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  #41  
Old 06-28-2019, 11:22 PM
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teflonrocketry1 teflonrocketry1 is offline
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The stock 1340/20 design, with a hollow transition section and nosecone, could loft 6 eggs, bulkheads, spacers, padding, and an altimeter (about 450 grams) to around 3000' AGL on an H128W-6; that might make for a challenging high power competition event!
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  #42  
Old 06-29-2019, 04:28 AM
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I believe the H128 exceeds the Enerjet fin-can physical thrust limit however.
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  #43  
Old 06-29-2019, 04:36 AM
Jack Hydrazine Jack Hydrazine is offline
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Quote:
Originally Posted by ghrocketman
I believe the H128 exceeds the Enerjet fin-can physical thrust limit however.


There are ways around the Enerjet fin can limitations.
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  #44  
Old 06-29-2019, 07:16 AM
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Quote:
Originally Posted by Jack Hydrazine
There are ways around the Enerjet fin can limitations.

Yeah. Replace it.
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  #45  
Old 06-29-2019, 07:58 AM
Jack Hydrazine Jack Hydrazine is offline
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Yes, replace it with a 3d-printed fin can and then coat it with some epoxy.
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  #46  
Old 06-29-2019, 06:40 PM
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Jerry Irvine Jerry Irvine is offline
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Quote:
Originally Posted by teflonrocketry1
The stock 1340/20 design, with a hollow transition section and nosecone, could loft 6 eggs, bulkheads, spacers, padding, and an altimeter (about 450 grams) to around 3000' AGL on an H128W-6; that might make for a challenging high power competition event!
We used to fly an unsanctioned event called unlimited eggloft. Number of eggs times the altitude achieved. My model used an Egg Crate part with IIRC 2" sections of ST-20 with a coupler and plate on each one. The most eggs I ever flew was six, but the optimum number for the event seemed to be 4. I cushioned them with balloons as recommended by Enerjet IIRC.

That was one of those events where the 1 pound mass limit was the limiting factor and IIRC we did either E or F. Typically Crown/SSRS motors were my choice.

Jerry
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  #47  
Old 06-29-2019, 09:58 PM
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1340/20 dry fit with 3D printed ABS nosecone, transition and fin can.
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  #48  
Old 06-30-2019, 01:03 PM
Jack Hydrazine Jack Hydrazine is offline
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Looks great!
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  #49  
Old 06-30-2019, 05:15 PM
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Jerry Irvine Jerry Irvine is offline
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Send a set to Hobby Bench in Phoenix.
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  #50  
Old 07-05-2019, 05:31 PM
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Quote:
Originally Posted by Jack Hydrazine
Glue in airframe tube into Plastic Fin Unit with about 1/8" of the motor end of the airframe tube sticking out past the fin unit.



One thing I've done since the early days of building the 1340's is to NOT glue/epoxy the fin unit to the body tube. I wrap a few layers of 1/4'' white art tape around the bottom of the airframe as a 'stop', and 1 layer of tape (or as much as will fit under the back end) just above that to keep the fin can from spinning. This makes it much easier to re-use the can should the rocket come to an untimely end.


S.
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