At 10:43 AM 24/09/04 +1000, you wrote:
>
>Mike Borgelt said
>
>"<quote>There are definite hazards to spinning and the recovery with
>modern gliders has a good chance of going outside the envelope if you
>are a little slow in your actions and let it get beyond the very first
>stages of the incipient. Flapped gliders usually have a quite low max
>positive flap speed which is very easily exceeded. Let a spin develop
>accidently from a thermalling turn and you likely are in positive flap.
>Somewhere before the recovery you really ought to go to negative flap. I
>wonder if this gets tested during certification ?</quote>"
>
>
>I would have thought (purely from a logical point of view), that if, as
>you seem to be suggesting, that modern slippery gliders are becoming
>more dangerous if a spin develops, ie, because of reduced
>responsiveness, they take longer to recover, they have a reduced safe
>speed range ie flaps have to be reset, they have faster acceleration on
>the dive-out-recovery, hence they have an increasing possibility /
>probability of over speeding, or, going into a spiral dive etc, that it
>was becoming *_/more necessary, not less necessary/_*, to ensure that
>spin training and all matters associated with flight at the back end of
>the envelope, and in particular, the consequences of tardiness putting
>you at the front end of the envelope in a hurry. In the case of the
>Nimbus accident in the US where there was structural failure, there was
>a lot of engineering done on that, and although no definitive answer was
>produced, as I remember, the consensus was that pulling brake presumably
>to stop a speed run-away during the recovery "pull" may have had the
>effect of concentrating the spar bending moments outboard of the brakes
>to a point beyond the design limit, hence the "sudden and near clean"
>separation of the outboard wing sections, with the inevitable result.
I spoke to Carl Herold who did the investigation on the US Nimbus 4DM.
While nobody knows why they got there the aircraft in both Nimbus 4DM cases
appear to have been outside the envelope when they broke.
The best theory I've heard is that it was a case of " I thought YOU were
flying."
>
>All this leads me to the opposite conclusion you seem to be pushing
>Mike. Prevention is better than cure as the old saying goes, but that
>doesn't mean rely on prevention and don't have the cure. By all means,
>push the theory, practice the incipients etc, but don't say, OK, we will
>stop there, because there is no statistically proven benefit of going
>further. I don't buy that, the Canadian study not withstanding. I
>don't trust statistical analysis in general, and in this case I think it
>is false logic.
In other words "Don't confuse me with the facts". Sounds like the NAS
opponents.
I'd like aviation regulation to be based on evidence. The Canadian
authorities removed the spin requirement bacause it wasn't doing any good.
I consider this quite rational in light of the evidence they had.
BTW you were here a week ago with some completely misleading statements
about airspace and haven't retracted them.
If anything that accident supports the opposite view.
>Those two US pilots killed in the Nimbus above were very experienced
>pilots, but, were they fully spin trained in the first place, were
>either of them "current" on spins, and were either fully aware of the
>particular handling characteristics of that aircraft at the front top
>corner of the V-N ? Since they were US pilots, given Mike Cleaver's
>post above re US-FAR requirements, probably not.
Don Engen was a former naval aviator, Bill Ivans was on the US soaring team
in 1956.
It was Bill's glider. I think given his background he probably knew how to
fly it.
Like the 3 DM it is placarded against intentional spins. So obviously you
do not go further than stalls and swift recoveries when exploring its
characteristics.
So, if prevention
>fails, at what point do you begin the cure, and more to the point, which
>cure, for which aircraft. Spinning in a Blanik can teach technique, but
>it is docile. Get into a spin in a hot glass ship, and you have to be
>"on the ball".
The point is not to get there. Recognise the incipient and in fact before
that you should be aware that an incipient is likely if you keeping doing
what you are doing. Nicer for the guys under you in the thermal too.
Puch's could do with a careful test flight program and the possibility of
a) restricting the aft c of G position
b) restricting up elevator travel
c) install stall strip/modify wing profile at the root to give some
aerodynamic stall warning
ought to investigated perhaps.
The point is, theoretical training, reading books etc,
>doesn't come close to real world experience, not in flying, not in
>anything. If you don't have the trained reflexes from your time in the
>Blanik at least, and you haven't been flying in a regulatory regime that
>requires a yearly check ride with an instructor in a Blanik say, what
>position are you in when it happens to you later in your career, perhaps
>years and hundreds of hours later, in a hot glass ship ? The
>likelihood of being "on the ball" at that stage, seems to me about as
>likely as successfully pissing into a force five.
Well at least I have the personal experience to back me up. No problem
recovering from fully developed spins in the Pitts or catching gust induced
incipients. In the Pitts in an hour I learned more about practical spinning
than ever before but that was only 4 years ago. Particularly effects of in
spin and out spin aileron. I don't feel any burning need to do it again.
I have to wonder just how rough some people are on the controls when flying
close to the stall. Gently and deliberately does it. Is it that some people
just don't ever develop any "feel" for how much lift margin they have? This
is discussed in Langeweische's "Stick and Rudder". It is easy to get
distracted but flying involves multitasking and prioritising the tasks.
Maybe some never get how to do this properly?
Mike
>
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