DIY Lightweight 5-meter tall Delay Tower PA System

[diyuser2010]

The pole deflects under load but shows no signs of instability, cracking, or uncontrolled oscillation.

Carbon fiber is fine, until it isn't. It doesn't undergo plastic deformation under load before failure like metals experience. CF might be OK for a horn.

Using only half the original 24′ carbon pole, the system benefits from a significantly higher load margin — likely 3–5× the nominal safety factor, since we're working within the thickest and strongest sections of the pole. The moment arm is shorter, and the flexural stiffness higher, reducing the risk of dynamic failure.

Likely 3-5 times isn't a statement you are capable of defending if you ever end up in court.

 

[Freedom666]

maybe a round and angled piezo array down to 1.8khz, like with this one would be lightweight enough and help the dispersion of highs and mids.

 

[Sonce]

I also had the impression that the folding was a compromise-laden way to simulate a longer horn with out taking up a longer space. Is that right, or does the folding have its own benefits?

Yes, re-entry horns are compromise, swapping length for frequency response. Besides halving length of the horn, no other benefits.

 

[Sonce]

I’m hoping to generate a lighter-weight horn design with comparable or slightly better frequency performance than the Goldwood GM-450PB, ...

My takeaways are to pay more for a better driver, one designed for midrange with a bigger coil, such as the B&C DCM420. Also to consider a folded horn, or perhaps a longer one

I think you should accept advice from weltersys and buy TOA TU651/TH660 combos - they are better performer than yours JBL D250-X/Goldwood GM-450PB, with much more low frequency extension.
I am not aware of any commercial folded horns for B&C DCM 420, BMS 4592, BMS 4594, or available data for folded horn DIY printing.