enerjet sounding rockets?

[Doug Holverson]

I was wondering if anybody had any experience with the old Enerjet sounding rockets like the 1390?

BTW, the nose and fin can lived on with kits like the Centuri Argus and Phoenix Bird and the Estes Maniac and Eliminator.

 

[ghughes1138]

I flew a couple of the 1340s back in the day carrying transmitters as part of a University project to build a small sounding rocket to look for temperature inversions. Worked well on Enerjet E and F engines.

The body tube was thicker than the Centuri ST-13 tube that was used in the Argus or other kits.

Another member of our club built the Enerjet 2250 cluster rocket (this later became the 2650, but I think he bought the original version). Quite spectacular.

 

[K'Tesh]

eRockets has the Rocketerium Trident which is based on the 2250 (if not an outright clone). The NC shape may be different than the old enerjet promotional info though.

 

[K'Tesh]

Enerjet 1340/20 Project

Back in the early 1980s I read the 4th edition of the Handbook of Model Rocketry... Handbook Of Model Rockety 4th Edition by Jack Hydrazine posted May 19, 2019 at 6:45 AM and found a photo of this rocket... Enerjet 1340-20 In Book by Jack Hydrazine posted May 19, 2019 at 6:44 AM The Enerjet...

www.rocketryforum.com

 

[dwinings]

I was wondering if anybody had any experience with the old Enerjet sounding rockets like the 1390?

BTW, the nose and fin can lived on with kits like the Centuri Argus and Phoenix Bird and the Estes Maniac and Eliminator.

I have an old North Coast Rocketry Enerjet 2650 clone and the Rocketarium Trident T263 is also a clone of the 2650.

 

[cvanc]

Am I reading the signature on those drawings correctly?

 

[Initiator001]

Am I reading the signature on those drawings correctly?

If you mean "Gary Rosenfield" you are correct.
For a short period of time Composite Dynamics sold drawings of the Enerjet 2250 made by one of the owners.

 

[cwbullet]

If you mean "Gary Rosenfield" you are correct.
For a short period of time Composite Dynamics sold drawings of the Enerjet 2250 made by one of the owners.

Pretty cool. I did not know he was an owner.

 

[SolarYellow]

I'm kinda curious why there doesn't seem to be activity out there around upscaling some of these things. With all the passion for the 1340 and variants, why not a 38mm MD version, or a four-inch?

 

[Scott_650]

I'm kinda curious why there doesn't seem to be activity out there around upscaling some of these things. With all the passion for the 1340 and variants, why not a 38mm MD version, or a four-inch?

Jerry Irvine’s U.S. Rockets had various upscales and reimagined versions of the clustered Enerjet designs - there’s several sim files for those kits on RocketReviews in the RockSim files.

 

[Cape Byron]

Love the clustering instructions. Those really were the days.

 

[astronwolf]

I'm kinda curious why there doesn't seem to be activity out there around upscaling some of these things. With all the passion for the 1340 and variants, why not a 38mm MD version, or a four-inch?

There is.

1. In a wider sense, many hobbyists seem to enjoy building upscales of kits. It's popular enough that people even build a business around providing goods and services for upscaling kits.

2. You are drawn to a particular kit or variant. Not everyone is. Some variants are more popular that others. People have been scaling up the Estes Goblin for decades. The Estes Goblin remains a very popular subject today. As for the Estes Eclipse (0846) - not so much.

3. Jack Hydrazine has created files of 3-D printing the 1340 and 1340/20 fin unit and parts. These can be upscaled.
https://www.thingiverse.com/thing:3641770

 

[SolarYellow]

3. Jack Hydrazine has created files of 3-D printing the 1340 and 1340/20 fin unit and parts. These can be upscaled.
https://www.thingiverse.com/thing:3641770

I'm well aware of those, have downloaded all the variants of STLs.

But I've googled and searched within the forum both here and at YORF, and haven't seen any posts about building 1340s in anything but LT-125 or ST-13 tube sizes. There are (a few) people who are very passionate about the design, but no up- or downscales that I've seen. Just seems odd to me.

To speculate a little, maybe it's a unique situation because the design is so tied into the tooled plastic fin can and the one PNC-56 nose cone design, and there aren't commercial variants of those in other sizes.

 

[astronwolf]

To speculate a little, maybe it's a unique situation because the design is so tied into the tooled plastic fin can and the one PNC-56 nose cone design, and there aren't commercial variants of those in other sizes.

I believe that you got something here. I agree with that assessment. The other possibility is that no one has successfully upscaled the 1340 or 1340/20 and survived to tell us all about it. Be careful.

 

[SolarYellow]

I believe that you got something here. I agree with that assessment. The other possibility is that no one has successfully upscaled the 1340 or 1340/20 and survived to tell us all about it. Be careful.

I have a 3D printer and Jack's files. I'm thinking I'll buy a pack of PNC-56s and some LT-125 do a 100 percent version. But I also really like the idea of a 38mm MD version and some CTI goodness. Might need to augment the fin can design a little for that.

 

[astronwolf]

I have a 3D printer and Jack's files. I'm thinking I'll buy a pack of PNC-56s and some LT-125 do a 100 percent version. But I also really like the idea of a 38mm MD version and some CTI goodness. Might need to augment the fin can design a little for that.

Consider upgrading the materials if you want to kick the 1340 up a notch in size and power. I don't know what the speed of a 3-D printing plastic like PLA is.

 

[SolarYellow]

My printer is SLA. Plan is Siraya Tech Blu-Tough Nylon Black. Jack has a "supersonic" (not actually tested) version with double-diamond fins. Might go with that, might work on my CAD skills and add some fillets. Might have to rebuild it all from scratch. TBD.

 

[hobie1dog]

eRockets has the Rocketerium Trident which is based on the 2250 (if not an outright clone). The NC shape may be different than the old enerjet promotional info though.


View attachment 549925

so that's where Scott Binder likely got his fin design from, cool stuff.

 

[jhill9693]

I have a 3D printer and Jack's files. I'm thinking I'll buy a pack of PNC-56s and some LT-125 do a 100 percent version. But I also really like the idea of a 38mm MD version and some CTI goodness. Might need to augment the fin can design a little for that.

I did, used an Estes Eliminator kit for the fin can and nose. Turned parts down slightly on a lathe to fit the LT-125 tube. Flew great, but if you attempt a G80, be sure to vent the lower section or this will happen to you too!

 

[SolarYellow]

I did, used an Estes Eliminator kit for the fin can and nose. Turned parts down slightly on a lathe to fit the LT-125 tube. Flew great, but if you attempt a G80, be sure to vent the lower section or this will happen to you too!
View attachment 561016

I'm not sure what you mean about venting the lower section. It looks like the fins broke off due to flutter. Not sure how venting would affect that. Are you saying the sections separated due to internal pressure and then the problems happened?

I'm actually wondering whether it might be better to make the fins conventionally, from something much stiffer than polystyrene, like maybe carbon fiber plate, and epoxy them to the tube. Or maybe plywood shaped into double diamonds and sheathed with glass. Maybe slot the outer LT-125 to give them more bonding area and some nice fillets. Should be less drag due to the elimination of the step at the front of the sleeve (and the larger diameter of the sleeve in any case). I reckon that step may be setting up a shock wave as it goes through Mach 1 that could be playing havoc with the fins.

An Enerjet without the fin can wouldn't exactly be an original Enerjet, but if it actually works, I'm all for it.

ETA: I tweaked the 1340 sim file that I found posted on YORF to eliminate the fin can and instead have c.f. plate fins of the same thickness. On an AT G80 SU, the apogee increased from ~4000 to ~4400 feet, with the max velocity increasing from Mach 0.98 to Mach 1.01.

 

[jhill9693]

Yes I’m certain that it separated prematurely due to the very rapid ascent. It reached Mach 1.3.

 

[Bruiser]

Has anyone else noticed this?



I see one in my future

-Bob

 

[SolarYellow]

Discussed in the AeroTech thread.

 

[AeroTech]

I was wondering if anybody had any experience with the old Enerjet sounding rockets like the 1390?

BTW, the nose and fin can lived on with kits like the Centuri Argus and Phoenix Bird and the Estes Maniac and Eliminator.

Yes, I've built and flown them all.

 

[AeroTech]

I did, used an Estes Eliminator kit for the fin can and nose. Turned parts down slightly on a lathe to fit the LT-125 tube. Flew great, but if you attempt a G80, be sure to vent the lower section or this will happen to you too!

View attachment 561017

View attachment 561016

That's exactly how I remember them shredding.

 

[AeroTech]

Gene Gibbs holding my Enerjet 1340 rocket with a mini-Cineroc payload on top, circa 1973 at Lucerne Dry Lake, CA.

 

[AeroTech]

If you mean "Gary Rosenfield" you are correct.
For a short period of time Composite Dynamics sold drawings of the Enerjet 2250 made by one of the owners.

The dimensions came from a telephone interview of Larry Brown himself following his historic flight at NARAM-14 in Seattle, WA. I wrote the dimensions down on his business card, I used to have it but I'm pretty sure it burned up in the AeroTech fire in 2001 along with other records and relics.

 

[Initiator001]

Has anyone else noticed this?
View attachment 561193


I see one in my future

-Bob

Who?

 

[Initiator001]

I'm kinda curious why there doesn't seem to be activity out there around upscaling some of these things. With all the passion for the 1340 and variants, why not a 38mm MD version, or a four-inch?

The models featured in the 1972 Enerjet catalog were the original 'High-Power' rockets.
Up to two-inches in diameter. Remember, this was when the Big Bertha was considered a large rocket.

I have built several Nike Ram, Aero-Dart and 1340 clones.

After building three Aero-Dart clones from the 1972 catalog each featuring a different manufacturer's paint scheme I decided to make an upscale Aero-Dart model using 2.6 inch diameter tubing. Carl at Semroc made a custom nosecone and TTW fins for it.

Only flew it once at NARAM-52.