Question about a viper's antenna\sensor?
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I’ve always seen this structure on the belly of the viper and thought it was for fuel dump (compare to the F-86 Saber) but the viper doesn’t have a fuel dump. So what exactly is this circled structure?
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Lower antenna.
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ahh I see, so that’s for the IFF only
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Well no. That antenna is used for the UHF and VHF radios as well as the data link. One antenna system, shared by multiple radio systems. I think its to minimise self interference?
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how about the piece that raptor is showing, do all blocks and variants have it? because I know older vipers don’t carry this panel but you see it in all of BMS cockpits.
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The Antenna and that panel goes back to at least early 1980s Block 15 according to the manuals and is shown on Block 10.
Could it have been moved in some blocks, Maybe?
The rear B cockpits don’t seem to have it.
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It could be that the utility of selecting antennas isn’t relevant to older models despite having all antennas. Like maybe pre IDM (is there such a thing?) there was no point picking.
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I think you are right, here is an F-16A right console which shows that panel:
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Like maybe pre IDM (is there such a thing?)
Don’t think IDM happened till about 1992-95 time frame. EPLRS possibly around the similar time for the ANG. Only know before that ATHS was trialled briefly on the A-16 concept.
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Up / Low switch positions are self explanatory, but for middle positions:
IFF / NORM - The system selects the antenna which is receiving the best signal.
UHF / NORM - The antennas cycle between upper and lower to provide omnidirectional antenna pattern.
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Most if not all modern jets have upper and lower com and/or IFF antennae. If the receiver is on the ground, you’d want to be using the lower antennae. If the receiver is airborne or on a mountain top, you’d want to be using the upper antenna. This gets around the airframe masking it’s own signal.
Some jets even have an AUTO select feature based on aircraft attitude - i.e.; if you’re inverted (like during in a roll-in for a diving bomb delivery), it will automatically select the upper antenna for transmission to ground units.