It was a member of COPA who is an aeronautical engineer. I’ll try to find it
If heading into a headwind, faster gets you further. That might explain it.
Explain what?
If heading into a headwind, faster gets you further.
Up to the point when the increased drag caused by the higher speed offsets the headwind effect. Much too difficult to compute in that situation, almost too difficult to calculate sitting at the desk…
In real life all that is rather pointless anyway. Imagine cruising at a typical non-turbo SEP level of FL90. With the ground at 1000ft. That makes 8000ft to glide off. The first 1000ft will be lost for finding out that the engine has failed, restarting attempts, trimming the aircraft and aiming in a general direction. The final 2000ft must be reserved for aligning the aircraft with the runway and flying some kind of pattern. Which leaves 5000ft that can be converted to distance. At a typical sink rate of 1000ft/min and a ground speed of 120KT this will give a gliding range of 10NM. What are the odds that a suitable airport lies within that range? Gliding at a sub-optimal speed will reduce this range by not more than 10 percent. One mile. What are the odds that this one mile would have made the difference?
The tests were done by a professional flight test engineer, and he foud out that he got the best angle at 110 KIAS, not at 88 as published (you bet that guy knows about the influence of headwind :-)
The L/D curve of the SR22 is very flat in the region between 95 and 110 KIAS, so there will be little difference between 95 and 105 KIAS … but (and other COPA members had similar results) … 88 as published in the POH is clearly a bit too slow.
Not that any of that will make much difference in real life … and with my 4 blade prop it will be different yet again. As long as the 4-blade is windmilling it is such a massive airbrake … but I have not tested it with the engine off yet.
I agree 100% with what_next above. As I wrote earlier, some time will be wasted working out what happened, especially if it happens as a gradual fuel starvation while you are on autopilot and having a pee 
If you are uncertain about your best glide speed, it is better to too fast than too slow. Within limits, of course.
It seems odd to have such a discrepancy. Two thoughts are that 1) 88 knots will be a lot closer to your landing speed and so may be a better forced-landing speed as you will be less likely to find yourself floating well past the touchdown point and 2) 88 knots may be closer to min-sink and therefore give you more time to consider what to do. But if either of these factors were in mind when they gave the low figure, why not simply give both figures and discuss the issue, rather than giving an incorrect figure?
When it comes to working out the best glide speed given a headwind, I wonder whether the best way to go is simply to do it empirically using optic-flow to adjust your speed (i.e. work out where you’re currently due to intersect terra-firma then see whether it changes as you adjust the speed). We do this when landing all the time, and it seems to me to be reasonably accurate.
It seems odd to have such a discrepancy. Two thoughts are that 1) 88 knots will be a lot closer to your landing speed and so may be a better forced-landing speed as you will be less likely to find yourself floating well past the touchdown point and 2) 88 knots may be closer to min-sink and therefore give you more time to consider what to do. But if either of these factors were in mind when they gave the low figure, why not simply give both figures and discuss the issue, rather than giving an incorrect figure?
Could the reason for the SR22 having such a low POH figure be that they want people to be going as slowly as possible when the chute is pulled?
The best glide distance will not be very different between 88kt and 100kt, yet at 88kt there is far less risk of the chute getting damaged. According to wiki, the BRS deployment speed is 133-140kt (according to model) which is way above 100kt, but the lower one goes the more margin there is.
If you are uncertain about your best glide speed, it is better to too fast than too slow. Within limits, of course.
Would that not depend on the chances of you never becoming visual before ground contact?
But with an SR22, the scenario is different because they want you to pull the chute – and obviously one should when at the min deployment height and still not seeing a suitable site. In fact the advice often repeated (no idea if this is in the POH… I would hope not) is to pull the chute if in any proper trouble, and you can always support that argument by saying a life is worth more than the aircraft.
The CAPS speed for older models is 135 knots but there’s been at least two incidents where the chute was deployed ar +190 kias without beeing damaged. The G5 does not even have the restriction anymore.
