bobmig Posted August 9, 2021 Share Posted August 9, 2021 While browsing through photos of T-38s something caught my eye. Although the majority of the aircraft have what I would call a “standard” fin/rudder assembly, some have an addition with some kind of antenna or sensor that extends out over the exhaust nozzles. Just what is this thing? And why would it only be added to some aircraft? Here’s what I refer to as the “standard” configuration. Here are a couple shots of the addition. Link to comment Share on other sites More sharing options...
darthspud Posted August 9, 2021 Share Posted August 9, 2021 ECM /Radar fin? Link to comment Share on other sites More sharing options...
bobmig Posted August 9, 2021 Author Share Posted August 9, 2021 2 hours ago, darthspud said: ECM /Radar fin? That crossed my mind, though it seemed a bit out of place on a trainer. Bob Link to comment Share on other sites More sharing options...
Giorgio N Posted August 9, 2021 Share Posted August 9, 2021 That fairing is one of the external features of the AT-38B variant, developed for the Lead-In Fighter Training program in the '70s. Don't know if there's anything inside, will check a couple of books tomorrow Link to comment Share on other sites More sharing options...
exdraken Posted August 10, 2021 Share Posted August 10, 2021 hmm interesting! on some F-5s this is where a brake chute is installed.... but I am not aware of T-38s having one..... here is another one: https://www.bredow-web.de/US_Air_Force/Kampfjets/Northrop_T-38_Talon/Northrop_AT-38B_Heck.jpg seems to be a wedge actually! http://data3.primeportal.net/hangar/bill_spidle2/at-38b_61-0817/images/at-38b_61-0817_04_of_51.jpg Link to comment Share on other sites More sharing options...
Giorgio N Posted August 10, 2021 Share Posted August 10, 2021 Found the answer: it's a ballast "box" used to counterbalance the extra weight that the ventral pylon adds ahead of the centre of gravity. 2 2 Link to comment Share on other sites More sharing options...
exdraken Posted August 10, 2021 Share Posted August 10, 2021 3 hours ago, Giorgio N said: Found the answer: it's a ballast "box" used to counterbalance the extra weight that the ventral pylon adds ahead of the centre of gravity. interesting! Kind of a stabilising function but would not adding/removing a second pilot or even a full fuel tank affect COG much more, than the pylon ? 🧩 Link to comment Share on other sites More sharing options...
darthspud Posted August 10, 2021 Share Posted August 10, 2021 Our Harriers had a very fine CoG. Even pilot changes could alter it more than a half meter forward or back Link to comment Share on other sites More sharing options...
Giorgio N Posted August 10, 2021 Share Posted August 10, 2021 31 minutes ago, exdraken said: interesting! Kind of a stabilising function but would not adding/removing a second pilot or even a full fuel tank affect COG much more, than the pylon ? 🧩 I am not familiar with the flight characteristics of the T-38 family. In general we have to consider that the AT-38 conversion involved adding a number of new parts to the front of the aircraft, including a pylon capable of ejecting loads (and as a consequence in some cases the load itself) and a rudimentary fire control system. It makes sense that something had to be added to the tail to restore the balance. It should be said that very early pictures of AT-38s do not always show the fairing, so it may be that this was added later in the career of this variant. 1 Link to comment Share on other sites More sharing options...
Giorgio N Posted August 10, 2021 Share Posted August 10, 2021 Here's a picture from the USAF flight manual for the T38. The items marked with a B beside the description are peculiar to the AT-38B. Notice the mention of the ballast box at the rear and the various items in the cockpit area. The MXU recorder if I understand right was not installed on all aircraft but I'll be happy to be corrected if others know more. 1 Link to comment Share on other sites More sharing options...
Murph Posted August 10, 2021 Share Posted August 10, 2021 1 hour ago, exdraken said: interesting! Kind of a stabilising function but would not adding/removing a second pilot or even a full fuel tank affect COG much more, than the pylon ? 🧩 The pylon was used to carry practice bomb dispensers and gun pods, which added to the weight. Regards, Murph 1 Link to comment Share on other sites More sharing options...
bobmig Posted August 11, 2021 Author Share Posted August 11, 2021 Thanks, everyone, for your input. With all your help I now understand what it's all about. Yes... a 'ballast box' as part of the AT-38B modification. Later, when they were upgraded to T-38Cs, the box (empty) was just left as part of the airframe. That's why there are relatively few Cs with the mod. Bob Link to comment Share on other sites More sharing options...
e8n2 Posted August 11, 2021 Share Posted August 11, 2021 13 hours ago, Giorgio N said: Here's a picture from the USAF flight manual for the T38. The items marked with a B beside the description are peculiar to the AT-38B. Notice the mention of the ballast box at the rear and the various items in the cockpit area. The MXU recorder if I understand right was not installed on all aircraft but I'll be happy to be corrected if others know more. Notice the hand pointing to the B in the drawing. That means it was a change from the drawing in the previous version of that particular T.O. Later, Dave 1 Link to comment Share on other sites More sharing options...
alt-92 Posted August 21, 2021 Share Posted August 21, 2021 On 8/10/2021 at 4:09 PM, exdraken said: but would not adding/removing a second pilot or even a full fuel tank affect COG much more, than the pylon ? 🧩 If it changes the CoG range beyond what the standard trim settings can compensate for, it's probably wiser to do this. 1 Link to comment Share on other sites More sharing options...
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