After a bit of searching here on TRF I found these helpful links..
Recovery Tools
Descent Rate Calculator
Enter the weight of your rocket and the size of the parachute to estimate the rate at which your rocket will descend.
Calculate Parachute Size
Estimate the size of the parachute to use for your rocket.
Calculate Streamer Size
Calculate the size of the streamer to use for your rocke
I looked at all of the above, and would still much prefer to rely on OpenRocket.
The challenge you might face is importing the complex bird, like yours, into OR. But for the sake of descent calculations, you can just mock-up a 3FNC rocket that matches the weight of yours.
The key question you likely want to answer is - what size chute do I want to put into my rocket?
To that end, plug in different size chutes, with manufactures specified Cd's (they do vary!), and see what descent rate you get.
20 f/s is a good, conservative target.
For an architecturally complex rocket like yours, I would play it safe and stay under 20 f/s to minimize damage upon landing.
The down-side to 20 f/s is that if you loft your rocket high enough, 20 f/s will take a LONG time to come down, subject to vagaries of cross winds. That can mean a long walk, or a rocket stuck on a tree, or lost altogether (depending on how high you fly).
One solution to that is JollyLogic Chute Release device (JLCR), but you need at least 42mm body tube to accommodate:
https://www.jollylogic.com/products/chuterelease/
I don't remember your model's dimensions, but it may not have large enough airframe to JLCR.
If so, prepare for a long walk.
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