Michael McGee wrote:

I feel like I should jump in here and clarify what we know so far.

The accident occurred on the entry to the downwind for 33.  It was almost
abeam the 15 on the north end.

I was the lead plane of four RV's arriving from Portland at Jackpot
Saturday afternoon.  The RV-6A with the owner/pilot Gary Hanson and RV-6
builder Mike Johnson in the right seat was the number four plane in the
group.  We entered the pattern on a 45 to left downwind for 33.  When I was
about mid field I heard the #3 plane call that Gary had gone in.  Both
pilot and passenger were killed.  He had initiated a steep turn where he
entered the pattern, we don't know why.  All accounts I heard of what
people saw (all pilots, in the air and on the ground) seem to point to an
accelerated stall.  The downwind leg is over higher ground and he wasn't
able to recover in the available altitude.  We had entered the pattern at
about 150 mph IAS as a group of four and we still don't understand how he
managed to pull hard enough and/or get slow enough to do what he
did.  Unfortunately the results seem to speak for themselves.  I am told he
had 500 hours in his plane.

Mike

Mike McGee, RV-4 N996RV, O320-E2G, Aurora, OR

About slowing down fast.

When you pull 4 G's the induced drag due to
lift is 15 times higher.

If the lift coefficient is .25 in cruise and you
pull 4G's the lift coefficient is four times higher or 1

The equation for induced drag is Cid = Cl^2/(Pi * A)

A is the aspect ratio of the wing.

A for an RV6 is about 5.

Pi * A  for an RV6 is = 15.7.

RV6 wing area is 116 square feet

Dynamic pressure at 150 MPH air speed is 58 pounds per square foot.

At Cl = 0.25 induced drag coefficient is .004 based on wing area
and 1682 pounds gross weight.

At Cl = 1 induced drag coefficient is  1/15.7 or .06.

Induced drag is Cid * wing area * dynamic pressure.

Induced drag is 16.8 pounds at 150 mph at cruise and 252 pounds
at 4G. This will slow a 1600 pound gross weight airplane at
.16 G or 5 feet per second per second or about 3.4 MPH per second.
initially.

As you slow the coefficient of lift must increase as does
the induced drag as a portion of total drag.
I would need to write a program to get the exact numbers.

My guess is about ten seconds and you are near stall speed
from 150 MPH at 4G.

If you also pull up at the same time the deceleration rate
could double.

Paul Lamar

Herb Sanders wrote:

Paul, If you are in trail and the three planes in front are doing the same slowing, g
pulling approach to the pattern close to the ground, you might get a mean twist from
the wingtip vortices you encounter.  Herb

 
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