General Discussion > Q&A Section

Shuttle Questions Q & A (Part 3)

<< < (83/246) > >>

joncz:
The crossrange requirement was due to the Air Force's requirements for launching the shuttle into polar orbit.  In an Abort Once Around event, any potential landing sites (such as Edwards) have rotated to the east at least 1500 miles.

Ikelos:
" there is a negative affect of 35 on the head verses 25. In simple terms this is about the orbiter's ability to make it to the runway - remember the orbiter is a high speed glider at this point and pushing up the power is not really an option."

Yes but you can account for a 25 knot headwind just the same as a 35. Where do you draw the line and should it a definitive line? especially when the backup landing site is a lake bed that is over 10 miles long? It seems stupid to me that they would call off a landing at EDW for 26 knot winds.

Namechange User:

--- Quote ---hyper_snyper - 19/6/2007  6:49 PM

I have a question.  Is it true or false that the Air Force imposed certain cross range requirements on the Shuttle during development?  This resulted in larger than necessary wings.  

If the above is true and also true that the cross range capability was never needed, how much smaller could the wings be and by how much would the payload be increased?

I thought I read somewhere about this once and I'm curious about it.  I could be mistaken.
--- End quote ---

It's true.  Also the size of the payload bay and up/down mass was heavily influenced by the USAF and the percieved requirements of the time based on the hopeful and assumed flight rate.  If these requirements were not there it's anyone's guess what the shuttle would have looked like.

Jorge:

--- Quote ---hyper_snyper - 19/6/2007  6:49 PM

I have a question.  Is it true or false that the Air Force imposed certain cross range requirements on the Shuttle during development?  This resulted in larger than necessary wings.  

If the above is true and also true that the cross range capability was never needed, how much smaller could the wings be and by how much would the payload be increased?

I thought I read somewhere about this once and I'm curious about it.  I could be mistaken.
--- End quote ---

Partially. The USAF did impose the crossrange requirement, and it did drive NASA toward the delta-winged orbiter, but whether that's "larger than necessary" depends on how you define "necessary". The USAF wanted the high crossrange in order to perform single-orbit polar missions from Vandenberg. The crossrange enabled the orbiter to land back at Vandenberg even though the Earth would have rotated far enough to move Vandenberg a thousand miles east of the orbiter's groundtrack.

 But that's not the only thing that crossrange is useful for. The crossrange can be used during ascent aborts, enabling an "Abort Once Around" mode and allowing NASA to need fewer TAL sites than would otherwise be required (with lower crossrange, you'd need one under every inclination the shuttle flies). The crossrange is also used nominally to increase landing opportunities - the standard is to provide two landing opportunities per day to each of the three CONUS primary landing sites. That simply wouldn't be possible with a low-crossrange orbiter. And it isn't true that the capability has never been used - take a look at the actual crossranges for the first 93 flights:

http://spaceflight.nasa.gov/shuttle/reference/green/entare.pdf

The crossranges are pretty much uniformly distributed within the orbiter's ~800 n.mi. crossrange limit.

For these reasons, Robert Thompson (shuttle program manager during the 70's) has said that NASA might well have ended up going with the high crossrange design anyway, even if the USAF wasn't a partner.

http://caib.nasa.gov/events/public_hearings/20030423/transcript_am.html

The leading alternative to the high crossrange design was Max Faget's straight wing design. It had a crossrange capability of about 300 n.mi. But it would not necessarily have had a larger payload than the high-crossrange orbiter, since it used internal fuel tanks. OV-106 is right; you really can't make too many assumptions about what the orbiter would have looked like if the high crossrange design hadn't won the day. Faget's design had some other shortcomings which Thompson discusses in his CAIB testimony.

gispa:
hi guys can somebody explain me wath is the flyaround of the iss after undockin?? thank you

Navigation

[0] Message Index

[#] Next page

[*] Previous page

Go to full version