Horton, V. W.

English

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MANNED P___GLIDER FLIGHT TESTS
By
V_ o.tO_ W. _J_ ^_
The current interest in utilizing the paraglider concept
as a means of effecting a soft landing for the Gemini capsule
prompted the Flight Research Center to design and construct a
manned paraglider vehicle with which to conduct a limited,
qualitative research program. This vehicle differs from
paragliders that individuals, Langley Research Center and the
Ryan Aircraft Company have flown in that it is manned, un-
powered and towed aloft for release like the conventional
glider.
The primary objective of the FRC flight test program is
to demonstrate the approach, flare and landingcapabillty of
a paraglider vehicle with a high wing loading (W/S = _ psf)
and a low L/D (L/D = 2.5).
To '
_,_ _ ubjective, the Paragllder Research Vehicle,
PARESEV-I, was constructed in a manner to provide the maximum
information in the shortest time. As you can see from the
slide - (Slide of PARESEV-I) the design was simple and allowed
for quick modifications if necessary.
Comments: Wing Sweep Angle 45 °
Fabric Plan Form 50 °
Area = 150 square feet
Fabric -, Doped Irish Linen
Battens -- 2/side
R_sid control linkage
= 3.55
Control available @_ 25 ° -+-lO o lateral _ ± 15 o
Two tow points -- high and low, no n¢,_iceable
difference so chose low one
Wing attach point -- 47..5% of keel aft of apex
Communications -- FM radio
Foot pedals for nose wheel steering only
Automobile powered tows up to heights of 200 feet and
airplane powered tows to altitudes of 2500 feet were made
with PARESEV-1. Satisfactory landings, were made from free-
flight with estimated sin[< rates of 2-@ fps at touchdown
attained. The rod control system has its inadequacies,
https://ntrs.nasa.gov/search.jsp?R=19730061702 2020-03-17T13:47:39+00:00Z
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ho,,cver, due to flexib:Llity in the system there was
considerable response lag and some question as to whether
or not the: smJount of stick displacement corresponded to
the proper amount of input to the wing. This, plus the
ir_ler_nt problems of being?; towed, resulted in major
damage to the vehicle during checkout of a new pilot. I
might add that the pilot was not injured during this
i_l.(._J..dCl ].t .
The c_a-Ct was rebuilt _md considerably modified to
i_m_orpora:t< ' a cable and pulley control system and better
_d.lock attenuation in the lan<!ing gear as seen from the
next slid<;. (Slide of PARW_._.I",V-IA).
CoIt_lOllt S : Wing Sweep Ik_zle _5 °
Fabric Plaul Form 50 °
Area = 1!50 square feet
Fabric --0 o;_. musealed dacron
R_t. tcn s - - 5/'_ ide
Cable and !k_ley Control system
w/s = ?5
- .,. - ,. _ 0_o _ o o(,ontroi a.v_.d.l.._ble . ,.o + 10 lateral=+ 7.5
Pivot Polnt =-- %7.5_ aft of apex
Comnumications -- V}_l? radio
Foot peda].s for nose wheel steering only
This control syst<_m c-:lJ.mJnated the slow response in that
.t<,_pcn,.(,,is now f;overned by the pilot's ability to over-
comc the ine]_tio, forces.
To da.to, PARESEV-IA ham been flown n_znerous times by 4
di.L'fe_'ent pi].ots of va___ying baclcgrotu_ds sued experience, and
the general concensus is that the cr_ft maneuvers and handles
quite well. at a W/S of _,_.__p'_:J,nda I/D maximum of 3.8.
At the _resent tJ_e, F]..J.ghl. testing is being conducted
a,t r.,VI/S of (_._ and am estimated L/D of 2.9. This change
:._nV,/S _.<ndL/D was accomplish.ed by decreasing the wing
a.roa from 3.!)0 square feet to lO0 square feet.
To obtain the end W/S value of 'Y.O, the present plans
are t.hat_ add:itional weight will be added to the undercarriage.
-["lJ4d_t data have beer_ obt___ined on PAI{ES.h_-IA and is pre-
.... nt,.u on 1,Ira; nexl, slide. (Slide of Longitudinal Performemce
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Data points were obtained d_ing stabilized glide by
a relatively simple method. Altitude callouts were timed
by stopwatch during descents of 2000' or more at constant
airspeed. Angle of attack was ohtalned by measurement of
wing incidence angle relative to fuselage and fuselage
inclination (attitude). V v with this wing varied from
16 to 33 fps with 7's of 14.5 to 21.5 ° in the IAS range
investigated higher airspeeds were not investigated due
to higJ_ stick force.
The next slide (slide of Predicted Longitudinal Per-
formance of PARESEV-1B) shows the predicted performance
of the PARESEV vehicle with a 100 square foot installed.
Our designation for this vehicle is PARESEV-1B. Some
preliminary results indicate an L/D of less than 3 between
glide speeds of 50 and 60 KIAS.
The last slide (slide of Control-System Force Gradients)
shows a non-d_nensional stick force plot.a_a-_st IAS. As
indicated, the forces increase rapidly wltn deviations from
trim airspeed. The upper dotted line shows how the force
curve can be shifted by moving the pivot po_z_t forward of
the cp. This could be done in flight, however, our vehicle
requires ground adjustment prior to flight. The curve
can be shifted downward into the push force region by
moving the pivot point behind the cp. Push forces, however,
were not considered desirable due to an apparent reduction
in longitudinal stability. Bolt rope can also be used to
adjust the pivot point-cp relationship, increas_ in
percent of bolt rope used moves wing cp aft.
Stick position versus IAS is not shown, but is approx-
imately linear and normal.
The wing appears in flight to be exceptio_ally stable
and not appreciably effected by rapid control inputs or
turbulence. The lower fuselage response, however, is
noticeable to the pilot and similar to helicopters, inthat
lateral and longitudinal motions involve linear accelerations
rather than angular accelerations. Because of this it would
seem that some stability of the lower _selage or payload
about the a.c. of the vehicle would be desirable for our
vehicle and could be included in the design, such as a mem-
brane between forward and aft keel cables to improve zero
damping.
II
._espm,:]<,'c:i to a contz"O.l input is first noted by the
und(.'.r<;arr:i..:._.:,y.omov.i r_:_,followed by total vehicle motion.
'.l'h_¢w,}:dc!e possesses !oJ.zr:itudlnal stick fixed static
_7,1m.bi;l..l<V. [:¢ind:t.tudhx_l :moil.ores are highly d_mped in this
COlld. 1 [: [OL,i.
!;:he v,_._icl..ec]o_;'s[_ot pos'_ess longitudinal stick force
,:_,,,,i,i' .J_L,_,,_ :hoe dy-n_unic motions h_vo heD been investigated.
+in t!u stick f:i.;xodc;_,se, the ].ateral stud directiona.l
_ odc;s are sb,;._tLcally st,'_bl<_ cud t]l.o d._:m,mic motions are
].;i. ,['<ht ].y O<.l,!:U.">,;d,.
OscJ..]!.'_tior[s h.avo o_.:d.y boom emcGmtor,<:d a,s a result of
cJ]]'_t().]?]],'_.i .] [-..] ]/[][][.:n (t[].]_bu]_(][](_(; or tol/$ ro_)o ) ,-].n_. result in
coupJ_o(i !a[:.c.t<,_l--directlower l'usc,l,r_go responses. Higher
masuitudc turbulence has :7_:_(h,_(:'odcoupl.ed motions about
,'.tiit!,roo _.L:<is.
More thzm 70 la..tudinlf,;_h,,±ve been. r_:_,defrom stabilized
frc_," flight cos:ditions. Abo_:_t _'_0were from release altitud,:-s
el" !00 to 500' _._nd _0 from re..le_:_ses <':_bovci000'. Only one
J_andL,._!._resu!t, od in sbructur,_J_ damage arml this was due to
_'l'_.!',.'. boil)L1 Lr.titiatcd at :.<[).[)roxin:Lal;el,y 1;he IAS for L/D
:i<-',.;{.]m[ljIIwith the i00 foot ;_ir_;. A[LI other landings have
_,_(:e.r_:,ccompILshed with loss t}_m], i0 f'ps vortical velocity
,;,t touchdo',._._l and 75_;D of t]_oso a]?e, estim%tcd at less tha,n
!,_ fps by the pilot and ob::_erw;rs. To achieve a satisfactory
.flat<'<:; _¢boLtL, ].0-12 kts. above t;]:_0 IAS for L/D maxi_mm _st
t)_.: Ob!::_.i.n;_d l_z,ior 1:,o f].,':me h_itLa, t[on. T/I) m._ximum for ].arf;c
w:[.ll,'": occurs u,t approx_,mal::ely )I.2].G:AS a,n(t IA.S use,(i prior to f',b_,',z'(;
.i r_i l-,i._ [;:i..oJ l _¢_ts 50 to 5r5 ].(.]:A_D. For small wire's, :I:AS for L/D
.m;:uKimt:_m is cot.bruited at _{.,_ ]<X/\.S a,eid successful flare have
boor! _:tc(:o._i[>].i:._h(;d st,'-trbiJt;': .i:'z,om 60 to _[5 KiAS. _'_ccss cnor,zy
i s c_.... :.(1 t,o a,,tJu_t fl_t.r.<, r,,,t .... [u_.[r_, flare or to adjust a].til.,udr;
<:_(;<;t'.,,-(I i']_,i_(:) _d.'t;or '.tch].evir._,; zor'o vortical vol.ooitT. Appro×-
7,:_,[_! Y _' _:_:,(_<)nd.s el<ff_s(; .[:'r_)m f]._J.r<', in;].tirztion to touchdown.
',"/]%' v i.:;u:d. 'i.'" _" " r " " ,i)_,-c,_,.pt].o... (:)Y (;;l.or,:i.rV7 r<_-L',c, _:£th. labeled surf,.:_ce
[:as _.'.<_ i_;;,:.r,i to dot:,orirtin,:,, i.'i.0.r(,' .ir_itiation point.
'i',_ui_r,' t,[_,,_ .Pi_{ES}.!]V _i_ z._.ot a z'oa2 p_'oblem but does require
: i i..oi _e,it_:i. j_j;:n._i}:&tion vrj t;]t tow line dyn'm_[cs.
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LLu_der the present plans, due to manpower requirements
for other projects, the PARESEV program will be termlr_ted
after the flight data are obtained with the PARESEV-IB
configuration. However, if prob.!_ms arise in specific
areas where the PARESEV could be of benefit, the project
would be revived. I might add that the knowledge gained
from short-term, relatively inexpensive test programs of
this nature cannot be over-estimated.
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Manned paraglider flight tests

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