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.

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!

__________________
Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc - Starfighter Scorpion Centuri - Mini Dactyl Estes - F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc - Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark

Great job!!

+1

Well done!

__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE

Straighter than some fins I've seen come out of new Estes packages.

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.

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, AGITATION, CHAOS, TURMOIL, FIASCOS, AGGRAVATION, INSTIGATION, NUISANCE-ACTION, and HAVOC !

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.

__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE

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.