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This comment in chat points to a "google search of the day" which was for Buran the Soviet version of the Space Shuttle. Looking there I saw images of a large transport aircraft with the Buran shuttle on top. What caught my eye were some photos of the transport aircraft with what looks like a large, orange air data boom at the end.

My understanding from Quora answers is that these are used for supersonic flight, and I wouldn't expect this shuttle to be transported supersonically.

Question: What is this transport aircraft, and why does it sometimes cary an air data boom when the Buran shuttle is on top of it?

According to this blog it is an Antonov AN-225 but I don't think that is a supersonic aircraft.

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above: From thelivingmoon.com. Click for full size views.

below: I believe this is Buran itself, According to @Hobbes' correction/comment, this is the "OK-GLI: a Buran analog (shape is correct, systems are not identical to the orbital vehicle) with 4 jet engines that was used for flight testing in the atmosphere", also with an air data boom. I've kept this here because it's actually pretty cool. From pinterest.

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    $\begingroup$ Another question would be why the aircraft seems to have only one wing? The right one should be visible at that angle, and in front of the tower structure... $\endgroup$ – jamesqf May 28 '18 at 5:49
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    $\begingroup$ It is indeed an An-225 (the first and only one built). A spike like this does not mean this aircraft is supersonic. It can also be to put sensors as far away from the disturbe airflow (du to the big flying machine carrying it) as possible. I don't know if it is the case here, but some prototype tow such sensors to calibrate the onboard sensors. $\endgroup$ – Manu H May 28 '18 at 6:03
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    $\begingroup$ I believe the air data sensor boom is indeed to get the sensors into undisturbed air in front of the craft, possibly to check whether its own sensors give correct readings even with the Buran on top modifying the air flow around the Antonov. Its right wing is visible behind the tower structure (different distances to left and right structures). $\endgroup$ – Cpt Reynolds May 28 '18 at 7:16
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    $\begingroup$ @jamesqf I can clearly see the right wing in the left part of the pictures $\endgroup$ – Federico May 28 '18 at 8:01
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    $\begingroup$ The last photo shows the OK-GLI: a Buran analog (shape is correct, systems are not identical to the orbital vehicle) with 4 jet engines that was used for flight testing in the atmosphere. $\endgroup$ – Hobbes May 28 '18 at 13:25
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The only aircraft that ever had a shuttle on top of them is NASA's modified Boeing 747 and Russia's Myasishchev and the Antonov 225. All of them were subsonic.

The one in the picture is the high wing 6 engine Antonov 225.

The air data boom is likely to gather data for test flights for the shuttle. Subsonic craft will affect the air in front of them (that's why you can hear them coming) so putting the sensor on a boom will help put the sensors in clean air.

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    $\begingroup$ @uhoh not really, you want an as clean as possible reading on the sensors, subsonic craft will affect the air in front of them (that's why you can hear them coming) so putting the sensor on a boom will help. $\endgroup$ – ratchet freak May 28 '18 at 11:41
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    $\begingroup$ Thanks! So if this is a one-of-a-kind aircraft and doesn't have much history flying like this, then it may be more necessary to add such an instrument since the effect of the shuttle is unknown. For the US Space shuttle, the carrier is (probably) a NASA 747 and there is probably much more experience. youtu.be/MhwSbeiRADA See also en.wikipedia.org/wiki/… and also this answer. $\endgroup$ – uhoh May 28 '18 at 12:58
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During flight testing, an aircraft's onboard instruments and sensors must be calibrated and validated. Pitot-static systems located on the fuselage are affected by the air flow around the aircraft. Some other measurement is needed to establish the relationship between actual atmospheric conditions and what the aircraft sensors measure.

One method is the boom extending from the nose. This takes measurements far enough in front of the aircraft that the air is undisturbed by the aircraft itself. Supersonic aircraft must use the boom method because the air flow behind the aircraft has been affected by the shockwaves created by the nose and other aircraft features. Especially in larger aircraft this is an expensive installation, and would interfere with the weather radar in the nose.

Another method of measuring actual conditions is a trailing cone extended behind the aircraft. This requires modification of the aircraft structure and is susceptible to damage.

The An-225 was built specifically to carry the Buran, so it makes sense that they would test it with the Buran on top. It would also create an especially large wake that might make a trailing cone difficult.

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It is indeed an An-225 (the first and only one built). A spike like this does not mean this aircraft is supersonic (as highlight by this question). It can also be to put sensors as far away from the disturbe airflow (du to the big flying machine carrying it) as possible. I don't know if it is the case here, but some prototype tow such sensors to calibrate the onboard sensors as explained in this video (french).

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  • $\begingroup$ Have you ever seen a sub-sonic aircraft with a boom? Both answers say it's possible, but so far no other examples have emerged. So far I can't get the video to play here either. $\endgroup$ – uhoh May 28 '18 at 16:06
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    $\begingroup$ @uhoh the C-5 is another example that used a boom in flight test. $\endgroup$ – fooot May 28 '18 at 17:45
  • $\begingroup$ @fooot excellent! (Same color too!) It would be great to see one or both images as part of an answer. $\endgroup$ – uhoh May 28 '18 at 17:48
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Supplementary to @ratchetfreak's accepted answer I'd like to include an image that demonstrates air data booms are used on sub-sonic aircraft as well.

From @fooot's comment linking to This Day in Aviation for 30 June 1968, here are photos of a prototype Lockheed C-5A Galaxy and it's first flight. This amplifies the point that the air data boom is important to establish better measurements for new aircraft or those with unusual configurations.

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above: The prototype Lockheed C-5A Galaxy, 66-8303, at Marietta, Georgia, 30 June 1968. (Bettmann/CORBIS) From here.

below: Lockheed C-5A Galaxy 66-8303 during its first flight. (Code One Magazine). From here. Click for full size.

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    $\begingroup$ I don't understand the downvote. $\endgroup$ – Carey Gregory May 31 '18 at 4:58

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