAR 79743
NARTrek Silver
I miss being SAM 062

Awaiting First Launch: Too numerous to count
Finishing: Zooch Saturn V; Alway/Nau BioArcas; Estes Expedition; TLP Standard
Repair/Rescue: Cherokee-D (2); Centuri Nike-Smoke; MX-774
On the Bench: 2650;
Dream Stage: 1/39.37 R-7
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  #9  
Old 06-01-2015, 12:51 AM
K'Tesh's Avatar
K'Tesh K'Tesh is offline
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Quote:
Originally Posted by MarkB.
So K'Tesh, your nose cone is + or - 4 5/8" (to the shoulder)?

And the remaining question is: what are the dimensions of jdbectec's balsa pieces?


As it stands now, it's exactly 5.75" long (plus the 9mm for the shoulder), and it would have been longer if it hadn't been munched.

My earlier comment about can't be certain about the exact length was intended to refer to the original length. To measure the nosecone, I cradled the body tube in a piece of angle aluminum, held the aluminum and rocket against a flat surface, marked it, then measured it from the end of the aluminum.
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__________________
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Dreaming of making the rockets I dreamed of as a kid (and then some).

"The Guide says there is an art to flying", said Ford, "or rather a knack."
"The knack lies in learning how to throw yourself at the ground and miss."


Launching is Optional... Landing? That Depends on Trees.
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  #10  
Old 06-01-2015, 01:05 AM
K'Tesh's Avatar
K'Tesh K'Tesh is offline
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One thing to keep in mind with Semroc (under Carl, and Sheryl) is that they didn't exactly clone old kits, for legality reasons. Their kits were built to be very close to the originals, but not so close as to get them in trouble with the lawyers. I understand at one time they were ordered to stop, but after talking to Vern, they were able to hammer out an agreement.

I discovered this to be true when I started comparing actual Estes parts for the Omega to the Semroc parts. That's why I'm always asking for scans of original parts, even when Semroc (or someone else) offers "the same kit".

I doubt that Randy will change this policy, but who knows, he might.
__________________
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.

Dreaming of making the rockets I dreamed of as a kid (and then some).

"The Guide says there is an art to flying", said Ford, "or rather a knack."
"The knack lies in learning how to throw yourself at the ground and miss."


Launching is Optional... Landing? That Depends on Trees.
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