Flight Test Yuma

By L. D. Alford

Pete and I finally made it out to Yuma – many times, in fact. Our squadron, the 418th Flight Test Squadron had a contract with the US Army to use our T-39 Sabreliners from Edwards as targets for Apache helicopter testing. The Army wanted the T-39s because they could fly real fast and slow, they could fly low, we could put electronic countermeasure pods on the bottom on at least one of them, we knew what we were doing as a target (our pilots could take instruction), the aircraft were a defined target size, and we were the cheapest jet available. Cheap always works well in flight test.

Generally, we flew out to Yuma to arrive at their base ops at 0800 or 0900. The flight out wasn’t very long and after a couple of sorties supporting the Apache, we could be back at Edwards in time for dinner. Other than the complete misadventure Pete and I had flying out one day, the biggest excitement going to Yuma was when one of the Edwards flight surgeons wanted to come along. The flight surgeons liked to be assigned to the T-39s because they could hop on most missions, and I always let them fly. Usually, at Edwards, if a flight surgeon was assigned to the fighter or the bomber squadrons, they might get one backseat flight a year. Most of the T-39s could hold 6 or more passengers, and there was usually a seat available on the positioning flight, the test flight, and the repositioning flight. The only missions the flight surgeons couldn’t fly with us were moderate risk and above and those were few. I also wouldn’t let them fly the test runs.

The flight out to Yuma with a flight surgeon in the right seat was always interesting because the T-39 has an overwhelming phugoid. The pugoid is one of the two natural pitch stability modes in an aircraft. The other pitch stability mode is the short period. The phugoid is also called the long period. The long period of the T-39 was about 45 to 60 seconds, and it was very strong especially at altitude. Stability in aircraft reduces with altitude; the higher you go the less stable the aircraft and the more active the natural modes. The T-39 didn’t have an autopilot so any T-39 pilot worth his salt could keep it nice and steady up to the aircraft’s maximum altitude; however, to inexperienced and unskilled pilots, the phugoid of the T-39 was like fighting a bronco. I always asked the Air Traffic Controllers for a 2000 foot block above and below our cruising altitude, and then I gave the flight controls to the flight surgeon. I’d always give it to him right in trim, and he would be okay for a while, then he’d make a small change in the pitch and the phugoid would take off, usually down. The aircraft would start a slow pitch down and lose 100 feet. ;In 45 seconds it would be 200 feet high, then in another 45 seconds 400 feet low. Pretty quickly, we’d be climbing again, and the flight surgeon would have this “help me” look on his face. I’d take the aircraft and get it back to altitude and trimmed, while explaining to him everything I’m telling you. Then I’d give him the aircraft and the cycle would start all over again. Pete would kneel between the seat snickering. Eventually, the flight surgeon who persevered would get the hang of it and maintain a sloppy plus or minus 100 feet, but by the next time he flew, he’d have to relearn the T-39 touch all over again. A full blown phugoid on a T-39 could vary plus and minus 1000 feet. Eventually, we’d make it to Yuma, then the real fun would begin.

When we took a flight surgeon or other observer out to Yuma, they either waited for us at the canteen or they rode along and got sick.

Sick is what could easily happen at Yuma. We had to fly low (very low) altitude runs for the Apaches while wearing the Army’s idea of birth control glasses. The Yuma ranges were laced with laser beams, and base ops would issue everyone on the crew pop bottle thick glasses in military issue black frames. The glasses were big, green, always scratched up, and you could barely see through them. Everyone on the aircraft had to wear them while on the laser active ranges. Eventually, I told my T-39 crews to take the glasses, but not to wear them during critical phases of flight, like takeoff, landing, low altitude runs… Laser radiation can do a number on your eyes if you look right at it, but hitting the ground at a high rate of speed will ruin your eyes and the rest of you – not to mention the jet you are flying in.

The passengers (pax) in the back always had to wear the glasses, and at Yuma, the Army wasn’t paying for slack turns and lazy setups. My crews were testers and we had a reputation to maintain. The T-39s were legal to fly 90 bank and pitch (although that much pitch was problematic because you didn’t have enough power behind you), and they could do 3 gs. We used these limits all the time during pace, photo, and safety chase. We used them like crazy for low altitude setups on the range. The Army loved it. To setup for a low, high speed run, we’d turn the jet up on a wing and make a descending turn into the correct heading and flight path. At the end of the run, you’d kick the jet up into a climbing wifferdil turn and pull it around at full power and 3 gs. If you did it right, you’d end up going the opposite direction at the correct airspeed and altitude until the next turn point. Of course all this yanking and banking for a pax wearing coke bottle glasses means after about two or three turns, they are observing the inside of an Air Force issue airsick bag. And they better not puke on the carpet of my jet because back at Edwards, the crew chief will sit on their head while they clean out every last bit of lunch from the cheap blue knap.

You have to remember, the T-39 was not a normal business jet – it was the first business jet, before they took all the fight out of them. ;It sported F-86 wings (based on the German Me-262) and the most responsive flight controls of any aircraft in its class. It was literally the best heavy chase aircraft ever built. Flying one around was like taking out a derated F-86, so when making hiyaka maneuvers, the guys in the back almost always got sick. A good flight test engineer could take data while puking in the little white bag. A great flight test engineer could analyze data, make radio calls, run the flight data computer, and write the test report, all while filling an Air Force issue airsick bag and not get a drop of liquid lunch on the seats or his uniform. I know quite a few engineers like that.

On the other hand, if I had to take data because the flight test engineer couldn’t hold his cookies – that was a dark day.

Pete was a great pilot, and we flew together often. He drove a Harley (had a dragon tattoo), was studying to get an Federal Aviation Administration (FAA) Airframe and Powerplant (A&P) mechanics rating, and had this thing for scorpions. I think one of the reasons he liked flying to Yuma so often was he wanted one of the big ones. When I say big ones, I don’t mean a scorpion measured in parts of inches, I mean one measured in parts of feet. His search became a challenge for the Yuma base ops guys. They would suggest places to find the “big” ones, and after our target flights, Pete would commandeer me and our Army issue staff car to look for them. He needed my help raise up the large objects these scorpions supposedly resided under. After seeing what one of these scorpions looked like, I’m glad we never confronted one in the wild by ourselves.

One morning, the base ops guys gave Pete a coffee can that emitted ominous scratching noises. They claimed to have caught a “big” one for him, and I had the pleasure of flying back to Edwards with the little monster in the back. I still imagine our flight home if that bug got loose – plus what I would say to the Wing Commander. The next day, Pete brought in a new display for our office – a 10 gallon terrarium with desert sand and a five inch long Yuma scorpion – our new mascot. Everyone in the wing made the pilgrimage to our office at least once to view the thing.

The next problem was what to feed it, and Pete had a solution for that. He started with crickets and supplemented his pet’s diet with black widow spiders. Sometimes the spiders would last long enough to catch a couple of crickets.

The scorpion lived longer than our work at Yuma. The Apache system finished testing, and our scorpion became the highlight for many of our visitors to the T-39 office. Eventually the scorpion was no more. Pete improved its environment by adding plants and hiding places – both were good places for the spiders to hide from the scorpion. When we had visitors, Pete would dribble water on the sand to make the scorpion come out of its hole, and scorpions can’t stand too much water. The water killed it or maybe it died from the stress of eating too many black widow spiders. The T-39s are gone too. ;They were the victims of budget cuts and age. Like the scorpion they couldn’t handle the constant change to a fancy modern environment – they just weren’t as sexy as the F-16s and F-15s.

– The End –

Postscript: The T-39 was one of the best aircraft in the Edwards stable. It was cheap to operate, had some great snakes that would not kill you (like the awesome phugoid), and flew like an F-86. Because they were old, they became the golden watch offered at the budget altar every year. Eventually someone sacrificed them to the budget and ended an era, but that is another story.

The author is a retired Air Force test pilot. His other aviation, technical, and fiction writing can be referenced at www.ldalford.com.