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Antenna Install in a Metal Glider
Happy Easter everyone! We have a IS-28B2 Twin Lark which we use quite a bit for instruction, it is good for spinning and intro into flying complex gliders (flaps & retractable gear). It is due for a complete overhaul which will include a new radio with a repeater control unit in the back for the instructor.
Since weŽll then be re-working the whole radio install anyway I have been considering doing something about the dragmaster factory radio antenna that looks more like a car antenna installed ontop of the fuselage tail boom. For you experts out there what would be your recommendation for an interior radio antenna install (or a low drag exterior install) in an all metal glider like the Twin Lark? Many thanks in advance, Markus Graeber Aeroclub de Colombia |
#2
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Antenna Install in a Metal Glider
On Apr 8, 9:12*am, Markus Graeber wrote:
Happy Easter everyone! We have a IS-28B2 Twin Lark which we use quite a bit for instruction, it is good for spinning and intro into flying complex gliders (flaps & retractable gear). It is due for a complete overhaul which will include a new radio with a repeater control unit in the back for the instructor. Since weŽll then be re-working the whole radio install anyway I have been considering doing something about the dragmaster factory radio antenna that looks more like a car antenna installed ontop of the fuselage tail boom.. For you experts out there what would be your recommendation for an interior radio antenna install (or a low drag exterior install) in an all metal glider like the Twin Lark? Many thanks in advance, Markus Graeber Aeroclub de Colombia Partial solution: 90 deg bent whip http://store.wagaero.com/product_inf...roducts_id=459 Depending on the material your current antenna is made from, you might try a tubing bender. The radiated power from a whip antenna comes disproportionately from the "bottom" quarter, which is why this works. It's still ugly, but the drag is much lower. T8 |
#3
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Antenna Install in a Metal Glider
I probably should mention for those that are not familiar with the Twin Lark that it is all metal but does have a fiberglass turtle deck and a fiberglass nose and tail cone.
Markus |
#4
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Antenna Install in a Metal Glider
Hi Markus,
I recommend this one. http://www.cumulus-soaring.com/rami.htm#AV-534 I had one of them on my Schweizer 1-35C. It worked great. I had it mounted on the fuselage behind the turtle deck. The fuselage acted as a nice ground plane. For a metal sailplane there is no way to mount a radio antenna internally and get good performance. And there aren't any available low drag radio antennas that I'm aware of. Best Regards, Paul Remde Cumulus Soaring, Inc. _____________________ "Markus Graeber" wrote in message news:28640239.2914.1333890736652.JavaMail.geo-discussion-forums@ynmc17... Happy Easter everyone! We have a IS-28B2 Twin Lark which we use quite a bit for instruction, it is good for spinning and intro into flying complex gliders (flaps & retractable gear). It is due for a complete overhaul which will include a new radio with a repeater control unit in the back for the instructor. Since weŽll then be re-working the whole radio install anyway I have been considering doing something about the dragmaster factory radio antenna that looks more like a car antenna installed ontop of the fuselage tail boom. For you experts out there what would be your recommendation for an interior radio antenna install (or a low drag exterior install) in an all metal glider like the Twin Lark? Many thanks in advance, Markus Graeber Aeroclub de Colombia |
#5
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Antenna Install in a Metal Glider
Once upon a time, I tried many different com antennas on an HP-18, an
all-metal sailplane with fiberglass nose and turtledeck. The most effective antenna was a bent 1/4-wave whip mounted over the aft fuselage. For the HP-24, I install a 1/4-wave dipole inside the rudder, but that is not a realistic possibility for the Lark. Thanks, Bob K. |
#6
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Antenna Install in a Metal Glider
On Sunday, April 8, 2012 11:04:13 PM UTC+2, Bob Kuykendall wrote:
Once upon a time, I tried many different com antennas on an HP-18, an all-metal sailplane with fiberglass nose and turtledeck. The most effective antenna was a bent 1/4-wave whip mounted over the aft fuselage. For the HP-24, I install a 1/4-wave dipole inside the rudder, but that is not a realistic possibility for the Lark. Thanks, Bob K. Thanks Bob, I was actually thinking about the possibility of installing the antenna in the rudder since it has fabric cover. The other more extreme option could be to replace the vertical stabilizer leading edge aluminum panels with fiber glass but that might have some structural side effects and I am not sure how much aluminum ribbing will affect an 1/4 wave antenna install. Certification wise it's not a problem since gliders are treated here similar to experimentals in the US... Markus |
#7
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Antenna Install in a Metal Glider
Markus,
The antenna recommended by Paul Remde, or similar antenna, mounted on the top of the fuselage aft of the cockpit will provide excellent radio communication. I really think that you overly concerned about the minimal drag produced by an externally mounted antenna on your Lark. Granted the antenna produces drag; however, on a gliders with similar polars to the Lark the performance differences is undetectable. The only reason to hide your antenna is that the Lark looks sleeker without it mounted on the top of the fuselage. Wayne "Markus Graeber" wrote in message news:15119856.896.1333962866197.JavaMail.geo-discussion-forums@yncd8... On Sunday, April 8, 2012 11:04:13 PM UTC+2, Bob Kuykendall wrote: Once upon a time, I tried many different com antennas on an HP-18, an all-metal sailplane with fiberglass nose and turtledeck. The most effective antenna was a bent 1/4-wave whip mounted over the aft fuselage. For the HP-24, I install a 1/4-wave dipole inside the rudder, but that is not a realistic possibility for the Lark. Thanks, Bob K. Thanks Bob, I was actually thinking about the possibility of installing the antenna in the rudder since it has fabric cover. The other more extreme option could be to replace the vertical stabilizer leading edge aluminum panels with fiber glass but that might have some structural side effects and I am not sure how much aluminum ribbing will affect an 1/4 wave antenna install. Certification wise it's not a problem since gliders are treated here similar to experimentals in the US... Markus |
#8
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Antenna Install in a Metal Glider
On Apr 9, 6:41*am, "Wayne Paul" wrote:
Markus, The antenna recommended by Paul Remde, or similar antenna, mounted on the top of the fuselage aft of the cockpit will provide excellent radio communication. I really think that you overly concerned about the minimal drag produced by an externally mounted antenna on your Lark. *Granted the antenna produces drag; however, on a gliders with similar polars to the Lark the performance differences is undetectable. *The only reason to hide your antenna is that the Lark looks sleeker without it mounted on the top of the fuselage. Wayne "Markus Graeber" *wrote in message news:15119856.896.1333962866197.JavaMail.geo-discussion-forums@yncd8... On Sunday, April 8, 2012 11:04:13 PM UTC+2, Bob Kuykendall wrote: Once upon a time, I tried many different com antennas on an HP-18, an all-metal sailplane with fiberglass nose and turtledeck. The most effective antenna was a bent 1/4-wave whip mounted over the aft fuselage. For the HP-24, I install a 1/4-wave dipole inside the rudder, but that is not a realistic possibility for the Lark. Thanks, Bob K. Thanks Bob, I was actually thinking about the possibility of installing the antenna in the rudder since it has fabric cover. The other more extreme option could be to replace the vertical stabilizer leading edge aluminum panels with fiber glass but that might have some structural side effects and I am not sure how much aluminum ribbing will affect an 1/4 wave antenna install. Certification wise it's not a problem since gliders are treated here similar to experimentals in the US... Markus Markus, The antenna will only work well in the rudder if the rudder frame is non-metalic. More modern ships often put the comm antenna in the fiberglass rudder as close to the trailing edge as practicable in order to keep it away from other conductive things. This is a reasonable compromise, though often with a narrow null or "radio free zone" directly ahead of the aircraft. bumper zz MKIV and QV |
#9
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Antenna Install in a Metal Glider
My club made a habit of converting Larks to scrap aluminum (3/5 of the way to black ace), so we got to see a number of different radio installations. IIRC, all of them used a pretty crude antenna installation similar to what you describe.
FWIW, have you considered a fiberglass encased 1/4 wave antennal like what you see on many metal GA aircraft? Comant is a major manufacturer. http://www.cobham.com/about-cobham/a.../vhf-comm.aspx On Sunday, April 8, 2012 9:12:16 AM UTC-4, Markus Graeber wrote: Happy Easter everyone! We have a IS-28B2 Twin Lark which we use quite a bit for instruction, it is good for spinning and intro into flying complex gliders (flaps & retractable gear). It is due for a complete overhaul which will include a new radio with a repeater control unit in the back for the instructor. Since weŽll then be re-working the whole radio install anyway I have been considering doing something about the dragmaster factory radio antenna that looks more like a car antenna installed ontop of the fuselage tail boom.. For you experts out there what would be your recommendation for an interior radio antenna install (or a low drag exterior install) in an all metal glider like the Twin Lark? Many thanks in advance, Markus Graeber Aeroclub de Colombia |
#10
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Antenna Install in a Metal Glider
Thanks all for the feedback. I know that the difference in drag will not be quantifiable but, as pointed out, it would look a lot sleeker. Just trying to take advantage of the complete overhaul we'll be doing and hoping to turn the Twin Lark into more of an eye candy, a sleeker looking machine. It currently does have to compete (often unsuccessfully) with our G103 for attention so first impressions do help.
The polar sucks especially on the high speed end (even the flaps won't get it near the G103 polar, the Germans give it a close to 10% better handicap....) but at least you'd be coming down faster in a nice looking glider that does allow students to get a good handle of spins, flaps and retractable gears :-) Markus |
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