At 07:31:44 on 22 Aug 2005 07:31:44 John Harris wrote:- > Hi Frank,
> Back in the 70's I used to fly Gliders (sailplanes) out of Gawler in South > Australia under the flightpath of the Edinborough Airforce Base. It used to > get quite exciting when one was at the 1900ft ceiling and the caribou's came > through with supposedly a 2000 ft floor but felt more like a beat up. > I think its a fairly long stretch though to compare what can happen when a > vortice destroys the lift over one wing of an aircraft and flips it to > suggesting the same can happen to a 60 lb round cannonball. > Even the vortice off the tips of the small tow plane (usually a Piper Cub in > those days) could give you a hard time when going from "low tow" below the > tug to "High tow" above the tug if one was careless. > I am not suggesting the effect is not real - but I would suggest caution in > using this analogy. > One sup rising thing was how long the vortices lasted after they where > generated - I have flown into them at least 10Km behind the generating > aircraft. > Regards > JohnH Many thanks for your most interesting first hand account, of the effect of vortex rings on small aircraft. There is nothing like hearing these things from the horse's mouth, so to speak. I only wish we had one of the Hutchison Effect witnesses on the list With regard to the cannon ball, I think you are extremely restrained in your comment that "it is a fairly long stretch". It is an enormously long stretch because the forces involved in the Beta-atmosphere (that which transmits light) are an enormously long way from the forces involved in the Alpha-atmosphere (that which transmits sound). Believe you me, I completely sympathise with your shock horror just as much as I would sympathise with a man who had never heard of meteorites and returned home to find that one had demolished his house. The cognitive dissonance must be awful. As for "caution", I am long past the age when I need to worry about the effect of my words on teachers/professors/division heads/directors/editors/peer reviewers. That, dear boy, is the beauty of our little Vortex discussion group. We can say it as it is. (excluding libel, pornography, sarcasm, religion and politics - and anything else our esteemed moderator might deem unfitting). Cheers, Frank
