Fatal crash Arizona

On Thursday, May 8, 2014 8:55:27 PM UTC-4, Bill D wrote:

Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed.

Perhaps I have a fundamental misunderstanding...
but I thought that the AofA at 65 knots on aerotow is steeper than the AofA at 65 knots in free flight. So if you don't reduce the AofA (aka drop the nose) after the rope breaks, the glider will slow down. If you start the turn before reducing the AofA, you may find yourself going too slow for the turn.

It is true that you can use the speed coming off aerotow or PTOT to gain a bit of altitude, but that just means lowering the nose gradually as you bleed off the speed. In both cases the AofA needs to be adjusted to match the desired free flight speed.

I thought that we practiced this 'gain altitude and slowly drop the nose' every time we release from aerotow?

On Thursday, May 8, 2014 7:43:42 PM UTC-6, son_of_flubber wrote:
On Thursday, May 8, 2014 8:55:27 PM UTC-4, Bill D wrote:



Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed.



Perhaps I have a fundamental misunderstanding...

but I thought that the AofA at 65 knots on aerotow is steeper than the AofA at 65 knots in free flight.
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I think you are confusing pitch attitude with angle of attack. In unaccelerated flight, for a given weight and airspeed, the AOA will always be the same whether you are being towed or not.
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So if you don't reduce the AofA (aka drop the nose) after the rope breaks, the glider will slow down.
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Yes it will slow down if the pitch attitude isn't reduced. However, lowering the nose to establish a normal glide at pattern speed will actually see an increase in AOA due to the lower speed - you're just changing the flight path from a climb to a glide at a slower speed.
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If you start the turn before reducing the AofA, you may find yourself going too slow for the turn.
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What you are saying is if the pilot attempts a turn while continuing the nose-up climb after a rope break, the glider will slow down. Of course it will but in most cases this is desirable since the tow speed was well above pattern speed. Just don't continue the slowdown below pattern speed. The AOA is more closely related to airspeed than pitch attitude.



It is true that you can use the speed coming off aerotow or PTOT to gain a bit of altitude, but that just means lowering the nose gradually as you bleed off the speed. In both cases the AofA needs to be adjusted to match the desired free flight speed. I thought that we practiced this 'gain altitude and slowly drop the nose' every time we release from aerotow?

Yes, this technique is correct but the glider is just transitioning from being towed to a normal glide. The AOA will actually increase as the glider slows down.

Discussions like this highlights why gliders should have an AOA indicator in addition to and ASI.

On Thursday, May 8, 2014 9:43:42 PM UTC-4, son_of_flubber wrote:
On Thursday, May 8, 2014 8:55:27 PM UTC-4, Bill D wrote:



Why would anyone lower the nose? The glider is presumably at aero tow speed - 65 - 70 knots which is way above the pattern speed.



Perhaps I have a fundamental misunderstanding...

but I thought that the AofA at 65 knots on aerotow is steeper than the AofA at 65 knots in free flight. So if you don't reduce the AofA (aka drop the nose) after the rope breaks, the glider will slow down. If you start the turn before reducing the AofA, you may find yourself going too slow for the turn.



It is true that you can use the speed coming off aerotow or PTOT to gain a bit of altitude, but that just means lowering the nose gradually as you bleed off the speed. In both cases the AofA needs to be adjusted to match the desired free flight speed.



I thought that we practiced this 'gain altitude and slowly drop the nose' every time we release from aerotow?

You have a few things wrong.
First- angle of attack is related to the geometry of the glider and airflow over it. On tow the attitude of the glider is slightly nose up relative to the ground compared to the attitude it would have at the same angle of attack in a gliding configuration.
Second- "Every time" implies that we handle all releases the same. In normal flight we will transition from tow attitude and speed to gliding attitude and the associated speed. If in lift, that likely means slowing to thermalling speed. If not in lift we would be going to the appropriate speed to fly.
Third- There is no reason to try to gain altitude in PTT as the amount of gain accomplished by going from tow speed to pattern/approach speed is likely to be quite small. The correct action is to lower the nose slightly to establish a gliding attitude and speed appropriate for the conditions. In many cases, tow speed is about right for the return to the runway.
Also note that "every time" we turn right on release because that is standard. There is a 50% chance that, due to wind velocity and direction(including shear that may be present), terrain considerations, and position, that the correct action is to turn left.
These considerations are why we MUST have an emergency response plan in mind on every launch. There is no time to figure it out- you must execute the plan you have in your head already.
And forget all the mumbo jumbo calculations espoused in this thread.
UH