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In the case of a turbojet (with no "cold" bypass flow), the airflow being directed forward by an hypothetical thrust reverser can be really hot.

Depending on the location of the engine, this flow may be dangerously redirected towards the empennage and the fuselage.

For instance, for a fighter this would be a hazard for sensors, equipment, payloads including missiles, likely many other elements, and pilots:

General Dynamics F-16C
General Dynamics F-16C (source: Wikipedia)

Are there turbojet engines fitted with a thrust reverser? Which aircraft are they used for? How is this problem dealt with?

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    $\begingroup$ The Panavia Tornado has it: aviation.stackexchange.com/q/14705/1467 With a BPR of 1.1:1, does it fit your definition of "turbojet"? $\endgroup$ – Federico Jul 29 '16 at 11:46
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    $\begingroup$ @Federico: It doesn't :-( the idea is anything without handy cold bypass. Interesting case though. Thanks. $\endgroup$ – mins Jul 29 '16 at 11:58
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    $\begingroup$ oh, then I am not sure there are many being used at all, I think all have some amount of bypass :| (another one is the Viggen: en.wikipedia.org/wiki/Saab_37_Viggen#Propulsion ) $\endgroup$ – Federico Jul 29 '16 at 12:04
  • $\begingroup$ @Federico: When you say "all have some bypass", do you mean all engines (meaning pure turbojets have all been replaced by low BPR turbofans, presumably for efficiency reasons), or all engines with reverser? $\endgroup$ – mins Jul 29 '16 at 12:11
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    $\begingroup$ The first: no-bypass engines are no more in use for the efficiency. But I have no hard data to back this up, it's just my expectation. we also have this question: aviation.stackexchange.com/q/3777/1467 where it is said that "conventional" TR deflects both cold and hot streams $\endgroup$ – Federico Jul 29 '16 at 12:12
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Yes.

The Rolls-Royce/Snecma Olympus 593 [Wikipedia] were pure turbojets and they had thrust reversers.

Source Wikimedia Source: Wikimedia

Also, T/R on Concorde were also used in flight (If I remember correctly, only the inboard ones were used in flight) because Concorde didn't have spoilers.

Being a civilian aircraft, with the engines mounted under the wing, Concorde didn't have any real problem with thrust reversers

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    $\begingroup$ the last image shows some amount of cold air, though (the intake below the compressor) $\endgroup$ – Federico Jul 29 '16 at 13:42
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    $\begingroup$ @Federico, well, this is still a turbojet as there is not a "bypass" by the definition of bypass used in a turbofan. It's a cold flow of air used for cooling, but as it doesn't provide thrust I don't think we should consider it as a bypass flow. :-) $\endgroup$ – Marco Sanfilippo Jul 29 '16 at 13:48
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    $\begingroup$ I accept your point, simply in my opinion is not strictly satisfying the requirement of the question (with no "cold" bypass flow), but I'll leave the final word to @mins. $\endgroup$ – Federico Jul 29 '16 at 13:49
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    $\begingroup$ @Federico: I'd accept this relatively small amount or ram air, which is not pre-compressed, and likely also hot due to the heat exchange. Besides I wonder if this air can continue to circulate when the reverser is deployed. $\endgroup$ – mins Jul 29 '16 at 13:58
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And, if you want a turbojet without any air flowing through the engine around the core, the 707-120 and DC-8-10 used Pratt & Whitney JT3C turbojets with thrust reversers.

Slightly-later models (the 707-220/-320 and DC-8-20/-30) used P&W JT4A turbojets, also with thrust reversers.

Over in Europe, the Caravelle VI-R used Rolls-Royce Avon 533R/535R turbojets with thrust reversers (the R in the designations of both the aircraft and the engine refers to their capability for Reverse thrust).

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