Looking at below picture, the Delta IV Heavy is clearly much taller than the Medium. Is there any specific reason why?

enter image description here



1 Answer 1


The fairing is bigger (Taller) for larger payloads.

  • 16
    $\begingroup$ To elaborate a little, it's a more powerful rocket than the DIVM, capable of carrying larger payloads - so it needs a bigger fairing space to put them in. $\endgroup$ Commented Feb 24, 2023 at 4:00
  • 4
    $\begingroup$ ...though there are exceptions, like the Parker Solar Probe which needed the Ⅳheavy not because of its payload capability but simply to get enough Δv. It actually looked a big hilarious, such a small probe sitting in that giant fairing. en.wikipedia.org/wiki/Parker_Solar_Probe#/media/… $\endgroup$ Commented Feb 24, 2023 at 17:42
  • 3
    $\begingroup$ @leftaroundabout: next question in this series is then probably why the fairing wasn't smaller.... $\endgroup$
    – PlasmaHH
    Commented Feb 24, 2023 at 21:36
  • 2
    $\begingroup$ @PlasmaHH there's space.stackexchange.com/questions/26725/… about a case where the fairing was similarly oversized for the payload. $\endgroup$ Commented Feb 24, 2023 at 21:42
  • $\begingroup$ @PlasmaHH in the case of the PSP, I suspect that qualifying Delta IVH to use either the shorter 5m fairing, or the narrower DCSS and 4m fairing would have exceeded the potential cost savings from using them by a large amount. ULA produces highly reliable rockets, but they have a very expensive cost structure. $\endgroup$ Commented Feb 26, 2023 at 1:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.