Enerjet 1340/20 Clone
 

I have been working on my Enerjet 1340/20 for several days now after collecting all the pieces and designing a couple of them. I'm not sure how to post photos of the construction progress.

Jack,

When writing your post scroll down to Additional Options and you will see a link that says Manage Attachments. From there you can upload up to 10 files in one post. Due to the old software I'm using you will need to reduce the file size of the pictures so they are each 2mb or less in size.

Thanks for the help on that.

It all started with reading the 4th edition of the Handbook of Model Rocketry by G. Harry Stein.

I found a pic of the Enerjet 1340/20 in the book and never forgot it. I really wanted to build and fly it, but didn't know where to buy it. I did some research and found information on it specifically the promo flyer by Enerjet.
http://www.oldrocketplans.com/enerj.../enj1340-20.htm

I also found out parts for it are available for sale on the Internet from eRockets.biz. I ordered them and have now put them together.

Since the photo of this rocket was in B&W I checked around to find out what color the fin can and the band on the payload bay were. The experts said the fin can was red and the band was silver. To confirm their answers I found a website that can colorize B&W photos.
https://demos.algorithmia.com/colorize-photos/

I cropped out the title and submitted the photo. The results confirmed what the experts said.

You say the recolorizer confirms that the fin can is red. I don't see a red fin can. Looks more a pale yellow.

The color of the fin can looks red to me and matches the red color of the word "jet" in the Enerjet decal.

Jack,

Really super job on the 3D files for the 1340 fin can!!!!! Great contribution to the hobby. I printed one overnight and it turned out terrific. I used PETG. It's strong and can withstand higher temperatures like ABS and is not brittle like PLA, it also doesn't shrink much and therefore great for printing large thin parts like this. It does have a few pitfalls, it doesn't do detail well, and can have blobbing and stringing, but that can be minimized once you figure out how to best print it with your printer. I should have taken a picture while it was on the printer, it looked like a hot mess with the stringing between the supports required to print the fins! But it cleaned up easy and the stringing was confined to the supports, not the actual part. Less cooling is better, the longer the PETG can stay hot and molten the better it bonds to the layer below, and the stronger the part. I printed this at 240 degrees C. It's not that much more difficult to print than PLA, easier than ABS, and the filament cost is similar to PLA.

Looks great, Tim! I have printed with ABS which I hated due it's problem with shrinking when it cooled. I've been printing with PLA for some time now and love it. I recently purchased a roll of PETG and can't wait to try it out. I also want to get into flexible filaments like TPU and Ninjaflex.

I've posted a second version that doesn't have a launch lug attached.

Future versions include an integrated 1010 rail guide and another that will have fins that have a diamond airfoil that will allow it to fly supersonic with little problem.

This fin can as well as other versions really needs to be flight tested before I start selling them.

Plans in PDF format:
http://www.oldrocketplans.com/enerj.../enj1340-20.htm

Parts List:

(1) Centuri #13 Plastic Fin Unit from an Estes Eliminator (also used in the Centuri Phoenix Bird (#5407), Centuri Argus (#5039), Estes Maniac(#2091), Estes Long Shot (#1980), Estes Challenger II (#1330), Estes Eliminator XL (#1460) among others.)
3D designed version you can download for free and print.
https://www.thingiverse.com/thing:3641770

(1) 12" Estes BT-56/Centuri #13 airframe tube
http://www.erockets.biz/st-13/

(1) #20 to #13 Balsa Reducer
http://www.erockets.biz/semroc-balsa-reducer-13-to-20/

(1) 10" Centuri #20 airframe tube
http://www.erockets.biz/new-category-3/

(1) Semroc Balsa Nose Cone 2025
http://www.erockets.biz/semroc-bals...al-sem-bc-2025/

(1) 29mm x 5.0" MMT

(1) 29mm to Centuri #13 motor mount rings (scratch built with 29mm tubing)

(1) Shock cord - 3/8" x 1 meter long elastic band

(1) Screw Eye

(1) Shock Cord Mount

(2) Parachutes (size will be determined later)

Decals
http://www.oldrocketplans.com/decals.htm

(1) 3/16" upper launch lug

(1) 3/16" lower launch lug with standoff
https://www.thingiverse.com/thing:3649643

1340-20 RockSim file.
https://www.rocketreviews.com/rocks...ing-rocket.html

That only took 45 years.