Mystery parts in Academy F-4B

[RKic]

Hi folks, I'm curious if any of you know what the two clear lenses (parts R12) are used for. They're not listed in the unused parts catalog, but I also didn't see them elsewhere in the instructions. Also, the instructions don't make mention of any dordal aerials on the the aircraft (nor do I see parts for them on the sprue), but I've seen photos with two small antennas there. Is this particular to only some aircraft?

[PlasticWeapons]

I just took a quick look at my kit and I'm guessing the clear lenses should replace the "lights" molded underneath both intakes. The diameters both match.

[PC12Driver]

<br />Hi folks, I'm curious if any of you know what the two clear lenses (parts R12) are used for. They're not listed in the unused parts catalog, but I also didn't see them elsewhere in the instructions. Also, the instructions don't make mention of any dordal aerials on the the aircraft (nor do I see parts for them on the sprue), but I've seen photos with two small antennas there. Is this particular to only some aircraft?<br />

<br /><br /><br />

This is just a "factoid" about the blade antennas you were asking about. First, antennas have a specific shape to enhance the reception of the wave-length & frequencies of the receiver or receiver/transmitters it's hooked-up to. Blade antennas are typically vox/comm (voice) and most aircraft have two or more vox/comm radios and they are Comm 1 and 2. Comm 1 is normally the primary radio and its antennas are usually positioned on the ventral and comm 2 is on the dorsal. This makes sense because an aircraft in-flight is communicating with ground-based radios. Comm 2 is often used for ground communications (tower ground control, taxiing, etc.) This is a pretty lengthy topic - so I just stop here.

Kevin

[Scott R Wilson]

<br /><br /><br />

This is just a "factoid" about the blade antennas you were asking about. First, antennas have a specific shape to enhance the reception of the wave-length & frequencies of the receiver or receiver/transmitters it's hooked-up to. Blade antennas are typically vox/comm (voice) and most aircraft have two or more vox/comm radios and they are Comm 1 and 2. Comm 1 is normally the primary radio and its antennas are usually positioned on the ventral and comm 2 is on the dorsal. This makes sense because an aircraft in-flight is communicating with ground-based radios. Comm 2 is often used for ground communications (tower ground control, taxiing, etc.) This is a pretty lengthy topic - so I just stop here.

Kevin

If I remember correctly, aircraft antenna lengths are 1/4 wavelength. It's been a very long time so I could be wrong about that.

I don't know about Navy F-4s, but F-4Cs and F-4Es had only one UHF transceiver for comm, with two antennas, the lower one on a nose gear door and the upper one inside the fiberglass fin cap until around 1984 when the upper was relocated to the starboard side of the backbone panels. One or the other antenna was selected by the pilot with a toggle switch on a side console, I forget which side. There was no VHF comm capability.

There was an auxiliary UHF receiver that also had UHF direction finding capability but no transmitter. The aux receiver had I think 20 frequencies set up by comm avionics techs in shop by installing crystals. Only those 20 freqs could be received by the aux receiver.

The USAF fighter F-4s had no other communications capabilities, but recces also had an HF radio with the antenna mounted in the leading edge of the vertical stab.

The other blade antennas were for TACAN and RHAW. The F-4C only had a lower TACAN antenna, originally a round flat plate antenna mounted flush on the aft nose gear door but later relocated to a small blade antenna just behind the nose wheel well. F-4Es had two TACAN antennas, switched automatically by the TACAN receiver. One was on the front nose gear door and the other on the backbone centerline a little ways behind the air refuel door.

The transponder antenna was another round flat plate antenna mounted flush just behind the rear cockpit on Door 19.

[PC12Driver]

The differences between GenAv & Military are legion! It probably has a lot to do with speed & altitude. Not that a Phantom can outrun light speed, but I would imagine that stress, static & harmonics play a role. As an example, the Transponder antenna resembles an AM radio antenna usually located on the forward belly. The glide-slope uses a small blade mounted in front of the nose gear well. The VHF/VOR antennas came in a variety of shapes & sizes & locations. They were cat-whiskers or horizontal blades on the vertical stab. On the Pilatus, I think the HF was a longwire - similar to the ADF which picked-up AM broadcast. For Nav purposes, all the freqs were below roughly 300kHz. However, we were able to go all the way up to 1600kHz for our listening pleasure, i guess!

[Stefan buysse]

Hi,

RKIC,

Do you mean the 2 small antenna's that are in step 15 of the Academy instructions? They are both called part "F42".

There were several configurations of the antenna's on the F-4B. Roughly: none(?) in 1965, then two and by 1972 three (a bigger one slanted back between the two small ones).

Our friend Rex knows a lot about those configurations.

I don't think the larger one is in the kit.

Cheers, Stefan.

[Ben Brown]

The differences between GenAv & Military are legion! It probably has a lot to do with speed & altitude. Not that a Phantom can outrun light speed, but I would imagine that stress, static & harmonics play a role. As an example, the Transponder antenna resembles an AM radio antenna usually located on the forward belly. The glide-slope uses a small blade mounted in front of the nose gear well. The VHF/VOR antennas came in a variety of shapes & sizes & locations. They were cat-whiskers or horizontal blades on the vertical stab. On the Pilatus, I think the HF was a longwire - similar to the ADF which picked-up AM broadcast. For Nav purposes, all the freqs were below roughly 300kHz. However, we were able to go all the way up to 1600kHz for our listening pleasure, i guess!

OT to the thread, but years ago, when I was a budding pilot, I took a physicist/electrical engineer friend up in a Cessna 172 many years ago, and he noticed the T-Shaped glideslope antenna in the upper part of the windscreen. "Is that an antenna? "Yup." "One-forth of the wavelength?" "Um, yes?" "Oh, so it's about XXX MHz, then?" "Um. OK?" So, when we landed, he went around the airplane, trying to figure out what frequency ranges all of the antennae were optimized for. I learned a heck of a lot about the physics of radio antennae that day! Actually, I learn a heck of a lot any time I hang out with him.

Ben :D

[Rex]

A man named Kim might be of help for your dorsal antennae, nose bumps and other small parts questions.

His page is under construction, but, it looks like he will end up with a very thorough guide for gluing on all the odds and ends on an F-4B.

If you know anything to correct him, or to otherwise help him out, he accepts criticism and nudges in the right direction gracefully.

http://phantomphacts.blogspot.com/

I hope he/they keep going past the F-4B/J and on up the alphabet.

[Stefan buysse]

Hi,

Fascinating blog, thanks a lot for the link, Rex.

I had another look at the Academy kit.

Oddly, I think there is only one part "F42" in the kit although the instructions tell us to use two of them.

I looked at the Eduard instructions sheet from the "Good morning, Da Nang" kit and found that they call these parts "Q39". There are 2 "Q" sprues in the kit, so you do get two "Q39"'s.

Still haven't found the larger slanted antenna.

Cheers, Stefan.