Does anyone have experience with the strength of the Estes/Centuri/Enerjet fincan?

majordude

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What modern motors can this handle? I think it was designed at a time when F67's were around.
 

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BEC

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I flew an Eliminator with a prototype Estes E57 with no issues. That's as hard as I've pushed one.
 

ghughes1138

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Centuri used that fin unit in their Enerjet-1340 sounding rocket. I flew a couple of those on Enerjet Es and Fs (E24, F55, F67) with no problems.

I flew one with an Enerjet-30 (mid range G, a G76 IIRC) and it disintegrated a second or so after liftoff. Granted, I launched about 30 degrees from vertical, on a mach 1 attempt. All that we recovered was the core of the fin unit, covered in white stress marks and the nose cone. Oh, and a thermistor. Observers down range reported hearing a noise like a rifle shot.

Should be fine if you stay subsonic :)
 

SolarYellow

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If I have it straight in my head, the rockets those were used in had BT-56 tubes, not BT-55. You can still get a four-pack of BT-56 nose cones from Estes and its dealers easily enough, but there are only a few short chunks of BT-56 left at erockets.biz. You might be looking at wrapping your own tubes to do anything with it.

Booster-55s are cheap enough.
 

Back_at_it

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If I have it straight in my head, the rockets those were used in had BT-56 tubes, not BT-55. You can still get a four-pack of BT-56 nose cones from Estes and its dealers easily enough, but there are only a few short chunks of BT-56 left at erockets.biz. You might be looking at wrapping your own tubes to do anything with it.

Booster-55s are cheap enough.
Wrap a single layer of notebook paper around a BT55 And you have a perfect fit for the BT56 fin can
 

Initiator001

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The Enerjet 1340 plastic fin can has been used on many Centuri and Estes rocket models over the years.

I have used them with a variety of projects..

One such project involved an Estes Maniac kit (# 2091).
At the time I had been communicating with Matt Steele who was working at Estes as part of the collaboration with North Coast Rocketry (NCR).
NCR had developed the High Impulse line of products in conjunction with Estes.
This included the F62 single-use Dark Star composite rocket motors.
Matt told me that besides the F62-4 and F62-6 motors which had been released there was also plans for an F62-9 motor to use in lighter weight rockets.
I told Matt I would build a Maniac kit with a 29mm motor mount and bring it to NARAM-42 which was being held not far from Penrose, Colorado.
I wanted to fly it with one of those F62-9 Dark Star motors.
Matt warned me that the Enerjet fin can could not handle the stress of flying with an F62 motor.
I asked Matt to bring an F62-9 to NARAM-42 and we would find out.

At NARAM-42 I loaded my modified Maniac kit with the F62-9 motor.
N42-048 Super Maniac.jpg

At ignition there was smoke then the model was gone!
(For a moment).
Then parts started raining down around the launch pad.
The fins has fluttered so much under acceleration that they had started to separate from the fin can.
This caused the model to go unstable, fold the body tube and come apart.
Matt was quick to say, "I told you so".

I built another Maniac with a 29mm mount and successfully flew it on AeroTech F25-9W motors several times.
 

majordude

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I flew an Eliminator with a prototype Estes E57 with no issues. That's as hard as I've pushed one.
The hardest I pushed one was on an Apogee F10-8. The damn thing weathercocked in no wind and ended up in Phoenix I think.
 

Initiator001

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But Enerjet had an F-67!

How long is that tube? I have a fin can and an 18" tube. It looks a bit short.
Like the Enerjet Nike Ram the 1340 had a payload section.
If some mass was added to a 1340 (Payload) that would keep the velocity at a manageable rate for the molded fin can.

The Maniac used two equal lengths of body tube joined with a coupler.
 

bad_idea

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I've flown the very similar Quest 35mm fin can up to the F42. Have wondered about how it would hold up to the F67 or G74. Sounds like perhaps that wouldn't be the best idea.
 

majordude

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I've flown the very similar Quest 35mm fin can up to the F42. Have wondered about how it would hold up to the F67 or G74. Sounds like perhaps that wouldn't be the best idea.
I agree! But maybe the plastic has changed over the years or the old engines weren't true to their designations?
 

bad_idea

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Not sure how old the cans I have are (bought them for a dollar apiece from the DARS stash, with body tubes another dollar apiece), but being 35mm ID instead of made for the slightly smaller 33.7mm OD BT55, I would assume they're nowhere near as old as the originals. (Edit to add: I see these were made for BT56 also, which is 34.6mm OD. Depending how loose the fit of the originals was, maybe the Quest 35mm fin cans are the same after all.) Quest sold this can on their website right up until last year's websiteocalypse nuked individual parts orders.

The F42 I've flown in one at least once was modern Aerotech production.
 
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SolarYellow

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The Enerjet 1340 plastic fin can has been used on many Centuri and Estes rocket models over the years.

I have used them with a variety of projects..

One such project involved an Estes Maniac kit (# 2091).
At the time I had been communicating with Matt Steele who was working at Estes as part of the collaboration with North Coast Rocketry (NCR).
NCR had developed the High Impulse line of products in conjunction with Estes.
This included the F62 single-use Dark Star composite rocket motors.
Matt told me that besides the F62-4 and F62-6 motors which had been released there was also plans for an F62-9 motor to use in lighter weight rockets.
I told Matt I would build a Maniac kit with a 29mm motor mount and bring it to NARAM-42 which was being held not far from Penrose, Colorado.
I wanted to fly it with one of those F62-9 Dark Star motors.
Matt warned me that the Enerjet fin can could not handle the stress of flying with an F62 motor.
I asked Matt to bring an F62-9 to NARAM-42 and we would find out.

At NARAM-42 I loaded my modified Maniac kit with the F62-9 motor.


At ignition there was smoke then the model was gone!
(For a moment).
Then parts started raining down around the launch pad.
The fins has fluttered so much under acceleration that they had started to separate from the fin can.
This caused the model to go unstable, fold the body tube and come apart.
Matt was quick to say, "I told you so".

I built another Maniac with a 29mm mount and successfully flew it on AeroTech F25-9W motors several times.

I was looking at the Enerjet 1340 brochure and other period literature recently and noticed two things:

Enerjet claimed that with their "30 pound/second" motor, it would go supersonic.
It was built with 1.34 OD, 1.25 ID tubing, or 0.045 wall, about double the thickness of most model rocket tubing in that diameter range.

Kinda wondering if a clone of the 1340 using the thicker wall tubing would actually survive going supersonic on a 133 N-sec total impulse motor.
 
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