EnerJet KE-4 Egg Crate In The Build Queue
 

I searched the YORF forum for Egg Crate and found at least a couple of members interested in the EnerJet version of this kit (ghrocketman, green dragon) and I’m sure there may be others. I have some files to submit for the Egg Crate as well as a few requests for information & suggestions from YORF forum members concerning the build.

I have two of the PNC-13E/ST-202 Egg Capsules on hand, one of which I’m using to build the EnerJet SR1340 with the large payload section as featured in the Handbook of Model Rocketry 4th Edition (My thanks to SEL for the much needed information he provided to me to assist with that build). A dry fit image of those parts is below waiting for my Semroc order to get here any day now with the EM-9115 engine mounts for 24mm.

I converted the bottom of each of the Egg Capsules to be used on the Semroc LT-125 series tubing instead of the ST-13 tubing these capsules were made to fit into. To accomplish this I cut off the very bottom of the capsule shoulder and left 1” of the plastic shoulder that should have fit inside the ST-13. I also cut 1” of BT-56 to cover this part of the shoulder and I used a piece of wood dowel (bulkhead) to recess up into the shoulder and an Estes BT-56 centering ring that fits nicely from the inside on a little molded ridge and butts up against the 1” of inserted dowel. With a little adhesive the dowel will not be able to pull out of the base because of the centering ring and I can glue a screw eye into the base of the dowel for a more robust recovery attachment than the provided molded eyelet that I removed. I did this since I will also fly a recording altimeter in the capsule when I’m not flying eggs and I don’t want it coming loose. An image of the parts is below and I mention this because if you intend to use ST-13 or BT-56 tubing you can remove the bulkhead & centering ring from the RockSim files below and change the tubing from LT-125 to ST-13 in the files.

I have three RockSim files below. One is for a 29mm mount like the original with the launch lugs mounted as suggested in the instructions. The other two files are for a 29mm mount and a 24mm mount with stand-offs and lugs mounted similar to the Estes 1996 Eggspress/2072 Scrambler instructions. I also provided a .pdf file for those of you that don’t have RockSim so you can have a peek at the design.

Here are the two major questions I have:

Does anyone here have an actual EnerJet Egg Crate fin pattern?
Does anyone here have a scan of the EnerJet Egg Crate decal sheet?

The fin pattern for the EnerJet Egg Crate appears to be different from the Eggspress/Scrambler. I could not read the dimensions because of the scan on Ninfinger to see the fin span measurement in the 72 EnerJet catalog but if you look closely the leading edge has no sweep like the Eggspress/Scrambler and the trailing edge is not clipped. Has anyone else noticed this? It’s also evident in the small picture at the bottom of the page where the kid is putting the parachute into the Egg Crate, as well as in the picture on the rack of rockets on the launch system page.

http://www.ninfinger.org/~sven/rock...2/72ejet10.html

http://www.ninfinger.org/~sven/rock...2/72ejet14.html

What I did was to enlarge the line drawing of the fin from the Egg Crate instructions that are posted on JimZ website until the span was 3” when I printed it out, equal to the span of the Eggspress/Scrambler.

http://www.dars.org/jimz/ke-4.htm

The pattern I estimated is what I used in RockSim and is also included in the .pdf for those of you that don’t have RockSim but would like the estimated pattern. I’d prefer to have a copy of the original pattern/dimensions if anyone here has it but I’m going with this if I’m unable to attain that. A decal scan would be nice as well. I remember when Kevin had Countdown Hobbies there was an original EnerJet Egg Crate decal there but they are rare and I doubt I’ll be able to obtain a scan of one.

Also, (third and final question for this post I promise) what type of paint would you guys recommend for this flexible polyethelene the capsule is made of? Any special paint/primer considerations I should be aware of? I wish I had an original that was molded in black but the Estes versions I have are yellow so I’m going to need to paint them black.

Let me know what you guys think. I’m open for any thoughts or suggestions to assist with the build. Thanks in advance!

Great work, Steve! Can we add this info to the BARCLONE site? Since it's a variation of the original, that would be the best place to put your plans.

Scott

That would be great! If you like I have a RockSim file on my other computer for an ST-13 version without the MODS if you would prefer that since it would be closest to the original, less the fin pattern estimate.

Let me know. If you want I can save a parts list within the .pdf file if that will help.

Thanks

Steve,

Have you also worked up a RKT file for the version you're describing? Might as well add both files to BARCLONE...



Ain't computer graphics fun?

I had to use this method on a few Estes kits when no one had a scan of the fins. Those line drawings are usually not too far off the mark in accuracy, even if they do come out a bit rough-looking at first.

[QUOTE=CPMcGraw]Steve,

Have you also worked up a RKT file for the version you're describing? Might as well add both files to BARCLONE...

Craig I attached the ST-13 version file for you. This one should be the closest to the original design with the fin estimation I did. I would think most would prefer to build this based on the ST-13 tubing to stay true to the original kit.


Ain't computer graphics fun?

I had to use this method on a few Estes kits when no one had a scan of the fins. Those line drawings are usually not too far off the mark in accuracy, even if they do come out a bit rough-looking at first.

If someone comes up with the fin pattern for this one I'll be really surprised. At least by using an estimate based on the similar fin span of the 2072 Scrambler I know it should be pretty close. If you need anything else just let me know.

You have a lot of cool stuff on BARCLONE. I really like the Ascender 29 sounding rocket and the Blue Sneek 29 designs in the proven designs section. :cool:

Understood. I should be back "in one piece" after the start of the year, then I can start looking at the file...



Having never built either, I have nothing else to reference the design to. But I love a challenge... :D



Thanks, Steve. I did a quick count the other day and was a bit stunned to find almost 120 designs posted, with a few more still in the works.

I've been looking for an opportunity to fly the Ascender and Blue Sneek (18mm) versions, but I've either had something to do on that weekend, or it's been a little wet, cold, or breezy along the Gulf Coast (where I live) since about August... :eek:

Anyone ever try to get Krylon Gloss Black to stick to that flexible polyethelene that Centuri and Estes used on their egg capsules and in the more recent Eggspress and (2072) Scrambler kits?

I tried a light sanding surface prep on both capsules. I used Krylon white primer on one and shot the other with Krylon Gloss Black, no primer. I'm going to use one of these on an Egg Crate and the other to top off a 1340.

Wish I had the original Centuri parts that were molded in black .....

http://www.ninfinger.org/~sven/rock...5rt/75rt10.html

.

Aren't the fins from the Eggspress the same as the EggCrate?
I have 2 of the Eggspress kits opened. The fins were die-punched.
Should I post a jpeg of them with dimensions or are you set already?

Also, where did you find that RED fin can?
Or did you paint it that way.

I was playing around with the Semroc balsa part equivalents last nite.
The 1340/20 clone is WILD when you replace both the #13 and #20 tubes with 34" long pieces!
It should cruise slow and sweet on an E9!

Interesting note---- the yellow plastic cone and transition weight LESS than the balsa equivalents.

Without motor mount and recovery device, the complete mock-up of plastic weighed 94 grams where the balsa came in at an even 100 grams.

I can't get anyone to either confirm or refute the EnerJet Egg Crate vs Estes Eggspress fin pattern. To me, these do not appear to be the same fins. If you look at the line drawings in the Egg Crate instructions on JimZ they are a different shape. If you look at the kit page in the 72 EnerJet catalog (bottom right photo and kit line drawing) and also on the rack of rockets on the "do it yourself" page, the Egg Crate fins taper more towards the tip than do the Eggspress. This is my opinion only, but these do appear to be different fins.

http://www.dars.org/jimz/ke-4.htm

http://www.ninfinger.org/~sven/rock...2/72ejet10.html

http://www.ninfinger.org/~sven/rock...2/72ejet14.html

And a pretty good shot of an original Egg Crate on page 2 in the Sept 72 EnerJet News on Old Rocket Plans:

http://www.oldrocketplans.com/pubs/.../enerjet972.htm

I have mine cut and ready to go with my extra Egg Capsule. All I need is a little more time and thanks for offering to post a .jpg image. I robbed both my capsules from Eggspress kits and I still have the fins around here somewhere ;)

The final pattern I went with (may differ from what I posted earlier) is attached. I think my RockSim image export looks pretty close to the image on JimZ but it's still a "best guess".

I know this is three months late, but I just spotted this product reviewed in Model Railroader magazine (Yes, I confess, I am seeing...other hobbies... :eek: ). This appears to be just what you're asking for (or, You asked for it!)...

Specialty Performance Products SXA 1050 Plastic Adhesion Promoter, sold through PPG dealers. About $15 for one can. You spray a good coat, or two thin coats, and allow to dry about 15-20 minutes. You can then spray on any good enamel, and it should stay attached without chipping.

The reviewer sprayed it on some HO scale locomotive handrails before shooting color, and it was able to take a lot of abuse like flexing and bending without chipping the paint. It also stood up to scraping with a fingernail.