The dark side of the roast

[folkery]

So I've started roasting for dark. It feels like new territory for me since I've been roasting as far as 22% Dev time, I don't know what to do past that.

My first roast was a Colombian I took it to 27% dev time with full airflow, but I chickened out and dropped it before second crack came.

My second roast was a Honduran I took it further and got to second crack but with a little over half airflow. Dropped right into SC

The Colombian tastes dark and clean and remnants of the varietal. No smokiness.

The Honduran dark like a Pete's Coffee, with a smokiness that has a small bite and when the cup is cooked l, remnants of the varietal, floral and blackberries.

I want to take my dark roasts to a pre SC or dropped right into it. I also want less smokiness.

My question is how should I handle air flow and Dev time? How can I achieve my goals above?

[edtbjon]

A dev phase of 20-25% is "good" according to Scott Rao. I try to do that with most of my roasts, regardless of roast degree. On the few occations I roast darkish, my dev phase usually are at 25%. Anything much longer than that often makes the coffee too dull.
When it comes to airflow, it's not discussed that much. The question is if it matters that much either, as long as you apply the "lo-mid-high" scheme in a sensible way. With our Hukys the fan is way too powerful for anything but the "high" setting. Trying to control it with the damper is very difficult, apart from the fan being noisy at full speed too. As discussed elsewhere the Huky standard exhaust setup may not be "optimal", but it's what is on offer from Mr Li. I'm personally experimenting with a cyclone documented in another thread.
For some perspective on fan/exhaust systems, many professional systems (Probat, Diedrich etc.) uses fixed speed fans with either damper(s) or a simple 3 airflow direction setting. E.g. a Diedrich IR12 has one fan, used for both roaster ventilation and bean cooling, with 3 settings. The Lorings uses a special "closed loop" system, also having a very "special" price tag. Even though many of us may be lusting for a North roaster as a possible upgrade from the Huky, I guess chinese roasters are frowned upon by many professionals. The reason for mentioning North roasters while discussing airflow, is because they do have variable fan speed control (with a potentiometer).
To conclude on airflow, for which I suggest a new thread if we are to discuss it further, it seems to be the "least significant part" of the roast, as long as you control it with sensibility.