Comments and insights requested!
Understood about water being verrrry sneaky, thanks Viking!
From the prodex site:
"High compression recuperation. It takes back 97% of its form after applying a load of 11 PSI (It does not collapse)"
"With a pressure of 6 PSI Prodex compresses just 6%. When the load is relieved it takes back its initial shape."
I find the #12-24 screws as exerting 1140~ pounds axial force at a torque of 48 in/lbs on the screws shaft itself, an area of .036" - this translates to roughly 13 psi clamp force on the surrounding circular inch (3.14/.036=87; 1140/87=13) which is right in the ballpark for prodex; the narrowest metal bolted face is 1-1/4" and the widest is 2"...
I am guesstimating the foam will compress 75-80% from the original 0.197" (5mm))... So I see the need for a wafer stand-off to get a true structural clamp w/o the prodex inbetween in certain places - say the middle of each outrigger and one at each end of the spar sections, each wafer having a height of 0.15"; and of course the shell-to-floor clamps will be w/o prodex.
The entire length of the main ladder frame runners has zero fasteners, they are all on the lateral frame parts - here is where the prodex sandwich will really quiet the creaky floor by allowing the length-wise sway to be hushed up...
The 48 in/lbs as dry torque comes from Pratt & Whitney Torque Chart
The use of maximum wet torque number in dry torque application intentional.
Axial force comes from
Bolt Torque Calculator - Engineers Edge
I just got off the phone with Insulation4Less after being hung up on when... 1) I had to be ask three times for them to speak loud enough to be heard, and 2) when they interrupted my project description by asking repeatedly for me to define 'laminate' from my just-spoken phrase 'I want to press-laminate prodex between my trailer floor and the steel frame'... and then the four other hang-ups when I requested to speak to Jonathan's supervisor or offered to help work through angst the supposed helpline tech was fabulously impacted with.
A quick reverse-directory address look-up gave me another land line to their shop and I learned it is nothing more than a small 'drop' shipping operation next door to a UPS retail store, that 'Jonathan' was having another bad day, and their tech support means reading 'not recommended' and hanging up if the discussed use veers from the boilerplate already detailed on their website. Anyhow - its always shameful when the Bosses' (insert relation) throws tantrums.