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As discussed in this Q&A, NASA pilots had to fly 15 hours a month on T-38 to maintain flight proficiency.

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NASA Dryden's T-38 Talon trainer jet in flight over the main base complex at Edwards Air Force Base. Source

As a newbie, this seems rather weird - from all little I know about the Shuttle, its flying characteristics in no way resemble T-38.

So why use T-38? (or any normal jet at all)?

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    $\begingroup$ For the most part, flying is flying. The more you do it, the better you'll be. 15 hours a month (180 hours a year) in a high-performance supersonic jet is going to polish the hell out of your skills, albeit not necessarily those immediately applicable to the Shuttle. $\endgroup$ – egid Dec 13 '16 at 20:56
  • $\begingroup$ See e.g. page 76 of "Excerpt from Astronaut T-38 Space Flight Readiness Training Syllabus". If you read pages above and below, you will have a good idea of the benefits of the training, and examples of situations recovered thanks to this proficiency. See also: Nasa's T-38 Operating Procedures $\endgroup$ – mins Dec 14 '16 at 9:33
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    $\begingroup$ Training on T-38 was already required for Gemini and Apollo missions. Actually the first astronaut to die was during a T-38 accident in 1964 and sadly other would follow. $\endgroup$ – mins Dec 14 '16 at 9:35
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What the T-38 airplane provides NASA is currency and proficiency in high performance aircraft operations in a jet which has many of the same characteristics as the shuttle in this respect ie high wing loading, high approach and landing speeds, similar glide descent ratios. The White Rocket is a temperamental and challenging little jet to land and will not tolerate sloppiness from her flight crew here. She requires the pilot to stay well ahead of it while making an approach, plan out and execute small corrections very precisely while maintaining airspeed, glide path and angle of attack. Maintaining good proficiency in these aspects of high performance aircraft flight and keeping sharp on that high speed mindset comes in handy in an astronaut's line of work.

And T-38s make excellent chase aircraft, capable of keeping up with the shuttle during the final phases of its descent and approach, and can provide an extra set of Mk 01 eyeballs to verify external functioning of systems, eg landing gear, speedbrakes, hydraulic leaks, etc.

Actually, outside of the shuttle sims, landing approach practice was done in a modified Gulfstream II which included a replica of the shuttle flight deck for the left seat guy. It apparently was remarkably similar to the shuttle in a deadstick landing.

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    $\begingroup$ So, why isn't ALL flight training done in Gulfstream II? $\endgroup$ – DVK Dec 13 '16 at 21:35
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    $\begingroup$ In order to simulate the aerodynamic sleekness (ahem) of the "flying brick", the Gulfstream was actually flying with landing gear deployed and full reverse thrust. That's not something you want to do on a regular basis, otherwise you'll find yourself minus one Gulfstream pretty soon. $\endgroup$ – Jörg W Mittag Dec 13 '16 at 21:46
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    $\begingroup$ Actuall the G-IIS has a modification to its landing gear control system with an additional mode allowing only the main gear to extend. It does not use thrust reversing during practice approaches. $\endgroup$ – Carlo Felicione Dec 13 '16 at 22:32
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    $\begingroup$ The biggest reason though, is probably that the T-38s date back to the early days of the astronaut corps - long before the shuttle was ever designed. There was never any reason to stop using them. $\endgroup$ – Bret Copeland Dec 14 '16 at 4:06
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    $\begingroup$ The STA absolutely did use reverse thrust on practice approaches, though I don't think they used full reverse as @Jörg suggests. There are many sources that talk about it. Here's one example: "... we lower the main gear of the STA and put the engines in reverse thrust," he said. "You know when a commercial plane lands and you're thrown forward after the wheels touch down? We do that at 30,000 feet." $\endgroup$ – Bret Copeland Dec 14 '16 at 4:13
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I flew the T-38 in pilot training. (They ended Vietnam and tossed most of us out before we could finish since they no longer needed pilots. Which also means I am now officially old.)

Reasons to use a T-38 for NASA.

  1. The T-38 is a HIGH performance aircraft designed to be a to see if trainees could handle that type of plane. And to also emulated performance fighter plane so you got high performance training. They later made a fighter out of it - the F-5 and the current Navy F/A-18 is based on the T-38 design, so it was a high performance fighter type plane. Also the XF-17 and the F-20 were based on T-38s. There is even a little T-38 in the new F-35. Great, great design.
  2. When I was in, the T-38 had the 2nd highest angle of attack landing (nose up very high) of any jet in the history of the U.S. Air Force - with the by then obsolete B-58 bomber the only plane with a higher angle - MUCH like how a Shuttle lands very high nose up.
  3. While you can probably refuel at any USAF base, you usually want to refuel at a base which knew your aircraft for qualified inspections/service and repair if needed. When I was in (1972-73), there were 10 T-38 training bases, all except 1 located between South Georgia and Texas. (1 was near Phoenix.) Most of the astronaut flying was between Houston, the home of the astronauts and Cape Kennedy, the launch point. So on those flights, you could land at 9 bases to properly refuel and get service. When the NASA T-38s would land for service at most training bases, they would always give the students a "show" by doing a very fast climb after takeoff. At one point the T-38 held the world time to climb record - over all the real actual jet fighters in the U.S., the Soviet Union and every other country. It is a performance plane. The F-4 took many, many attempts and special modifications before it could barely take the record from the T-38.
  4. MOST IMPORTANT. Throw out everything else, the T-38 was designed to be a high performance plane the was CHEAP (compared to other jets planes) to fly. Very low maintenance cost (1/3 of the design team were USAF mechanics) and quick turnaround (most training T-38 flew 2-3 missions a day. Compare to say the B-38 which usually flew at most 1 time a week due to high maintenance time). Cheap and quick turnaround were requirements of a training aircraft. For NASA, that means you could get in much more training for your budget $$ and quick turnaround meant fewer planes were needed to train more astronauts.

Besides training, the T-38 is still used today as one of the primary chase planes when testing new aircraft, since at least during much of the testing it can keep up with the newest faster aircraft yet has 2 seats for a pilot and observer or fly's well with just a single pilot. At one time, the F-5 version of the T-38 was used as the enemy fighter at both the USAF and Navy TOP GUN schools (it's was used in the movie). So in proper hands, it can go head to head with F-14, F15, F16 and F-18 fighters. No bad for a "mere trainer". Its fast, maneuverable yet cheap. Nothing comes close for the NASA mission.

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    $\begingroup$ And it also provided for routine basic transportation for the astronauts. They got those monthly hours flying all over the country. Sometimes it was between NASA centers for meetings and other times to various places for PR purposes. In the Shuttle era, mission specialists ode around in the back seat. Better than flying coach. $\endgroup$ – Gerry Apr 28 '17 at 17:56
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The general idea is to keep the pilot thinking like a pilot. Even ordinary pilots have to have 3 landings in the previous 90 days before they can fly with passengers. It's like warming up before playing tennis; you have to be doing it to stay in the groove.

Just like the first few balls you hit after not playing tennis for a while go over the fence, you can do some pretty crazy things in a plane if you are not tuned up. I once saw a guy jump in a high performance glider for his first flight of the season after doing a very minimal checkout and he misjudged the approach and ended up in the trees.

The choice of a T-38 is obviously because that is the standard AF trainer, but you are right, it is weird. The mentality of AF jocks is jets, jets, jets. But you are right that the Space Shuttle is not anything like a jet, so the T-38 is not the best choice of practice platform.

A better practice platform would be to use a glider and then weight it so it comes down like a rock. If NASA modified the glider the right way it could be made so that it would fly its approach like the shuttle. That would be a far more apropos way to keep the shuttle commanders current.

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    $\begingroup$ Actually, a "glider weighted like a rock" glides just as well as when unweighted, except the optimum glide speed is faster. Of course if you keep adding weight, eventually you go fast enough to break the wings off, but that's the reason that in competitive gliding, the regulations give the maximum weight limit, but no minimum. Trying to land a glider (safely) at a slower speed than it naturally wants to fly is not the same situation as flying a plane with a worse L/D ratio. $\endgroup$ – alephzero Dec 14 '16 at 1:20
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    $\begingroup$ @alephzero I am trying to explain the basic ideas to the OP without using a lot of jargon. $\endgroup$ – Tyler Durden Dec 14 '16 at 1:40
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    $\begingroup$ Jargon isn't the issue. The last paragraph gives the wrong intuition. It's not about weight, it's about L/D. Gliders have a high L/D ratio, which would make them a terrible choice for simulating the shuttle's low L/D. An airplane modified to create more drag, such as the STA, is a much better choice. Also, having engines means you can make several approaches without needing a tow - much more practical (and safer) than a true glider. Astronauts consistently said the shuttle flies exactly like the STA, so saying there was a better choice feels like unjustified backseat engineering. $\endgroup$ – Bret Copeland Dec 14 '16 at 4:29
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    $\begingroup$ @AntonTropashko Shuttle Training Aircraft - see Bret's reply further up. $\endgroup$ – Graham Dec 14 '16 at 12:01
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    $\begingroup$ L/D = 5 is still slightly better than the shuttle. Again, I see no justification for claiming that a glider would have been a better test platform than the one NASA picked, and the one professional test pilots claim flew exactly like the shuttle. On the other hand, picking a glider would have required completely re-engineering it (as even you admit), and would be substantially more dangerous due to its speed and single chance at landing. So again, your last paragraph is misleading, at best. $\endgroup$ – Bret Copeland Dec 14 '16 at 15:43
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Shuttle astronaut Mike Millane's autobiography, Riding Rockets, suggests that the mindset of flying a fast jet is a big factor, rather than the precise flight characteristics:

NASA's simulators were great at preparing astronauts to fly the space shuttle, but they had one critical shortcoming. They lacked a fear factor. No matter how badly you screwed up, simulators couldn't kill you. But high-performance jet aircraft could. Flying the T-38s kept the pilots razor sharp in dealing with potentially deadly time-critical situations, something spaceflight had in abundance.

And as it happened, unfortunately, the T-38 did kill four astronauts in the 1960s.

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Another reason for using the T-38 was simply logistics. Astronauts were required to travel quite a lot; their base was in Houston, but depending on assignments they had to visit contractors and other NASA facilities to participate in development, testing and training. By letting them fly themselves they could get to wherever they needed and logging flight time.

Flying from Houston to either coast takes a few hours one way, so this was a lot of time saved which would otherwise have been spent on additional training.

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