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What is the altitude record for a turbofan? The (usually) turbofan-powered U2 has gone to 74,000 ft (22.6 km) MSL, but did any turbofan plane surpass that, in a zoom climb for instance and with afterburners' help?

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  • $\begingroup$ Related: aviation.stackexchange.com/questions/45781/… $\endgroup$ Commented Feb 20, 2022 at 16:55
  • $\begingroup$ The SR-71 goes higher, but its engines are in ramjet mode. $\endgroup$
    – John K
    Commented Feb 20, 2022 at 20:46
  • $\begingroup$ @JohnK Yes and it's a turbojet and ramjet, my question is about turbofans (some bypass ratio above 0). $\endgroup$ Commented Feb 21, 2022 at 6:17
  • $\begingroup$ To have a bypass ratio above 0 you need to have more air than you need in the combustion chamber. That's why you can afford to let air "bypass". This is far from true at that altitude. $\endgroup$ Commented Feb 22, 2022 at 6:02
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    $\begingroup$ mig 31 foxhounds regularly do 80,000 ft+ with a low bypass turbofan $\endgroup$
    – Mridul
    Commented Feb 23, 2022 at 11:55

2 Answers 2

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No.

In 1975, the F-15A Streak Eagle, propelled by 2 afterburning turbofans, climbed to 98,425 feet in 3½ minutes, coasting nearly up to an altitude of 103,000 feet.

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I am not entirely certain where you have your information from. The U2's service ceiling was 70.000 feet and I can't find any reports about it going higher.

The F-104 mentioned in @bjelleklangs answer uses a turbojet engine so that disqualifies it from your question. The F-15A Streak Eagle mentioned in @Bob Mathews answer would be a valid contender but I want to mention the McDonnell Douglas F-4 Phantom, which had turbofan variants for the Royal Navy and the Royal Air Force and reached an official maximum height off 98.557 feet a tad bit higher than the F-15. Most likely not with the correct variant though.

Both these planes definitely used afterburners. The highest altitude ever reached by a plane simply powered by a propeller, which is a category I would put turboprops under, without an afterburner was NASA's Helios HP01 at 96.863 feet.

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    $\begingroup$ The F-4 is a contender, but I was correct in using “streak” vice “strike”. The F-15 Strike Eagle is a completely different variant of the F-15 — the “E” model. The F-15 Streak Eagle was a specially-configured F-15A, and is the only jet with the name “Streak Eagle”. There were 513 “Strike Eagle” jets built. $\endgroup$ Commented May 18, 2022 at 12:42
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    $\begingroup$ @BobMathews You indeed were, my bad $\endgroup$
    – SirHawrk
    Commented May 18, 2022 at 12:48
  • $\begingroup$ No big deal. I had actually forgotten about the difference myself until I started looking at old articles about the Streak Eagle and the team of pilots who flew the record-breaking flights. $\endgroup$ Commented May 18, 2022 at 12:49
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    $\begingroup$ What's posted here are basically comments on other posts, a discussion in other words, and not an answer to the stated question. $\endgroup$
    – Ralph J
    Commented May 18, 2022 at 13:32
  • $\begingroup$ I disagree with other answers and then supply additional information that answers the question. How is that not an answer? $\endgroup$
    – SirHawrk
    Commented May 19, 2022 at 6:39

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