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#41
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#42
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On 6 Jan 2004 08:21:29 GMT, Ray Payne
wrote: ASW 27B is only certificated for aerotow operation when the forward tow release is used! This is correct. And an ASW-27 where no nose hook is installed is certified for aerotow operation on the CG hook. Bye Andreas |
#43
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I got a question for any mate from OZ. IIRC low tows
are mandatory done there. So how does that work with a CG hook? |
#44
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Ted,
It's tough to say what the real cause of your upset was, but goodness knows we're going to try. Your tow pilot makes a good point, and one you should take to heart. Before your next take off, note a physical feature on the runway where the tow plane starts its take off roll. Most tow pilots apply full power immediately. Since the tow plane is moving slowly at this point, it is generating a good bit of turbulence that you are going to have to negotiate at less than flying speed and probably well below a speed where your controls will have anything close to full authority. Tail draggers like the B4 are especially prone to upset at this point. As I roll toward the tow plane start point, I try to anticipate the upset (almost always a drop of the right wing) and catch it as it starts rather than letting it catch me unawares. The B4 has an especially strong elevator. If you get out of sorts, you have to be extra careful not to over control. PIOs are common in the model, especially during the first few aerotows. |
#45
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#46
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I probably should resist the urge to jump in on this thread, but what
the heck. I've made several hundred aerotows using CG hook only equipped gliders, and have had exactly 3 incidents which might have been avoided with a nose hook. Two were my first flights in newly purchased gliders, where I guessed wrong about the takeoff trim position, got quite high on takeoff, but managed to recover with full forward stick. The other time I got sideways early in the ground roll with half water, released, and got stopped before going too far off the runway. Being the skeptical sort, I went to the US National Transportation Safety Board site, and did a query for all reports of accidents during the past 20 years with the words "tow" and "glider" in them. This yielded 280 hits. I eliminated those accidents that happened after safe release, where there was a mechanical failure (disconnected controls, etc.), where one of the pilots was likely to be impaired (heart attack, etc.), or where the glider ran off the side of the runway early in the takeoff roll. This left 17 accidents. Of those, 8 gliders (two probably with CG hook, one more possible) had large pitch excursions on takeoff, were released and subsequently crashed without damage to the towplane. That left 9 in which a glider high and out of position pulled up the tail of the towplane causing it to crash. Of these, 3 very likely had CG hooks (Std Cirrus, Open Cirrus, Ka-6E), 2 likely had nose hooks (G103C and 1-26), and the remainder either the glider type was not stated, or may have had either type of hook (Twin Astir). The thing that struck me about these accidents was how many of them were due to the pilot fiddling with an open canopy, or inadvertently deployed spoilers. If the pilots simply payed attention to flying the aircraft, most of the above would never have happened. The other thing that is clear is that those freakin' Schweizer towplane hooks are a menace to tow pilots, and *should* be banned. These statistics don't suggest to me that we should prohibit aerotow of CG hook only gliders in the US. A significant proportion of the single seat gliders here only have CG hooks, as some of the European manufacturers charged a fairly hefty premium to put in a nose hook until recently (if they offered them at all), and, well, a lot of glider pilots are kind of cheap. As for the other side of the Atlantic, it would be interesting to see some actual statistics... Marc |
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#48
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Marc Ramsey wrote:
That left 9 in which a glider high and out of position pulled up the tail of the towplane causing it to crash. Of these, 3 very likely had CG hooks (Std Cirrus, Open Cirrus, Ka-6E), 2 likely had nose hooks (G103C and 1-26), and the remainder either the glider type was not stated, or may have had either type of hook (Twin Astir). Very interesting numbers. Too bad we don't know what proportion of launches are nose-hook or CG hook, then we could see if one was over-represented. The thing that struck me about these accidents was how many of them were due to the pilot fiddling with an open canopy, or inadvertently deployed spoilers. If the pilots simply payed attention to flying the aircraft, most of the above would never have happened. The other thing that is clear is that those freakin' Schweizer towplane hooks are a menace to tow pilots, and *should* be banned. Amen. These statistics don't suggest to me that we should prohibit aerotow of CG hook only gliders in the US. A significant proportion of the single seat gliders here only have CG hooks, as some of the European manufacturers charged a fairly hefty premium to put in a nose hook until recently (if they offered them at all), and, well, a lot of glider pilots are kind of cheap. The US might have less trouble with CG hooks than a country where aero tow isn't as common. -- ----- change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
#49
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Chris Rollings wrote:
I am a staunch defender of anyone's right to risk his or her own life in pursuit of any goal they hold dear (including saving money). In launching on a C og G hook you are risking the tow-pilots life more than your own, and this I will not defend. I personally prefer to fly aerotow with nose hooks, and both of the gliders I now fly have them. But, I'm not convinced that anyone has provided actual evidence of an observed safety issue with CG hooks. Some numbers like these for, say, the past 20 years in the UK: How many aerotow operations were there per year? What percentage of aerotow operations used CG hooks? How many aerotow upset accidents were there during that period? What percentage of the aerotow upset accidents involved CG hooks? If these figures aren't available, is the use of CG hooks being discouraged based simply on the assumed lack of positive longitudinal stability during aerotow? Marc |
#50
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