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  #11  
Old 03-02-2023, 01:12 PM
Tramper Al Tramper Al is offline
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Quote:
Originally Posted by 5x7
It’s likely the injection temp given is under pressure so 150 degrees will likely do nothing at normal pressure, but I respect wanting to preserve this rare fin can.


Yeah, those temps seem low (car parked in the sun?), but I'll work my way until I see some changes.

There is also something called a heat deflection temp that is up closer to water boil but still well below melting point. That may be the one I'm after, when the shape is workable.

Plastics.

Last edited by Tramper Al : 03-03-2023 at 05:15 PM.
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  #12  
Old 03-03-2023, 06:50 AM
Tramper Al Tramper Al is offline
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Just a quick follow-up on my 1340 fin can straightening effort.

It all happened at 75 C (about 170 F), water bath, well clamped in Estes jig. I kept them in for about an hour at each (increasing) temperature, and let the last one cool down overnight. Straight and still like new. No kidding, these are the same fins.

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  #13  
Old 03-03-2023, 07:11 AM
A Fish Named Wallyum A Fish Named Wallyum is offline
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Quote:
Originally Posted by Tramper Al
Just a quick follow-up on my 1340 fin can straightening effort.

It all happened at 75 C (about 170 F), water bath, well clamped in Estes jig. I kept them in for about an hour at each (increasing) temperature, and let the last one cool down overnight. Straight and still like new. No kidding, these are the same fins.


Wow. That's impressive!
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  #14  
Old 03-03-2023, 07:40 AM
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5x7 5x7 is offline
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Great job!!
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  #15  
Old 03-03-2023, 04:32 PM
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Quote:
Originally Posted by A Fish Named Wallyum
Wow. That's impressive!

+1

Well done!
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  #16  
Old 03-03-2023, 05:31 PM
SolarYellow SolarYellow is offline
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Straighter than some fins I've seen come out of new Estes packages.
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  #17  
Old 03-03-2023, 06:00 PM
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ghrocketman ghrocketman is offline
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That was too easy and results in a PENALTY.
Looks too good; at LEAST one fin needs a touch of WARPAGE. Paint the fin can with brushed-on Aero Gloss Dope. Thaty'll add some warpage back for sure .
You needed to heat each fin individually with a heat gun instead.

Seriously though, it came out better than expected. Looks great.
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  #18  
Old 05-02-2024, 12:29 PM
SolarYellow SolarYellow is offline
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I know I've seen it before, but have searched for an hour and not found it again.

What is the thickness of the fins on the Enerjet/Centuri/Estes fin can under discussion in this thread? I have a dimensioned sketch posted by Jack Hydrazine, but that shows planform only. I'm interested in the root thickness (just above the fillet radius) and tip thickness of the fin itself, in the event that it is tapered.

Hopefully, someone around here has a can and a halfway decent pair of calipers.
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  #19  
Old 05-02-2024, 06:05 PM
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Quote:
Originally Posted by SolarYellow
I know I've seen it before, but have searched for an hour and not found it again.

What is the thickness of the fins on the Enerjet/Centuri/Estes fin can under discussion in this thread? I have a dimensioned sketch posted by Jack Hydrazine, but that shows planform only. I'm interested in the root thickness (just above the fillet radius) and tip thickness of the fin itself, in the event that it is tapered.

Hopefully, someone around here has a can and a halfway decent pair of calipers.

I don't know how decent my calipers are (CEN-TECH digital from Harbor Freight) but here's what I have.

Note that the fins are tapered from LE to TE as well as from root to tip. So here are four thicknesses:

TE root: 0.085 inch
TE tip: 0.051 inch
LE root (projecting the point of the trapezoid shape, not the tip of the strake): 0.054 inch
LE tip: 0.049 inch

That last is close for the forward edge of the strake.

My caliper technique is probably poorer than the calipers themselves.
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  #20  
Old 05-03-2024, 02:32 PM
SolarYellow SolarYellow is offline
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Quote:
Originally Posted by BEC
I don't know how decent my calipers are (CEN-TECH digital from Harbor Freight) but here's what I have.

Note that the fins are tapered from LE to TE as well as from root to tip. So here are four thicknesses:

TE root: 0.085 inch
TE tip: 0.051 inch
LE root (projecting the point of the trapezoid shape, not the tip of the strake): 0.054 inch
LE tip: 0.049 inch

That last is close for the forward edge of the strake.

My caliper technique is probably poorer than the calipers themselves.


You're an engineer and a very careful person, I'm sure this is good enough for me. Don't need JPL QA inspector level precision. Although I admit to being surprised that you don't have something from Mitutoyo, B&S, etc.

Thanks again for the help.
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