[net.aviation] Schweizer sailplane wing loadings

Mary.Shaw%CMU-CS-A@sri-unix.UUCP (07/14/83)

Here are some numbers for Schweizer sailplanes.  Schweizer is the
dominant American manufacturer, and most rentals in this country come
from this list:

MODEL	MAX	WING	WING	WING	GLIDE RATIO
	GR WT	AREA	LOADING	SPAN	 L/D @ speed
	(lb)	(sq ft)	(lb/sqft) (ft)	(ratio)	(mph)
2-33	1040	219	4.75	51	23:1 @ 50  (std 2-place trainer)
1-26E	 700	160	4.38	40	23:1 @ 53
2-32	1430	180	7.94	57	34:1 @ 66
1-34	 840	151	5.56	49	34:1 @ 55
1-35	 930	104	8.94	49	39:1 @ 47
1-36	 710	140	5.05	46	31:1 @ 53

They are rated for loads from about -2.5 or -3g to around +5g.
However, a "progressive-failure" design allows them to hang together
under much higher stress.  Last weekend I got a look at one that had
had its wing roots twisted about 30 degrees and structural rivets
sheared.  In addition, the seat failed and there was structual damage
to the fuselage.  The pilot had dived about 2000 ft at high speed and
done a sharp pullup; the factory estimated that it would take 11g
forces to do the damage.

Mary Shaw

mark@hp-kirk.UUCP (07/14/83)

#R:sri-arpa:-288300:hp-kirk:5500010:000:426
hp-kirk!mark    Jul 12 07:17:00 1983

Are you sure about the numbers on the 1-35.  It seems counter-intuitive to me
that the plane with the highest wing-loading would have the lowest best glide
speed.  Can anyone explain this?
                                        not an aeronautical engineer
                                        Death Rowe
                                        hp-pcd!hp-cvd!mark
                                        Corvallis, Oregon

Mary.Shaw%CMU-CS-A@sri-unix.UUCP (07/19/83)

All the numbers except the 1-35 were from my Schweizer manuals; the 1-35
numbers were from Jane's Sailplanes.  However, many high-performance
sailplanes have wing loadings in the 8-10 lb/sq ft range.  Here are
some more numbers from Jane's:
	What			Best glide	Wing loading
				ratio		(lb/sq ft)
    Schneider ES 52 Kookaburra	20		5.36
    PIK-20B			42		9.21
    Akaflieg SB-9 Stratus	48		5.53
    Akaflieg SB-10 Schirokko	53		7.98  (tandem, 29m wings)
    Akaflieg Mu 27		47		8.19
    Akaflieg FS-24 Phoenix	40		3.79
    Glaser-Dirks DG-200		42		9.22
    Glasfluegel 604		49		8.6
    Schemp-Hirth Nimbus		49		8.25
    Schemp-Hirth Mininimbus	42		9.34
    Schleicher Rhoenadler	20		2.84  (1932 design)
    Schleicher ASW 12		47		6.57
    Schleicher ASW 17		48.5		7.86
    Schneider Grunau Baby	17		3.62  (1932 design)
    Schweyer Rhoensperber	20		3.46  (1935 design)
    SZD-42A Jantar 2		47		8.52
    ICA-Brasov IS-32		46		8.31
    FFA Diamant			45		6.31
    Neucom AN-66C Super-Elfe	48		6.8
    Sigma I			48		11.79  (1971 design)
    Slingsby T.31 Tandem Tutor	18.5		4.87  (1950 design)
    Vickers-Slingsby Kestrel 22	51.5		8.74
    Bede BD-5S			23		7.09  (BD5 with no fan)
    Bryan HP-15			45		7.99
    LAK-9			48		7.92

Looks like design counts for something, too.

Mary Shaw