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I have seen some military jets have a needle-like structure at the nose and some others do not have that. Lockheed SR-71 Blackbirds have that structure and Lockheed Martin F-22 Raptors do not, why so?

SR71Nose
(Image Source: www.aviationexplorer.com)

F22 (Image Source: www.wikipedia.com)

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  • $\begingroup$ Both of them are super sonic $\endgroup$ – fawaz Jul 16 '15 at 7:01
  • $\begingroup$ I added pictures for reference, do you mean the little tube that the SR71 has branching off the tip of the nose or are you interested in the entire tip? In the latter case, you will see that the F22 has that as well.... $\endgroup$ – SentryRaven Jul 16 '15 at 7:03
  • $\begingroup$ SR-71 is not a fighter $\endgroup$ – Federico Jul 16 '15 at 7:03
  • $\begingroup$ yes,i mean little tube at nose,i checked Wikipedia and did not find it for raptor f-22,en.wikipedia.org/wiki/… $\endgroup$ – fawaz Jul 16 '15 at 7:05
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    $\begingroup$ @Andy - That's mostly it; the longer tube places the pitot well out into "undisturbed" airflow in front of the aircraft, where it can gather unbiased airspeed/altitude/VV data in initial test flights. That data is then used to compensate for airflow disturbance effects at the final pitot position. The longer test probe is delicate, not very stealthy, and is often less accurate at high AoA, so the test probe is removed after the production pitot system is calibrated. The SR-71 kept the nose probe because any other placement had accuracy problems, and the high-AOA disadvantage was a non-issue. $\endgroup$ – KeithS Jul 16 '15 at 17:38
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What you see on the SR-71 is an Alpha-Beta probe, with a pitot tube branching off the side of it. The nose cone of the SR-71 (and its variants) were changeable depending on its loadout.

From the A12 Configuration:

The sharply tapered nose section was pressurized and contained navigational and communications equipment, a remote compass transmitter, periscope optics, air inlet computer and angle transducer, and other radio equipment. A combination pitot-static and alpha-beta probe was installed at the forward tip to capture airspeed and altitude data.

About the SR-71 versatility

The SR-71 also served as a testbed for an Optical Air Data System (OADS), a fiber optic device using laser technology to replace the pitot tube (airspeed probe) on high-performance aircraft. It used laser light instead of air pressure to produce airspeed and attitude reference data such as angle of attack and sideslip normally obtained with small tubes and vanes extending into the air stream or from tubes

Both sources above: Design and Development of the Blackbird

The F22 serves quite a different purpose to the variants of the Blackbird, and thus probably has less need for sensitive sensor equipment of the SR-71. It still has a pitot tube which can be seen in the photo you posted

enter image description here

And it, no doubt gets other avionic information from a traditional pitot-static system rather than rely on an alpha-beta probe as the Blackbird did.

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    $\begingroup$ As a "new generation" fighter with a complex control system I'd suggest that the F22 has just as much need for sensitive sensor equipment as the SR71. I'd say that the reason that the F22 has moved the pitot-static probes and AoA, AOS sensors to the fuselage is that sticking a nice big metal pole on the nose right in front of the radar on the F22 probably causes a few palpitations for the radar engineers and would not be considered "a good thing" to do. $\endgroup$ – Adrian Jul 16 '15 at 10:57
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    $\begingroup$ Some explanation of what an alpha-beta probe is would be good. Wikipedia search hits radiation counters but I'm guessing that's not what these are? $\endgroup$ – Russell Borogove Feb 11 '17 at 5:00
  • $\begingroup$ @RussellBorogove Seconded. I’ve been around this site for a long time and, while I wouldn’t call myself an expert by any means, I know way more about aviation than the average member of the public. And I’ve never heard of an alpha-beta probe. Kevin, please at least add a link to explain what one is. $\endgroup$ – David Richerby Jul 19 '18 at 9:54

protected by ymb1 Jul 17 '18 at 13:35

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