A little update on the Coupe

[Paul Gillespie]

I was asked to post some pics of the Coupe. I do post some pics on FB and I have a build thread here Gen 3 "Mystique" Coupe Build

[Blacklemming]

That’s looking good

[Ron61]

That is really looking good Paul. What engine are you going to be running?

Ron

[FWB]

hmm, Paul what temper aluminum are you bending there? looks like AMS 4027 T6
6061-T6, if thats correct stop, as the beds will crack on you T-6 can't be bent to that small of a radius and not crack under load. i wouldn't go over T-4, if you want the finished product to be T6 then stick the alum piece after its bent in the oven at 350
for 24 hours to age to T6

looks like for .040 T6 rad no less than .060

[redmt]

I'm not sure exactly about that class without looking it up but I believe you can successfully soften it where you want to bend it with an acetylene torch soot/heat process. It will eliminate or at least lessen the tendency to crack. Another option would be to shear it and TIG weld it.

[Paul Gillespie]

I have a 2015 Coyote crate engine with a T-56 six speed. As for the Al panels they are all cut and bent and mostly fitted from Factory Five. There have been a couple minor cuts and tweaks the panels to fit around some of the frame welds. I have a MK 1 Factory Five Roadster that was built in 1999, it has over 106,000 miles on it, I have one panel that has maybe a 1/8" crack on it on a hard bend, that panel has been removed a couple times over 18 years.

[mikeinatlanta]

Looking good!

Regarding the panel bends. My FFR panel bends were all between .062 and .078. Yours appear to be about the same.

6061 isn't really a structural aluminum so you don't see it in Boeing commercial aircraft manual charts, and industry charts have differing opinions. Supplier charts are all over the place but short story is that FFR bends are at 1.5t-2t range which is well within industry norms. As a side note: T4 tends to show the same minimum bend radius as T6.

[Scotchman]

Paul,
Thanks for the post. Looking forward to seeing it on the road !!

[moore_rb]

Coming along very nicely Paul !

Since the Aluminum panels on Factory Five cars serve essentially as little more than non-structural veneer (and weather protection), All this side-chatter about bend raddii and temper is fascinating... but probably irrelevant

[Danr55]

Not structurally important but not irrelevant. Even though they are just for show they are still subject to work hardening. As such may crack. Stress corrosion is always a consideration with aluminum. So you do not want to bend them into too small a radius. If you are using anything in T6 condition, annealing before bending is always a good idea. Aluminum will naturally harden after working and will become less maliable with age. I dont recall for certain but I believe the rule of thumb for bending aluminum was Minimum R(bend radius)= [1.5T(thicknecss) +.03]. So for .032 stock, the minimum bend radius would be .032 x 1.5=.048+.030=.078R.....or something like that..

[Karl Bebout]

Danr, you make my brain hurt.

[mikeinatlanta]

Agree with the irrelevant in this case part. Disagree with the idea that stress corrosion is an issue on cockpit aluminum sheet, and most definitely disagree that unnecessary and uncontrolled annealing is a good idea for most situations. Sorry for the hijack, just feel that lack of counterpoint is what leads to misinformation becoming internet fact.

The car looks great. I've been helping a friend with an earlier generation and the new stuff looks much improved.

[moore_rb]

Veneer doesn't do work. The work is done by the steel frame beneath the veneer.

Same way your car's fiberglass & resin body adds only an insignificant fraction of your car's overall structural rigidity, the aluminum skin panels under hood are equivalently insignificant... It's there for show, and to deflect water and road debris... That's it.

Yes, time (and engine heat) will probably harden the aluminum sheet, and make it more brittle.

No, it will not matter one damn bit... at least, not any more than it matters that your fiberglass also gets more brittle with age...

Peace kids... I'm out...

[FWB]

Originally Posted by mikeinatlanta

Agree with the irrelevant in this case part. Disagree with the idea that stress corrosion is an issue on cockpit aluminum sheet, and most definitely disagree that unnecessary and uncontrolled annealing is a good idea for most situations. Sorry for the hijack, just feel that lack of counterpoint is what leads to misinformation becoming internet fact.

The car looks great. I've been helping a friend with an earlier generation and the new stuff looks much improved.

not internet fact, actual fact, as i do this crap for a living.
Bell helicopter, LM-F16, F35, F22, C130....i can go on.
aircraft sheetmetal is what i eat and breath on a daily basis, the structural use of the aluminum is irrelevant, it will just bust period.
so kindly before you write off someones concerns as irrelevant please educate yourself before stepping in it.

[Danr55]

The point of that post was not to suggest that a lot of extra annealing was necessary but to caution against bending too small radii in hardened aluminum sheet. Nothing I can think of would be more disheartening than to see a brand new project with stress cracks through the paint on one or more bend radii. Like FWB, I've spent the last several years of my life working around flying things specifically rotorary wing things. Mostly things named after mean Indian tribes that spend a lot of time in the desert. Stress cracking in aluminum is a fact not fiction, but one that is easily avoided by taking a little extra caution in being careful with the size of the bend radius. That was the only point I was trying to make. Nothing else.

[nniets]

Why am I thinking about the Monty Python bit about what kind of bird can carry a coconut shell...

Sorry, couldn't help myself. For what it's worth, I'd come down on Moore_rb's side. The panels are mostly cosmetic and need not be worried about for street use. (and I ain't got no credentials!)

[moore_rb]

There should be no taking sides...

I think we can all agree that when this car is finished, Paul should never attempt to elevate it out of the ground-effect envelope...

You hear that Paul? Keep that thing on the ground when it's done, because the aluminum veneer panels in your engine compartment are not designed to handle the stresses associated with sustained flight...

There, now we can all go back to talking about our RotoWay kit helicopters.. I mean Cobras

[mikeinatlanta]

Originally Posted by FWB

not internet fact, actual fact, as i do this crap for a living.
Bell helicopter, LM-F16, F35, F22, C130....i can go on.
aircraft sheetmetal is what i eat and breath on a daily basis, the structural use of the aluminum is irrelevant, it will just bust period.
so kindly before you write off someones concerns as irrelevant please educate yourself before stepping in it.

Wow. Sorry dude. In my 38 years of aviation maintenance experience I'm used to guys having a bit thicker skin. Govment guys must just be sensitive.

Paul,
Your bends from FFR are absolutely within industry norms and would be fine even if they were structurally loaded. Here are some pics where stress is a concern. These are from my FFR MKII. Duct bracket at top is 2024T4 and others are 6061T6