X-31 Flying Beyond the Stall & Elegance in Flight - F-16XL

Unread postPosted: 27 Feb 2018, 08:53
by spazsinbad
The two PDFs are from these original web pages: http://aviationarchives.blogspot.com.au/

http://aviationarchives.blogspot.com.au ... stall.html
http://aviationarchives.blogspot.com.au ... story.html

X-31 Flying Beyond the Stall & Elegance in Flight (The F-16XL Story)

https://www.docdroid.net/wVJKKd1/flying ... -stall.pdf (11Mb)

https://www.docdroid.net/7c9vLN7/elegan ... -story.pdf (5.6Mb)

Captions from combined X-31 FCLP Trials: “X-31 flying a simulated carrier approach at Edwards AFB using a Fresnel Lens Optical Landing System reference system. (NASA DFRC)” & “The X-31 executing a go-around following its simulated carrier approach; note the FLOLS in the lower left of the photograph. (NASA DFRC)”
"...The X-31, having not been designed as a carrier airplane, presented challenges to its use in a carrier-landing evaluation. First, the X-31 had an approach speed of approximately 170 knots calibrated airspeed, reflecting its sharply swept fixed-delta planform. Typical carrier aircraft are designed for an approach speed of 140 knots calibrated airspeed or less. The X-31’s high approach speed resulted in high closure speeds on the landing area, and thus in less time for the pilot to make flightpath corrections on final approach, which was exacerbated by a low-drag configuration that necessitated low approach power settings. This could have been a problem because, by its very nature, thrust vectoring requires relatively high power settings. Additionally, low power settings made glide-slope control more difficult due to slower engine response. Low power settings also resulted in poor go-around, or “wave-off,” performance. An automatic disengage feature was incorporated into the software when the power-lever angle (i.e., throttle angle) dropped below 55° to avoid quasi-tailless operation at insufficient thrust levels. The high approach speed also caused high rates of descent on final approach at the normal carrier approach glide slope of 3.25°.

Another issue that made the X-31 challenging was its delta planform. Delta aircraft have an inherently higher-than-average angle of attack during landing approaches that, in extreme form, can compromise the pilot’s ability to see the runway (this was why, for example, the Concorde SST had a so-called “droop” nose that lowered for takeoff and landing). The X-31’s planform gave it a carrier-approach angle of attack of 12°, affording its pilot a barely acceptable over-the-nose field of view. Higher approach angles were thus not possible due to visual field-of-view problems and unacceptable visual distortion through the windscreen...."

The eight page PDF is the X-31 FCLP story (I will make 4 pages from the eight by reprinting to two per page). The changed to the original is to fit my PDF form factor.

Re: X-31 Flying Beyond the Stall & Elegance in Flight - F-16

Unread postPosted: 27 Feb 2018, 11:38
by juretrn
Thanks for this, spaz!
I am definitely looking forward to reading about these two fascinating projects!

Re: X-31 Flying Beyond the Stall & Elegance in Flight - F-16

Unread postPosted: 02 Mar 2018, 10:11
by spazsinbad
X-29A Sweeping Forward: https://www.docdroid.net/SJS6jjc/sweeping-forward.pdf (2.7Mb)

"The first Grumman X-29A FSW demonstrator in flight over the Edwards range, 1985. (NASA)"