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On Jun 5, 9:47 pm, Eric Greenwell wrote:
It depends very much on the antenna; e.g., the dirty looking transponder 3" stubby rod with a ball on top has insignificant drag on an 18 meter glider. Probably for a 15 meter glider, too, but I don't recall the numbers. Blade style transponder antennas are even sleeker. Com antennas are much larger than the 900-1090 MHz antennas we are talking about, and can have significant drag, but it's a mistake to rule out external antennas for the higher frequencies. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) Guess it sort of depends on what you consider to be "insignificant", Eric. 15 or 18 meter ship, dry, at best L/D only has maybe 20 lbs TOTAL drag. 1 lbs may not seem like much, but it is 5%. In contest terms, 50 points. Per day. If there was a really good, really accurate TE system without using a probe (Schuemann B Box comes to mind), the really hot pilots would all think just a bit more about finding a way to put one of those in their plane and do away with the now seemingly very draggy TE probe. The vertical portion of it is about the same length as the transponder antenna, but bigger in diameter. It may seem like fly specs in the pepper, but over time, it adds up. So, why do we have TE probes? Because they work, and nobody else has come up with something that works as well. At least, not as far as I know. Steve Leonard |
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On 6/4/2012 7:46 AM, CLewis95 wrote:
.... .....You want to keep it simple? STEP 1: Buy a Portable PowerFLARM STEP 2: Stick it on top of your glareshield STEP 3: Make sure the antennas are pointed straight up. STEP 4: (Optional?) Run a wire from your power-bus/battery to the PowerFLARM. How hard is that? --Noel This (Noel's comment) is what I "planned/hoped" to do in my Genesis. Interested if there have been any reports of interference between a CAI Model 20 mounted near Portable Flarm(?). My Model 20 is mounted behind instrument pod with antenna ~flush with top. The portable would be about 10" ahead on top of pod (so antenna bases would be ~1" above GPS-20 antenna). Flarm antennas can easily stand vertical. Any comments appreciated! I've been told about 12" separation in GPS antennas is adequate, and your situation sounds like it qualifies. In practice, I've had no trouble with GPS antennas only 8" apart and at the same height. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) |
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