NCR 4" Katana

[bobby_hamill]

I went to the Ye Olde Rocket Forum and found the side view of a Mini Katana so that gave me the shape of the fins
The Mini K had a fin span of 9.1 inches with a airframe of 2.6 inches diameter. So if I subtract 2.6 from 9.1 that would give me
the simi span of 2 fins divided by 2 that would give me simi span of 1 fin of 3.25 inches

I did a tracing of the fin shape and went to open rocket and inserted the fin shape on a 2.6 diameter airframe . then inserted 1 fin with a fin span of 3.25 inches
I then scaled up the open rocket from a 2.6 diameter to a 4 inch diameter.

Then I went to a pdf of a NCR catalog and read the 4 inch Katana total length was 67 inches and the 4 inch nosecone was 16 inches long attached to a 12 inch
payload compartment . So 16 + 12 =28 inches 67 inches - 28 inches is 39 inches or the length of the main airframe

link to the YORF

https://forums.rocketshoppe.com/showthread.php?s=d09e47b6123c7b850cdf098954263816&t=18670

 

[bobby_hamill]

Long story short here are the results
the 4 inch K fin simi span is 5.5 inches
open rocket file + the pdf file of the fin pattern for the 4 inch K

 

[bobby_hamill]

One last photo

 

[bobby_hamill]

I hope this post is not to long but here are some of the steps I use in up scaling a rocket and I wanted to pass on the
information to help some people just starting in the up scaling process.. I was up scaling the Estes and the Centuri versions
of the Payloader II to a 4.024 outside diameter airframe

Enjoy !

Up scaling the Centuri and Estes versions of the Payloader II Rocket


Centuri First


Main airframe ST-1010 = 10.5 inches long
Clear Payload Tube CPT-102 = 2.5 inches long
Outside diameter of airframe = 1.040 inches
Find percent increase from 1.040 diameter to 4.024 diameter
Percent increase = 286.923 percent
286.923 percent of 10.5 = 30.12 inches for main body tube
286.923 percent of 2.5 = 7.17 inches for clear payload tube
So for a 4.024 up scale the
Main body tube = 30.12 inches
Clear payload tube = 7.17 inches

Now the Estes version
Main airframe 030456 ( BT-50A ) = 10 inches long
Clear Payload Tube 030608 ( PST-50S ) = 4 inches long
Outside diameter of airframe = 0.976
Find percent increase from 0.950 diameter to 4.024 diameter
Percent increase = 312.295 percent
312.295 percent of 10 inches = 31.22 inches for main body tube
312.295 percent of 4 inches = 12.49 inches for clear payload tube
So for a 4.024 up scale the
Main body tube = 31.22 inches
Clear payload tube = 12.49 inches

Bobby