US2612327A - Towed glider with automatic tow cable release - Google Patents

Description

Sept. 30, 1952 R. M. CARLSON 2,612,327

TOWEID GLIDER WITH AUTOMATIC TOW CABLE RELEASE Filed March 6. 1947 5 Sheets-Sheet l I INVENTOR. I BY Russell M. Carlson ATTORNEY Sept. 30, 1952 R. M. CARLSON 2,612,327

TOWED GLIDER WITH AUTOMATIC TOW CABLE RELEASE Filed March a, 1947 I '5 Sheets-Sheet 2 INVENTOR.

I BY Russell M. Carlson m Wm ATTORNEY Sept. 30, 1952 R. M. .CARLSON 2,612,327

TOWED GLIDER WITH AUTOMATIC TOW CABLE RELEASE Filed March 6, 1947 v v 5 Sheets-Sheet 5 INVENTOR.

Russell M.- Carlson ATTORNEY Sept. 30, 1952 R. M. CARLSON 2,612,327

TOWED GLIDER WITH AUTOMATIC TOW CABLE RELEASE Filed March 6, 1947 5 Sheets-Sheet 4 Fig. 4

' INVHVTOR.

Russell M. Carlson RY ATTORNEY Sept. 30, 19 52 I R. M. CARLSON TOWED GLIDER WITH AUTOMATIC ."lfOW CABLE- RELEASE w 1% m mm S V a WC m 0 w 4 M h I H S e 5 m Filed March 6, 1947 7- f3. Fla

ATTORN Y Patented Sept. 30, 1 952 TOWED GLIDER WITH AUTOMATIC TOW CABLE RELEASE Russell M. Carlson, Milford, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware.

Application March 6, 1947, Serial No. 732,805

' This invention relates to towed gliders and has as one of its objects the provision of mechanism for automatically releasing the towing bridle .of a'towed glider upon ground contact following flight. I

Another object of the invention is the provision of mechanism of this type which will enable the glider to be towed by the bridle during take-oif and which will automatically reset itself following take-off to release the towing bridle upon ground contact following flight.

A further object of theinvention is the provision of tow release mechanism operated by a ground contacting member and having air speed responsive means for conditioning the mecha nism during flight for automatic release by said member upon landing.

A further object of the invention is .generally to improve the construction and performance of towed gliders.

These and other objects and advantages of the invention will become apparent from the appended claims and from the following detailed description of the accompanying drawings which illustrate one embodiment of the invention.

In these drawings: 7 v

Fig. 1 is a perspective view of a towed glider embodying the invention shown in flight;

Fig. 2 is a perspectiveview on an enlarged scale, with parts broken away, of apart of the automatic release mechanism;

Fig. 3 is a sectional view through this mechanism showing the parts in the position which they occupy when the glider is on the ground ready for take-off;

Fig. 4 is a similar view showing the. parts in the position they occupy when the glider is in flight with the mechanism reset for automatic release upon ground contact and indicatin in broken lines the position of the parts upon auto-v matic release of the bridle;

Fig. 5 is a section on line 55 of Fig. 3;

Fig. 6 is a section through an outboard fitting on a bridle post showing the releasable connection for one end of the bridle; and

Fig. 7 is a modification showing an offset tow apparatus. v

As herein shown the towed glider, generally indicated in Fig. 1 by the numeral It. comprises a long cylindrical fuselage I2 supporting two wings I4 and I6 located substantially mid-way 12 Claims. (01. 244-3) The alightinggear comprisesvtwo main wheels I 26 and 28.mounted on laterallyextended cantilever leaf springs 38 and 32 just aft of the main wings I .4, l6 and a nose skid 34 carried by a hollow nose section 36 of the fuselage. Nose section 36 also supports the tow bar assemblies 22, 24 each of which comprises identical, tubular bridle posts, or tow bars; 38 ofstreamlined cross section, the outboard ends of which receive the shanks of fittings 48 and the. inboard ends of which have fittings 42 rigidly secured in a .solid nose portion 44 of section 36. The'fittings areof streamlined cross section extending'fore and aft thereof and are. supported by tension cables 46 extending inboard and aft therefrom to the fuselage nose section 36 for the purpose of supporting the bridle posts against bending moments caused by a tow cable ,48' which is connected to the glider by;

means of a V-bridle 50, the divergent aft ends of which are secured to fiat plates 52 which are received in slots, or kerfs, 54 extending fore and aft inthe end fittings 40. Each plate 52 is provided with a circular aperture-56 adjacent its aft end which registers with a transverse passage 58 in its fitting 40 in which a latch pin '60 is reciprocable between a, plate released position in which it is withdrawn from the aperture 56 in plate and a plate locking position in which it passes throughthis aperture. I

The pins 60 are normally biased to locking position in which they enter into apertures 56 and releasably hold the ends of the bridle 50- attached to the fittings 48. Tothis-end the inboard end of each passage 58 in the shanks'of fittings 40 is provided withan enlarged portion 62 to receive a compression spring 64 surrounding the pin 60 therein. The spring acts at-one of'its ends against a transverse pin66 fixed in pin 60 between the fore and aft ends of the fuselage,

the inboard end of the enlargedjportion 62.

Plates '68 have holes 18 therein through whichpins extend, and the inboard ends of pins 60 are fixed to cables 12 which extend inboard through tubularbars 38 into the hollownose section 36, a short length of the cables l2-beingexposed at the base of bridle posts 38 a's'is'shown most clearly in Fig. 2.

The cables 12 from the .two latch pins 68 at the ends of bridle posts 38 are identical and sym-- metrical with respect to thenose section 36-and are attached at their inboard ends to theopposite forward corners of a rigid, generallyrectangular frame 14 pivoted intermediate its ends on a transverse bolt 16 which extends through the opposite side walls of the nose 560121011336, as'shown most clearly in Figs.,2 and 5. The aft end of 2,612,327 i 'i'" J;

The nose skid 34 is pivotally supported at its l o' forward end on a pin 84 mounted in a rigid-v bracket 86 formed integral with the solid'nose portion 44 of nose section 36. At its aft end the skid is supported by a shock absorbing oleo strut} including an upper cylinder element 88 having. an end fitting 90 and a cooperatinglower piston element 92 having an end fitting 94'; A; pivot 96 carried by a pair of upstanding ears v98 on skid 34 extends through fitting 94 tOIJiVOtELHIZ connect piston element 92 with the skid. The oleo. strut extends freely upward through an ample opening IBD in the bottom of nose section V 36 andhas its upper end fittingQfl pivotally mounted on aipin I02 which extends between'the upper ends of two'parallel links I04, the lower ends of which are 'pivotally supported between the sides of frame on bolt 16. A suitable tubular spacer IllGis provided on the bolt I6 between the lower ends of links I04, and shorter but similar spacers. I08 are provided between the upper end of eachof these links and fitting 90 ofoleo cylinder element (88. 1 r

Atone of itsends a compression sprin II!) abuts the .lower extremity of cylinder. element 88 and at its "other end abuts pin 96 to constantly biasthe elements 88 and 92 of the oleo strut into the fully extendedposition thereof shown in Fig.

-4,'in which the parts are shown in theposition theyoccupyiustprior to landing. An outstanding lug I I2 fixed to the upper end of cylinder elementBB and projecting aft of the latter has a flat upper face II4 adapted to engage the lower end of the latch plate I! when the skid and attached oleo strut. areln theirlowermost' position as illustratedin this figure, into which position .theyi'are biased lby= ravity when the airplane is off the ground; With the parts in the position shown in Fig, i it willbe evident thatengagementof skid 34 with the ground in landing will result in the rotation of frame I4 counterclockwise," as indicated by the arrow in this figure, and the withdrawalof locking pins 60 to release the plates 52 at the ends of the bridle 50.

.JT-he oleo. will continue its upward movement intgtheDQSition shown in Fig.3 in which it is 55 held .releasably by a latch I I6 carried by aspring loaded drag flap II'8 pivotally supported, at I20 on nose section '36. Flap H8 is biased by a tori n Spring I22 into the elevated position shown in Fig. 3, thestrength of the springs being designed to maintain the flap elevated until a predetermined airspeed has been attained in flight, the spring I22 permitting the flap to move downward, as the fitting an on the upper end of the oleo in moving upward engages the latch I I6 and moves, back of the latter into engagement with a stop I24.

When in flight the selected airspeed has been reached which may be, for example, 150 miles an hour. the flap. will be deflected downwardly 7 against the, action of spring I22 sufficiently to move latch H6. out of holding engagement with fitting 9|], of the oleo strut and permit the-latter to move by gravity into. the Fig. 4 position in wmohathe lug; H2 is beneath latch plate '11; and;

the automatic release mechanism for the tow bridle 50 is reset.

In the position of the skid and its attached oleo strut when the airplane is on the ground, as shown in Fig. 3, the cylinder element 88 of the oleo strut is fixed its fitting 99 being held against stop-124 i; nose-section 6=-byl1atch I IS with lug "Il2'well above tl'i'd'latch plate II so thatthe piston element of the strut is free to move into and out of cylinder 88 to absorb the landing energy in -compressionspring H0 and the oleo strut in a ,usual manner. In operation, prior to making a flight the spring -loaded latch pins '60 will be withdrawn from the 'kerfs 54in fittings 40 by pulling the cables I2 where'the latter are exposed near the base of the towabarsi-lfi. .This enables the plates '52 on the ends of the bridle 50 to be inserted into the fittings Mend releasably engaged by pins to.

As the glider stands on the ground prior to take-oif the oleo strut occupies; the'po'sition shown iii-Fig; sun which its ntuhg e'o h ages tlie'stop I24'Rand the lug "I12 'carried- 'by cylinder; 88 is a substantial distance above latch Il on fr-ame 1 4. The flap H8 under these conditions is biased by its sprin I 22 "into the -'el evated --po'sition of the flap shown in Fig.3 inwhich the latch l Iii for-m ing a part thereofabuts the fitting '99 and prevents the latter :fror'n rnoving away from stop I24.

The parts will: remain in the Fig.3 position during take-off and. initial- 'fiightfuntil the airs speedis sufiicientito overcome the force of spring I 22 and depress: the "flap 1 I8 a suffi'cient amount to release theole'dstrut' from the'h'ol'd'ing eng agement' of latch. 1116. During 'take 'off' the oleo strut is free to operate? in its usual manner to'absorb shocks in the event that the glider bounces but the cylinder element 88 thereofwhichi'carries the abutment H2v will .remain.'stationary relative to frame I4 and hence the bridle release-mechanism cannot operate; :When released the oleo strut and the; skid 3 1 :will' drop" by gravity into the Fig. l position which lug H2 is-'beneaththe' latch plate IT, thus resettingithe l automatic bridle re-- lease mechanism. 1,

Upon landing, the initial engagement of nose skid 34With the ground will result in movement of frame, min a counterclockwise direction about its pivot.16,,viewed=ih Fig. 4,:as cylinder 8:8 of the oleo strutuwhichcarrieslugIIZ moves; upward; As frame I4 reaches the'broken line position shown in Fig. 4,,the. cables-l2 will have been .withdrawn sufi ciently 11in passages 5.8. to free. theplates 52 on the ends of the. tow bridletSIl', thus'releasing the glider from the towing plane.- As-1the oleo. strut continues. its upward movement. surface t I l of lug I12 moves away from latch plate H allow-' ing the frame I4 toresume its normal horizontal p ition this m v ment. being-,eifectedby thev force of springsfill which acting-through cables. 12 bias the frame constantly :into :the" normal position thereofrshdwnin-Figzfi;jand in: full lines n Fig. 4. A-srvlfitting 9figalipmaiohesrstop; I24. it n a s. la ch. Hit andjdepresses thenaplis sufcien ly o ow; the fitting t more behind this latch into the position shoWnIiI'LFi .;i3;,inJwhich the glider is ready for another flight.

- n F 7; a-so ewhat modined'towappa atus s'heen -,sb.Q which p rmits: oni-setitowing of the l d r! I Inzthisl modificati n: the plate tfi insteadofzbeing'fattached directly to: the Lends of the :y-brid e'jare provided withpul'leysflze'over: which the ends .-.-t28.:"of tow-bridle t3lltrun. The ends. of thetow; bridles'are. connected by. aftran's-r versechain l32zwhichruns oyer-ardriving sproeket I34 mounted in the nose portion 44 on the splined end I36 of the shaft I38. It will be evident that rotation of shaft I38 in flight will shorten one end of the bridle I 30 while lengthening the other. Simultaneously with the rotation of shaft I38, control surfaces I40 on the bridle posts 38 are differentially operated in such manner as to produce a side force the resultant of which lies along the axis about which the V-bridle I30 rotates and the magnitude of which exactly balances the side forces induced by the bridle'so as to cause the glider to fly in an ofi-set position relative to the towing airplane. The sprocket I34 is loosely received on the splined end I36 of shaft I38 so that a forward movement of the chain I32 will cause the sprocket to be pulled off the shaft. The cable ends I28 and chain I32 run in tubular casings I42 one of which is in front of each bridle post 38 and is secured to the post by means of a pair of clips I44 and I46.

It will be evident that upon release of the plates 52 as described in connection with the construction of Figs. 1-6 the casings I42 will be pulled out of clips I44, I46 and the pulley I34 will be pulled off the splined end I36 of the drive shaft I 38, thus releasing the glider from the bridle I30. During this releasing operation the bridle I 30 will occupy a symmetrical position relative to the glider, automatic mechanism (not shown) being provided for controlling the rotation of the shaft I38 in response to movement of flap II8 so that upon a reduction of airspeed affecting this flap the glider will be restored to an in-line position with the towing plane. This off-set towing mechanism is. shown in detail and claimed in Patent No. 2,507,957 and reference is made thereto for a more complete understanding of this mechanism.

It will be evident that as a result of this invention, mechanism has been provided which enables a glider to be towed during take-off and which automatically resets itself following takeoff to enable the towing bridle to be released upon ground contact following flight.

It will be further evident that an automatic tow release mechanism has been provided which is operated by a ground contacting member and which has airspeed responsive means for resetting the mechanism during flight. While two embodiments of the automatic tow release mechanism of this invention have been disclosed for purposes of illustration, it will be evident that various changesin the construction and arrangement of the parts may be made without departing from the inven-' tion as defined by the following claims.

I claim:

I against which the glider connected end of said strut abuts, mechanism for releasing said tow 1. A glider adapted to be towed by a powered I airplane including, a ground engaging member, a tow bridle having a releasable connection to said glider, means for releasing said connection upon ground engagement of said member, means for disabling said releasing means during takeoff, and airspeed responsive means including a flap pivoted to said glider and projecting into the airstream operative during flight for disabling said disabling means.

2. A glider adapted to be towed by a powered airplane including, a tow bridle, means for releasably connecting said bridle to said glider, mechanism for operating said releasing means including a ground engaging member on said glider, means conditioned when said glider is on the ground including a latch for holding said mechanism in an inoperative position, and airspeed responsive means including a flap pivoted to said glider and projecting into the airstream for movbridle connection having an'operative connection with said strut in the fully extended position of said landing gear, means for latching said landin gear with said strut engaging said stop, and airspeed responsive means controlling the release of said latching means during flight for releasing said landing gear and resetting said releasing mechanism.

4. A glider adapted to be towed by a powered airplane including, a ground engaging member having a lost motion connection with said glider whereby said member occupies one position relative to said glider when the latter is on the ground and a second position when the glider is airborne,

a tow bridle having a releasable connection to said glider, means for automatically releasing said releasable connection as said member moves from said second position into said one position upon ground engagement of said member in landing, and airspeed responsive means including a flap pivotally supported on said glider and adapted to have the major portion of its surface project into the airstream for latching said member in said one position during take-01f and for releasing the same for movement to said other position to reset said releasing means following take-oil.

5. A glider adapted to be towed by a powered airplane including, a tow bridle, means for releasably connecting said bridle to said glider, landing gear including a ground engaging member and an oleo strut connecting said member with said glider, said strut and member adapted to occupy an upper position when said member is in contact with the ground and a lower position holding said landing gear in its upper position,

and airspeed responsive means for releasing said latch and returning said landing gear to its lower position during flight.

6. A glider adapted to be towed by a powered airplane including, a fuselage, main sustaining surfaces projecting laterally from said fuselage intermediate the ends thereof, bridle posts projecting laterally adjacent the forward end of said fuselage, a V'-bridle having the ends thereof releasably. connected to said bridle posts, means for releasing said bridle ends including a pivoted member, a adjacent the forward end thereof, an oleo strut having its lower end pivoted to said skid, link means having one end-pivoted to said fuselage and the other end pivoted to the upper end of said strut, a stop for arresting the upward movement of said strut, a latch for holding said strut in its upper position against said stop, and an airspeed responsive member for moving said latch out of strut holding position during flight, and cooperating means carried by said strut and said pivoted nose skid-pivoted to said fuselage '7 member for pivoting the latter as said strut moves upward upon engagement of said ground engaging member during landing.

'7. A glider adapted to be towed by a powered airplane including, a towbridle, mechanism for releasably connecting. said bridle to said glider, landing gear including a ground engaging member and an oleo strutconnected at its opposite ends to said member and said glider, said strut having a lost motion connection with said glider, a stop against which said glider connected end of saidstrut abuts when said member is on the ground, means for latching said landing gear with said oleo strut engaging said stop, airspeed responsive means controlling said latching means, and means operated by ground engagement of said member in landing for releasing said connecting mechanism as said oleo strut moves through said lost motion into engagement with said stop.

8. .A glider adapted to be towed by a powered airplane including, a fuselage having a nose portion, main sustaining surfaces extended laterally from said fuselage intermediate the ends thereof, bridle posts extended laterally from said nose section, a V-bridle having its divergent ends releasably connected to said posts, mechanism including a pivoted member mounted in said nose section for effecting release of said bridle connections, a nose skid having its forward end pivotally connected to said nose section, an oleo strut pivotally connected to said skid adjacent the aft end of the latter, a lost motion connection between said strut and glider-including .link means having one end pivotally connected withsaid nose section and the other end pivotally connected with the upper end of said oleo strut,.abutment means for limiting the upward movement of said oleostrut, a latch for holding said strut and skid in position in which said strut engages said abutment, .a drag flap responsive to a predetermined airspeed for moving said latch out of holding engagement whereby said strut is free'to extend, cooperating latch and abutment means, and one supported on said strut and the jother on "saidipivoted member for efiecting movement of the latter to release said bridle upon upward movement of vsaid strut due to ground engagement ofsaid skid.

9. ma glider adapted to be towed by-apowered airplane including, a fuselage having a nosesection, a V-bridle, bridle posts extended laterally from said nose section having latch means at theirextremities providing releasable connections for the divergent ends of said bridle, means1c'ontrolling the release of said connections including a pivoted element, a groundengaging member, a strut connecting said member to the :glider having an operative connection with said pivoted element, means for releasing said'latchconnections upon ground engagement of saidimember in landing, and abutment means engaging said strut for disabling said releasing means "during take-off.

10. A glider adapted to be towed bya powered airplane including, a fuselage, :bridle posts extended laterally from said fuselageglatchmeans at'the'extremities of said posts, .latchengaging members'releasably connected to said posts by said :latch means, each having a pulley mounted thereon, a V-bridle having its divergent ends passing over said pulleys, means for connecting said bridle ends, means carried by said fuselage for laterally displacing said connecting means to off-set said bridle, a ground engaging member,

and means operative upon ground engagement of said member following'fiight for actuating said latch means to release said latch engagin members.

11. A glider adapted to be towed by a powered airplane including, a fuselage, bridle posts extendedon opposite sidesof said fuselage, tubular members disposed in front of said posts, means frictionally connecting said members to said posts, latch means at the extremitiesof said posts, latch engaging members releasably connected to said posts by said latch means, each having a pulley mounted thereonya V-bridle having its divergent ends passing over said pulleys and extending into saidtubular members, a drive shaft mounted in said fuselage having its end projecting into the planeof said tubular members, a sprocket loosely splined .to the end of said shaft, a chain running over; said sprocket and connected to the ends of said bridle within said tubular members, means for driving said shaft to off-set said .bridle, a ground engaging member, and means operative upon ground engagement of said ground engaging member following flight for actuating said latch means to release said latch I engaging members.

12. In a glider adapted to be towed by a powered airplane including, a fuselage having a nose section, bridle posts extended laterally from said nose section having latch means at their eX- tremities, latch engaging members releasably connected to the ends of said posts by said latch means, each having a pulley, a V-bridle having its divergent ends passing over said pulleys, a chain between said pulleys connecting said bridle ends, a fore and aft extended shaft having a driving end projecting forward of said nose section, a sprocket loosely carried by. said shaft and operatively engaging said. chain, a ground engaging member, and means operated upon ground engagement of said member for releasing said bridle' including a pivoted member having operative connections with said member and said latch means.

' RUSSELL M. CARLSON.

' REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES .P ATENTS Great Britain Apr. 22, 1943 v

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