F-105 “Thud” mechanic recalls Vietnam days

An F-105 Thunderchief avionics technician remembers what is was like to work on the jet and live in Southeast Asia during the Vietnam War.

I’ll be writing from memory after 48 years and it grows dimmer with the passage of time and the aging process. But during this revisit to my time in the USAF, I am left to wonder what is it about an aircraft that causes pilots, ground crews, and support staff to build a “brand loyalty?”

I spent all of 1968 at Takhli RTAFB, Thailand with the 355th Tactical Fighter Wing. In my opinion and many others, the F105 Thud was the aircraft of choice. I served as an avionics technician ( instrument repairman), so I’ll just scattershot some of what I recall about the F-105 and some of the information about serving during the time of the Tet offensive in 1968.

I recently read that the F-105 carried out about 75% of all the bombing missions north of the DMZ over North Vietnam. I would never denigrate any other airplane, but it seems to me that the F-4 Phantom underservedly received the lion’s share of the credit in Southeast Asia–even still to this day. Additionally, the F-111 Aardvark was brand new at the time and came to Takhli about midyear of ’68. Unfortunately, it had really bad results in those early combat situations.

So, for an airplane designed for a completely different mission (nuclear delivery), the Thud did really well in the Vietnam War.   The pilots loved the airplane. It was tough and it could return home with major damage. I did not fly the Thud, so I’ll quote Fighting Jets from the chapter called The War of a Million Sorties.

“Though F-110s, F-102s, F-104’s and F-4s all served in Vietnam, none played as large a role in the air war north of the 17^th Parallel as the Thunderchief. The fastest plane at low altitudes in Vietnam—it could exceed Mach 1 at sea level—the F-105 flew 75 per cent of the air strikes directed against the North.

The jet was 64 feet long and had a 35 foot wingspan. Powered by a Pratt and Whitney J-75 engine that developed 26,500 pounds of thrust, it had been planned as a nuclear weapons carrier, designed to streak in low, zoom up and lob a small atomic bomb toward its target.

But in Vietnam it was pressed into service as a delivery truck for conventional bombs. It could carry seven tons of explosives. The Thud proved extraordinarily tough.

One F-105 came home safely after heat-seeking missile exploded against the tailpipe, causing damage that would have been fatal to a less sturdily built aircraft. After flying a few missions in it, many a pilot came to revere the plane.

‘A startling fact became apparent,’ recalled Colonel Broughton, ‘The Thud was getting to North Vietnam as nothing else could.. Nobody could keep up with the Thud as it flew at high speed on the deck, at tree top level. Nobody could carry that load and penetrate those defenses except the Thud. It was the old Thud that day after day, every day, lunged into that mess, outdueled the opposition, put bombs on the target and dashed back to strike again.’”

Maintenance and Instrumentation on the F-105

My experience with the 105 came between the delivery of the ordinance and the next launch—in other words maintenance time to get the jet back in working order. Upon return, the pilot went thru a debriefing with all the different systems technicians, autopilot, weapons, radar, navigation, instruments and others. They would write up their problems, and discuss it with the techs.

Not often, but once in awhile, the claimed malfunction was an impossibility. Of course, I only had knowledge of part of the aircraft and no one was launching missiles at me, so I have to give the pilot a break on that one! However, debriefing was a choice assignment for a maintenance tech. Being able to stand in an air conditioned building in the middle of a Southeast Asia summer, even for a brief moment, was heaven on earth.

From an instrumentation standpoint, the F-105 used what was called the “T concept”. The attitude instrument was top center of the cluster, underneath was the HIS (horizontal situation indicator). Flanking those were the tape instruments showing airspeed, angle of attack, and to the right was the altitude and rate of climb. When everything was under the lubber lines forming a “T”, the aircraft was in straight and level flight.

One interesting note was the profile the plane used for delivery of an atomic weapon called an “over the shoulder” bomb toss. The jet gained as much speed as it could in a dive, then pulled up in a climb to near vertical and released the bomb at the apex. The jet then continued the profile with an immelman to maneuver away from the target. The thinking was the aircraft would be miles into its escape when the bomb hit its target.

All of the instrumentation was controlled through a CADC (central air data computer). The main computer was in a cavity reached from an access panel on the belly of the aircraft. A technician’s worst nightmare was having to pull the instrument panel in the middle of the afternoon.

Working on the aircraft in the hot Thailand sun–coupled with no breeze–was akin to being in a Iowa cornfield in the summer. There is absolutely no air to breath.   The gyro controlling the ADI (attitude) was in the nape just behind the cockpit. Of course there was air to breathe there, but it was too hot to enjoy.

I wonder if some old Thud driver is laughing right now while reading this and thinking “you should have been in a flight/g suit with a closed cockpit waiting at the end of the runway”. I would have to agree, no one could escape the blazing sun.

In summation the aircraft wasn’t hard to work on, but Thailand gave no relief from the heat.

Some scattered thoughts to wind this down: The aircraft had a Variable Air Inlet system to change the shape of the inlets when going supersonic. There was an ongoing discussion (argument) about who was responsible for VAI maintenance between maintenance departments. We, the instrument shop, unfortunately won! (sarcasm)

So myself and a friend, Frank Kaylor, got out the T.O. (tech order) and taught ourselves all about the VAI. Someone had to learn the system, so we felt why not us? An interesting side note, in the book titled Dirty Little Secrets of the Vietnam War, the authors claim that the F-105 was not flown supersonic in Nam. However, a pilot who Frank is in contact with says he went supersonic often, but did not realize that the jet had a VAI.

The expression, “Speed is Life” depended on the VAI. The pilots liked to talk about going “downtown” (i.e. Hanoi). Their flight profiles to Hanoi took them just above the treetops and at supersonic speed. I’m proud to say I had a part in making sure they “could hit the number” on their way to and from downtown.

We worked 12 hour plus shifts to keep the Thud in the air and loved every minute of it. So I would say brand loyalty comes with hard work, a lot of sweat, and a great satisfaction in seeing your plane come back from a successful mission. If I pissed off some fan of the ultra ugly F-4, I don’t apologize–the droop nose was ugly!

–Phil Ruzicka, SSgt USAF (1966-1970) and proud of it!

Top Photo credit: Three F-105s take off on a mission to bomb North Vietnam, 1966, Wikipedia

Editor’s note: It’s great to get a maintenance tech’s point of view, especially when it’s from your hero and dad!