---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Sat 07/28/07: 15 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:09 AM - Re: europa list mod 74 (Carl Pattinson) 2. 01:14 AM - Re: Europa list mod 74 (Carl Pattinson) 3. 01:17 AM - Re: Mod 74 (Carl Pattinson) 4. 01:22 AM - Re: Dynon (Laptop JR) 5. 03:02 AM - Re: Pip pins (John Price) 6. 04:48 AM - ANR Headsets (TELEDYNMCS@aol.com) 7. 07:04 AM - Re: Europa Mod 74 (Roger Bull) 8. 07:52 AM - Re: Europa Mod 74 (Pete Lawless) 9. 09:12 AM - Re: Europa Mod 74 (Carl Pattinson) 10. 09:49 AM - Re: Europa accident G-HOFC - PFA comment (Simon Smith) 11. 10:03 AM - Europa Mod 74 (Fred Klein) 12. 11:12 AM - Re: Europa Mod 74 (Pete Lawless) 13. 01:42 PM - noise-cancelling mic [was: anr headsets] (Rowland & Wilma Carson) 14. 03:15 PM - Re: noise-cancelling mic [was: anr headsets] (Fred Klein) 15. 06:13 PM - Re: Europa accident G-HOFC - PFA comment (Finklea) ________________________________ Message 1 _____________________________________ Time: 01:09:42 AM PST US From: "Carl Pattinson" Subject: Re: Europa-List: europa list mod 74 Apologies for the misleading comment - I hadnt read the Europa Tech Talk when I wrote that. It seems events have overtaken me here. > >> One aspect of Mod 74 (yet to be decided) is that it may >> incorporate a tie bar similar to the weight increase >> mod - or the present weight increase mod may become >> mandatory. There is a question mark over the effectiveness of the top hat >> stiffeners currently >> specified in the older Europas (without tie bars). > > I am sure it is decided as Mod 74 is now published with > the need for a tie bar if you don't have Mod 52. > > The access hole in the Mod is 2 1/4 inches > > RH > > > ________________________________ Message 2 _____________________________________ Time: 01:14:11 AM PST US From: "Carl Pattinson" Subject: Re: Europa-List: Europa list mod 74 Hi Tim, I had the same thought - the answer is almost certainly NO ! Theres a lot more work/ parts involved in Mod 52 - unfortunately. I think its probably better to do Mod 52 if possible first. We are intending to fit a VP prop shortly so Mod 52 is a must for us anyway. Probably wait till the winter (assuming that isnt NOW) and get all these jobs out the way in one go). Regards Carl & Dot ----- Original Message ----- From: Sent: Saturday, July 28, 2007 12:06 AM Subject: Re: Europa-List: Europa list mod 74 > > My reading of the info on the Europa web site is that a Classic when > fitted with mod 74 including the tie bar but not the rest of the mod 52 > will not have its weight increase to 1370 lbs. > This seems odd to me but that is the way I read it. > > Any way to get the weight up 1370 lbs without doing first mod 52 and then > mod 74 ? > > Tim Houlihan > G-BZTH > >> >>> I have seen the work on the only Europa which has >>> undergone Mod 74 courtesy Andy Draper. We asked the >>> same question and the feeling is there isnt enough room >>> to get a spanner around the securing nut to tighten it >>> - its a lot easier through the wing underside. >> >>> The access hole is about 1.5" diameter and the repair >>> afterwards extends to about 9" square. As its on the >>> underside it has little effect on the aerodynamics of >>> the wing and is easy to conceal. >> >>> My understanding is the PFA will consider an >>> alternative means of access and someone is looking into >>> this. >> >>> One aspect of Mod 74 (yet to be decided) is that it may >>> incorporate a tie bar similar to the weight increase >>> mod - or the present weight increase mod may become >>> mandatory. There is a question mark over the >>> effectiveness of the top hat stiffeners currently >>> specified in the older Europas (without tie bars). >> >> I am sure it is decided as Mod 74 is now published with >> the need for a tie bar if you don't have Mod 52. >> >> The access hole in the Mod is 2 1/4 inches >> >> RH >> >> >> >> >> >> > > > ________________________________ Message 3 _____________________________________ Time: 01:17:14 AM PST US From: "Carl Pattinson" Subject: Re: Europa-List: Mod 74 Looks like that just doubled (100) ! GROAN ----- Original Message ----- From: "Carl Pattinson" Sent: Friday, July 27, 2007 10:48 PM Subject: Re: Europa-List: Mod 74 > > No one likes having to shell out for mandatory mods but fifty quid for a > safer aircraft sounds like a bargain to me. > ________________________________ Message 4 _____________________________________ Time: 01:22:29 AM PST US From: "Laptop JR" Subject: Re: Europa-List: Dynon Dear Tony Is this code going to be transferable to others fitting the D180 and other Dynons please? JR (Bob) Gowing UK Kit 327 in Oz ----- Original Message ----- From: "Tony Krzyzewski" Sent: Thursday, July 12, 2007 9:03 AM Subject: RE: Europa-List: Dynon > > >>>> Tony, it's out now, looks good too..... > > I've just downloaded it and now have to wait until the end of my day so > I can go home and upload it to the D180! > > I'm just working on a code change which will permit my fuel gauge sender > to be used as an input into the D180 - in effect making my sender > emulate a capacitance probe. Dynon have been really helpful with getting > me information on how their inputs are designed which has made my job > much easier. > > Tony > > > ________________________________ Message 5 _____________________________________ Time: 03:02:35 AM PST US From: "John Price" Subject: Re: Europa-List: Pip pins Thanks Richard, Mine arrived today John Price. ----- Original Message ----- From: "Richard Holder" Sent: Friday, July 27, 2007 7:06 PM Subject: Europa-List: Pip pins > > To all those who ordered pip pins and sent me envelopes > - they are on their way to you ! Please let me know when > they arrive. > > They fitted OK on mine ! > > Richard Holder > G-OWWW High Cross, ungrounded as of today (for 10 hours !) > > > > > > ________________________________ Message 6 _____________________________________ Time: 04:48:47 AM PST US From: TELEDYNMCS@aol.com Subject: Europa-List: ANR Headsets In a message dated 7/28/2007 2:58:40 AM Eastern Daylight Time, europa-list@matronics.com writes: I have a couple of Lightspeed 15xc's which work just fine. At $350 USD, the price wasn't bad, either. Don't know if they are still available, though... Hey Jeff, I will echo what you've said about Lightspeed. I have a set of 20XL's and I've been using them almost daily for about 5 years now. They were under $400/ea from Spruce. I've used them both with the Europa/Jabiru and the Ximango/Rotax and they work equally well. I've also used them in a Pawnee, Citabria, C-210, Navion and a T-6 excellent results. Battery life for the ANR seems to be in excess of 40 hours on two AA batteries. I once broke part of the earpiece after sitting on it and Lightspeed sent replacement parts at no charge. My only gripe is the audio quality from my XM radio isn't the best, IOW, not enough bass response. However, after looking at the schematic for my Flightcom intercom, the lack of bass in the audio probably has more to do with the size of the capacitors they used in the intercom as opposed to a problem with bass response in the the 20XL's. I would highly recommend Lightspeed headsets. Regards, John Lawton Whitwell, TN (TN89) N245E - Putting the pieces back together after annual inspection ************************************** Get a sneak peek of the all-new AOL at http://discover.aol.com/memed/aolcom30tour ________________________________ Message 7 _____________________________________ Time: 07:04:19 AM PST US From: "Roger Bull" Subject: RE: Europa-List: Europa Mod 74 I think I should point out that Mod 74 does not call for Mod 52 to be incorporated if not already done so; the requirement is to fit a tie bar to the existing rear wing pin sockets, the tie bar being part of Mod 52 as well. Builders can of course fit Mod 52 in its entirety, which, plus the new pin arangement in the wing, will satisfy Mod 74. We at Europa were unaware until earlier this week that the tie bar would be required, so it has been a rush to get the parts as soon as possible. If builders want to incorporate Mod 52 in its entirety the lead time will be longer, proably about 3 weeks, as it will be necessary to get extra supplies of the 3 part wing socket included in that Mod. Getting out the Mod leaflet, sorting out the logistics, etc. has been a bit of a nightmare, so I would be extremely grateful if Richard Holder would come and take over the company - he would undoubtedly be able to offer a better and cheaper service, and then John and I would be able to retire on our (non-existent) ill gotten gains! Regards, Roger -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com]On Behalf Of David.Corbett Sent: 27 July 2007 7:10 pm To: Europa Forum ; Europa committee Subject: Europa-List: Europa Mod 74 Europhiles everywhere - Francis Donaldson has asked me to advise you all that Europa Mod 74 is now on the Europa 2004 Ltd website, under Technical and then Modifications. There is a very strict time limit - within 10 hours from 1 August 2007. Mod 74 affects classic aircraft with foam-filled wings; those classic aircraft that do not already have Mod 52 (the weight increase mod) will be required to fit Mod 52 as part of Mod 74. As it is Friday evening here, I cannot check with Roger Bull to find out what the lead time is going to be for the parts; but I am copying this to him, and hope that, in order to save every one of us ringing him, he will put a short statement on this forum to advise likely delivery availability. I will also be forwarding to the forum, within a few minutes, a copy of an e-mail written by Francis to Ted Gladstone setting out the PFA's view of the accident sequence; this is not a definitive account - that can only be issued by UK AAIB. However, Francis's e-mail does give the reasoning behind the decisions to issue the MPD's and now the Mods. David, on behalf of PFA EC and Europa Club G-BZAM ________________________________ Message 8 _____________________________________ Time: 07:52:13 AM PST US From: "Pete Lawless" Subject: RE: Europa-List: Europa Mod 74 Hi Roger You guys working on a Saturday - now that is what I call service and should qualify for at least double time! No complaints from me regarding the costs or the speed of response to our joint problems - and I am sure the majority of owners feel the same. Just out of interest is there a lead time should I decide to do a full mod 52 instead of the new tie bar arrangement in Mod 74. Kind regards Pete -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] On Behalf Of Roger Bull Sent: 28 July 2007 15:11 Subject: RE: Europa-List: Europa Mod 74 I think I should point out that Mod 74 does not call for Mod 52 to be incorporated if not already done so; the requirement is to fit a tie bar to the existing rear wing pin sockets, the tie bar being part of Mod 52 as well. Builders can of course fit Mod 52 in its entirety, which, plus the new pin arangement in the wing, will satisfy Mod 74. We at Europa were unaware until earlier this week that the tie bar would be required, so it has been a rush to get the parts as soon as possible. If builders want to incorporate Mod 52 in its entirety the lead time will be longer, proably about 3 weeks, as it will be necessary to get extra supplies of the 3 part wing socket included in that Mod. Getting out the Mod leaflet, sorting out the logistics, etc. has been a bit of a nightmare, so I would be extremely grateful if Richard Holder would come and take over the company - he would undoubtedly be able to offer a better and cheaper service, and then John and I would be able to retire on our (non-existent) ill gotten gains! Regards, Roger -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com]On Behalf Of David.Corbett Sent: 27 July 2007 7:10 pm Subject: Europa-List: Europa Mod 74 Europhiles everywhere - Francis Donaldson has asked me to advise you all that Europa Mod 74 is now on the Europa 2004 Ltd website, under Technical and then Modifications. There is a very strict time limit - within 10 hours from 1 August 2007. Mod 74 affects classic aircraft with foam-filled wings; those classic aircraft that do not already have Mod 52 (the weight increase mod) will be required to fit Mod 52 as part of Mod 74. As it is Friday evening here, I cannot check with Roger Bull to find out what the lead time is going to be for the parts; but I am copying this to him, and hope that, in order to save every one of us ringing him, he will put a short statement on this forum to advise likely delivery availability. I will also be forwarding to the forum, within a few minutes, a copy of an e-mail written by Francis to Ted Gladstone setting out the PFA's view of the accident sequence; this is not a definitive account - that can only be issued by UK AAIB. However, Francis's e-mail does give the reasoning behind the decisions to issue the MPD's and now the Mods. David, on behalf of PFA EC and Europa Club G-BZAM href="http://www.matronics.com/Navigator?Europa-List">http://www.matron href "http://forums.matronics.com">http://forums.matronics.com -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ________________________________ Message 9 _____________________________________ Time: 09:12:25 AM PST US From: "Carl Pattinson" Subject: Re: Europa-List: Europa Mod 74 14 Hantone HillHi Roger, I second Petes response and I would be happy to come and run the company but you would probably want me to work for free (just as RH expects you to). I think we will ultimately opt for Mod 52 but not until the rush is over. I doubt we will get through the allowed 10hrs before the year is over if the present weather continues (today excepted). You dont offer a submarine conversion for the Europa by any chance. Keep up the good work. Regards, Carl Pattinson. ----- Original Message ----- From: Pete Lawless To: europa-list@matronics.com Sent: Saturday, July 28, 2007 3:50 PM Subject: RE: Europa-List: Europa Mod 74 Hi Roger You guys working on a Saturday - now that is what I call service and should qualify for at least double time! No complaints from me regarding the costs or the speed of response to our joint problems - and I am sure the majority of owners feel the same. Just out of interest is there a lead time should I decide to do a full mod 52 instead of the new tie bar arrangement in Mod 74. Kind regards Pete -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] On Behalf Of Roger Bull Sent: 28 July 2007 15:11 To: europa-list@matronics.com Subject: RE: Europa-List: Europa Mod 74 I think I should point out that Mod 74 does not call for Mod 52 to be incorporated if not already done so; the requirement is to fit a tie bar to the existing rear wing pin sockets, the tie bar being part of Mod 52 as well. Builders can of course fit Mod 52 in its entirety, which, plus the new pin arangement in the wing, will satisfy Mod 74. We at Europa were unaware until earlier this week that the tie bar would be required, so it has been a rush to get the parts as soon as possible. If builders want to incorporate Mod 52 in its entirety the lead time will be longer, proably about 3 weeks, as it will be necessary to get extra supplies of the 3 part wing socket included in that Mod. Getting out the Mod leaflet, sorting out the logistics, etc. has been a bit of a nightmare, so I would be extremely grateful if Richard Holder would come and take over the company - he would undoubtedly be able to offer a better and cheaper service, and then John and I would be able to retire on our (non-existent) ill gotten gains! Regards, Roger -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com]On Behalf Of David.Corbett Sent: 27 July 2007 7:10 pm To: Europa Forum ; Europa committee Subject: Europa-List: Europa Mod 74 Europhiles everywhere - Francis Donaldson has asked me to advise you all that Europa Mod 74 is now on the Europa 2004 Ltd website, under Technical and then Modifications. There is a very strict time limit - within 10 hours from 1 August 2007. Mod 74 affects classic aircraft with foam-filled wings; those classic aircraft that do not already have Mod 52 (the weight increase mod) will be required to fit Mod 52 as part of Mod 74. As it is Friday evening here, I cannot check with Roger Bull to find out what the lead time is going to be for the parts; but I am copying this to him, and hope that, in order to save every one of us ringing him, he will put a short statement on this forum to advise likely delivery availability. I will also be forwarding to the forum, within a few minutes, a copy of an e-mail written by Francis to Ted Gladstone setting out the PFA's view of the accident sequence; this is not a definitive account - that can only be issued by UK AAIB. However, Francis's e-mail does give the reasoning behind the decisions to issue the MPD's and now the Mods. David, on behalf of PFA EC and Europa Club G-BZAM href="http://www.matronics.com/Navigator?Europa-List">http://www.matron href="http://forums.matronics.com">http://forums.matronics.com -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ________________________________ Message 10 ____________________________________ Time: 09:49:33 AM PST US From: "Simon Smith" Subject: RE: Europa-List: Europa accident G-HOFC - PFA comment Francis's e-mail seems to suggest the opposite sequence of events to that given by the AAIB in S3/2007. If the tailplane moved as a result of the wing detachment is it known for certain that the TP6 was already detached or did the wing cause that too? Have we all just modified our aircraft for no reason????? Simon _____ From: Francis Donaldson [mailto:francis.donaldson@pfa.org.uk] Sent: 27 July 2007 10:33 Cc: Andy Draper Subject: RE: Europa statement Dear Alan Following our discussion I have decided not to issue a PFA statement about the Europa accident, for the reasons you suggested. However instead I would like your agreement to sending the e-mail below to individuals who e-mail us speculating about the accident sequence. Is this OK ? Francis Donaldson Dear Ted Thanks for the copy e-mail. The reason why the rear wing pin pulled out of the right wing was almost certainly because the construction of the hard point in the root rib was defective, the laminations of the plate were staggered so that the threaded hole was not through the middle of the metal plates as designed. It was near the edge of the first one and penetrating the edge of the underneath ones, ie only the first laminate would have been able to carry significant load. This is why the outer laminate ripped out. I think that release of the rear wing attachment allowed the right wing to swing forward and split the right wing spar, causing the right wing to break up and tearing the pins out retaining the other wing in the process. The massive jerk caused by the wing failure would explain what moved the right tailplane off its pitch pins and allow it to flutter and depart, and the left tailplane could have fluttered and then departed because in moving outboard, the right tailplane had dragged the anti-balance tab operating tee-bar off the pin on the left tailplane's anti-balance tab. Had the main wing pins failed, there would not have been the massive damage to the right wing which occurred, as failure of the pin would immediately off-load the wings. Both crew were found with the cockpit wreckage, there was no question of either falling out of the aircraft in flight. We are taking what we see as appropriate steps to allow the Europa fleet to carry on flying, with a acceptable level of safety. If we wait for the AAIB report to be published in full, we would have to ground the fleet meanwhile, which could last many months. The work on the root pin attachment does not involve a huge amount of work or a massive hole in the skin, Andy has managed to devise a keyhole surgery approach. It has been tried on a sample Europa and went OK. Please note that the above is our present line of thought about the accident sequence but is not yet definitive, that will be the prerogative of the AAIB and their final report. There is further testing to be done to test the theory, which we are helping AAIB to prepare. Please do not broadcast the above on the Europa net or elsewhere as it would not be appropriate to promulgate the present theory in advance of the AAIB report. Best regards Francis Donaldson ________________________________ Message 11 ____________________________________ Time: 10:03:37 AM PST US Subject: Europa-List: Europa Mod 74 From: Fred Klein I appreciate the gentile restraint of Roger Bull's post almost as much as I appreciate the value of Mod 74 as a measure of the analysis and clear documentation prepared by the folks at E04 to enhance the integrity of our fleet and the Europa brand rather than simply the measure of the cost of bagging and shipping a few pieces of hardware. Fred A194 do not archive On Saturday, July 28, 2007, at 07:11 AM, Roger Bull wrote: > I think I should point out that Mod 74 does not call for Mod 52 to be > incorporated if not already done so; the requirement is to fit a tie > bar to the existing rear wing pin sockets, the tie bar being part of > Mod 52 as well.- Builders can of course fit Mod 52 in its entirety, > which, plus the new pin arangement in the wing, will satisfy Mod 74. > - > We at Europa were unaware until earlier this week that the tie bar > would be required, so it has been a rush to get the parts as soon as > possible.- If builders want to incorporate Mod 52 in its entirety the > lead time will be longer, proably about 3 weeks, as it will be > necessary to get extra supplies of the 3 part wing socket included in > that Mod. > - > Getting out the Mod leaflet, sorting out the logistics, etc. has been > a bit of a nightmare, so I would be extremely grateful if Richard > Holder would come and take over the company - he would undoubtedly be- > able to offer a better and cheaper service, and then John and I would > be able to retire on our (non-existent) ill gotten gains! > - > Regards, > - > Roger -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ________________________________ Message 12 ____________________________________ Time: 11:12:35 AM PST US From: "Pete Lawless" Subject: RE: Europa-List: Europa Mod 74 Roger Having answered my own question re lead times by properly reading your original email another question; is there any reason why Mod 74 could not be done straight away and then at a latter date the remaining work to fully implement Mod 52 be completed. My concern would be that having installed the new wing pin for the existing fuselage sockets, will that then work with the new sockets required by Mod 52? Obviously if the adjustment of the new wing pin is required to subsequently implement Mod 52 then doing Mod 74 first would be a non starter. Regards Pete -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com] On Behalf Of Roger Bull Sent: 28 July 2007 15:11 Subject: RE: Europa-List: Europa Mod 74 I think I should point out that Mod 74 does not call for Mod 52 to be incorporated if not already done so; the requirement is to fit a tie bar to the existing rear wing pin sockets, the tie bar being part of Mod 52 as well. Builders can of course fit Mod 52 in its entirety, which, plus the new pin arangement in the wing, will satisfy Mod 74. We at Europa were unaware until earlier this week that the tie bar would be required, so it has been a rush to get the parts as soon as possible. If builders want to incorporate Mod 52 in its entirety the lead time will be longer, proably about 3 weeks, as it will be necessary to get extra supplies of the 3 part wing socket included in that Mod. Getting out the Mod leaflet, sorting out the logistics, etc. has been a bit of a nightmare, so I would be extremely grateful if Richard Holder would come and take over the company - he would undoubtedly be able to offer a better and cheaper service, and then John and I would be able to retire on our (non-existent) ill gotten gains! Regards, Roger -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com]On Behalf Of David.Corbett Sent: 27 July 2007 7:10 pm Subject: Europa-List: Europa Mod 74 Europhiles everywhere - Francis Donaldson has asked me to advise you all that Europa Mod 74 is now on the Europa 2004 Ltd website, under Technical and then Modifications. There is a very strict time limit - within 10 hours from 1 August 2007. Mod 74 affects classic aircraft with foam-filled wings; those classic aircraft that do not already have Mod 52 (the weight increase mod) will be required to fit Mod 52 as part of Mod 74. As it is Friday evening here, I cannot check with Roger Bull to find out what the lead time is going to be for the parts; but I am copying this to him, and hope that, in order to save every one of us ringing him, he will put a short statement on this forum to advise likely delivery availability. I will also be forwarding to the forum, within a few minutes, a copy of an e-mail written by Francis to Ted Gladstone setting out the PFA's view of the accident sequence; this is not a definitive account - that can only be issued by UK AAIB. However, Francis's e-mail does give the reasoning behind the decisions to issue the MPD's and now the Mods. David, on behalf of PFA EC and Europa Club G-BZAM href="http://www.matronics.com/Navigator?Europa-List">http://www.matron href "http://forums.matronics.com">http://forums.matronics.com -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ________________________________ Message 13 ____________________________________ Time: 01:42:27 PM PST US From: Rowland & Wilma Carson Subject: Europa-List: noise-cancelling mic [was: anr headsets] At 2007-07-27 20:07 +0100 Carl Pattinson wrote: >IMHO noise cancelling microphones dont seem to cancel out very much >noise - maybe someone with a superior technical understanding might >volunteer an explanation Carl - they certainly don't work perfectly, but if you compared a recording made with the usual aviation-type noise-cancelling mic side-by-side with one made using a conventional microphone, I think you would notice the difference! I know they do work; I use a Sennheiser MD430 "close-talking" mic to record speech (for announcements, etc) in normal domestic locations, and that frees me from having to worry much about intrusion of external noises. {As an aside, I recently swapped headsets with my instructor to try out his ANR set. At first it didn't seem dramatically quieter than my own Sennheiser HME 100, but switching the NC off & on again soon convinced me that there was a big difference, particularly in the low frequencies. Just being exposed to the engine noise while swapping headsets had disturbed my own threshold enough to make the comparison difficult to make. (Incidentally, we did this on the ground!) The moral is that a direct comparison with a NON noise-cancelling mic would be needed to judge the effectivenes of the noise-cancelling mic.} Many "noise-cancelling" microphones work on the principle of accepting spherical pressure wave-fronts and rejecting planar wave-fronts. The idea is that a sound source very near the mic will produce a spherical wave, expanding in all directions from the source. The wave-front from a distant sound source will be much closer to a plane. Designers take advantage of this in various ways, often involving labyrinth construction, so that the pressure variations from plane waves arrive at the transducer out of phase, and thus tend to cancel out, whereas pressure variations from wavefronts differing significantly from planar do not cancel and may actually achieve a reinforcing effect. Of course the effectiveness of this will be quite frequency-dependent. MIcrophones of this type are uusually referred to as pressure-gradient types; those which respond equally to sounds from all directions and distances are called pressure (or omnidirectional) types. The most common ype of pressure-gradient mic is the cardiod (or unidirectional) type, typically seen on stage for singers or announcers, which responds much more sensitively to sounds from the front than from the back or sides. However, the standard cardiod is not noise-cancelling; it will respond equally to all sounds arriving along its axis of sensitivity. The true noise-cancelling mic is rarer, and (apart from the ones in aviation headsets) the most likely place to see one is on a PA system where the announcer is in the room served by the sound system (eg at airports). It does require the talker to be very close to the mic inn order to work properly. That's why you need to get your headset mic as close to your mouth as possible, but without putting it in the direct path of the breath puffs from plosive sounds (words with syllables starting with P, B, T, D etc). Hence the advice often seen to position the mic at the corner of your mouth. One of the finest examples of the noise-cancelling mic technique was the STC 4104, sometimes referred to as the "Raymond Glendenning" model because he was seldom pictured without one. It had a small pad which was placed against the upper lip (or moustache as the case may be) in use, thus ensuring accurate positioning of the lips in the location intended by the designer. It was designed for radio use, before the days of sound-insulated commentary boxes, but was latterly also used by TV commentators on Saturday afternoons for reading the football results live from a (very noisy) teleprinter. Very occasionally one can be seen still, typically with a reporter wearing ear-muffs and standing beside a running jet engine or other very noisy artifact. My own Telex 66C aviation mic (acquired way back before the universal use of headsets, when I couldn't be sure the mic in the flying school aircraft would always be working, and carried until recently as an emergency backup) is very similar in principle, having a protruding ridge that you can rest on your top lip for accurate positioning. It also benefits from the slight non-linear sensitivity of the carbon-granule transducer. (That's why old-fashioned phones with carbon mics tended to discriminate in favour of the speech from the user and somewhat attenuate lower-level sound, whether speech or other; of course the carbon granules introduced lots of noise of their own, but that's a different issue!) I think the common approach for aviation headset boom mics now is to have matching orifices front and rear, each communicating with opposite sides of the transducer diaphragm. Thus plane pressure waves (ie those from relatively far away) will tend to be displacing the diaphragm both forwards and backwards at the same time, so cancelling out. The distance from the talkers lips to the nearest orifice should be of a similar scale to the air-path round to the orifice on the other side of the mic. Thus (over a restricted frequency range) the user's speech can generate positive pressure on the front of the diaphragm, accompanied by a reduction in pressure at the back of the diaphragm (and vice versa). Sorry, this is probably much more info than anybody wanted, but hope it helps to understand the principles. regards Rowland -- | Wilma & Rowland Carson http://home.clara.net/rowil/ | ... that's Rowland with a 'w' ... ________________________________ Message 14 ____________________________________ Time: 03:15:49 PM PST US Subject: Re: Europa-List: noise-cancelling mic [was: anr headsets] From: Fred Klein ...ah...the special joys of "matching orifices front and rear"... do not archive On Saturday, July 28, 2007, at 09:17 AM, Rowland & Wilma Carson wrote: > > I think the common approach for aviation headset boom mics now is to > have matching orifices front and rear, each communicating with > opposite sides of the transducer diaphragm. Thus plane pressure waves > (ie those from relatively far away) will tend to be displacing the > diaphragm both forwards and backwards at the same time, so cancelling > out. The distance from the talkers lips to the nearest orifice should > be of a similar scale to the air-path round to the orifice on the > other side of the mic. Thus (over a restricted frequency range) the > user's speech can generate positive pressure on the front of the > diaphragm, accompanied by a reduction in pressure at the back of the > diaphragm (and vice versa). -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ________________________________ Message 15 ____________________________________ Time: 06:13:03 PM PST US Subject: Europa-List: Re: Europa accident G-HOFC - PFA comment From: "Finklea" How many Europa deaths in how many months? 8 in 18 mos... I am concerned!! 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