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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?

Better not tell
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  • Related: https://aviation.stackexchange.com/questions/45781/can-high-bypass-turbofans-cruise-at-high-altitude – Better not tell Feb 20 '22 at 16:55
  • The SR-71 goes higher, but its engines are in ramjet mode. – John K Feb 20 '22 at 20:46
  • @JohnK Yes and it's a turbojet and ramjet, my question is about turbofans (some bypass ratio above 0). – Better not tell Feb 21 '22 at 06:17
  • 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. – user3528438 Feb 22 '22 at 06:02
  • @user3528438 Most U2s have turbofans. A high altitude can be achieved on an afterburner as well (if the plane has any, the U2 doesn't), and eventually with engines shut off, being carried by momentum to apogee. – Better not tell Feb 22 '22 at 06:30
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    mig 31 foxhounds regularly do 80,000 ft+ with a low bypass turbofan – Mridul Feb 23 '22 at 11:55
  • @Mridul: Feel free to make that an answer. – Vikki May 23 '22 at 00:57

2 Answers2

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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.

Jpe61
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Bob Mathews
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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.

FreeMan
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SirHawrk
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    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. – Bob Mathews May 18 '22 at 12:42
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    @BobMathews You indeed were, my bad – SirHawrk May 18 '22 at 12:48
  • 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. – Bob Mathews May 18 '22 at 12:49
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    What's posted here are basically comments on other posts, a discussion in other words, and not an answer to the stated question. – Ralph J May 18 '22 at 13:32
  • I disagree with other answers and then supply additional information that answers the question. How is that not an answer? – SirHawrk May 19 '22 at 06:39