What you have stated about streamers NQN is interesting and I don't find what you postulate controversial at all.
A streamer utilized as a downward falling stabilizer based on smaller rockets surface area does work. Scaling up on larger free falling rockets requires a greater level of knowledge usually gained from experience over time and flights.
For the main, agree. For the drogue, I think my rule holds. Specifically:
Mains should be sized for the weight of the rocket - the target is a specific touch down speed.
Drogues should be sized for the
area of the rocket - the target is balancing drag between the rocket body and the parachute.
Double the weight of a rocket (bigger motor/more payload), and you should double the area of the main, but the drogue size should remain exactly the same. It will just fall 40% faster, but even at the degenerate case (metal motor casing falling sideways) you've got enough drag.
With enough material (lengthxwidthxthickness) one could theoretically bring any size (did not say weight) rocket down safely on streamer only depending on the landing surface. As rocket weight goes up or the landing surfaces hardens a streamer only fall becomes problematic in the ...end.
Absolutely agreed. Drag is drag is drag. An elliptical chute has a Cd of 1.6, a parasheet 0.8, and a streamer 0.2.
So for the same amount of drag as a parasheet, you need half the parachute area if you get an elliptical, or four times the area if you use a streamer.
In the case of a drogue where you don't need much drag and you're very high up/hard to see, the larger size of the streamer is beneficial.
In the case of the main, the opposite is true: you're sized for weight, the streamer size will impose a weight/volume penalty. That being said, if you can bear the weight, a huge streamer is super cool!
I'm actually thinking of buying one of Buddy's big streamers to use as a main in my MPR38. Not the most efficient choice, but it actually flies a little better with more noseweight (small fins, and I do like bigger motors), so the extra weight vs. a parachute is actually a plus.
Back to the OP's question about a proper sized drogue ... Buddy suggested a 12" drogue and that seems to be a good size for the described rocket size and weight wise. Simple and straight forward.
Agreed on that. Glad to see an actual parachute professional agree with my napkin math. 12" drogue or a 7x70 streamer should provide a perfect balance between drogue and body drag and give you the perfect stable "flying V"