Lightning Mate: maybe lightening up would be in order, eh mate?
Here, have a pint.
Lyman:
From the original, the question has to do with accelerating a reduction in velocity.
From the original, the question has to do with deceleration. What you typed there is ...
It is a Rate question, and demands a little latitude in parameters.
Depending upon if you are solving it in the classroom, or in the cockpit.
So my assumption was from the beginning that the engines on both slowing a/c were 'mass only', not thrust.
Engines are generally used on an aircraft to provide sufficient thrust to fly.
Hanging an engine on an airframe for the purpose of mass would be counter productive, would it not?
Hanging engines on a glider seems to defeat the purpose of building a glider, does it not?
We could get into "windmilling" v. Flight idle, but as we see with seven pages, most here are not satisfied unless the discussion can be made more complex, not less.
Various means of increasing drag are yours to employ if you know your aircraft well. They become tools for deceleration, which as I noted is the core of the question in post number 1.
To some extent it is a "Straw Thread", a vehicle for trotting out some algebra in the interest of appearing cerebrally massive.
The Original Post, as I noted, begged the questions.
From there to now, it's been fun and games.
I, for one, have been most entertained.
Would you care for a pint as well?