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#21
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How do most of you pilots set up a flight plan and what nav-aidsdo you use.
Yes indeed, Mike. Or close enough. If you buy the copper tape antenna
and stoppers from the avionics guru who lurks on r.a.homebuilt he will want to sell you something to trim a little shorter to account for the local speed of light (c) on a 1/4 . My nose was a little out of joint initially with yet another slightly snippy and mis-spelled note from an anonymous poster on this crap-infested group. [Brings to mind the idea of adolescent poseurs with dirty ears and dirtier mouths...] ....But he was in fact doing me a service in prompting me to look out the requirements for 406MHz ELTs in the US. These turn out to include the requirement for a 406MHz ELT on NEW light aircraft and ANY light aircraft going international (if I got it right). This could happen, I suppose. I have made the Oshkosh pilgrimage, and I am fixing to visit Corpus Christi in the other direction.... I am not thrilled by the prices however. Surely there must be cheaper examples out there than the $800 specimens? A new Ameriking dual Fx costs $150 after all.... The initial point was that a glance at a light aircraft will show whether it is equipped for 121.5 (or 121.5 and 243Mz) or 406Mhz. The great majority of aircraft that I see, have a 20+ inch whip or rod. Brian W MikeW wrote: g'day Brian, Call frequency "f". Speed of light c = 3*10^8 metres/second. Wavelength = c/f in metres. Quarter-wave antenna length then is c/4*f. So, 406 MHz, call it 400 to simplify a bit. Wavelength = 3*10^8/400*10^6 = 3*10^8/4*10^8 = 0.75 metres. Quarter wave a bit under 20 cm, which would be a bit under 8 inches old scale. Cheers ... MikeW. /snip/ Hi, User posting as Dave, do you know how to relate emission frequency to the length of a corresponding quarter wave whip? Brian W |
#22
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How do most of you pilots set up a flight plan and what nav-aids do you use.
Hi Brian,
I've just bought a new 406MHz EPIRB for the boat, cost me AUD400, so about $350 of your variety I think. The "real" problem is that the COSPAS/SARSAT constellation of satellites had the 121.5/243MHz capability turned off at the beginning of this year, which suggests tht the 20 inch whip is basically useless unless there's an aircraft monitoring 121.5 within line of sight. We've all had to re-equip during this year to cope (I've managed to leave it until the beginning of our summer, when new stocks became available). Incidentally, just measured the antenna: 175 mm from the top of the case so rough approximation not too bad in this case. Cheers ... MikeW "brian whatcott" wrote in message ... Yes indeed, Mike. Or close enough. If you buy the copper tape antenna and stoppers from the avionics guru who lurks on r.a.homebuilt he will want to sell you something to trim a little shorter to account for the local speed of light (c) on a 1/4 . My nose was a little out of joint initially with yet another slightly snippy and mis-spelled note from an anonymous poster on this crap-infested group. [Brings to mind the idea of adolescent poseurs with dirty ears and dirtier mouths...] ...But he was in fact doing me a service in prompting me to look out the requirements for 406MHz ELTs in the US. These turn out to include the requirement for a 406MHz ELT on NEW light aircraft and ANY light aircraft going international (if I got it right). This could happen, I suppose. I have made the Oshkosh pilgrimage, and I am fixing to visit Corpus Christi in the other direction.... I am not thrilled by the prices however. Surely there must be cheaper examples out there than the $800 specimens? A new Ameriking dual Fx costs $150 after all.... The initial point was that a glance at a light aircraft will show whether it is equipped for 121.5 (or 121.5 and 243Mz) or 406Mhz. The great majority of aircraft that I see, have a 20+ inch whip or rod. Brian W MikeW wrote: g'day Brian, Call frequency "f". Speed of light c = 3*10^8 metres/second. Wavelength = c/f in metres. Quarter-wave antenna length then is c/4*f. So, 406 MHz, call it 400 to simplify a bit. Wavelength = 3*10^8/400*10^6 = 3*10^8/4*10^8 = 0.75 metres. Quarter wave a bit under 20 cm, which would be a bit under 8 inches old scale. Cheers ... MikeW. /snip/ Hi, User posting as Dave, do you know how to relate emission frequency to the length of a corresponding quarter wave whip? Brian W |
#23
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406 ELTs, EPIRBS & PSBs (was How do most of you pilots set up...)
I reset my search to PSBs: personal Survival Beacons.
I think this is the style of device that you are using. These are more reasonable. $300-$400 - but the ones with GPS built in seem to run $600. They seem to come in two flavors: those with built in GPS, and those with an interface to an external GPS source which are cheaper. Some beacons feature 121.5 AND 406.1xxx because a coordinate transmission gets rescue in the near ball park but (for aircraft at least) a 121.5 transmission can be homed right to the (hidden by trees?)site. However, the climber/backpacker version PSB/EPIRB is probably not approved for aircraft use - it's duration is certainly more limited. The revised regs DID say a survival 406 ELT may be used for light aircraft though. Brian W MikeW wrote: Hi Brian, I've just bought a new 406MHz EPIRB for the boat, cost me AUD400, so about $350 of your variety I think. The "real" problem is that the COSPAS/SARSAT constellation of satellites had the 121.5/243MHz capability turned off at the beginning of this year, which suggests that the 20 inch whip is basically useless unless there's an aircraft monitoring 121.5 within line of sight. We've all had to re-equip during this year to cope (I've managed to leave it until the beginning of our summer, when new stocks became available). Incidentally, just measured the antenna: 175 mm from the top of the case so rough approximation not too bad in this case. Cheers ... MikeW |
#24
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406 ELTs, EPIRBS & PSBs (was How do most of you pilots set up...)
Yes Brian, pretty much true. My device is guaranteed for 48 hours
transmission after activation as it's intended for off-shore use, but no GPS interface. But it doesn't need it - the satellite(s) works that out to within 6km radius within an hour or so and then the inbuilt 121.5 MHz secondary homes the aircraft in on the signal. That's how most of the deep-water sailors (think British Ocean Challenge, Whitbread Round the World, etc) get home when things go pear shaped. We've got some very good maritime search aircraft that can damn near reach Antarctica if they've got an EPIRB report. As indeed do your people. So why re-invent the wheel each time when there's a perfectly good spare in the shop next door? Unfortunately it's been a long time since I had the prop in front of me, but I've kept an interest. Cheers ... MikeW "brian whatcott" wrote in message ... I reset my search to PSBs: personal Survival Beacons. I think this is the style of device that you are using. These are more reasonable. $300-$400 - but the ones with GPS built in seem to run $600. They seem to come in two flavors: those with built in GPS, and those with an interface to an external GPS source which are cheaper. Some beacons feature 121.5 AND 406.1xxx because a coordinate transmission gets rescue in the near ball park but (for aircraft at least) a 121.5 transmission can be homed right to the (hidden by trees?)site. However, the climber/backpacker version PSB/EPIRB is probably not approved for aircraft use - it's duration is certainly more limited. The revised regs DID say a survival 406 ELT may be used for light aircraft though. Brian W MikeW wrote: Hi Brian, I've just bought a new 406MHz EPIRB for the boat, cost me AUD400, so about $350 of your variety I think. The "real" problem is that the COSPAS/SARSAT constellation of satellites had the 121.5/243MHz capability turned off at the beginning of this year, which suggests that the 20 inch whip is basically useless unless there's an aircraft monitoring 121.5 within line of sight. We've all had to re-equip during this year to cope (I've managed to leave it until the beginning of our summer, when new stocks became available). Incidentally, just measured the antenna: 175 mm from the top of the case so rough approximation not too bad in this case. Cheers ... MikeW |
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