B105 handling
Okay ... the differences is 'inertia.' Something I routinely demonstrate in PPL steep turn and quick stop training.
In display manoeuvres, and for that matter any manouevre involving a 180 degree change of direction parallel to the current airflow, inertia of the airframe IS directly related to 'groundspeed.' The effect is more significant on the heavier helicopters.
Given a 25 knot breeze and a rapid 180 degree turn, the airframe IS NOT going to accelerate instantly with the reversed airflow. Indeed in demonstrating the effect, I've noted 3/4 seconds delay before the ASI indicates a positive reading even though the ground below is passing by at 20knots. That time is more than enough to lose the little height Hoffman appeared to have had based on my video viewing.
The difficult thing to get ones head around, is that in a steep nose down attitude with 'nothing on the clock' the cyclic has to be pushed further forward to regain translation lift as quickly as possible to enable the subsequent aft cyclic to be fully effective!
At Rochester in the mid 1990s, I saw a similar situation, when a Hughes TH55 sank into the ground turning off a strong wind in a low level steep turn. It does happen.
We can all observe the 'inertia' effect by practicing at height. Commence a 30 knot rapid turn on to a downwind heading and monitor the ASI. The reading will often decrease to zero or less than translational lift speed for a second or so.
I'm suggesting that may have happened in the Hoffman case. As I noted in the earlier post ... it has certainly happened to me, albeit it won't again.
Other views very welcome please. I'll bet my bottom $ Nick Lappos has the real answer!
Take care all,
Dennis Kenyon.